JP2018148674A - Power conversion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent, in a power conversion apparatus for a dispersion type power source, a sudden increase in current flowing in a system interconnection switch or an autonomous system switch in the start of the apparatus without providing a rush current prevention circuit and, moreover, to check disconnection and deposition of the system interconnection switch or the autonomous system switch before a system interconnection operation or an autonomous operation is initiated in the start of the apparatus.SOLUTION: To perform a system interconnection operation in the start of the apparatus, the amplitude of voltage output from a power storage hybrid power generation system 1 is gradually increased from a predetermined value, and is matched to an amplitude used before the system interconnection operation, which has a predetermined amplitude deviation from the amplitude of a commercial system voltage. Then, after disconnection and deposition of the system interconnection relay are detected, the system interconnection operation is initiated. To perform an autonomous operation in the start of the apparatus, the amplitude of voltage output from the apparatus is gradually increased from 0 and is matched to a command value for the amplitude of an autonomous system voltage. Then, after disconnection and deposition of an autonomous system relay are detected, the apparatus is connected to autonomous load and the autonomous operation is initiated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device applicable to a power storage hybrid power generation system.

  In recent years, in order to utilize natural energy from a solar cell, a power storage hybrid power generation system combining a solar power generation system and a power storage device has been spread all over the world. In the field of such an electric storage hybrid power generation system, there is an increasing demand for mounting two functions, that is, a function linked to a commercial power system and a function of supplying power to a self-sustained system in the event of a power failure.

The power storage hybrid power generation system performs maximum power point tracking control (hereinafter referred to as MPPT (Maximum Power Point Tracking) control) for converting the DC power generated from the solar battery into the optimum output power. The input voltage from the solar cell is adjusted so that the output power becomes maximum (optimum). That is, the storage hybrid power generation system includes a DC / DC converter that raises and lowers the DC output voltage (DC bus voltage V _dc ) within a certain range by _stepping up and down the input voltage from the solar battery to a predetermined voltage, and the solar battery. A power storage device that stores the power output from the solar cell, and a bidirectional DC / DC converter that performs charge / discharge power control according to the command power for the power storage device And an inverter for converting DC power output from these DC / DC converters into AC power.

  The inverter includes a switching element such as an IGBT (Insulated Gate Bipolar Transistor), and these switching elements are switched by a PWM (Pulse Width Modulation) signal sent from a control unit of the power storage hybrid power generation system. In order to remove the carrier of the PWM signal, the above-mentioned storage hybrid power generation system includes an LC filter for removing a high frequency component between the inverter and the commercial power system.

  In the above storage hybrid power generation system, when the inverter is connected to the commercial power system at the time of starting the device, the voltage applied to the capacitor of the LC filter (the capacitor provided on the output side of the inverter) is from 0V. Since it rapidly increases to the commercial system voltage, an inrush current flows through the capacitor. For this reason, there is a possibility that the current flowing through the grid interconnection relay will rapidly increase, and the contacts of the grid interconnection relay may be welded, and other circuit elements in the power storage hybrid power generation system (for example, switching elements of the inverter) I think there is a possibility of destruction.

  Therefore, in order to suppress the inrush current to the capacitor on the output side of the inverter and prevent a sudden increase in the current flowing through the grid interconnection relay, as described in Patent Document 1, a parallel circuit of a switch and a resistor is used. There is known a power conversion device in which a configured inrush current prevention circuit is connected in series to the above-described capacitor, and a failure of a switch in the inrush current prevention circuit is detected.

  There is also a power conversion device having only a self-sustaining operation function. This power converter is, for example, a power conditioner that converts DC power from a solar cell into AC power and supplies the converted AC power to a self-supporting load. Even in this type of power conversion device, when the device is started up, the output current may increase rapidly depending on the type of self-supporting load. For example, when the resistance value of the self-supporting load is small, there is a possibility that the output current rapidly increases when the apparatus is started. In that case, the current flowing through the relay for the autonomous system may increase rapidly, and the contact of the relay for the autonomous system may be welded, destroying other circuit elements (for example, switching elements of the inverter) in the power converter. There is also a possibility to do.

  In this type of power conversion device, as described in Patent Document 2, a control signal for opening the stand-alone system relay (second switch 16) is output, and then an inverter (power conversion unit 13) is output. ) To output the test voltage V3, and at this time, based on the voltage value of the self-sustained operation terminal detected by the self-supporting side voltage detector, welding of the contacts of the self-sustained system relay (inside the second switch 16) A device that detects welding between terminals) is known.

  Furthermore, in this type of power conversion device, as described in Patent Document 3, the switching element of the power conversion unit can be used based on the rate of change of the voltage applied to the capacitor without adding a dedicated current detection sensor. It is known to detect a power supply short-circuit state when the upper and lower arms are simultaneously turned on due to a continuity failure or a control abnormality.

  Also, in the field of power conversion devices, as described in Patent Document 4, in order to detect an abnormal state of the grid interconnection relay (system interconnection switch), a disconnection control instruction is issued to the grid interconnection relay. In this state, the current flowing through the capacitor of the LC filter circuit provided between the inverter and the commercial power system and the commercial system voltage are detected, and the phase difference between the current flowing through the capacitor and the commercial system voltage is approximately It is known that when 90 ° is present, it is determined that a reactive current is flowing through the capacitor, and it is determined that the grid interconnection relay is in a welded state.

Japanese Patent Laying-Open No. 2015-27146 JP 2014-64415 A JP 2005-318704 A JP 2008-35655 A

  However, in the conventional power conversion device as described in Patent Document 1, it is necessary to newly add an inrush current prevention circuit composed of a parallel circuit of a switch and a resistor. Becomes higher. Moreover, in the power converter device described in the above-mentioned Patent Document 2, even if it is possible to detect welding of the relay for the independent system, it is not possible to detect disconnection of the relay for the independent system, It is also impossible to prevent a sudden increase in the current flowing through the relay for the independent system. Furthermore, in the power conversion device described in Patent Document 3, the switching element (corresponding to a grid interconnection relay or a stand-alone system relay) can be detected, but the switching element is disconnected. It cannot be detected, and it is impossible to prevent a sudden increase in the current flowing through the external connection switch (system interconnection relay or independent system relay) when the apparatus is activated. Moreover, although the technique which detects the short circuit state of the switching element described in patent document 3 is applicable to the detection of the welding state of the relay for grid connection or the relay for independent systems, it was described in patent document 3 Thus, based on the rate of change of the voltage applied to the capacitor on the input side, the method of detecting the short circuit state (welding state) of the switching element (system interconnection relay or self-sustaining system relay) When the set value of the rate of change of the applied voltage to the capacitor (hereinafter referred to as “capacitor voltage”), which is the threshold, is large, the switching element of the power conversion unit (inverter) is excessive when the short-circuit state is reached. There is a high possibility of being destroyed by electric current. Conversely, if the set value of the rate of change of the capacitor voltage serving as the threshold value is decreased, the possibility of erroneous detection due to noise or the like increases. Moreover, in the power converter device described in Patent Document 4, an abnormal state such as welding of the grid interconnection relay can be detected, but the current flowing through the grid interconnection relay at the time of starting the device It is not possible to prevent the sudden increase.

  SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem, and without an inrush current prevention circuit, an external connection switch (for a grid interconnection switch or a self-sustained system) provided on the output side of an inverter at the time of startup of the device. This prevents a sudden increase in the current flowing through the switch, and before starting system interconnection operation or autonomous operation at the time of startup of the device, the above external connection switch (for system interconnection switch or autonomous system) An object of the present invention is to provide a power converter capable of confirming disconnection and welding of a switch.

  In order to solve the above problems, a power conversion device according to a first aspect of the present invention is a power conversion device for connecting a distributed power source to a commercial power system, and connects the distributed power source to the commercial power system. A power conversion device for connecting to a power source, wherein direct current power based on power input from at least one of the distributed power source and a power storage device that stores power output from the distributed power source is converted into alternating current power From the inverter, the capacitor connected between the inverter and the commercial power system, the commercial voltage amplitude detecting means for detecting the amplitude of the commercial system voltage that is the voltage of the commercial power system, and the power converter The amplitude of the output voltage is increased stepwise from a predetermined value so that the amplitude before the grid connection operation has an amplitude difference within a predetermined range from the amplitude of the commercial system voltage detected by the commercial voltage amplitude detecting means. An amplitude adjusting means for switching, a pair of grid connection switches for switching between a connected state and a disconnected state of the distributed power source to the commercial power system, and when switching the grid connection switch Based on the amount of change in the output value from the power converter, the disconnection welding detection means for detecting disconnection and welding of the grid connection switch, and when performing grid connection operation at the start of the device, After adjusting the amplitude of the output voltage from the power converter by the amplitude adjusting means to the amplitude before the grid interconnection operation, the disconnection and welding detection means detects the disconnection and welding of the grid interconnection switch. The power conversion device is connected to the commercial power system, and is provided with a start control means for controlling to start the grid interconnection operation.

  The power conversion device further includes an apparent power change amount detecting unit that detects a change amount of the apparent power that is a product of an effective value of the output voltage and an effective value of the output current from the power conversion device, and the disconnection welding detection The amount of change in the output value from the power converter used for detecting disconnection and welding of the grid connection switch by the means is the amount of change in the apparent power detected by the apparent power change amount detecting means. desirable.

  In this power conversion device, the disconnection welding detection means is a change amount of the apparent power detected by the apparent power change amount detection means when the grid connection switch is switched from the disconnected state to the connected state. From the state in which the disconnection of the grid interconnection switch is detected and both of the grid interconnection switches are not connected to the commercial power system from the pair of grid interconnection switches, Based on the change amount of the apparent power detected by the apparent power change amount detection means when only the connection switch is connected to the commercial power system, the pair of grid connection switches It is desirable to detect the welding of the grid connection switch that is not connected to the commercial power system.

  In this power conversion device, output voltage amplitude instantaneous value detecting means for detecting an instantaneous value of the amplitude of the output voltage from the power conversion device, and output current amplitude for detecting an instantaneous value of the amplitude of the output current from the power conversion device An instantaneous value detecting means, wherein the apparent power change amount detecting means is an instantaneous value of the amplitude of the output voltage detected by the output voltage amplitude instantaneous value detecting means, and an output detected by the output current amplitude instantaneous value detecting means. It is desirable to calculate the change amount of the apparent power based on the instantaneous value of the amplitude of the current.

  In this power converter, when the apparent power change amount detecting means detects the disconnection of the grid interconnection switch by the disconnection welding detection means, the output of the grid interconnection switch is set to the disconnected state and the output The average value of the amplitude value of the output voltage for a predetermined number of times detected by the voltage amplitude instantaneous value detecting means and the output detected by the output voltage amplitude instantaneous value detecting means with the grid interconnection switch in the connected state A first instantaneous voltage amplitude difference that is an absolute value of a voltage amplitude difference from an instantaneous value of the amplitude of the voltage, and a predetermined value detected by the output current amplitude instantaneous value detecting means with the system interconnection switch in the disconnected state. The average value of the instantaneous value of the output current amplitude for the number of times and the instantaneous value of the amplitude of the output current detected by the output current amplitude instantaneous value detecting means with the grid interconnection switch in the connected state Based on the first instantaneous current amplitude difference, which is the absolute value of the current amplitude difference, the amount of change in the apparent power is calculated, and among the pair of grid interconnection switches, the commercial power is detected by the disconnection welding detection means. When detecting welding of the grid connection switch that is not connected to the power system, the output voltage in a state where both switches of the pair of grid connection switches are not connected to the commercial power system. The output voltage amplitude instantaneous value detecting means detects the average value of the instantaneous value of the output voltage amplitude for a predetermined number of times detected by the amplitude instantaneous value detecting means and only one switch connected to the commercial power system. The second instantaneous voltage amplitude difference, which is the absolute value of the voltage amplitude difference from the instantaneous value of the output voltage amplitude, and both of the pair of grid interconnection switches are connected to the commercial power system. The output current amplitude instantaneous value is averaged for a predetermined number of times detected by the output current amplitude instantaneous value detecting means in the absence of the output current amplitude, and the output current amplitude instantaneous value in a state where only one switch is connected to the commercial power system. It is desirable to calculate the change amount of the apparent power based on the second instantaneous current amplitude difference that is an absolute value of the current amplitude difference from the instantaneous value of the amplitude of the output current detected by the value detecting means.

  In this power converter, the output voltage amplitude instantaneous value detecting means includes a first low-pass filter for removing noise of the output voltage from the power converter, and the output current amplitude instantaneous value detecting means includes the power conversion. A second low-pass filter for removing noise from the output current from the apparatus, and when detecting disconnection and welding of the grid interconnection switch by the disconnection welding detection means, the first low-pass filter and the second low-pass filter It is desirable that the cutoff frequency of the filter is set to the commercial system frequency.

  In this power conversion device, output current value detecting means for detecting an output current value from the inverter, passing current value estimating means for estimating a capacitor passing current value that is a value of a current flowing through the capacitor, and the output current value A device output current for calculating an output current value from the power converter based on an output current value from the inverter detected by a detecting unit and a capacitor passing current value estimated by the passing current value estimating unit Further comprising a value calculation means, wherein the disconnection welding detection means is calculated by the device output current value calculation means in a state where both of the pair of grid interconnection switches are not connected to the commercial power system. It is desirable to detect welding of both switches of the pair of grid interconnection switches based on the output current value

  A power conversion device according to a second aspect of the present invention is a power conversion device for converting DC power from a distributed power source into AC power and supplying the converted AC power to a self-supporting load, An inverter that converts DC power based on power input from at least one of a power source and a power storage device that stores power output from the distributed power source, and an output voltage from the power converter. Amplitude is increased stepwise from 0, and the amplitude adjustment means at the time of independent operation that matches the command value of the amplitude of the autonomous system voltage, which is the voltage at the time of autonomous operation, and the connection state between the autonomous load and the power converter Based on the amount of change in the output value from the power converter when the switch for the independent system and the switch for the independent system are switched for switching between the disconnected state and the independent system When a self-sustained operation is performed at the time of startup of the stand-alone system switch disconnection / welding detecting means for detecting disconnection and welding of the switch, the amplitude of the output voltage from the power converter is adjusted by the self-sustaining operation amplitude adjusting means. Then, after adjusting to the command value of the amplitude of the stand-alone system voltage, the stand-alone system switch disconnection and welding detection means detects the disconnection and welding of the stand-alone system switch, and then the power converter is connected to the stand-alone load. And an activation control means for controlling to start and operate independently.

  In this power conversion device, the power conversion device further comprises an apparent power change amount detecting means for detecting a change amount of the apparent power, which is a product of an effective value of the output voltage from the power conversion device and an effective value of the output current, The amount of change in the output value from the power converter used for detection of disconnection and welding of the switch for the independent system by the switch disconnection welding detection means is the amount of change in the apparent power detected by the apparent power change amount detection means. It is desirable to be.

  In this power conversion device, the switch disconnection welding detecting means for the independent power system detects the apparent power detected by the apparent power change amount detecting means when the switch for the independent power system is switched from the disconnected state to the connected state. Based on the amount of change, the disconnection of the switch for the independent system is detected, and from the state in which both of the switches for the independent system are not connected to the independent load, the switch for one of the independent systems Based on the change amount of the apparent power detected by the apparent power change amount detecting means when the switch is switched to the state where only the switch is connected to the self-supporting load, among the pair of independent power system switches, It is desirable to detect the welding of the switch for the independent system that is not connected.

  In this power conversion device, output voltage amplitude instantaneous value detecting means for detecting an instantaneous value of the amplitude of the output voltage from the power conversion device, and output current amplitude for detecting an instantaneous value of the amplitude of the output current from the power conversion device An instantaneous value detecting means, wherein the apparent power change amount detecting means is an instantaneous value of the amplitude of the output voltage detected by the output voltage amplitude instantaneous value detecting means, and an output detected by the output current amplitude instantaneous value detecting means. It is desirable to calculate the change amount of the apparent power based on the instantaneous value of the amplitude of the current.

  In this power converter, when the apparent power change detection means detects the disconnection of the switch for the independent system by the disconnection welding detection means for the independent system, the switch for the independent system is set to the disconnected state. The average value of the instantaneous value of the output voltage amplitude for a predetermined number of times detected by the output voltage amplitude instantaneous value detecting means, and the output detected by the output voltage amplitude instantaneous value detecting means with the independent system switch in the connected state The third instantaneous voltage amplitude difference, which is an absolute value of the voltage amplitude difference from the instantaneous value of the voltage amplitude, and the predetermined number of times detected by the output current amplitude instantaneous value detecting means with the independent system switch in the disconnected state. Output value detected by the output current amplitude instantaneous value detecting means with the switch for the independent system in the connected state. Based on the third instantaneous current amplitude difference that is the absolute value of the current amplitude difference from the instantaneous value of the current amplitude, the amount of change in the apparent power is calculated, and the switch disconnection welding detection means for the independent system, When detecting welding of a switch for a self-supporting system that is not connected to the self-supporting load among a pair of self-supporting system switches, both switches of the pair of self-supporting system switches are connected to the self-supporting load. In the state where the output voltage amplitude instantaneous value is detected by the output voltage amplitude instantaneous value detecting means, the output voltage amplitude instantaneous value is averaged for a predetermined number of times and only one switch is connected to the self-supporting load. A fourth instantaneous voltage amplitude difference that is an absolute value of a voltage amplitude difference from an instantaneous value of the amplitude of the output voltage detected by the value detecting means, and both switches of the pair of independent system switches The state where the instantaneous value of the output current amplitude for the predetermined number of times detected by the output current amplitude instantaneous value detecting means is not connected to the self-supporting load, and only one switch is connected to the self-supporting load. The amount of change in the apparent power is calculated based on the fourth instantaneous current amplitude difference that is the absolute value of the current amplitude difference from the instantaneous value of the output current amplitude detected by the output current amplitude instantaneous value detecting means. It is desirable.

  In this power converter, the output voltage amplitude instantaneous value detecting means includes a first low-pass filter for removing noise of the output voltage from the power converter, and the output current amplitude instantaneous value detecting means includes the power conversion. A second low-pass filter for removing noise from the output current from the apparatus, and when detecting the disconnection and welding of the switch for the independent system by the disconnection welding detection unit for the independent system, the first low-pass filter and the second low-pass filter It is desirable that the cutoff frequency of the low-pass filter 2 is set to a self-sustained system frequency that is a frequency of the output voltage and output current from the power converter during the self-sustaining operation.

  In this power conversion device, a capacitor connected between the inverter and the self-supporting load, an output current value detecting means for detecting an output current value from the inverter, and a capacitor passing that is a value of a current flowing through the capacitor Based on the passing current value estimating means for estimating the current value, the output current value from the inverter detected by the output current value detecting means, and the capacitor passing current value estimated by the passing current value estimating means And a device output current value calculating means for calculating an output current value from the power converter, wherein the independent system switch disconnection welding detecting means includes both switches of the pair of independent system switches. Based on the output current value calculated by the device output current value calculation means without being connected to the self-supporting load, Of switch the autonomous system, it is desirable to detect the welding of both switches.

  In this power conversion device, a commercial voltage phase angle detection means for detecting a phase angle of the commercial system voltage, and a commercial system in which the phase angle of the output voltage from the power conversion device is detected by the commercial voltage phase angle detection means. A phase angle adjusting means for adjusting to the phase angle of the voltage, and when the start control means performs grid connection operation at the time of starting the apparatus, the output voltage from the power converter by the phase angle adjusting means. It is desirable to control so that the grid connection operation is started after the power converter is connected to the commercial power system after the phase angle of the power system is matched with the phase angle of the commercial system voltage.

  In this power conversion device, when starting the device, the start control means performs a self-sustained operation control before shifting to the grid-connected operation when performing the grid-connected operation. The amplitude of the output voltage from the apparatus may be adjusted to the amplitude before the grid interconnection operation by the amplitude adjusting means.

  In this power converter, the amplitude adjusting means increases the amplitude of the output voltage from the power converter in a stepwise manner from the amplitude of the self-sustained system voltage output from the power converter during self-sustained operation or 0. Therefore, it is desirable to match the amplitude before the grid interconnection operation.

  According to the power conversion device of the first aspect of the present invention, when performing grid connection operation at the time of starting the device, the amplitude of the output voltage from the power conversion device is increased stepwise from a predetermined value. Then, after matching the amplitude of the commercial grid voltage with the amplitude before grid interconnection operation having an amplitude difference within a predetermined range, the power converter is connected to the commercial power grid and the grid interconnection operation is started. As a result, when this device is connected to the commercial power system, the increase in voltage applied to the capacitor provided between the inverter and the commercial power system can be made an amplitude difference within the above predetermined range. Therefore, it is possible to prevent the voltage applied to the capacitor provided between the inverter and the commercial power system from suddenly increasing from 0 V to the commercial system voltage when the apparatus is started. Therefore, by setting the amplitude difference within the predetermined range to a sufficiently small value compared with the amplitude of the commercial system voltage, the grid interconnection operation is performed at the time of starting the apparatus without providing an inrush current prevention circuit. Suppresses the inrush current to the capacitor (provided on the output side of the inverter) provided between the inverter and the commercial power system, and the grid interconnection switch (externally provided on the output side of the inverter) A sudden increase in current flowing in the connection switch) can be prevented.

  Moreover, according to the power converter device by the 1st aspect of this invention, when starting a system interconnection operation at the time of starting of an apparatus, after detecting disconnection and welding of the switch for system connection, a power converter device Was connected to the commercial power system, and grid-connected operation was started. Thereby, at the time of starting of the apparatus, before starting the grid connection operation, it is possible to confirm the disconnection and welding of the grid connection switch (external connection switch provided on the output side of the inverter).

  According to the power conversion device of the second aspect of the present invention, when performing independent operation at the time of startup of the device, the amplitude of the output voltage from the power conversion device is increased stepwise from 0 to The power converter is connected to a self-supporting load and the self-sustaining operation is started after matching the command value of the amplitude of the self-supporting system voltage, which is the voltage of the power source. As a result, it is possible to prevent a sudden increase in the current flowing through the switch for the independent system (the switch for external connection provided on the output side of the inverter) when the autonomous operation is performed when the apparatus is activated.

  Moreover, according to the power converter device by the 2nd aspect of this invention, when starting an independent operation at the time of starting of an apparatus, after detecting disconnection and welding of the switch for independent systems, a power converter device is made into an independent load. Connected to to start independent operation. Thereby, at the time of starting of an apparatus, before starting a self-sustained operation, disconnection and welding of a switch for a self-support system (external connection switch provided on the output side of the inverter) can be confirmed.

1 is a schematic system configuration diagram of a power storage hybrid power generation system according to an embodiment of the present invention. The block diagram which shows the outline of DC / AC inverter control of the said electric power generation system. The block diagram which shows the adjustment control of the amplitude and phase of the output voltage from the said power generation system performed at the time of the independent operation control at the time of starting of the said power generation system. (A) is a schematic block diagram of the PLL circuit in FIG. 1, (b) is a block diagram showing control of the PLL circuit. The flowchart of the control processing at the time of starting of the grid connection operation mode in the said electric power generation system. The figure which shows the switching process of ON / OFF of the grid connection relay in the disconnection and welding detection process of the grid connection relay of the said electric power generation system. FIG. 2 is a control block diagram of an output voltage amplitude instantaneous value detection circuit in FIG. 1. FIG. 2 is a control block diagram of an output current amplitude instantaneous value detection circuit in FIG. 1. The flowchart of the control processing at the time of starting of independent operation mode in the said electric power generation system. The figure which shows the switching process of ON / OFF of the relay for independent systems in the disconnection and welding detection process of the relay for independent systems of the said electric power generation system. The figure which shows the setting value of the parameter in the welding detection experiment of the said grid connection relay. The graph which shows the experimental result of the welding detection of the said grid connection relay. The graph which shows the experimental result of the welding detection of the said relay for independent systems. The flowchart of the control processing at the time of starting in the electrical storage hybrid electric power generation system of the modification 1 of this invention. The schematic system block diagram of the electrical storage hybrid electric power generation system of the modification 5 and the modification 6 of this invention. The schematic system block diagram of the electrical storage hybrid electric power generation system of the modification 7 of this invention.

  Hereinafter, a power converter according to an embodiment of the present invention will be described with reference to the drawings. This embodiment demonstrates the example in case the power converter device in a claim is an electrical storage hybrid electric power generation system. That is, the power storage hybrid power generation system according to the present embodiment is also a power conversion device for connecting the distributed power source to the commercial power system, and converts the DC power from the distributed power source into AC power, and converts the AC after conversion. It is also a power converter for supplying power to a self-supporting load. FIG. 1 shows a configuration of a power storage hybrid power generation system 1 according to the present embodiment.

The power storage hybrid power generation system 1 is a combination of a so-called power conditioner with a solar battery 2a that is a distributed power source and a power storage device 2b that stores power output from the solar battery 2a. It is possible to connect to the power system 3. This power storage hybrid power generation system 1 has a self-sustaining operation function during a power failure. The activation of the power storage hybrid power generation system 1 includes activation in the grid interconnection operation mode and activation in the independent operation mode. The power storage hybrid power generation system 1 includes a DC / DC converter 4a for converting DC power generated by the solar battery 2a into optimum output power, and a power storage device 2b to make maximum use of natural energy. Bidirectional DC / DC converter 4b that can be charged / discharged according to the indicated power, and DC output power from these DC / DC converters 4a and 4b (that is, input from at least one of solar cell 2a and power storage device 2b) A DC / AC inverter 5 (hereinafter abbreviated as “inverter 5”) for converting AC power into DC power is provided. In addition, the storage hybrid power generation system 1 includes a DC bus voltage smoothing electrolytic capacitor C _dc , an LC filter 6, a control circuit 7, grid interconnection relays S _u and S _w (system interconnection switches in the claims), And the relay _{Sstd. u} , S _{std. w} (independent claim switch) is also provided.

The DC / DC converter 4a performs maximum power point tracking control (hereinafter referred to as MPPT (Maximum Power Point Tracking) control) of the solar cell 2a so that the output power from the solar cell becomes maximum (optimum). Adjust the input voltage from. That is, the DC / DC converter 4a raises or lowers the input voltage from the solar battery to a predetermined voltage, and raises or lowers the DC output voltage (DC bus voltage V _dc ) within a certain range. The bidirectional DC / DC converter 4b performs charge / discharge power control as instructed by the power storage device 2b for maximizing the use of natural energy. That is, the bidirectional DC / DC converter 4b performs charge / discharge power control on the power storage device 2b based on information such as the amount of surplus power out of the power supplied from the solar cell 2a and the amount of power purchased. . Thereafter, the storage hybrid power generation system 1 uses the inverter 5 to convert the DC output power from the DC / DC converter 4a and the bidirectional DC / DC converter 4b into AC power. In the storage hybrid power generation system 1, during the self-sustained operation control, the DC / DC converter 4a always performs maximum power point tracking control so that the output (power generation) power from the solar cell is always maximized to store power. The device 2b performs constant control of the DC bus voltage _Vdc via the bidirectional DC / DC converter 4b.

  The inverter 5 includes switching elements SW1 to SW4 configured by IGBTs (Insulated Gate Bipolar Transistors). These switching elements are PWM (Pulse Width Modulation) signals sent from the control circuit 7 of the power storage hybrid power generation system. Switched.

LC filter 6, and two reactors L _f which is connected in series with each supply line, is composed of a capacitor connected C _f between the power supply line, the AC voltage output from the inverter 5, the harmonic components ( Mainly, the carrier frequency of the PWM signal is removed. R _f and R _c in the figure indicate the internal resistance of the reactor L _{f and} the internal resistance of the capacitor C _f , respectively. The capacitor C _f in the LC filter 6 corresponds to “a capacitor connected between the inverter and the commercial power system” and “a capacitor connected between the inverter and the self-supporting load” in claims. .

  The control circuit 7 is configured using a so-called microcomputer, and includes a commercial voltage amplitude detection circuit 11, an amplitude adjustment circuit 12, an activation control circuit 13, a PLL (Phase Locked Loop) circuit (synchronization circuit) 14, and a phase angle adjustment circuit 15. , Disconnection welding detection circuit 16, device output voltage amplitude detection circuit 17, output voltage amplitude instantaneous value detection circuit 18, output current amplitude instantaneous value detection circuit 19, apparent power variation detection circuit 20, output current value detection circuit 21, passing current It includes circuits such as a value estimation circuit 22, a device output current value calculation circuit 23, a relay disconnection welding detection circuit 24 for a self-sustaining system, an amplitude adjustment circuit 25 during self-sustaining operation, and an output voltage value detection circuit 26. These circuits 11 to 26 are circuits created using basic functional blocks of the microcomputer.

  Commercial voltage amplitude detection circuit 11, amplitude adjustment circuit 12, start control circuit 13, phase angle adjustment circuit 15, disconnection welding detection circuit 16, output voltage amplitude instantaneous value detection circuit 18, output current amplitude instantaneous value detection circuit 19, apparent The power change amount detection circuit 20, the output current value detection circuit 21, the passing current value estimation circuit 22, the device output current value calculation circuit 23, the independent system relay disconnection welding detection circuit 24, and the independent operation amplitude adjustment circuit 25 are respectively Commercial voltage amplitude detection means, amplitude adjustment means, activation control means, phase angle adjustment means, disconnection welding detection means, output voltage amplitude instantaneous value detection means, output current amplitude instantaneous value detection means, apparent power change detection means, Corresponds to output current value detection means, passing current value estimation means, device output current value calculation means, switch disconnection welding detection means for independent systems, and amplitude adjustment means during independent operation4A and 4B, the PLL circuit 14 includes a PLL circuit 14a for detecting the phase angle of the independent system voltage and a PLL circuit 14b for detecting the phase angle of the commercial system voltage ( Commercial voltage phase angle detecting means) in the claims.

The commercial voltage amplitude detection circuit 11 detects the amplitude of the commercial system voltage _euw . The amplitude adjustment circuit 12 determines the amplitude of the output voltage from the power storage hybrid power generation system 1 as the amplitude of the self-sustained system voltage _esd output from the power storage hybrid power generation system 1 during the original self-sustained operation (the maximum of the self-sustained system voltage _esd described later). The amplitude of the commercial system voltage e _uw detected by the commercial voltage amplitude detection circuit 11 is increased stepwise from the command value E ^* _cst of the value (amplitude) (see FIG. 3). To the amplitude before grid connection operation having an amplitude difference ΔE. In the present embodiment, the amplitude difference ΔE is set to 10V. When starting the apparatus, the start control circuit 13 performs the grid interconnection operation (when starting in the grid interconnection operation mode), and the amplitude adjustment circuit 12 determines the amplitude of the output voltage from the power storage hybrid power generation system 1 by the amplitude adjustment circuit 12. system after adjusting the interconnected operation before amplitude (10V amplitude smaller than the amplitude of the grid voltage e _uw), disconnection welding detection circuit 16 according to the system interconnection relay S _u, to detect a disconnection and welding of S _w of After that, the storage hybrid power generation system 1 is connected to the commercial power system 3 and controlled so as to smoothly shift to grid interconnection operation control (start grid interconnection operation). In addition, when the start-up control circuit 13 performs the self-sustained operation at the time of start-up of the device (at the time of start-up in the self-sustained operation mode), the amplitude of the output voltage from the power storage hybrid power generation system 1 is determined by the self-sustained operation amplitude adjustment circuit 25. After adjusting to the command value E ^* _cst of the maximum value (amplitude) of the independent system voltage _esd , which will be described later in the description of FIG. 3, the independent system relay S _{std. u} , S _{std. After} detecting the disconnection and welding of _w , the storage hybrid power generation system 1 is connected to the self-sustained load R _load and controlled to start the self-sustained operation.

The PLL circuit 14 is a circuit for outputting a signal synchronized with a reference input signal, and is mainly used for generating a voltage signal synchronized with the phase angle θ _uw of the commercial system voltage e _uw . The PLL circuit 14 is also used to detect a phase angle θ _{uw of} a commercial system voltage e _uw described later and a phase angle of an output voltage from the power storage hybrid power generation system 1 when the apparatus is activated. The phase angle adjustment circuit 15 adjusts the phase angle of the output voltage from the power storage hybrid power generation system 1 to the phase angle of the commercial system voltage _euw detected by the PLL circuit 14 when the power storage hybrid power generation system 1 is started. Disconnection welding detection circuit 16 is a circuit for detecting the disconnection and the welding of the relay S _u and S _w for system interconnection. The disconnection welding detection circuit 16 is based on the change amount of the apparent power detected by the apparent power change amount detection circuit 20 when the grid connection relays S _u and S _w are switched from the disconnected state to the connected state. system interconnection relay S _u, detects the disconnection of S _w, the relay S _u a pair of system _{interconnection,} of the S _w, connected relay both of the grid interconnection S _u, the S _w in commercial power system 3 Based on the change amount of the apparent power detected by the apparent power change amount detection circuit 20 when the state is not switched to the state where only one of the grid interconnection relays is connected to the commercial power system 3, Of the grid connection relays S _u and S _w of the grid connection relay, the welding of the grid connection relay that is not connected to the commercial power system 3 is detected. That is, the disconnection welding detection circuit 16 is based on the amount of change in the output value (apparent power) from the storage hybrid power generation system 1 when the grid connection relays S _u and S _w are switched. S _u, to detect the disconnection and the welding of the _{S w.} The detection process performed by the disconnection welding detection circuit 16 will be described in detail later.

The device output voltage amplitude detection circuit 17 determines the amplitude of the output voltage (self-sustained system voltage e _sd ) from the storage hybrid power generation system 1 based on the effective value of the output voltage (self- _supported system voltage e _sd ) from the storage hybrid power generation system 1. Is detected. The output voltage amplitude instantaneous value detection circuit 18 detects an instantaneous value of the amplitude of the output voltage (self-sustained system voltage e _sd ) from the power storage hybrid power generation system 1. The output current amplitude instantaneous value detection circuit 19 detects an instantaneous value of the amplitude of the output current _isp from the electricity storage hybrid power generation system 1. Apparent power variation detecting circuit 20 detects a change amount of apparent power which is the product of the effective value of the effective value and the output current i _sp of the output voltage from the power storage hybrid power system 1 (self system voltage e _sd). The output current value detection circuit 21 detects the value of the output current i _inv from the inverter 5. The passing current value estimation circuit 22 estimates a value (capacitor passing current value) of a current flowing through the capacitor C _f (capacitor passing current) _ic . The device output current value calculation circuit 23 is configured to output the output current from the inverter 5 (hereinafter, abbreviated as “inverter output current”) i _inv detected by the output current value detection circuit 21 and the passing current value estimation circuit 22. Based on the estimated value of the capacitor passing current _ic , the value of the output current from the power storage hybrid power generation system 1 (reverse flow current from the power storage hybrid power generation system 1 to the commercial power system 3) _isp is calculated. The output voltage value detection circuit 26 detects the value of the self-sustained system voltage _esd output from the electricity storage hybrid power generation system 1.

The grid interconnection relays _Su and _Sw are a pair of switches for switching between an interconnection state and a disconnection state to the commercial power system 3 of the power storage hybrid power generation system 1 including the solar battery 2a. Further, R _{load in} FIG. 1 indicates a specific load device (hereinafter referred to as a self-supporting load) to which power is supplied from the power storage hybrid power generation system 1 during the self-sustaining operation of the power storage hybrid power generation system 1. Independent system relay S _{std. u} and S _{std. w} is a pair of switches for switching between a connected state and a disconnected state between the self-supporting load R _load and the power storage hybrid power generation system 1. In the following explanation, the relay S _{std. u} and S _{std. A state where w} is turned on and the self-sustained load R _load and the power storage hybrid power generation system 1 are connected is referred to as a “connected state”, and the self-sustained system relay S _{std. u} and S _{std. A state where w} is turned off and the self-supporting load R _load and the power storage hybrid power generation system 1 are not connected is referred to as a “non-connection state”.

The independent-system relay disconnection welding detection circuit 24 is connected to the independent-system relay _{Sstd. u} and S _std. Based on the change amount of the apparent power detected by the apparent power change amount detection circuit 20 when _w is switched from the non-connected state to the connected state, the independent system relay S _{std. u} and S _std. a disconnection of at least one of _w , and a pair of independent system relays S _{std. u} and S _{std. w} of both independent power system relays S _{std. u} and S _{std. From the state where w} is not connected to the self-supporting load _Rload , one of the self-supporting system relays S _{std. u} or S _std. Based on the change amount of the apparent power detected by the apparent power change amount detection circuit 20 when only _w is connected to the stand-alone load R _load , a pair of independent system relays S _{std. u} and S _{std. w} of the independent power system relay S _std. that is not connected to the self-supporting load R _{load . w} or S _std. Detect _u welding. That is, the independent-system relay disconnection welding detection circuit 24 is connected to the independent-system relay _{Sstd. u} , S _std. Based on the amount of change in the output value (apparent power) from the storage hybrid power generation system 1 when _w is switched, the independent system relay S _{std. u} , S _std. Detect disconnection and welding of _w . Further, the independent operation amplitude adjustment circuit 25 increases the amplitude of the output voltage from the power storage hybrid power generation system 1 (independent system voltage e _sd ) stepwise from 0 at the time of startup in the independent operation mode. To the command value E ^* _cst (see FIG. 3) of the amplitude of the self-sustaining system voltage that is

FIG. 2 is a block diagram showing an outline of control of the inverter 5 by the control circuit 7 of the electricity storage hybrid power generation system 1. FIG. 2 shows a grid interconnection operation control unit and an independent operation control unit. The control circuit 7 of the power storage hybrid power generation system 1 performs _{grid connection} operation control at a position where the switch S _Grid is 0, and performs independent operation control at a position where the switch S _Grid is 1. Further, during the grid connection operation, the output current control of the effective component and the ineffective component is performed, and the constant control of the AC output voltage is performed during the independent operation.

As shown in FIG. 2, the grid interconnection operation control unit includes an active component generation unit 31, an ineffective component generation unit 32, an inverter output current control unit 33, and a PWM control unit 34. The effective component generation unit 31 multiplies the output current command value I ^* _P of the effective component by the sine value sin (θ _uw ) of the phase angle θ _uw of the commercial system voltage e _uw output from the PLL circuit 14, An instantaneous value of the current command value of the active component is generated. The invalid component generation unit 32 multiplies the output current command value I ^* _q of the invalid component by the cosine value cos (θ _uw ) of the phase angle θ _uw of the commercial system voltage e _uw output from the PLL circuit 14, An instantaneous value of the current command value of the invalid component is generated. In FIG. 2, the free-standing system frequency f _sd input to the PLL circuit 14 corresponds to the fundamental frequency necessary for the conventional PLL circuit. Further, the commercial system frequency f _uw is obtained from the PLL circuit 14. That is, even if the actual commercial system frequency and the independent system frequency are different, the correct commercial system frequency f _uw can be detected by using the PLL circuit 14.

The output value from the effective component generation unit 31 and the output value from the invalid component generation unit 32 are added at the addition point SP1, and become the output current command value i ^* _{inv of} the inverter 5. The output current command value i ^* _inv and the output current i _inv as a feedback value from the inverter 5 are sent to the inverter output current control unit 33. Inverter output current control unit 33 calculates the value of the output current i _inv of the inverter 5 is, to follow the output current command value i ^* _inv, performs feedback control, the duty ratio d _a when the system-interconnected run To do. The duty ratio _{d a} is input to the PWM control unit 34. PWM control unit 34, based on the input duty ratio _{d a,} generates a PWM signal having a pulse width corresponding to the duty ratio _{d a.} On / off of each switch SW1, SW2, SW3, SW4 (see FIG. 1) of the inverter 5 is controlled based on these PWM signals.

In FIG. 2, the independent operation control is performed when the switch S _Grid is 1. The independent operation control unit includes an AC output voltage control unit 35, an AC output current control unit 36, and a PWM control unit 34.

The AC output voltage control unit 35 receives the independent system voltage command value e ^* _sd and the independent system voltage e _sd as a feedback value, and the AC output current command value i ^* _inv for making the AC output voltage constant. Is calculated. Thereafter, the AC output current command value i ^* _inv and the output current i _inv as a feedback value are input to the AC output current control unit 36, and the AC output current control unit 36 is based on these during the autonomous operation. calculating a duty ratio _{d b.}

PWM control unit 34, based on a duty ratio d _b calculated by the AC output current control unit 36, generates a PWM signal having a pulse width corresponding to the duty ratio d _b. On / off of each switch SW1, SW2, SW3, SW4 of the inverter 5 is controlled based on these PWM signals. As a result, the autonomous system voltage e _sd output from the power storage hybrid power generation system 1 during the autonomous operation is substantially maintained at the autonomous system voltage command value e ^* _sd . Note that Enable and Disable in FIG. 2 are a permission signal and a prohibition signal of the output of the PWM signal sent from the control circuit 7 to the PWM controller 34.

This power storage hybrid power system 1 (when performing system interconnection operation at startup of the device) at startup by system interconnection operation mode, in order to suppress the inrush current to the output side of the capacitor C _f of the inverter 5, Self-sustained operation control is performed before shifting to grid-connected operation. Then, during this independent operation control, the amplitude adjustment circuit 12 _converts the amplitude of the output voltage from the power storage hybrid power generation system 1 into the amplitude before the grid connection operation (the amplitude E _uw.max of the commercial grid voltage e _{uw −the} amplitude difference). ΔE) and the phase angle adjustment circuit 15 adjusts the phase angle of the output voltage from the electric storage hybrid power generation system 1 to the phase angle θ _uw of the commercial system voltage e _uw , and then the system link shown in FIG. The start-up control method of shifting to system operation control is adopted.

FIG. 3 shows the control circuit 7 (mainly the amplitude adjustment circuit 12, the phase angle adjustment circuit 15, and the self-sustained operation at the time of self-sustained operation control at the time of start-up in the grid interconnection operation mode and at the time of start-up in the self-sustained operation mode. This is an adjustment control block for the amplitude and phase angle of the output voltage (self-sustained system voltage _esd ) from the power storage hybrid power generation system 1 performed by the amplitude adjustment circuit 25). Power storage control circuit 7 of the hybrid power generation system 1, when the switch _{S sd} is position 1, the maximum value _{E sd} autonomous system voltage _{e sd. max} and the phase angle (amplitude), performs control to match the command value ^E _{* cst} and phase angle theta _sd maximum value of the original free-standing system voltage _{e sd.} In the present specification, the “original self-sustained system voltage e _sd ” refers to a self-sustaining operation (original self-sustained operation) for supplying AC power to the self-supporting load R _load shown in FIG. It means the self-supporting system voltage _esd when Further, the control circuit 7, when the switch _{S sd} is position 0, the amplitude (maximum _value) of the self-supporting system voltage _{e sd E sd. max} and the phase angle, before the system interconnection operation of said amplitude (amplitude (maximum value of the commercial power system voltage _{e uw) E uw.max} - amplitude difference Delta] E) matched to the phase angle of the commercial system voltage _{e uw} theta _uw Take control.

In FIG. 3, E _{uw. max} is the maximum value (amplitude) of the commercial grid voltage e _uw , E _{sd. max} is the maximum value (amplitude) of the self-supporting system voltage _esd , E ^* _{sd. max} (k−1) is the command value of the maximum value of the autonomous system voltage immediately before the k-th sampling period, and θ _sd is the phase angle of the original autonomous system voltage _esd (during normal autonomous operation). , Θ _uw is the phase angle of the commercial system voltage e _uw . Note that (k) means the value of the kth-order sampling period, that is, the current value. (K-1) is a value sampled immediately before the current value. Further, the sampling period of this embodiment is the reciprocal of the switching frequency.

When the switch S _sd is in the 1 position, the control circuit 7 (mainly, the self-sustained operation amplitude adjusting circuit 25) of the power storage hybrid power generation system 1 sets the maximum value of the original self-sustained system voltage _{esd at} the addition point SP2. from the command value ^E _{* cst,} maximum value _{E sd} autonomous system voltage _{e sd} at that _time. The difference between these values is obtained by subtracting _max . Proportional control unit 37, with respect to the difference value is multiplied by the proportional gain K _p, and outputs it to the summing point SP3 added. Here, the proportional gain _{K p,} much less positive than 1 (e.g., 0.01) is used. The output value from the proportional control unit 37 is the command value E ^* _{sd. Of} the maximum value of the previous independent system voltage at the addition point SP3 _. The command value E ^* _sd. of the maximum value of the current self-sustained system voltage is added to _max (k−1) _{. It} is sent to the multiplier 38 as _max (k). The multiplier 38 obtains the value sent from the addition point SP3 and the sine value sin (θ _sd ) corresponding to the phase angle θ _sd of the self-sustained system voltage _esd obtained by the PLL circuit 14a of FIG. Multiplication is performed to calculate an independent system voltage command value e ^* _sd .

As described above, the proportional gain K _p, much less positive than 1 (e.g., 0.01) by employing the command value of the maximum value of the previous self system voltage E ^* _{sd. max} (k-1) that will gradually increasing the maximum value of the free-standing system voltage _{e sd (amplitude) E sd. max,} and can follow the command value ^E _{* cst} maximum value of the original free-standing system voltage _{e sd.}

During autonomous operation immediately after activation of the power storage hybrid power system 1, the maximum value E _sd of the autonomous system voltage e _sd. The initial value of _max and the command value E ^* _sd. The initial value of _max (k−1) is set to 0. Thus, E _{sd. max} and E ^* _{sd. After} the initial value of _max (k−1) is set to 0, as described above, the maximum value (amplitude) E _{sd. max} and by employing gradually adapt how the amplitude of the command value E ^* _cst of the original free-standing system voltage e _sd, can be at startup of the device, obtain the effect of soft start. In addition, when supplying power to an independent load, it is considered that there is an effect that the amplitude value of the independent system voltage command value e ^* _sd can be adjusted so as not to deviate from the amplitude value of the independent system voltage due to a sudden load change.

Power storage control circuit 7 of the hybrid power generation system 1, when the self-supporting run immediately after activation by the system interconnection operation mode, as described above, the maximum value of the free-standing system voltage e _sd (amplitude) E _{sd. After the max} and the phase angle are matched with the maximum command value E ^* _cst and the phase angle θ _sd of the original independent system voltage e _sd , the switch S _sd is switched to the 0 position to establish the independent system voltage e _sd. Maximum value (amplitude) E _sd. the _max and phase angle, combined with the phase angle theta _uw commercial system voltage _{e uw} above system interconnection operation before the amplitude (maximum value of the commercial system voltage _{e uw (amplitude) E uw.max -ΔE).} That is, the amplitude of the output voltage from the power storage hybrid power system 1, the amplitude E _uw commercial system voltage e _uw. The phase angle of the output voltage from the power storage hybrid power generation system 1 is matched with the phase angle θ _uw of the commercial grid voltage e _uw while matching with the amplitude before grid interconnection operation having _max and a predetermined amplitude difference ΔE.

Next, a process for adjusting the amplitude of the output voltage from the above-described electric storage hybrid power generation system 1 to the amplitude before grid connection operation (E _uw.max −ΔE) will be described in detail. When the switch S _sd is at the 0 position, the control circuit 7 (mainly the amplitude adjustment circuit 12) of the power storage hybrid power generation system 1 performs the above-mentioned amplitude before system interconnection operation (E _uw.max −) at the addition point SP2. from Delta] E), the maximum value _{E sd} autonomous system voltage _{e sd} at that _time. The difference between these values is obtained by subtracting _max . Proportional control unit 37, with respect to the difference value is multiplied by the proportional gain K _p, and outputs it to the summing point SP3 added. Here, as in the case where the switch S _sd is in the 1 position, a positive value far smaller than 1 (for example, 0.01) is used for the proportional gain K _p .

The output value from the proportional control unit 37 is the command value E ^* _{sd. Of} the maximum value of the previous independent system voltage at the addition point SP3 _. The command value E ^* _sd. of the maximum value of the current self-sustained system voltage is added to _max (k−1) _{. It} is sent to the multiplier 38 as _max (k). The multiplier 38 sends a command value E ^* _{sd., Which is} the maximum value of the current autonomous system voltage sent from the addition point SP3 _. Multiplying _max (k) by the sine value sin (θ _uw ) of the phase angle θ _uw of the commercial system voltage e _uw , the free-standing system voltage command value e ^* _sd is calculated. As described above, by adopting a positive value far less than 1 as the proportional gain K _p , the command value E ^* _{sd. By} increasing _max (k-1) stepwise, the maximum value (amplitude) E _{sd. max} is the amplitude of the commercial grid voltage E _u. It is possible to gradually follow the amplitude before system interconnection operation (E _uw.max −ΔE) having _max and an amplitude difference ΔE.

Immediately after the switch S _sd is switched from the 1 position to the 0 position, the maximum value (amplitude) of the output voltage from the power storage hybrid power generation system 1 E _{sd. max} , and the command value E ^* _{sd. max} (k-1) is adapted to substantially the same value as the instruction value ^E _{* cst} maximum value of the original free-standing system voltage _{e sd.}

As described above, the maximum value (amplitude) E _{sd. Of the} voltage output from the power storage hybrid power generation system 1 after the switch S _sd is switched from the 1 position to the 0 position _. By adopting a method in which _max is gradually adjusted to the amplitude before grid connection operation (E _uw.max −ΔE), the switch S _sd is switched from the position 1 to 0 when the apparatus is started in the grid connection operation mode. Even after switching to the position, the effect of soft start can be obtained.

Maximum value of the free-standing system voltage _{e sd (amplitude) E sd.} The formula for calculating _max is the following formula (1) and formula (2) when the switch S _sd is in the 0 position, and the formula (3) and formula below when the switch S _sd is in the 1 position. (4). The maximum value of the commercial system voltage _{e uw (amplitude) E uw.} The formula for calculating _max is the following formula (5). In these equations, T _uw is the period of the commercial system voltage e _uw . Further, f _uw is the frequency (commercial system frequency) of the commercial system voltage e _uw . T _sd is the period of the original free-standing system voltage _esd . Further, f _sd is the original frequency of the autonomous system voltage _esd (independent system frequency).

Also used in the control shown in FIG. 3, and phase angle theta _sd of the original free-standing system voltage e _sd, the phase angle theta _uw commercial system voltage e _uw, respectively, shown in Fig. 4 (a) Values obtained by the PLL circuit 14a for the independent system voltage and the PLL circuit 14b for the commercial system voltage are used. In FIG. 4A, f _sd represents the frequency of the original self-supporting system voltage _esd (self-supporting system frequency).

Here, with reference to FIG. 4B, control blocks of the PLL circuit 14a for the independent power system voltage and the PLL circuit 14b for the commercial system voltage will be described. Although the PLL circuit 14a and the PLL circuit 14b perform the same control although the types of the input voltage e _in are different, in the description of FIG. 4B, these PLL circuits 14a and 14b are collectively referred to as the PLL circuit 14. Will be described. 4 (b), the input voltage _{e in} a commercial system voltage _{e uw,} or an original free-standing system voltage _{e sd.} E _{in. When} the input voltage e _in is the commercial system voltage e _uw , _max and θ _o are E _{uw. max} and θ _uw, and when the input voltage e _in is the original self-supporting system voltage _esd , E _{sd. max} and θ _sd are shown.

The PLL circuit 14 includes a divider 41, a multiplier 42, a loop controller (loop filter) 43, an integrator 44, a feedback signal generator 45, and a frequency calculator 46. Divider 41 has an input voltage _{e in} to the PLL circuit 14, the maximum value of the input voltage _{e in} the control circuit 7 is determined _{(amplitude) E in.} Based on _max , a sine value sin (θ _in ) of the phase angle θ _in of the input voltage e _in is calculated. The sine value sin (θ _in ) is multiplied by the feedback signal voltage value cos (θ _o ) output from the feedback signal generator 45 in the multiplier 42 and input to the loop controller 43. Based on the input value, the loop controller 43 outputs an adjustment value proportional to the difference in angular frequency between the input voltage e _in and the feedback signal voltage. In summing point SP4, from (the switch _{S sd} is when the position of 1) the original free-standing system voltage _{e sd} angular frequency omega _sd (= 2 [pi] f _sd), the adjustment value described above is subtracted, the corners of the adjusted A frequency ω _o is determined. The integrator 44 integrates the adjusted angular frequency ω _o and calculates the phase angle θ ₀ of the input voltage e _in . The output frequency f ₀ from the PLL circuit 14 is calculated from the angular frequency ω _o using the frequency calculator 46.

By using the PLL circuit 14 as described above, when the isolated operation control at the time of startup, the amplitude _{E sd} autonomous system voltage _{e sd. max} is, even when the initial value of 0, can be based on the angular frequency omega _sd of the original free-standing system voltage e _sd, obtains the phase angle theta ₀ corresponding to the frequency f _sd of the original free-standing system voltage e _sd . Further, as described above, the fundamental frequency different from the frequency f _uw commercial system voltage e _uw, even if it is set to the frequency f _sd of the original free-standing system voltage e _sd, at the time of system interconnection operation, the loop controller With the function of 43, the phase angle θ _uw of the commercial system voltage e _uw can be obtained without any problem.

If the frequency _{f sd} of the original free-standing system voltage _{e sd} is set to 50 Hz, the grid frequency _{f uw} voltage _{e uw} is, even for 60 Hz, the grid voltage _{e uw} in the above PLL circuit 14 By _obtaining the phase angle θ _uw , the phase angle of the voltage output from the power storage hybrid power generation system 1 can be maintained at the phase angle θ _uw of the commercial grid voltage e _uw at the time of startup in the grid interconnection operation mode. .

At startup by system interconnection operation mode, the control method shown in FIG. 3, by which to adjust the amplitude and phase of the output voltage from the power storage hybrid power system 1, the maximum of the original free-standing system voltage e _sd command value ^E _{* cst} and commercial system voltage _e maximum value of _uw value _{(amplitude) E uw.} or when _{the max} is different, it can be activated even if the phase angle theta _uw phase angle theta _sd and commercial system voltage e _uw of the original free-standing system voltage e _sd different, the power storage hybrid power system 1 smoothly. Here, “can be started smoothly” means that the maximum value (amplitude) E _sd. It means that _max can be avoided from increasing rapidly.

For example, the effective value and frequency of the commercial system voltage e _uw are 200 V and 60 Hz, and the effective value and frequency of the (original) independent system voltage _esd during normal autonomous operation are 100 V and 50 Hz. However, after the autonomous operation control at the time of start-up in the grid interconnection operation mode is performed by the control method shown in FIG. 3, the power storage hybrid power generation system 1 is connected to the commercial power grid 3, and the grid interconnection operation is performed. By controlling to start, the storage hybrid power generation system 1 can be smoothly connected to the commercial power system 3 without rapidly increasing the maximum value (amplitude) of the output voltage from the storage hybrid power generation system 1.

Next, with reference to the flowchart of FIG. 5, the flow of control at the start of the grid interconnection operation mode in the power storage hybrid power generation system 1 will be described. At the start of the grid connection operation mode, the control circuit 7 (mainly the start control circuit 13) of the power storage hybrid power generation system 1 first switches the switch S _Grid to the position 1 before connecting to the commercial power system 3. Switch S _sd at position 1, grid connection relays S _u , S _w off, self-sustained system relay S _{std. u} , S _{std. w} is switched off to perform independent operation control (S1). In addition, the “self-sustaining operation control” in the claims means the self-sustaining system relay S _{std. u} , S _{std. It} means the control performed by the self-sustaining operation control unit shown in FIG. 2 in a state where _w is turned off. After a predetermined time has elapsed since the start of the autonomous operation control (YES in S2), the maximum value (amplitude) of the output voltage from the power storage hybrid power generation system 1 becomes the command value E ^* of the maximum value of the original autonomous system voltage _esd ^. _When reaching _cst , the control circuit 7 switches the switch S _sd to the position of 0, and sets the amplitude, phase and frequency of the output voltage (independent system voltage e _sd ) from the power storage hybrid power generation system 1 to the commercial system voltage e. _Match the amplitude, phase and frequency of _uw (S3). However, as described above, for the amplitude of the output voltage from the power storage hybrid power system 1, the amplitude E _uw commercial system voltage e _uw. Not the _max itself, but the amplitude E _{uw. It} is adjusted to the amplitude before grid connection operation (E _uw.max −ΔE) having _max and amplitude difference ΔE.

Next, (mainly activation control circuit 13 and the disconnection welding detection circuit 16) electrical storage hybrid power generation system 1 of the control circuit 7, as shown in FIG. 6, the grid interconnection relay S _u, the S _w on and off and switching between, switching is performed between the Enable signal and the Disable signal output to the PWM control unit 34, the relay _S u for system interconnection, detects the disconnection and the welding of the _{S w} (S4 in Fig. 5).

Specifically, in FIG. 6, in the period (1), the control circuit 7 (the disconnection welding detection circuit 16) keeps the grid interconnection relays S _u and S _w off. , Whether or not both grid interconnection relays S _u and S _w are welded is detected. Further, (2) During the period, the control circuit 7 (disconnection welding detection circuit 16) is switched on only relay S _u for system interconnection, which remains off the relay S _w for system interconnection In the state, it is detected whether or not the grid interconnection relay _Sw is welded. Further, when the lapse of a predetermined time period T _dly from the end of the period (2), the control circuit 7 (disconnection welding detection circuit 16) in the period of (3), turns off the relay S _u for system interconnection, system The interconnection relay _Sw is turned on, and it is detected whether or not the grid interconnection relay _Su is welded. Then, (3) When the predetermined time period _{T dly} has elapsed from the end of the period, the control circuit 7 (disconnection welding detection circuit 16), (4) in the period, the system interconnection relay _S u, any _{S w} It is detected whether or not is disconnected. In the above S3, the amplitude of the output voltage from the power storage hybrid power system 1, the amplitude _{E uw} commercial system voltage _{e uw.} Not the _max itself, but the amplitude E _{uw. The} reason for matching with the pre-grid operation amplitude (E _uw.max -ΔE) having _max and amplitude difference ΔE is that this amplitude difference ΔE is used for disconnection welding detection processing in the period (2) to (4) above. It is to do.

Next, a specific method for detecting welding / disconnection of the grid interconnection relays S _u and S _w will be described. First, the welding determination method performed during the period (1) in FIG. 6 will be described. In the period (1) in FIG. 6, as shown in FIG. 6, the control circuit 7 prohibits the output of the PWM signal from the PWM control unit 34, and the system interconnection relays S _u and S _w Based on the value of the output current _isp calculated by the device output current value calculation circuit 23 in a state where both are turned off (not connected to the commercial power system 3), both the grid interconnection relays S _u , S _w detects whether or not the welding. More specifically, first, the control circuit 7 (the passing current value estimation circuit 22) does not output the PWM signal from the PWM control unit 34 and is detected by the output voltage value detection circuit 26. based on the value of the voltage _{e sd,} by the following equation (6), to the current flowing through the capacitor _{C f} estimate the value of (the capacitor passing current) _{i c} (calculated). Next, the control circuit 7 (the device output current value calculation circuit 23) calculates the value of the inverter output current i _inv detected by the output current value detection circuit 21 by the following equation (7) and the equation (6). Based on the calculated value of the capacitor passing current _ic , the value of the output current _isp from the power storage hybrid power generation system 1 is calculated. The control circuit 7 (mainly, the disconnection welding detection circuit 16) is configured so that the absolute value | i _sp | of the output current i _sp obtained by the equation (7) is not less than the threshold value I _chk obtained by the following equation (8). For example, it is determined that the welding state is generated in both the grid interconnection relays S _u and S _w .

The numerator (2πf _uw C _f E _u.max (= ω _uw C _f E _u.max )) in the calculation formula (8) for the above threshold I _chk indicates that both of the grid interconnection relays S _u and S _w are on. The maximum value of the current flowing through the capacitor C _f (capacitor passing current) _ic is shown. In Expressions (8) and (9), a is a setting coefficient for the threshold I _chk for the detection level. Moreover, since said Formula (6) is known in the field of control engineering as a transfer function of RC series circuit, description is abbreviate | omitted.

As described above, if the absolute value | i _sp | of the output current i _sp obtained by the equation (7) is equal to or greater than the threshold value I _chk obtained by the equation (8), the grid interconnection relays S _u and S _w The reason why it is determined that a welded state has occurred in both is as follows. That is, as shown in FIG. 6, in the state where the output of the PWM signal from the PWM control unit 34 is prohibited and both of the grid connection relays S _u and S _w are turned off, both grid connection relays S _{If u} and _Sw are not welded, the inverter output current i _inv , the capacitor passing current i _c , and the output current i _sp do not flow (becomes 0 A), but both grid interconnection relays S _u , S _{When w} is welded, the self-sustained system voltage _esd in the equation (6) becomes equal to the commercial system voltage e _uw that is an AC voltage, and the capacitor passing current _ic flows. Therefore, according to the equation (7) This is because the absolute value | i _sp | of the obtained output current i _sp is equal to or greater than the threshold value I _chk obtained by the equation (8).

Next, the welding determination method in the periods (2) and (3) in FIG. 6 will be described. For the welding determination in these periods, the apparent power variation (apparent power difference) ΔS _inv calculated using the apparent power variation detection circuit 20 is used. For calculating the apparent power change amount (apparent power difference) ΔS _inv , the maximum of the independent system voltage _esd (output voltage from the storage hybrid power generation system 1) detected by the output voltage amplitude instantaneous value detection circuit 18 is used. The instantaneous self-sustained system voltage maximum value E _max which is an instantaneous value of the value (amplitude) and the instantaneous output current which is the instantaneous value of the maximum value (amplitude) of the output current i _sp detected by the output current amplitude instantaneous value detection circuit 19 The maximum value I _max is used. Note that the self-sustained system voltage e _sd (see FIG. 7), which is an input voltage to the output voltage amplitude instantaneous value detection circuit 18, is the self-sustained system voltage e _sd (switch S _sd is 1 when the original self-sustained operation is performed). autonomous system corresponds to the voltage e _sd) rather than when the position of the interconnection immediately before the commercial power system (after the end of the adjustment process at S3 in FIG. 5) is a self-supporting system voltage e _sd.

The control block of the output voltage amplitude instantaneous value detection circuit 18 will be described with reference to FIG. The output voltage amplitude instantaneous value detection circuit 18 includes an LPF (Low Pass Filter) 51 (first low-pass filter), an APF (All Pass Filter) 52, and a square sum square root calculator 53. The LPF 51 is a digital low-pass filter for removing noise from the input independent system voltage e _sd (output voltage from the storage hybrid power generation system 1). Cutoff frequency _{f c} of the LPF51, at the time of activation by the system interconnection operation mode (disconnected welding detection circuit 16 according to the system interconnection relay _S u, when detecting the disconnection and the welding of the _{S w),} the grid voltage _{e uw} Frequency (commercial system frequency) f _uw . Thus, the cutoff frequency f _c, reason for setting to a commercial power system frequency f _uw is the moment when one of the system interconnection relay is welded, the other side of the system interconnection relay is turned on , the autonomous system voltage e _sd is equal to the commercial system voltage e _uw, in this case, even if a high overall distortion factor of the commercial system voltage e _uw, the cut-off frequency f _c is set to the grid frequency f _uw If this is the case, harmonic components (noise) that are higher than the fundamental frequency component can be removed from the autonomous system voltage e _sd (= commercial system voltage e _uw ), so that the instantaneous autonomous system voltage maximum value E _max can be accurately obtained. Because it can. Incidentally, startup by autonomous operation mode to be described later in the (self-supporting system relay _S Std.U by autonomous system relay disconnection welding detection circuit _24, detecting the time of disconnection and the welding of the _{S std.w),} cutoff of LPF51 frequency f _c is set to the output voltage from the power storage hybrid power generation system 1 during the autonomous operation (the autonomous system voltage e _sd when the switch S _sd is in the position 1) and the autonomous system frequency f _sd which is the frequency of the output current i _sp. The

The AC voltage that is an output value from the LPF 51 is input to the square sum square root calculator 53 and the APF 52 as an α-phase instantaneous AC voltage e _α . The APF 52 is a filter for adjusting the phase angle of the AC input signal, and holds the magnitude of the α-phase instantaneous AC voltage e _α input from the LPF 51 and delays the phase by (π / 2). by, and outputs it as the instantaneous AC voltage beta phase e _beta. That is, here, the APF 52 is used to obtain the β-phase instantaneous AC voltage e _β from the α-phase instantaneous AC voltage e _α . The square sum square root calculator 53 calculates a square root value (√ (e _α ²⁾ of the square sum of the α-phase instantaneous AC voltage e _α input from the LPF 51 and the β-phase instantaneous AC voltage e _β input from the APF 52. + _Eβ ² )) is calculated, and the calculation result is output as the instantaneous self-sustained system voltage maximum value E _max . The LPF 51 corresponds to the first low-pass filter in the claims.

Next, the control block of the output current amplitude instantaneous value detection circuit 19 will be described with reference to FIG. The output current amplitude instantaneous value detection circuit 19 includes an LPF (Low Pass Filter) 61 (second low-pass filter), an APF (All Pass Filter) 62, and a square sum square root calculator 63. The LPF 61 is a digital low-pass filter for removing noise from the input output current i _sp (output current from the power storage hybrid power generation system 1). Cutoff frequency _{f c} of the LPF61, like the cut-off frequency _{f c} of the LPF51 of the output voltage instantaneous amplitude detection circuit 18, upon activation by the system interconnection operation mode is set to the grid frequency _{f uw.} The reason for setting the cutoff frequency _{f c} of the LPF61 to the grid frequency _{f uw} is also a cut-off frequency _{f c} of the LPF51 output voltage instantaneous amplitude detection circuit 18 for the same reason set in the grid frequency _{f uw,} output to remove the fundamental frequency (utility power frequency) component or higher harmonic components (noise) from current i _sp, in order to determine the instantaneous output current maximum value I _max accurately. At the time of activation by autonomous operation mode, the cutoff frequency _{f c} of the LPF61, like the cut-off frequency _{f c} of the LPF51 of the output voltage instantaneous amplitude detection circuit 18 is set to a self-supporting system frequency _{f sd.}

The alternating current that is an output value from the LPF 61 is input to the square sum square root calculator 63 and the APF 62 as an α-phase instantaneous alternating current i _α . The APF 62 is a filter for adjusting the phase angle of the AC input signal, and holds the magnitude of the α phase instantaneous AC current i _α input from the LPF 61 and delays the phase by (π / 2). And output as a β-phase instantaneous alternating current i _β . That is, here, the APF 62 is used to obtain the β-phase instantaneous alternating current i _β from the α-phase instantaneous alternating current i _α . The square sum square root calculator 63 is a square root value (√ (i _α ²⁾ of the square sum of the α-phase instantaneous alternating current i _α input from the LPF 61 and the β-phase instantaneous alternating current i _β input from the APF 62. + I _β ² )) is calculated, and the calculation result is output as the instantaneous output current maximum value I _max . The LPF 61 corresponds to a second low-pass filter in the claims.

In the welding determination in the periods (2) and (3) in FIG. 6, the disconnection welding detection circuit 16 first uses the apparent power change detection circuit 20 to both the grid interconnection relays _Su and _Sw . from a state of being turned off (it is not connected to the commercial power system 3), system interconnection relay S _u, the state of being turned on only one of the S _w (when connected to a commercial power system 3) The change amount of the apparent power at the time of switching is detected. In this detection, apparent power variation detecting circuit 20, first, the grid interconnection relay S _u, was detected by the output voltage amplitude instantaneous value detection circuit 18 in a state that turns off both S _w, instantaneous plurality of past times the average value E _avg of autonomous system voltage maximum value E _max, system interconnection relay S _u, the output voltage instantaneous amplitude while turning on only one of the S _w (when connected to a commercial power system 3) The absolute value ΔV (“second instantaneous voltage amplitude difference” in the claims) of the voltage amplitude difference with the latest instantaneous self-sustaining system voltage maximum value E _max detected by the detection circuit 18 is obtained. Specifically, the apparent power change detection circuit 20 outputs the output voltage amplitude instantaneously in a state where both the grid interconnection relays S _u and S _w are turned off based on the following equations (10) and (12). In the period (2) and (3) in FIG. 6, the average value E _{avg of} the past (c−b + 1) times of instantaneous self-sustaining system voltage maximum value E _max detected by the value detection circuit 18 The absolute value ΔV of the voltage amplitude difference from the most recent instantaneous self-sustained system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 with only one of the relays S _u and S _w turned on calculate.

Next, the apparent power variation detection circuit 20 outputs the instantaneous output current amplitude value detection circuit 19 in a state where both the grid interconnection relays S _u and S _w are turned off (not connected to the commercial power system 3). It was detected by and past connections and the average value I _avg of a plurality of times of instantaneous output current maximum value I _max, system interconnection relay S _u, the state (commercial power system 3 is turned on only one of the S _w The absolute value ΔI (“second instantaneous current amplitude difference” in the claims) of the current amplitude difference from the most recent instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 is obtained. Specifically, the apparent power change detection circuit 20 outputs the output current amplitude instantaneously in a state where both the grid interconnection relays S _u and S _w are turned off based on the following equations (11) and (13). The average value I _{avg of} the past (c−b + 1) times of the instantaneous output current maximum value I _max detected by the value detection circuit 19 and the period of (2) and (3) in FIG. The absolute value ΔI of the current amplitude difference from the most recent instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 in a state where only one of the relays S _u and S _w is turned on is obtained.

The apparent power variation detecting circuit 20, based on the above ΔV and [Delta] I, system interconnection relay S _u, from a state in which off both of S _w, relay system interconnection S _u, S _w A change amount of apparent power (a difference in apparent power) ΔS _inv when only one of them is switched on is calculated (calculated). Specifically, the apparent power change detection circuit 20 calculates the apparent power change ΔS _inv by dividing the product of ΔV and ΔI by 2 as shown in the following equation (14). Here, the reason why the product of ΔV and ΔI divided by 2 is used as the apparent power change amount ΔS _inv is the product of the effective value of the voltage and the effective value of the power. This is because the value and the effective value of the current are (1 / √2) of the amplitude of the voltage and (1 / √2) of the amplitude of the current, respectively.

Disconnection welding detection circuit 16, based on the change amount [Delta] S _inv apparent power calculated by the equation (14), the relay S _u for system _{interconnection,} of the S _w, relay which is not to be connected to a commercial power system 3 Judgment (detection) of welding is performed. Specifically, as shown in the following formula (15), the disconnection welding detection circuit 16 has a change amount of apparent power (a difference in apparent power) ΔS _inv as a threshold value d · ΔS _rated (where d is when it is a proportional constant) or higher, the relay S _u for system _{interconnection,} of the S _w, relay which is not to be connected to a commercial power system 3 detects that the welded. Here, ΔS _rated indicates the rated apparent power of the electricity storage hybrid power generation system 1.

More specifically, in the welding determination in the period (2) in FIG. 6, the disconnection welding detection circuit 16 determines that the grid connection is detected when the change amount ΔS _inv of the apparent power is equal to or greater than the threshold value d · ΔS _rated. Of the system relays S _u and S _w , it is detected that the relay S _w not turned on is welded. Further, in the welding determination in the period (3) in FIG. 6, the disconnection welding detection circuit 16 determines that the grid interconnection relay S when the apparent power change ΔS _inv is equal to or greater than the threshold value d · ΔS _rated. It is detected that the relay S _u which is not turned on among _u and S _w is welded. In the welding determination in the period of (2) and (3), disconnection welding detection circuit 16, among the system interconnection relay S _u, S _w, it is determined that the relay which is not turned on is welded In this case, the control circuit 7 stops the operation of the electricity storage hybrid power generation system 1.

In the disconnection determination in the period (4) in FIG. 6, the disconnection welding detection circuit 16 first uses the apparent power change detection circuit 20 after completing the adjustment process of S3 in FIG. use relay S _u, from a state in which off both the S _w (disconnection state), observed when you switch the state of relay S _u for system _{interconnection,} both S _w on (interconnection state), the apparent Detects the amount of power change. In this detection, apparent power variation detecting circuit 20, first, the grid interconnection relay S _u, was detected by the output voltage amplitude instantaneous value detection circuit 18 in a state that turns off both S _w, instantaneous plurality of past times the average value E _avg of autonomous system voltage maximum value E _max, system interconnection relay S _u, was detected by the output voltage amplitude instantaneous value detection circuit 18 while turning on both the S _w, the most recent instantaneous self system voltage The absolute value ΔV of the voltage amplitude difference from the maximum value E _max (“first instantaneous voltage amplitude difference” in the claims) is obtained. Specifically, the apparent power change detection circuit 20 outputs the output voltage amplitude instantaneously in a state where both of the grid interconnection relays S _u and S _w are turned off based on the equations (10) and (12). The average value E _{avg of} the past (c−b + 1) times of the instantaneous autonomous system voltage maximum value E _max detected by the value detection circuit 18 and the grid interconnection relay S _u during the period (4) in FIG. was detected by the output voltage amplitude instantaneous value detection circuit 18 while turning on both the S _w, and calculates the absolute value ΔV of the voltage amplitude difference between the most recent instantaneous self system voltage maximum value E _max.

Next, the apparent power change detection circuit 20 detects the past multiple times detected by the output current amplitude instantaneous value detection circuit 19 in a state in which both of the grid interconnection relays S _u and S _w are turned off (disconnected state). The output current amplitude instantaneous value detection circuit 19 detects the average value I _avg of the instantaneous output current maximum value I _max and the grid connection relays S _u and _{Sw in} the on state (linked state). An absolute value ΔI (“first instantaneous current amplitude difference” in the claims) of the current amplitude difference from the latest instantaneous output current maximum value I _max is obtained. Specifically, the apparent power change detection circuit 20 outputs the output current amplitude instantaneously in a state where both of the grid connection relays S _u and S _w are turned off based on the equations (11) and (13). The average value I _{avg of} the past (c−b + 1) times of the instantaneous output current maximum value I _max detected by the value detection circuit 19 and the grid interconnection relay S _u during the period (4) in FIG. was detected by the output current instantaneous amplitude detection circuit 19 while turning on both the S _w, the absolute value ΔI of the current amplitude difference between the most recent instantaneous output current maximum value I _max.

The apparent power variation detecting circuit 20, based on the above ΔV and [Delta] I, system interconnection relay S _u, from the state (disconnecting state) that turns off both S _w, system interconnection relay A change amount (apparent power difference) ΔS _inv of the apparent power when switching to a state in which both of S _u and S _w are turned on (connected state) is obtained (calculated). Specifically, the apparent power change detection circuit 20 uses the above ΔV and ΔI to calculate the apparent power change ΔS _inv according to the above equation (14).

Disconnection welding detection circuit 16, based on the change amount [Delta] S _inv apparent power calculated by the equation (14), for detecting whether the system interconnection relay S _u, either S _w is broken. Specifically, as shown in the above equation (16), the disconnection welding detection circuit 16 has a change amount of the apparent power (a difference in apparent power) ΔS _inv as a threshold value d · ΔS _rated (where d is , It is detected that at least one of the grid interconnection relays S _u and S _w is disconnected.

When the disconnection welding detection circuit 16 detects disconnection of the grid interconnection relays S _u and S _w (NO in S4 in FIG. 5), the control circuit 7 stops the operation of the storage hybrid power generation system 1. (S5 in FIG. 5). In the above equations (10) and (11), k represents a k-th (kth) sampling period. Further, in Expression (10), E _max (k−n) represents the instantaneous self-sustained system voltage maximum value E _max in the sampling period n times before the k-th (k-th) sampling period, and in Expression (11) , I _max (k−n) indicates the instantaneous output current maximum value I _max in the sampling period n times before the k-th (k-th) sampling period. In this embodiment, b in the equations (10) and (11) is set to a value that is 0.5 times the switching frequency of the inverter 5, and c is set to the switching frequency of the inverter 5. Therefore, the average value E _avg of (c−b + 1) times of the instantaneous autonomous system voltage maximum value E _max calculated by the equation (10) is the value when the value of the sampling cycle of the kth order (kth) is the current value. , Which corresponds to the average value of the instantaneous self-sustained system voltage maximum value E _max for 0.5 seconds from 0.5 seconds before to 1 second before, and the instantaneous output current for (c−b + 1) times calculated by the equation (11) The average value I _avg of the maximum value I _max is the maximum instantaneous output current for 0.5 seconds from 0.5 seconds to 1 second before when the value of the k-th (k-th) sampling period is the current value. This corresponds to the average value I _max .

When the welding or disconnection of the grid interconnection relays S _u and S _w is not detected in the detection process of S4 in FIG. 5 (YES in S4), the control circuit 7 (mainly the startup control circuit 13) The switch S _{Grid is set} to the 0 position and the grid connection relays S _u and S _w are turned on to switch from the independent operation to the grid connection operation (S6). Take control.

To summarize the process of detecting disconnection or welding in FIG. 6 (2) to (4), the control circuit 7 (disconnection welding detection circuit 16), the solution of the relay S _u, S _w for system interconnection column state observed when switching to interconnection state from, based on the apparent power variation [Delta] S _inv detected by apparent power variation detecting circuit 20, the system interconnection relay S _u, detects the disconnection of S _w, the grid interconnection From the state where both of the relays S _u and S _w are turned off (not connected to the commercial power system 3), only one of the grid connection relays S _u and S _w is turned on (commercial power Based on the apparent power change amount ΔS _inv detected by the apparent power change amount detection circuit 20 at the time of switching to the state of being connected to the power system 3, one of the grid interconnection relays S _u and S _w is turned on. (Not connected to commercial power system 3 Have not) to detect the welding of the system interconnection for the relay of the person.

In the power storage hybrid power generation system 1 of the present embodiment, the amplitude before the grid connection operation that is the amplitude of the output voltage from the power storage hybrid power generation system 1 immediately before shifting to the grid connection operation control, and the amplitude E of the commercial system voltage e _uw . _sd. Amplitude difference ΔE was intentionally provided between this value and _max . Even when the amplitude difference ΔE is set to a small value, the moment when the grid interconnection relays S _u and S _{w change from the} disconnected state to the interconnection state (out of the grid interconnection relays S _u and S _w The amplitude (maximum value) of the output current i _sp is large at the time of switching to the state where the other grid connection relay is connected to the commercial power system 3) Therefore, the apparent power change amount ΔS _inv that is the product of the effective value of the output voltage from the power storage hybrid power generation system 1 (independent system voltage e _sd ) and the effective value of the output current i _sp also changes greatly. Therefore, the disconnection of the grid connection relays S _u and S _w is detected based on the change ΔS _inv of the apparent power when the grid connection relays S _u and S _w are switched from the disconnected state to the connected state. The change in the apparent power when the both of the grid connection relays S _u and S _w are turned off to the state where only one of the grid connection relays S _u and S _w is turned on. based on the amount [Delta] S _inv, relay S _u for system _{interconnection,} of the S _w, by detecting the welding of the system interconnection relay of which is not turned on, performs detection of a disconnection-welded securely be able to.

  Here, the technique for detecting the welding of the grid interconnection relay is also described in Patent Document 4, but in the technique described in Patent Document 4, the current flowing through the capacitor of the LC filter circuit and the commercial system voltage Based on the phase difference between the grid and the relay, it is detected whether or not the grid connection relay is welded. Therefore, when the distortion of the commercial grid voltage is high, the welding of the grid connection relay must be accurately determined. Is difficult. That is, when the power conversion device employing the welding determination method described in Patent Document 4 is installed in a place where the distortion rate of the commercial grid voltage is high, erroneous detection is performed in the welding detection of the grid interconnection relay. Probability is high.

Unlike the technique described in Patent Document 4 above, in the electric storage hybrid power generation system 1 of this embodiment, in the disconnection / welding detection process of (2) to (4) in FIG. the instantaneous self system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 from the e _sd comprises LPF51 that is configured to remove the grid frequency f _uw more harmonics, input output Using the instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 including the LPF 61 set to remove the harmonic component of the commercial system frequency f _uw or more from the current i _sp , the apparent The amount of power change ΔS _inv is obtained (calculated). As a result, even if the commercial grid voltage is distorted, the apparent power variation ΔS _inv can be accurately detected. Based on the apparent power variation ΔS _inv , the grid interconnection relays S _u and S _w among one of the welding and the system interconnection relay of system interconnection relay S _u, at least one of disconnection of S _w, it can be detected accurately.

Moreover, in the disconnection / welding detection process of (2) to (4) in FIG. 6 in the electricity storage hybrid power generation system 1 of the present embodiment, as described above, the output voltage (independent system voltage) from the electricity storage hybrid power generation system 1 The disconnection or welding of the grid interconnection relays S _u and S _w is detected based on the apparent power change ΔS _inv that is the product of the effective value of e _sd ) and the effective value of the output current i _sp . . As a result, when disconnection or welding of the grid interconnection relays S _u and S _w is detected based only on the amount of change in the output voltage (independent grid voltage e _sd ) from the power storage hybrid power generation system 1, the output current i Even if the commercial system voltage is distorted compared to the case where the disconnection or welding of the grid connection relays S _u and S _w is detected based only on the amount of change in _sp , the grid connection relays S _u and S _w Disconnection and welding can be reliably detected.

Next, with reference to the flowchart of FIG. 9, the flow of control at the start of the self-sustaining operation mode in the power storage hybrid power generation system 1 will be described. At the start of the self-sustained operation mode, the control circuit 7 (mainly the start-up control circuit 13) of the power storage hybrid power generation system 1 first sets the switch S _Grid to the position 1, the switch S before supplying power to the self-supporting load _{Rload. sd} is in position 1, grid connection relays S _u , S _w are turned off, independent system relay S _{std. u} , S _std. Turn off the _w, performs autonomous operation control, by self-sustained operation when the amplitude adjustment circuit 25, the maximum value E _sd autonomous system voltage e _{sd. max} (amplitude), by controlling to match the command value ^E _{* cst} maximum value of the original free-standing system voltage _{e sd,} performs constant control of the output voltage from the inverter 5 (S11). After a predetermined time has elapsed since the start of the autonomous operation control (YES in S12), the maximum value (amplitude) of the output voltage from the storage hybrid power generation system 1 becomes the command value E ^* of the maximum value of the original autonomous system voltage _esd ^. _When reaching _cst , the control circuit 7 (mainly the activation control circuit 13 and the independent system relay disconnection welding detection circuit 24), as shown in FIG _{. u} , S _std. The on / off switching of _w and switching of the Enable signal and the Disable signal output to the PWM control unit 34 are performed, and the independent system relay S _{std. u} , S _std. The disconnection and welding of _w are detected (S13 in FIG. 9).

Specifically, in FIG. 10, during the period of (1), the control circuit 7 (the independent system relay disconnection welding detection circuit 24) is _{operated by the} independent system relay S _{std. u} , S _std. the _w, both in a state of being turned off, both free-standing system for the relay S _{std. u} , S _std. Whether _w is welded or not is detected. Further, during the period (2), the control circuit 7 (the independent system relay disconnection welding detection circuit 24) is _{operated by the} independent system relay S _std. Only _u is turned on, and the relay S _{std. In} the state where _w is turned off, the relay _Sstd. Whether _w is welded or not is detected. When the predetermined period T _dly elapses from the end of the period (2), the control circuit 7 (the independent system relay disconnection welding detection circuit 24) performs the independent system relay S _{std. u} is turned off, and the relay _{Sstd. w} is turned on and the relay _Sstd. It is detected whether _u is welded or not. That is, during the periods (2) and (3), the control circuit 7 (the independent system relay disconnection welding detection circuit 24) is _{operated by the} independent system relay S _{std. u} , S _{std. In w} , it is detected whether or not the relay for the independent system that is not connected to the independent load R _load is welded. Then, when a predetermined period T _dly has elapsed from the end of the period (3), the control circuit 7 (the independent system relay disconnection welding detection circuit 24) performs the independent system relay S _{std. u} , S _std. It is detected whether any of _w is disconnected.

Next, the above-described independent system relay S _{std. u} , S _std. A specific method for detecting _w welding / disconnection will be described. First, the welding determination method performed during the period (1) in FIG. 10 will be described. In the period (1) in FIG. 10, the control circuit 7 (the independent system relay disconnection welding detection circuit 24) permits the output of the PWM signal from the PWM control unit 34 as shown in FIG. , Relay for stand-alone system S _{std. u} , S _std. Based on the value of the output current i _sp calculated by the device output current value calculation circuit 23 in a state where both of _w are turned off (not connected to the self-supporting load R _load ), both of the stand-alone system relays S _{std. u} , S _std. Whether _w is welded or not is detected.

More specifically, first, the control circuit 7 (the passing current value estimation circuit 22) is a self-supporting system detected by the output voltage value detection circuit 26 in a state where the PWM signal is output from the PWM control unit 34. based on the value of the voltage _{e sd,} by the above equation (6), to the current flowing through the capacitor _{C f} estimate the value of (the capacitor passing current) _{i c} (calculated). Next, the control circuit 7 (the device output current value calculation circuit 23) calculates the value of the inverter output current i _inv detected by the output current value detection circuit 21 according to the above equation (7) and the equation (6). Based on the calculated value of the capacitor passing current _ic , the value of the output current _isp from the power storage hybrid power generation system 1 is calculated. Unlike the welding detection performed during the period (1) in FIG. 6, the PWM signal from the PWM control unit 34 is output during the welding detection performed during the period (1) in FIG. The values of the output current i _inv and the capacitor passing current _ic do not become 0, but the independent system relay S _{std. u} , S _{std. Since} both of _w are turned off, the relay _{Sstd. u} , S _{std. If} both _w are not welded, the value of the output current i _sp should be zero. Accordingly, the control circuit 7 (mainly, the relay disconnection welding detection circuit 24 for the self-supporting system) _calculates the absolute value | i _sp | of the output current i _sp obtained by the equation (7) by the following equation (18). Threshold I _chk. Based on whether or not it is greater than or _{equal to std} , the relay for a stand- _alone system S _{std. u} , S _std. It can be determined whether or not a welded state has occurred in both of _w .

Specifically, the control circuit 7 (mainly, the relay disconnection welding detection circuit 24 for the self-supporting system) sets the command value E ^* _cst of the maximum value of the original self-supporting system voltage _esd as shown in the equation (18). As a reference, the threshold value I _{chk. std} is calculated, and the absolute value | i _sp | of the output current i _sp is the threshold I _chk. If it is equal to or greater than _std , the relay _{Sstd. u} , S _std. It determines with the welding state having generate | occur | produced in both of _w .

The threshold value I _chk. molecules in calculation formula (18) ^{_{std (2πf sd C f E *}} cst (= ω sd C f E * cst)) is self-supporting system relay _{S std. u} , S _std. When both _w is turned on, indicating the maximum value of the current (capacitor passing current) i _c flowing to the capacitor C _f. In the equations (18) and (19), x is a threshold I _{chk. This is} a setting coefficient for _std .

Next, the welding determination method in the periods (2) and (3) in FIG. 10 will be described. In the welding determination in the periods (2) and (3), the independent system relay disconnection welding detection circuit 24 first uses the apparent power change detection circuit 20 to detect the independent system relay S _{std. u} , S _{std. From} the state where both of _w are turned off (the state where the _load is not connected to the self-supporting load R _load ), the self-sustained system relay S _{std. u} , S _std. A change amount of the apparent power when the state is switched to a state where only one of _w is turned on (a state where it is connected to the self-supporting load R _load ) is detected.

In the above detection, the apparent power change amount detection circuit 20 first starts the independent system relay S _{std. u} , S _std. The average value E _{avg of the} maximum instantaneous self-sustained system voltage E _max for the past plural times detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both of _w are turned off (not connected to the self-supporting load R _load ). And a relay _{Sstd. u} , S _std. Voltage amplitude difference from the most recent instantaneous self-sustained system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 with only one of _w turned on (connected to the self-supporting load R _load ) Of the absolute value ΔV (“fourth instantaneous voltage amplitude difference” in the claims). Specifically, the apparent power change detection circuit 20 is based on the above equations (10) and (12), and the independent power system relay S _{std. u} , S _std. An average value E _{avg of} the past (c−b + 1) times of the instantaneous autonomous system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both of _w are turned off, and ( In the period of 2) and (3), the relay _{Sstd. u} , S _std. The absolute value ΔV of the voltage amplitude difference from the most recent instantaneous self-sustained system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where only one of _w is turned on is calculated.

Next, the apparent power change detection circuit 20 includes the independent system relay S _{std. u} , S _std. The average value I _avg of the maximum instantaneous output current I _max for the past plural times detected by the output current amplitude instantaneous value detection circuit 19 in a state where both of _w are turned off (not connected to the self-supporting load R _load ) , Relay for stand-alone system S _{std. u} , S _std. The current amplitude difference from the most recent instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 in a state where only one of _w is turned on (connected to the self-supporting load R _load ) The absolute value ΔI (“fourth instantaneous current amplitude difference” in the claims) is obtained. Specifically, the apparent power change amount detection circuit 20 is based on the above equations (11) and (13), and the independent power system relay S _{std. u} , S _std. The average value I _avg of the maximum instantaneous output current I _max for the past (c−b + 1) times detected by the output current amplitude instantaneous value detection circuit 19 in a state where both of _w are turned off, and (2 ) And (3), the self-sustained system relay S _{std. u} , S _std. The absolute value ΔI of the current amplitude difference from the most recent instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 in a state where only one of _w is turned on is obtained.

Then, the apparent power change amount detection circuit 20 uses the above equation (14) based on the above ΔV and ΔI, and uses the self-sustaining system relay S _{std. u} , S _{std. From} the state where both of _w are turned off, the relay _{Sstd. u} , S _std. A change amount (apparent power difference) ΔS _inv of the apparent power when only one of _w is switched to the on state is calculated (calculated).

Based on the apparent power change ΔS _inv calculated by the equation (14), the independent power system relay disconnection welding detection circuit 24 is configured to operate the independent power system relay S _{std. u} , S _std. Of _w , the welding determination (detection) of the relay for the independent system that is not connected to the independent load R _load is performed. Specifically, in the welding determination in the period (2) in FIG. 10, as shown in the above equation (15), the independent system relay disconnection welding detection circuit 24 determines the amount of change in the apparent power (apparent value). When the power difference) ΔS _inv is equal to or greater than a threshold value d · ΔS _rated (where d is a proportionality constant), the autonomous system relay S _{std. u} , S _{std. w} of the relays S _std. It is detected that _w is welded. In addition, in the welding determination in the period (3) in FIG. 10, the relay disconnection welding detection circuit 24 for the independent system has the independent system when the apparent power change ΔS _inv is equal to or greater than the threshold value d · ΔS _rated. Relay S _{std. u} , S _{std. w} of the relays S _std. It is detected that _u is welded. In the welding determination in the periods (2) and (3), the independent system relay disconnection welding detection circuit 24 is connected to the independent system relay S _{std. u} , S _std. If it is determined that the relay that is not turned on in _w is welded, the control circuit 7 stops the operation of the power storage hybrid power generation system 1.

In the disconnection determination in the period (4) in FIG. 10, the independent system relay disconnection welding detection circuit 24 first uses the apparent power change detection circuit 20 to detect the independent system relay S _{std. u} , S _{std. From} the state where both of _w are turned off (the state where the self-sustained load R _load and the power storage hybrid power generation system 1 are not connected (hereinafter referred to as “non-connected state”)), the relay S _{std. u} , S _std. Detecting the amount of change in apparent power when switching to a state in which both of _w are turned on (a state where the self-supporting load R _load and the storage hybrid power generation system 1 are connected (hereinafter referred to as “connected state”)) .

The self-sustained system relay S _{std. u} , S _{std. In} detecting the amount of change in the apparent power when _w is switched from the disconnected state to the connected state, the apparent power change amount detection circuit 20 first starts the independent power system relay S _{std. u} , S _std. An average value E _avg of the maximum instantaneous autonomous system voltage E _max for the past plural times detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both of _w are turned off (non-connected state), and an independent system relay S _{std. u} , S _std. The absolute value ΔV of the voltage amplitude difference from the most recent instantaneous self-sustained system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 in a state in which both of _w are turned on (connected state) (“No. 3) is obtained. Specifically, the apparent power change detection circuit 20 is based on the above equations (10) and (12), and the independent power system relay S _{std. u} , S _std. An average value E _{avg of} the past (c−b + 1) times of the instantaneous autonomous system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both of _w are turned off, and ( 4) In the period of 4), the relay _{Sstd. u} , S _std. The absolute value ΔV of the voltage amplitude difference from the latest instantaneous self-sustained system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both _w are turned on is calculated.

Next, the apparent power change detection circuit 20 includes the independent system relay S _{std. u} , S _std. The average value I _avg of the maximum instantaneous output current value I _max for the past plural times detected by the output current amplitude instantaneous value detection circuit 19 in a state where both of _w are turned off (non-connected state), and the independent system relay S _{std . u} , S _std. The absolute value ΔI of the current amplitude difference from the most recent instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 in a state where both _w are turned on (connected state) (“third” in the claims) The instantaneous current amplitude difference of “)” is obtained. Specifically, the apparent power change amount detection circuit 20 is based on the above equations (11) and (13), and the independent power system relay S _{std. u} , S _std. The average value I _avg of the maximum instantaneous output current I _max for the past (c−b + 1) times detected by the output current amplitude instantaneous value detection circuit 19 in a state where both of _w are turned off, (4 in FIG. ) During the period of self-supporting system S _{std. u} , S _std. The absolute value ΔI of the current amplitude difference from the most recent instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 in a state where both _w are turned on is obtained.

Then, the apparent power variation detection circuit 20 determines the independent power system relay S _std. Based on the above ΔV and ΔI _{. u} , S _{std. From} the state in which both of _w are turned off (non-connected state), the relay _{Sstd. u} , S _std. A change amount (apparent power difference) ΔS _inv of the apparent power when switching to a state in which both of _w are turned on (connected state) is obtained (calculated). Specifically, the apparent power change detection circuit 20 uses the above ΔV and ΔI to calculate the apparent power change ΔS _inv according to the above equation (14).

Based on the apparent power change ΔS _inv calculated by the equation (14), the independent power system relay disconnection welding detection circuit 24 is configured to operate the independent power system relay S _{std. u} , S _std. It is detected whether any of _w is disconnected. Specifically, as shown in the above equation (16), the relay disconnection welding detection circuit 24 for the self-sustained system has a change amount of the apparent power (a difference in the apparent power) ΔS _inv of the threshold value d · ΔS _rated ( However, d, when less than proportional constant), self-supporting system relay _{S std. u} , S _std. It is detected that at least one of _w is disconnected.

The independent-system relay disconnection welding detection circuit 24 is connected to the above-mentioned independent-system relay _{Sstd. u} , S _{std. When} the disconnection of _w is detected (NO in S13 of FIG. 9), the control circuit 7 stops the operation of the electric storage hybrid power generation system 1 (S14 of FIG. 9).

In the welding / disconnection determination process in the period (2) to (4) in FIG. 10, the independent system relay S _{std. u} , S _std. Based on the amount of change in the apparent power (the difference in apparent power) ΔS _inv when _w is switched, the relay S _{std. u} , S _{std. Since} the welding / disconnection of _w is determined, the independent system relay S _{std. is} independent of the capacity and connection state of the independent load R _{load . u} , S _std. It is possible to reliably determine the welding / disconnection of _w .

In the power storage hybrid power generation system 1 of the present embodiment, the independent system relay S _{std. u} , S _{std. The} reason why the welding / breaking of _w can be reliably determined will be described in detail. In the electric storage hybrid power generation system 1, in the disconnection / welding detection processes (2) to (4) in FIG. 10, as described above, the effective output voltage (independent power system voltage _esd ) from the electric storage hybrid power generation system 1. Based on the change amount ΔS _inv of the apparent power, which is the product of the value of the output current i _{sp and} the effective value of the output current i _{sp . u} , S _{std. w} disconnection and welding were detected. As a result, the self-sustained system relay S _{std. Is} based only on the amount of change in the output voltage (self- _supported system voltage e _sd ) from the power storage hybrid power generation system 1 _{. u} , S _{std. When} detecting disconnection or welding of _w , or based only on the amount of change in the output current i _sp , the independent system relay S _{std. u} , S _{std. As} compared with the case where disconnection or welding of _w is detected, even when the independent system voltage _esd and the output current _isp are distorted, the independent system relay S _{std. u} , S _std. Disconnection and welding of _w can be reliably detected.

Further, in the power storage hybrid power generation system 1 in FIG. 10 (2) to the detection process of welding or disconnected in the period (4), the input independence system voltage e _sd from the fundamental frequency (autonomous system frequency f _sd) From the instantaneous self-sustained system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 including the LPF 51 set so as to remove the above harmonic components and the input output current i _sp , the self-sustained system frequency f _The apparent power change amount ΔS _inv is obtained using the instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 including the LPF 61 set so as to remove higher harmonic components than _sd. (Calculate). Thereby, even when the independent power system voltage _esd and the output current i _sp are distorted, the apparent power change amount ΔS _inv can be accurately detected. Based on the apparent power change amount ΔS _inv , the independent power system Relay S _{std. u} , S _std. welding of one of the self-sustaining system relays of _w or the self-sustaining system relay S _{std. u} , S _std. A disconnection of at least one of _w can be detected more accurately.

In the detection process of S13 of FIG _{. u} , S _{std. If} the welding or disconnection of _w has not been detected (YES in S13), the control circuit 7 (mainly the startup control circuit 13) is _{switched to the} independent system relay _{Sstd. u} , S _{std. w} is turned on, the power storage hybrid power generation system 1 is connected to the self-supporting load R _load , and the original self-supporting operation (self-supporting operation for supplying AC power to the self-supporting load R _load ) is started.

There are five characteristics in the control method at the start-up of the electricity storage hybrid power generation system 1 of the present embodiment. The first feature is that autonomous operation control is performed before the power storage hybrid power generation system 1 is connected to the commercial power system 3. Immediately after startup, when the commercial power system 3 and the interconnection, at the time of startup, is applied suddenly commercial system voltage e _uw capacitor C _f, the voltage applied to the capacitor C _f is rapidly increased, inrush current to the capacitor C _f May flow. In contrast, when the switch S _sd is set to the 1 position and the autonomous operation control is performed by soft start before the commercial power system 3 is connected, the capacitor C _f since the voltage applied to increase gradually when the commercial power system 3 and the interconnection, it is possible to eliminate the possibility of flowing rush current to the capacitor C _f.

The second feature is that the switch S _sd shown in FIG. 3 is set to the 0 position before the power storage hybrid power generation system 1 is connected to the commercial power system 3, and the output voltage from the power storage hybrid power generation system 1 is set. of the amplitude (amplitude of the self-standing system voltage _{e sd),} gradually, the amplitude _{E uw} commercial system voltage _{e uw. This} is to perform feedback control in accordance with the amplitude before grid connection operation having _max and amplitude difference ΔE. The third feature is that the value of the current (capacitor passing current) _ic flowing through the capacitor C _f is estimated before the grid interconnection operation is started or the original self-sustained operation is started. The level of the output current i _sp of the system connection is detected, the welding state of both the grid connection relays S _u and S _w is detected, or the independent system relay S _{std. u} , S _std. It is to detect both welding states of _w . The fourth feature is that before the start of the system-interconnected run, or before the start of the actual autonomous operation, system interconnection relay S _u, S _w or autonomous system relay S _{std. u} , S _std. By capturing the change state of the apparent power (amount of change ΔS _inv in the apparent power) when the _w is switched on and off, the grid interconnection relays S _u , S _w or the independent grid relay S _{std. u} , S _std. It is to confirm the presence or absence of defects (disconnection / welding) of _w .

According to the power storage hybrid power generation system 1 of the present embodiment, by adopting the control method at the time of startup as described above, the grid interconnection operation can be performed at the time of startup of the apparatus without providing a conventional inrush current prevention circuit. When this is done, the inrush current to the capacitor C _f provided between the inverter 5 and the commercial power system 3 can be suppressed, and a sudden increase in the current flowing through the grid interconnection relays S _u and S _w can be prevented. . Further, according to the electric storage hybrid power generation system 1, the independent system relay S _{std. u} , S _std. A sudden increase in the current flowing through _w can be prevented. Furthermore, according to the present power storage hybrid power system 1, at the time of starting the system interconnection operation mode, before the commercial power system 3 and the interconnection relay S _u for system _{interconnection,} the disconnection state and the welding state of the S _w It can reliably be detected, at the time of startup of the isolated operation mode, autonomous load before connection to the R _load, self-supporting system relay S _{std. u} , S _std. The disconnection state and welding state of _w can be reliably detected. Further, according to the power storage hybrid power generation system 1, the input self-supporting system in the disconnection / welding detection process in the periods (2) to (4) in FIG. 6 and (2) to (4) in FIG. a fundamental frequency (the grid frequency f _uw or autonomous system frequency f _sd) above the instantaneous detected using LPF51 that is configured to remove the harmonic components of the self-supporting system voltage maximum value E _max from the voltage e _sd, is input The instantaneous output current maximum value I _max detected using the LPF 61 set so as to remove the higher harmonic component of the fundamental frequency (commercial system frequency f _uw or free-standing system frequency f _sd ) from the output current i _sp. The apparent power change amount ΔS _inv was calculated, and the disconnection / welding detection was performed based on the apparent power change amount ΔS _inv . Thus, when starting the system interconnection operation mode, even if distorted commercial system voltage e _u, it can be detected relay S _u for system _{interconnection,} the disconnection and the welding of the S _w accurately, also, self Even when the autonomous system voltage _esd is distorted when the operation mode is activated, the autonomous system relay S _{std. u} , S _std. Disconnection and welding of _w can be accurately detected.

In order to confirm the effect of the control method at the start of the grid interconnection operation mode, the grid interconnection relay _Su is welded and the AC hybrid power source is used to start up the power storage hybrid power generation system 1. The experiment was verified. The start-up experiment shows the effect of suppressing the inrush current to the capacitor C _f and the grid connection relays S _u and S _w when the above-described control method at the start of the grid connection operation mode is adopted. This is to confirm the effect of confirming the welding at a time.

FIG. 11 shows experimental parameter settings. _{Td in} FIG. 11 indicates a dead time (time for turning off both the upper arm and the lower arm (for example, the switching element SW1 and the switching element SW3) in each of the switching elements SW1 to SW4 of the inverter 5). The switching frequency in Figure 11 shows the switching frequency of the switching elements SW1~SW4 of the inverter 5, THD _v is the total distortion factor of the AC simulated power supply voltage _{e uw} likened to a commercial system voltage.

In this experiment, it was confirmed that the welding detection method based on the apparent power change ΔS _inv calculated using the above equations (10) to (14) is effective even when the commercial system voltage e _uw is distorted. In order to achieve this, the total distortion rate THD _v of the commercial grid voltage (actually an AC simulated power supply voltage) e _uw shown in FIG. 11 is set to 25.6%, and one of the grid interconnection relays _Su Experimental verification of welding detection was performed. FIG. 12 shows the output from the electric storage hybrid power generation system 1 when this experiment (the welding detection experiment of (3) in FIG. 6) is performed with one grid interconnection relay _Su being welded. It shows that the voltage (autonomous system _{voltage) e sd,} the grid voltage _{e uw,} and the waveform of the output current _{i sp.} In FIG. 12, the independent system voltage e _sd is indicated by a one-dot chain line, and the commercial system voltage e _uw is indicated by a solid line. Further, in FIG. 12, the output current _{i sp,} are indicated by dashed lines. In the portion on the right side of the graph in FIG. 12 (the portion after the grid interconnection relay _Su is turned off and the grid interconnection relay _Sw is turned on), the waveform of the independent system voltage _esd and the commercial grid The waveforms of the voltage e _uw are almost overlapped. In FIG. 12, the vertical axis represents voltage (V) and current (A), and the horizontal axis represents time t (seconds). In this experiment, turn off the relay S _u for system interconnection, the moment of turn on the relay S _w for system interconnection, the detection method shown in the above formula (10) to (15), system interconnection relay _Su welding could be detected.

In this experiment, as shown in FIG. 12, at the moment when the grid connection relay _Su is turned off and the grid connection relay _Sw is turned on, the output current (reverse flow current) i _sp is spiked. Inrush current. Here, the reason why the output current i _sp has become a spike-like inrush current is that the amplitude difference ΔE between the self-sustained system voltage e _sd and the commercial system voltage e _uw (when the switch S _sd is in the 0 position). 10V), the current due to the amplitude difference ΔE flows to the capacitor C _f at the moment when the grid connection relay _Su is turned off and the grid connection relay _Sw is turned on. As a result, an instantaneous inrush current flows. However, since the amplitude difference ΔE is set to a small value (10 V) as described above, the instantaneous inrush current that is generated is a value up to 24 A, as shown in FIG. Even if an instantaneous inrush current of this level occurs, the maximum allowable current of the switching elements SW1 to SW4 of the inverter 5 is not exceeded, so the entire power storage hybrid power generation system 1 including the inverter 5 operates normally.

As a result of the above experiment, even when the commercial grid voltage e _uw is distorted by the welding detection based on the apparent power change ΔS _inv calculated using the above formulas (10) to (14), We were able to confirm that it is possible to accurately detect the welding of the relay S _u. Further, in the power storage hybrid power generation system 1, the amplitude and phase of the output voltage from the power storage hybrid power generation system 1 are adjusted at the time of start-up by the control method shown in FIG. use relay S _u, at the time of startup of) grid-connected operation mode when not detected a welding or disconnection of S _w, when switching to a system interconnection operation (system interconnection relay S _u, turn on the S _w At the same time, the current flowing through the capacitor C _f can be suppressed to only the current caused by the amplitude difference ΔE, as in the moment when the grid interconnection relays S _u and S _w are switched in the above experiment. Therefore, in the above experiment, when the power storage hybrid power generation system 1 switches to grid interconnection operation at the start of the normal grid interconnection operation mode (the moment when the grid interconnection relays _Su and _Sw are turned on). ), It was confirmed that the inrush current to the capacitor _Cf can be suppressed.

In addition, the above-mentioned independent system relay S _{std. u} , S _{std. In} order to confirm the effectiveness of the welding detection method for _w, a relay for a self-sustained system S _{std. u} is welded, and the autonomous system relay S _{std. u} , S _std. Experiment verification of welding confirmation of _w was performed. FIG. 13 shows the results of this experiment. Unlike FIG. 12, FIG. 13 shows the waveform before turning on the other relay (self-sustaining system relay Ssd.w) with one relay (self-sustaining system relay Ssd.u) welded. Only the waveform after turning on the other relay (self-sustaining system relay Ssd.w) with one relay (self-sustaining system relay Ssd.u) welded is shown. When the self-supporting load R _load includes a non-linear load (in this experiment, a rectifier is used as the non-linear load), as shown in FIG. 13, the self-supporting system voltage e _sd (output voltage from the storage hybrid power generation system 1) Is considerably distorted. In this case, as shown in FIG. 13, since the output current i _sp does not become a sine wave state, the change of the output current i _sp is detected and the relay Ssd. It is difficult to detect u welding.

However, in the power storage hybrid power generation system 1 of the present embodiment, the independent system relay S _{std. u} , S _std. According to the detection method of disconnection / welding of _w , even when the independent system voltage e _sd and the output current i _sp are distorted, by detecting the change in the apparent power, the relay for the independent system S _{std. u} , S _std. Disconnection and welding of _w can be accurately detected. Here, the relay _{Sstd. For the} self-sustaining system in the power storage hybrid power generation system 1 of the present embodiment _{. u} , S _{std. The} reason why _w can be accurately detected by the disconnection / welding detection method is that, in this disconnection / welding detection method, the change amount ΔS _{inv of the} apparent power used for the determination of disconnection / welding is LPF 51, 61. The reason is that it is calculated based on the self-sustained system voltage _esd and the output current i _{sp from} which the harmonic component is removed using.

As a result of the above experiment, even when the independent system voltage _esd and the output current _isp are distorted by the welding detection based on the apparent power change ΔS _inv calculated using the equations (10) to (14), , Relay for stand-alone system S _std. It was confirmed that the welding of _u can be accurately detected.

As described above, according to the electricity storage hybrid power generation system 1 of the present embodiment, when the grid interconnection operation is performed when the device is activated (when the device is activated in the grid interconnection operation mode), The output voltage amplitude of the commercial system voltage e _uw is increased stepwise from a predetermined value _{. The} grid hybrid operation system 1 is connected to the commercial power system 3 after adjusting the _maximum amplitude and the amplitude before grid interconnection operation (E _ew.max -ΔE) having an amplitude difference ΔE within a predetermined range, and grid interconnection operation is performed. I started. Thereby, when this apparatus is connected to the commercial power system 3, the voltage applied to the capacitor C _f provided between the inverter 5 and the commercial power system 3 (provided on the output side of the inverter 5) is increased. Therefore, the voltage applied to the capacitor C _f provided between the inverter 5 and the commercial power system 3 can be changed from 0 V to the commercial system voltage e. _A sudden increase in _uw can be prevented. Accordingly, by setting the amplitude difference ΔE to a sufficiently small value (10 V in this embodiment) compared to the commercial system voltage e _uw , the system can be started at the time of starting the apparatus without providing an inrush current prevention circuit. When the grid operation is performed, the inrush current to the capacitor C _f provided between the inverter 5 and the commercial power system 3 is suppressed, and the current flowing through the grid connection relays _Su and _Sw is increased rapidly. Can be prevented.

Moreover, according to the electricity storage hybrid power generation system 1 of the present embodiment, when performing grid connection operation at the time of starting the apparatus (when starting the apparatus in the grid connection operation mode), the grid connection relays S _u and S _After detecting disconnection and welding of _w , the power storage hybrid power generation system 1 was connected to the commercial power system 3 to start the grid interconnection operation. As a result, disconnection and welding of the grid connection relays _Su and _Sw (switches for external connection provided on the output side of the inverter 5) are confirmed before starting the grid connection operation when starting up the device. can do.

Moreover, according to the electrical storage hybrid power generation system 1 of the present embodiment, based on the amount of change in the apparent power from the electrical storage hybrid power generation system 1 when the grid connection relays _Su and _Sw are switched, The disconnection and welding of the relays S _u and S _w were detected. Thus, based only on the amount of change in the output voltage from the power storage hybrid power system 1 (self system voltage e _sd), and the case of detecting the relay S _u for system _{interconnection,} the disconnection and the welding of S _w, the output current i The disconnection and welding of the grid connection relays S _u and S _w are reliably detected as compared to the case where the disconnection and welding of the grid connection relays S _u and S _w are detected based only on the amount of change in _sp. be able to.

When Furthermore, according to the power storage hybrid power generation system 1 of the present embodiment, the control circuit 7 (disconnection welding detection circuit 16) is, after switching system interconnection relay S _u, the S _w from disconnection state to the interconnection state The disconnection of the grid connection relays S _u and S _w is detected based on the change amount ΔS _inv of the apparent power in the state where both of the grid connection relays S _u and S _w are turned off (commercial power grid 3 from the state) is not connected to the relay S _u for system _{interconnection,} the variation of the apparent power at the time of switching only was on (were connected to the commercial power system 3) to state one of the S _w based on the [Delta] S _inv, relay S _u for system _{interconnection,} of the S _w, is not turned on and configured to detect the welding of the (commercial power system 3 to not be connected) towards system interconnection relay of. Here, the grid interconnection relays S _u and S _w are connected from the disconnected state to the interconnection state (in the state where one of the grid interconnection relays is welded, the other grid interconnection relay is connected to the commercial power system 3 The amplitude of the output current _isp from the storage hybrid power generation system 1 changes greatly at the moment when the output current _isp from the power storage hybrid power generation system 1 changes. A change amount ΔS _inv of the apparent power, which is a product of the effective value of _sp , also changes greatly. Therefore, based on the apparent power change ΔS _inv when the grid connection relays S _u and S _w are switched as described above, detection of disconnection of the grid connection relays S _u and S _w , Even when the commercial system voltage is distorted by detecting the welding of the grid connection relay that is not turned on among the system relays S _u and S _w , these grid connection relays S _u , the detection of disconnection and the welding of the S _w can be carried out accurately.

In addition, according to the electricity storage hybrid power generation system 1 of the present embodiment, the apparent power change amount detection circuit 20 is an instantaneous independent system that is an instantaneous value of the amplitude of the output voltage (independent system voltage e _sd ) from the electricity storage hybrid power generation system 1. Based on the maximum voltage value E _max and the instantaneous output current maximum value I _max which is the instantaneous value of the amplitude of the output current i _sp , the apparent power change amount ΔS _inv is calculated. Thereby, the amplitude E _{sd. Of} the output voltage calculated based on the effective value of the output voltage (independent system voltage e _sd ) from the storage hybrid power generation system 1 _{. max} and the amplitude _{I sp} of the output current _{i sp} calculated based on the effective value of the output current _{i sp.} based on the _{max (see} equation (22) below), as compared with the case of calculating the amount of change [Delta] S _inv apparent power, it is possible to shorten the time required for the calculation of the apparent power variation [Delta] S _inv.

In addition, according to the electricity storage hybrid power generation system 1 of the present embodiment, the average value E _avg of the instantaneous self-sustaining system voltage maximum value E _max and the instantaneous output current maximum value I _{max for} a predetermined number of times (the past (c−b + 1) times). The absolute value ΔVg of the voltage amplitude difference and the absolute value ΔI of the current amplitude difference are calculated using the average value _{Iavg of the} current value, and the change amount ΔS _inv of the apparent power is calculated based on these ΔV and ΔI. I made it. As a result, the absolute value ΔV of the voltage amplitude difference and the absolute value ΔI of the current amplitude difference are calculated using only the instantaneous self-sustained system voltage maximum value E _max and the instantaneous output current maximum value I _max. Since the change amount ΔS _inv of the apparent power can be calculated, the grid interconnection relays S _u and S _w and the independent grid relay S _{std. u} , S _std. It is possible to reduce the probability of erroneously detecting _w defects (disconnection and welding).

Further, according to the power storage hybrid power generation system 1 of this embodiment, the output voltage instantaneous amplitude detection circuit 18 includes a LPF51 for removing noise from the autonomous system voltage e _{sd (output} voltage from power storage hybrid power generation system 1) , the output current instantaneous amplitude detection circuit 19, upon which is adapted comprises a LPF 61 for removing noise from the output current _{i sp,} the cutoff frequency _{f c} of the LPF51 and LPF 61, at startup by system interconnection operation mode (disconnected welding detection circuit 16 according to the system interconnection relay S _u, the S when detecting a disconnection and welding of _w), the grid frequency f _uw set, upon activation by autonomous operation mode (autonomous system relay disconnection welding detection circuit autonomous system relay _S Std.U by _24, the detection time) of the disconnection and the welding of the _{S Std.W,} to set the self-supporting system frequency _{f sd} It was. As a result, the apparent power variation ΔS _inv can be accurately detected at the time of start-up in the grid interconnection operation mode even if the commercial grid voltage is distorted. Based on this apparent power variation ΔS _inv , system relay S _u, one of welding or the system interconnection relay of S _w, system interconnection relay S _u, at least one of disconnection of S _w, can be detected accurately. Further, at the time of start-up in the self-sustained operation mode, even if the self-sustained system voltage _esd and the output current _isp are distorted, the apparent power change ΔS _inv can be accurately detected, so this apparent power change ΔS _inv. Based on the relay S _{std. u} , S _std. welding of one of the self-sustaining system relays of _w or the self-sustaining system relay S _{std. u} , S _std. The disconnection of at least one of _w can be accurately detected.

Further, according to the power storage hybrid power generation system 1 of the present embodiment, the relay S _u for system _{interconnection,} while off both S _w (state not to be connected to a commercial power system 3), device output current value Based on the value of the output current i _sp calculated by the calculation circuit 23, it is detected whether or not both of the grid connection relays S _u and S _w are welded. Thus, it is not necessary to detect the value of the output current i _sp directly, moreover, the system interconnection relay S _u, in the state where the turn off both S _w, for both of the grid interconnection relay S _u, S _w and if There has been welded, system interconnection relay S _u, in the case where at least one of S _w is not welded, since the difference between the output current i _sp increases, relay both of the grid interconnection S _u , it is possible to reliably detect the welding of the S _w.

Further, according to the electricity storage hybrid power generation system 1 of the present embodiment, when the autonomous operation is performed at the time of startup of the device (when activated in the autonomous operation mode), the energy storage hybrid power generation system 1 is operated by the amplitude adjustment circuit 25 during the autonomous operation. The amplitude of the output voltage from the inverter is increased stepwise from 0 to match the command value E ^* _cst of the amplitude of the autonomous system voltage _esd , which is the voltage at the time of autonomous operation. Connected to R _load to start independent operation. As a result, the autonomous system relay S _std. When the autonomous operation is performed when the apparatus is activated (when activated in the autonomous operation mode) _{. u} , S _std. It is possible to prevent a sudden increase in current flowing through _w (an external connection switch provided on the output side of the inverter 5).

Further, according to the electricity storage hybrid power generation system 1 of the present embodiment, when the autonomous operation is performed at the time of activation of the device (when activated in the autonomous operation mode), the autonomous system relay S _{std. u} , S _{std. After} detecting disconnection and welding of _w , the power storage hybrid power generation system 1 was connected to the self-sustained load R _load and the self-sustained operation was started. Thereby, at the time of starting of the apparatus, before starting the autonomous operation, the autonomous system relay S _{std. u} , S _std. Disconnection and welding of _w (an external connection switch provided on the output side of the inverter 5) can be confirmed.

In addition, according to the electricity storage hybrid power generation system 1 of the present embodiment, the autonomous system relay S _{std. u} , S _std. Based on the amount of change ΔS _inv in the apparent power when the state is switched from a state in which both of _w are turned off (non-connected state) to a state in which both are turned on (connected state) S _{std. u} , S _std. The disconnection of _w is detected, and the relay S _{std. u} , S _{std. From} the state where both of _w are turned off (the state where the _load is not connected to the self-supporting load R _load ), the self-sustained system relay S _{std. u} , S _std. Based on the amount of change ΔS _inv in the apparent power when switching to a state in which only one of _w is turned on (a state where it is connected to the self-supporting load R _load ), the relay S _{std. u} , S _std. Among the _w, it was to detect the welding of the self-supporting system for the relay of the person that has not been connected to the self-load R _load. As a result, the self-sustained system relay S _{std. Is} based only on the amount of change in the output voltage (self- _supported system voltage e _sd ) from the power storage hybrid power generation system 1 _{. u} , S _{std. When} detecting disconnection or welding of _w , or based only on the amount of change in the output current i _sp , the independent system relay S _{std. u} , S _{std. As} compared with the case where disconnection or welding of _w is detected, even when the independent system voltage _esd and the output current _isp are distorted, the independent system relay S _{std. u} , S _std. Disconnection and welding of _w can be reliably detected.

In addition, according to the electric storage hybrid power generation system 1 of the present embodiment, the independent system relay disconnection welding detection circuit 24 includes the independent system relay _{Sstd. u} , S _std. Based on the value of the output current i _sp calculated by the device output current value calculation circuit 23 in a state where both of _w are turned off (not connected to the self-supporting load R _load ), both of the stand-alone system relays S _{std. u} , S _std. Whether or not _w is welded is detected. As a result, it is not necessary to directly detect the value of the output current i _sp , and the self-sustained system relay S _{std. u} , S _{std. In} a state in which both of _w are turned off (a state where they are not connected to the self-supporting load R _load ), both of the self-supporting system relays S _{std. u} , S _{std. The} case where _w is welded and the relay _{Sstd. u} , S _{std. When} at least one of the _w is not welded, the difference in the output current i _sp becomes large, so both of the independent system relays S _{std. u} , S _std. It is possible to reliably detect the welding of _w .

Further, according to the electricity storage hybrid power generation system 1 of the present embodiment, when the control circuit 7 (the activation control circuit 13) performs the grid interconnection operation at the time of activation of the device, the electricity storage hybrid is operated by the phase angle adjustment circuit 15. After the phase angle of the output voltage from the power generation system 1 (the independent system voltage e _sd when the switch S _sd is 0) is matched with the phase angle θ _uw of the commercial system voltage e _uw , the storage hybrid power generation system 1 is connected to the commercial power It connects to the system | strain 3 and it controls to start a grid connection operation | movement. Thus, the above output voltage from the power storage hybrid power system 1 (self system voltage _{e sd} when the switch _{S sd} is 0), the amplitude _{E uw} of the above commercial system voltage _{e uw. In addition} to adjusting the amplitude according to _max, and also adjusting the phase angle according to the phase angle θ _uw of the commercial grid voltage e _uw , the power storage hybrid power generation system 1 is connected to the commercial power grid 3 to Interconnected operation can be started. Therefore, the power storage when the hybrid power generation system 1 is a commercial power system 3 and the interconnection inverter 5 and since the commercial power system 3 to be able to further reduce fluctuations of the voltage applied to the capacitor C _f provided between the Further, the inrush current to the capacitor C _f can be further suppressed, and a sudden increase in the current flowing through the grid interconnection relays S _u and S _w can be prevented.

Variation:
In addition, this invention is not restricted to the structure of said embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. Next, a modified example of the present invention will be described.

Modification 1:
In the above embodiment, in the adjustment control of the amplitude of the output voltage (self-supporting system voltage e _sd ) from the power storage hybrid power generation system 1 shown in FIG. 3, the switch S _sd is set to the 1 position to the maximum value of _{sd (amplitude) E sd.} The _max, after adjusting the command value ^E _{* cst} of the maximum value of the free-standing system voltage _{e sd,} the switch _{S sd} is switched to the 0 position, freestanding system voltage _e maximum value _{sd (amplitude) E sd. The max} was adjusted to the amplitude before grid connection operation (E _uw.max −ΔE). However, in the start-up control shown in FIG. 5, the independent operation process of S1 is not performed, and as shown in FIG. 14, the switch S _sd is set to the 0 position immediately after the start of the device, Maximum value (amplitude) of the voltage e _sd E _{sd. The max} may be gradually increased from 0 to match the amplitude before the grid interconnection operation (E _uw.max −ΔE) (S21 in FIG. 14). In this case, the adjustment control of the amplitude shown in FIG. 3, when the set switch S _sd at the position of 0, the maximum value of the free-standing system voltage e _sd (amplitude) E _{sd. max} , and the command value E ^* _sd. The initial value of _max (k−1) is set to 0.

  When the control shown in FIG. 14 is performed, the effect of soft start can be obtained when the apparatus is started, as in the case where the control shown in FIG. 5 is performed.

  Note that steps S22, S23, and S24 in FIG. 14 correspond to steps S4, S5, and S6 in FIG. 5, respectively.

Modification 2:
In the above embodiment, in order to detect disconnection and welding of the grid interconnection relays S _u and S _w , the control circuit 7 outputs the output voltage (self-sustained system voltage e) from the power storage hybrid power generation system 1 after the device is started. _sd ) amplitude E _{sd. max} and the amplitude E _{uw. of} the commercial system voltage e _uw detected by the commercial voltage amplitude detection circuit 11 _. The amplitude of the output voltage from the power storage hybrid power generation system 1 was adjusted so that the amplitude difference from _max would be a predetermined value (ΔE = 10V), but the control circuit (amplitude adjustment circuit) The amplitude of the output voltage from the power storage hybrid power generation system may be adjusted so that the amplitude difference becomes a value within a predetermined range (for example, a value within a range from 5 V to 15 V). In this configuration as well, inrush current to the capacitor constituting the LC filter can be suppressed.

Modification 3:
In the above-described embodiment, an example in which the “capacitor” in the claims is the capacitor C _f constituting the LC filter 6 has been described. What is necessary is just the capacitor | condenser connected between the system | strains, or the capacitor | condenser connected between the inverter and the self-supporting load.

Modification 4:
In said embodiment, the example in case the power converter device of this invention is the electrical storage hybrid electric power generation system 1 for solar power generation was demonstrated. However, the power conversion device to which the present invention is applied is not limited to this, and a wide variety of DC / DC converters for distributed power sources such as wind power generators, and bidirectional DC / DC converters for power storage devices, The present invention can also be applied to other types of power storage hybrid power generation systems. Further, the power conversion device to which the present invention is applied is not necessarily limited to the one provided with the distributed power source and the power storage device, but is connected to the external distributed power source and the power storage device, and the power storage hybrid power generation system May be included.

Modification 5:
In the above embodiment, as shown in equation (10) to (14), the difference (the voltage amplitude difference between the average value _{E avg} and last instantaneous self system voltage maximum value _{E max} of the instantaneous self system voltage maximum value _{E max} the absolute value ΔV of), based on the absolute value ΔI of the difference between the average value I _avg and the most recent instantaneous output current maximum value I _max of the instantaneous output current maximum value I _max (current amplitude difference) changes in the apparent power The quantity ΔS _inv was calculated. However, the calculation method of the apparent power change amount ΔS _inv is not limited to this. For example, as shown in the above formulas (1) to (4) and the following formulas (20) to (22), maximum value _{E sd} of the mean value _{E avg} and last autonomous system voltage _{e sd} of the system voltage maximum value _{E max.} the absolute value of the voltage amplitude difference between the _max [Delta] V and the maximum value _{I sp} of the average value _{I avg} and the nearest output current _{i sp} instantaneous output current maximum value _{I max. The} apparent power change amount ΔS _inv may be calculated based on the absolute value ΔI of the current amplitude difference from _max . However, in this case, the time required to determine the disconnection / welding of the grid interconnection relay or the self-sustaining system relay is the shortest and is a half cycle (half cycle) of the waveform of the self-sustaining system voltage _esd .

Next, with reference to FIG. 15, an example of a disconnection / welding detection method according to Modification 5 will be described. FIG. 15 shows an example of a schematic system configuration in the fifth and sixth modifications. FIG. 15 is a control circuit 7, the maximum value of the output current _{i sp (amplitude) I sp.} 1 except that a device output current amplitude detection circuit 70 for detecting _max is provided. In this example, (by disconnection welding detection circuit 16) during startup of the system interconnection operation mode system interconnection relay S _u, upon detection of the disconnection of S _w is the apparent power variation detecting circuit 20, a system interconnection The relays S _u , S _w are disconnected and the output voltage amplitude instantaneous value detection circuit 18 detects the average value E _avg of the instantaneous independent power system maximum voltage E _max for the past plural times, and the grid interconnection relay S _u. , _Sw is connected, and the amplitude E _{sd. Of the} (most recent) output voltage detected by the device output voltage amplitude detection circuit 17 is detected _. The absolute value ΔV of the voltage amplitude difference from _max and the instantaneous output current maximum value I for the past plural times detected by the output current amplitude instantaneous value detection circuit 19 with the grid interconnection relays S _u and S _w disconnected. The maximum value (amplitude) I of the (most recent) output current i _sp detected by the device output current amplitude detection circuit 70 with the average value I _{avg of max} and the grid interconnection relays S _u and S _w in the interconnection state. _sp. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated (detected).

Further, the disconnection welding detection circuit 16, the system interconnection relay S _u, of S _w, when detecting the welding towards the relay that has not been connected to a commercial power system 3, apparent power variation detecting circuit 20, Instantaneous independent system voltage for a plurality of past times detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both of the grid connection relays S _u and S _w are turned off (not connected to the commercial power system 3) By means of the device output voltage amplitude detection circuit 17 in a state where only one of the average value E _avg of the maximum value E _max and the grid interconnection relays S _u and S _w is turned on (connected to the commercial power system 3). Detected (most recent) output voltage amplitude E _{sd. The maximum} instantaneous output current for a plurality of past times detected by the output current amplitude instantaneous value detection circuit 19 in a state where both the absolute value ΔV of the voltage amplitude difference from _max and the grid interconnection relays S _u and S _w are turned off. the average value _{I avg} value _{I max,} system interconnection relay _S u, was detected by the device output in the state where only the oN one current amplitude detecting circuit 70 of the _{S w,} (most recent) output current _{i sp} Maximum value (amplitude) I _sp. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated (detected).

In addition, the independent system relay S _std. (By the independent system relay disconnection welding detection circuit 24) at the start of the independent operation mode _{. u} , S _{std. When} the disconnection of _w is detected, the apparent power change amount detection circuit 20 uses the independent system relay S _{std. u} , S _std. An average value E _avg of the maximum instantaneous autonomous system voltage E _max for the past plural times detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both of _w are turned off (non-connected state), and an independent system relay S _{std. u} , S _{std. The} output voltage amplitude detection circuit 17 detects the output voltage amplitude E _sd. The absolute value ΔV of the voltage amplitude difference from _max and the relay S _{std. u} , S _std. The average value I _avg of the instantaneous output current maximum value I _max for a plurality of past times detected by the output current amplitude instantaneous value detection circuit 19 in a state where both of _w are turned off, and the independent system relay S _{std. u} , S _std. The maximum value (amplitude) I _{sp. of the} (most recent) output current i _sp detected by the device output current amplitude detection circuit 70 in a state where both of _w are turned on _. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated.

Further, the independent system relay _{Sstd. u} , S _{std. w} , when detecting the welding of the relay for the independent system that is not connected to the independent load R _load , the apparent power change amount detection circuit 20 uses the independent system relay S _{std. u} , S _std. The average value E _{avg of the} maximum instantaneous self-sustained system voltage E _max for the past plural times detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both of _w are turned off (not connected to the self-supporting load R _load ). And a relay _{Sstd. u} , S _{std. The} output voltage amplitude E _sd. detected by the device output voltage amplitude detection circuit 17 in a state where only one of _w is turned on (connected to the self-supporting load R _load ) _. The absolute value ΔV of the voltage amplitude difference from _max and the relay S _{std. u} , S _std. The average value I _avg of the instantaneous output current maximum value I _max for a plurality of past times detected by the output current amplitude instantaneous value detection circuit 19 in a state where both of _w are turned off, and the independent system relay S _{std. u} , S _std. detected by one device output current while only the on amplitude detection circuit 70 of _w, the maximum value of (the most recent) output current i _sp (amplitude) I _sp. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated.

Modification 6:
In the above embodiment, the absolute value ΔV of the voltage amplitude difference is calculated using the average value E _avg of the maximum instantaneous self-sustained system voltage value E _max shown in Equation (10), and the maximum instantaneous output current shown in Equation (11) is calculated. The absolute value ΔI of the current amplitude difference was calculated using the average value I _avg of the value I _max . However, the absolute value [Delta] V, and a method of calculating the absolute value ΔI of the current amplitude difference of the voltage amplitude difference is a limited without it, for example, the maximum value E _sd autonomous system voltage e _sd shown in the following equation _(23). using the average value _{E avg} of _max, calculating the absolute value ΔV of the voltage amplitude difference, the maximum value _{I sp} of the output current _{i sp} shown in the following equation _(24). The absolute value ΔI of the current amplitude difference may be calculated using the average value I _{avg of max} . The average value E _avg calculated by the equation (23) is the maximum value E _sd. It is the average value of _max . Therefore, for example, when the commercial system frequency is 50 Hz and E = 50 is set to f = 100 and e = 50, E _avg is obtained when the z-th (z-th) sampling period (half cycle) value is the current value. The maximum value E _{sd. Of} the self-sustained system voltage for 0.5 seconds from 0.5 seconds before to 1 second before _. It corresponds to the average value of _max . The same applies to the average value I _avg calculated by the equation (24).

Then, the absolute value ΔV of the voltage amplitude difference is calculated by substituting the average value E _avg obtained by the equation (23) into the above equation (12) to obtain the maximum value E _sd. The absolute value of the difference between the average value E _{avg of max} and the most recent instantaneous self-sustaining system voltage maximum value E _max may be obtained, or the average value E _avg obtained by the equation (23) 20) and the maximum value E _sd. The average value E _{avg of max} and the maximum value E _sd. You may carry out by the method of _{calculating |} requiring the absolute value of the difference with _max . Further, the calculation of the absolute value ΔI of the current amplitude difference, the mean value _{I avg} determined by equation (24), are substituted into the above equation (13), the maximum value _{I sp} of the output current _{i sp.} The absolute value of the difference between the average value I _{avg of max} and the most recent instantaneous output current maximum value I _max may be obtained, or the average value I _avg obtained by the equation (24) is expressed by the above equation (21 ) to be substituted, the maximum value _{I sp} of the output current _{i sp.} maximum value _{I sp} of the average value _{I avg} and the nearest output current _{i sp} of _max. You may carry out by the method of _{calculating |} requiring the absolute value of the difference with _max . Note that z in the equation (23) is an independent system voltage calculated by the device output voltage amplitude detection circuit 17 for each half cycle (half cycle) of the waveform of the autonomous system voltage _esd using the equation (3). maximum value _{E sd} of e _sd. The sampling value of _max . Further, the z in the formula (24), using equation (22), the device output current amplitude detection circuit 70, which is calculated for each half cycle of the waveform of the output current _{i sp} (half cycle), the output current _{i sp} Maximum value I _sp. The sampling value of _max .

More specifically, in this sixth modification, at the time of detecting disconnection / welding of the grid interconnection relays S _u and S _w at the start of the grid interconnection operation mode, any one of the following changes ΔS of the apparent power: _{The inv} calculation method is used.

The first one of the calculation methods, apparent power variation detecting circuit 20 (disconnection by welding detection circuit 16) system interconnection relay S _u, S _w at the time of disconnection detection, relay S _u for system _{interconnection,} S _w Are disconnected and detected by the device output voltage amplitude detection circuit 17. The output voltage amplitude E _sd. The average value E _{avg of max} and the (latest) instantaneous self-sustained system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 with the grid connection relays S _u and S _w in the linked state The absolute value ΔV of the voltage amplitude difference and the maximum value (amplitude) of the past plural output currents i _sp detected by the device output current amplitude detection circuit 70 with the grid interconnection relays S _u and S _w disconnected. I _{sp. The current} between the average value I _{avg of max} and the (most recent) instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 with the grid interconnection relays S _u and S _w in the interconnection state A change amount ΔS _inv of the apparent power is calculated based on the absolute value ΔI of the amplitude difference. Further, the disconnection welding detection circuit 16, the system interconnection relay S _u, of S _w, when detecting the welding towards the relay that has not been connected to a commercial power system 3, apparent power variation detecting circuit 20, The amplitude E of the output voltage for the past plural times detected by the device output voltage amplitude detection circuit 17 in a state in which both of the grid connection relays S _u and S _w are turned off (not connected to the commercial power system 3). _sd. Detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where only one of the average value E _{avg of max} and the grid interconnection relays S _u and S _w is turned on (connected to the commercial power system 3). , the absolute value ΔV of the voltage amplitude difference between the (last) instantaneous self system voltage maximum value E _max, system interconnection relay S _u, the S both devices while turning off the output current of the _w amplitude detection circuit 70 was detected past the maximum value of the plurality of times of the output current _{i sp (amplitude) I sp. The maximum} instantaneous current value detected by the output current amplitude instantaneous value detection circuit 19 in a state where only one of the average value I _{avg of max} and the grid connection relays S _u and S _w is turned on. Based on the absolute value ΔI of the current amplitude difference from I _max , the apparent power change amount ΔS _inv is calculated.

Further, in the second calculation method, the apparent power variation detection circuit 20, (due to disconnection welding detection circuit 16) system interconnection relay S _u, S _w at the time of disconnection detection, relay S _u for system interconnection, It was detected by S _w the disconnection state to device output voltage amplitude detection circuit 17, the amplitude of the past several times of the output voltage E _sd. The average value E _{avg of max} and the grid output relays S _u and S _w are connected to each other, and the output voltage amplitude E _sd. The absolute value ΔV of the voltage amplitude difference with respect to _max, and the maximum value of the past output current i _sp detected by the device output current amplitude detection circuit 70 with the grid interconnection relays S _u and S _w disconnected. (Amplitude) I _sp. The maximum value (amplitude) I of the (most recent) output current i _sp detected by the device output current amplitude detection circuit 70 with the average value I _{avg of max} and the grid interconnection relays S _u and S _w in the interconnection state. _sp. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated. Further, the disconnection welding detection circuit 16, the system interconnection relay S _u, of S _w, when detecting the welding towards the relay that has not been connected to a commercial power system 3, apparent power variation detecting circuit 20, The amplitude E of the output voltage for the past plural times detected by the device output voltage amplitude detection circuit 17 in a state in which both of the grid connection relays S _u and S _w are turned off (not connected to the commercial power system 3). _sd. Detected by the device output voltage amplitude detection circuit 17 in a state where only one of the average value E _{avg of max} and the grid interconnection relays S _u and S _w is turned on (connected to the commercial power system 3), Output voltage amplitude E _sd. The absolute value ΔV of the voltage amplitude difference with respect to _max and the output current i _sp for the past plural times detected by the device output current amplitude detection circuit 70 in a state where both the grid interconnection relays S _u and S _w are turned off. Maximum value (amplitude) I _{sp. The maximum} (most recent) output current i _sp detected by the device output current amplitude detection circuit 70 in a state where only one of the average value I _{avg of max} and the grid connection relays S _u and S _w is turned on. Value (amplitude) I _sp. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated.

Further, in the modified example 6, the autonomous system relay S _{std. u} , S _std. At the time of detecting the disconnection / welding of _w , one of the following calculation methods of the apparent power change ΔS _inv is used.

In the first calculation method, the apparent power change amount detection circuit 20 is configured to use the independent system relay S _{std. u} , S _{std. When} disconnection of _w is detected, the relay _{Sstd. u} , S _{std. A} plurality of output voltage amplitudes E _sd. detected by the device output voltage amplitude detection circuit 17 in a state where both of _w are turned off (non-connected state) _. The average value E _{avg of max} and the relay S _{std. u} , S _std. The absolute value ΔV of the voltage amplitude difference from the (most recent) instantaneous autonomous system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where both _w are turned on (connected state), and the autonomous system Relay S _{std. u} , S _std. The maximum value (amplitude) I _sp. of the output current i _sp for a plurality of past times detected by the device output current amplitude detection circuit 70 in a state where both of _w are turned off _. The average value I _{avg of max} and the relay S _{std. u} , S _std. Based on the absolute value ΔI of the current amplitude difference from the (most recent) instantaneous output current maximum value I _max detected by the output current amplitude instantaneous value detection circuit 19 in a state where both of _w are turned on (connected state), A change amount ΔS _inv of the apparent power is calculated. Further, the independent system relay _{Sstd. u} , S _{std. w} , when detecting the welding of the relay for the independent system that is not connected to the independent load R _load , the apparent power change amount detection circuit 20 uses the independent system relay S _{std. u} , S _std. The output voltage amplitude E _sd. for the past multiple times detected by the device output voltage amplitude detection circuit 17 in a state where both of _w are turned off (not connected to the self-supporting load R _load ) _. The average value E _{avg of max} and the relay S _{std. u} , S _{std. A} voltage with the (most recent) instantaneous autonomous system voltage maximum value E _max detected by the output voltage amplitude instantaneous value detection circuit 18 in a state where only one of _w is turned on (connected to the autonomous load R _load ) The absolute value ΔV of the amplitude difference and the independent system relay S _{std. u} , S _std. The maximum value (amplitude) I _sp. of the output current i _sp for a plurality of past times detected by the device output current amplitude detection circuit 70 in a state where both of _w are turned off _. The average value I _{avg of max} and the relay S _{std. u} , S _std. It was detected by the output current instantaneous amplitude detection circuit 19 while turning on only one of _w, based on the absolute value ΔI of the current amplitude difference between the (most recent) instantaneous output current maximum value I _max, apparent The amount of power change ΔS _inv is calculated.

In addition, in the second calculation method, the apparent power change detection circuit 20 uses the independent system relay S _{std. u} , S _{std. When} disconnection of _w is detected, the relay _{Sstd. u} , S _{std. A} plurality of output voltage amplitudes E _sd. detected by the device output voltage amplitude detection circuit 17 in a state where both of _w are turned off (non-connected state) _. The average value E _{avg of max} and the relay S _{std. u} , S _{std. The} output voltage amplitude detection circuit 17 detects the output voltage amplitude E _sd. The absolute value ΔV of the voltage amplitude difference from _max and the relay S _{std. u} , S _std. The maximum value (amplitude) I _sp. of the output current i _sp for a plurality of past times detected by the device output current amplitude detection circuit 70 in a state where both of _w are turned off _. The average value I _{avg of max} and the relay S _{std. u} , S _std. The maximum value (amplitude) I _{sp. of the} (most recent) output current i _sp detected by the device output current amplitude detection circuit 70 in a state where both of _w are turned on _. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated. Further, the independent system relay _{Sstd. u} , S _{std. w} , when detecting the welding of the relay for the independent system that is not connected to the independent load R _load , the apparent power change amount detection circuit 20 uses the independent system relay S _{std. u} , S _std. The output voltage amplitude E _sd. for the past multiple times detected by the device output voltage amplitude detection circuit 17 in a state where both of _w are turned off (not connected to the self-supporting load R _load ) _. The average value E _{avg of max} and the relay S _{std. u} , S _{std. The} output voltage amplitude E _sd. detected by the device output voltage amplitude detection circuit 17 with only one of them turned on _. The absolute value ΔV of the voltage amplitude difference from _max and the relay S _{std. u} , S _std. The maximum value (amplitude) I _sp. of the output current i _sp for a plurality of past times detected by the device output current amplitude detection circuit 70 in a state where both of _w are turned off _. The average value I _{avg of max} and the relay S _{std. u} , S _std. detected by one device output current while only the on amplitude detection circuit 70 of _w, the maximum value of (the most recent) output current i _sp (amplitude) I _sp. Based on the absolute value ΔI of the current amplitude difference from _max , the apparent power change amount ΔS _inv is calculated.

Modification 7:
In the above-described embodiment, as shown in the equations (10) to (14), the difference between the average value E _avg of the maximum instantaneous autonomous system voltage value E _max for the past multiple times and the most recent instantaneous autonomous system voltage maximum value E _max the absolute value ΔV (voltage amplitude difference), and the absolute value ΔI of the difference between the average value I _avg and the most recent instantaneous output current maximum value I _max of the instantaneous output current maximum value I _max of the past plurality of times (current amplitude difference) Based on the above, the change amount ΔS _inv of the apparent power was calculated. However, as shown in FIG. 16, the control circuit 7 has an apparent power instantaneous value detection circuit 80 for detecting an instantaneous value of the apparent power (hereinafter referred to as “instantaneous apparent power”), thereby detecting the apparent power change amount. The absolute difference between the average value S _{avg of} the past instantaneous powers detected by the circuit 20 by the instantaneous power instantaneous value detection circuit 80 and the latest instantaneous power S _uw detected by the apparent power instantaneous value detection circuit 80 is absolute. By calculating the value, the change amount ΔS _inv of the apparent power may be obtained. Specifically, the apparent power instantaneous value detection circuit 80 outputs the αβ-phase instantaneous AC voltages e _α and e _β output from the LPF 51 and the APF 52 shown in FIG. 7 and the LPF 61 and the APF 62 shown in FIG. The instantaneous active power P _uw , the instantaneous reactive power Q _uw , and the instantaneous apparent power are _expressed by the following equations (25), (26), and (27) using the αβ-phase instantaneous alternating currents i _α and i _{β. Find Suw} . Then, the apparent power change amount detection circuit 20 calculates an average value S _avg of the past (c−b + 1) times of instantaneous apparent power detected by the apparent power instantaneous value detection circuit 80 using the equation (28), By using the equation (29), the absolute value of the difference between the average value S _avg of the instantaneous apparent power and the latest instantaneous apparent power S _uw detected by the instantaneous power instantaneous value detection circuit 80 is calculated. Change amount ΔS _inv is obtained.

Modification 8:
In the above embodiment, the cutoff frequency _{f c} of the digital low-pass filter (LPF 51 and LPF 61) in the output voltage instantaneous amplitude detection circuit 18 and the output current instantaneous amplitude detection circuit 19, the grid frequency _{f uw} or autonomous system frequency f was set to _sd, the cutoff frequency _{f c} of the LPF51 and LPF 61, may be set to a value in consideration of the surface of the switching noise removal. For example, the cutoff frequency _{f c} of the LPF51 and LPF 61, may be set to less than one-tenth of the switching frequency.

Modification 9:
In the above embodiment, all the circuits in the output voltage amplitude instantaneous value detection circuit 18 shown in FIG. 7 are constituted by digital circuits, and the output values from the digital filters (LPF 51 and APF 52) and the interrupt processing program of the microcomputer are programmed. The instantaneous self-sustained system voltage maximum value E _max is obtained from the calculation result (calculation result by the square sum square root calculator 53). The instantaneous self-sustained system voltage maximum value E _max may be obtained from the output of the analog circuit by replacing at least part of the circuit (the square sum square root calculator 53 of the present embodiment) with an analog circuit. Also for the output current amplitude instantaneous value detection circuit 19 shown in FIG. 8, all the digital circuits (LPF 61, APF 62, and peak value detection circuit (square sum square root calculator 63 of this embodiment)) constituting this circuit are also included. The instantaneous output current maximum value I _max may be obtained from the output of the analog circuit by replacing at least part of the analog circuit.

Modification 10:
In the above-described embodiment, there is a start in the grid connection operation mode and a start in the stand-alone operation mode. At the start in the grid connection operation mode, the disconnection welding of the grid connection relay is detected and the start in the stand-alone operation mode. Sometimes, the electric storage hybrid power generation system that detects the disconnection welding of the relay for the independent power system has been described, but the present invention is not limited to this, and the present invention is applied to a power conversion device having only the grid connection operation mode. Disconnection welding detection of the grid interconnection relay at the time of start-up may be performed, or the present invention is applied to a power conversion device having only the independent operation mode to detect the disconnection welding of the relay for the stand-alone system at start-up. Also good.

Modification 11:
In the above-described embodiment, an example in which the control circuit 7 is configured using a so-called microcomputer has been described. However, the control circuit 7 is not limited thereto, and may be a system LSI, for example.

Modification 12:
In the above embodiments, the disconnection and the welding detection process during a period in FIG. 6 (2) to (4), disconnection welding detection circuit 16, observed when switching the relay S _u, S _w for system interconnection, based on the apparent power variation [Delta] S _inv output from the power storage hybrid power generation system 1, system interconnection relay S _u, detects the disconnection and welding of S _w, in Fig. 10 (2) to (4) In the disconnection / welding detection process during the period, the independent system relay disconnection detection circuit 24 is connected to the independent system relay S _{std. u} , S _std. Based on the change amount ΔS _inv of the apparent power output from the power storage hybrid power generation system 1 when _w is switched, the autonomous system relay S _{std. u} , S _std. The disconnection and welding of _w were detected. However, the present invention is not limited to this. For example, when the disconnection welding detection circuit or the stand-alone system relay disconnection welding detection circuit switches the grid interconnection relay or the independent system relay (from the storage hybrid power generation system). The disconnection and welding of the grid interconnection relay or the independent grid relay may be detected based on the amount of change in the output voltage, current, active power, reactive power, and the like.

1 Power storage hybrid power generation system (power converter)
2a Solar cell (distributed power supply)
2b Power storage device 3 Commercial power system 5 Inverter 11 Commercial voltage amplitude detection circuit (commercial voltage amplitude detection means)
12 Amplitude adjustment circuit (amplitude adjustment means)
13 Start control circuit (start control means)
14b PLL circuit (commercial voltage phase angle detection means)
15 Phase angle adjustment circuit (phase angle adjustment means)
16 Disconnection welding detection circuit (disconnection welding detection means)
18 Output voltage amplitude instantaneous value detection circuit (output voltage amplitude instantaneous value detection means)
19 Output current amplitude instantaneous value detection circuit (output current amplitude instantaneous value detection means)
20 Apparent power change detection circuit (Apparent power change detection means)
21 Output current value detection circuit (output current value detection means)
22 Passing current value estimation circuit (passing current value estimation means)
23 Device output current value calculation circuit (device output current value calculation means)
24 Relay disconnection welding detection circuit for autonomous system (switch disconnection welding detection means for autonomous system)
25 Amplitude adjustment circuit during independent operation (Amplitude adjustment means during independent operation)
51 LPF (first low-pass filter)
61 LPF (second low-pass filter)
C _f capacitor E _{u. max} −ΔE Amplitude R _load independent load S _{std. u} , S _{std. w} Relay for independent system (switch for independent system)
S _u , S _w Grid connection relay (Switch for grid connection)
ΔE Amplitude difference ΔI Absolute value of current amplitude difference ΔS _Inv Apparent power change ΔV Absolute value of voltage amplitude difference

Claims (17)

A power converter for connecting a distributed power source to a commercial power system,
An inverter that converts DC power based on power input from at least one of the distributed power source and a power storage device that stores power output from the distributed power source into AC power;
A capacitor connected between the inverter and the commercial power system;
Commercial voltage amplitude detection means for detecting the amplitude of the commercial grid voltage, which is the voltage of the commercial power grid;
Grid interconnection having an amplitude difference within a predetermined range from the amplitude of the commercial grid voltage detected by the commercial voltage amplitude detection means by gradually increasing the amplitude of the output voltage from the power converter from a predetermined value Amplitude adjustment means to match the amplitude before operation,
A pair of grid connection switches for switching between a connected state and a disconnected state of the distributed power source to the commercial power system;
Based on the amount of change in the output value from the power converter when the grid connection switch is switched, a disconnection welding detection means for detecting disconnection and welding of the grid connection switch,
When grid connection operation is performed at the time of start-up of the apparatus, the amplitude adjustment unit adjusts the amplitude of the output voltage from the power converter to the amplitude before the grid connection operation, and then the disconnection welding detection unit Power conversion comprising: an activation control unit configured to connect the power conversion device to the commercial power system and perform control so as to start a grid interconnection operation after detecting disconnection and welding of the grid interconnection switch apparatus. Apparent power change amount detecting means for detecting a change amount of the apparent power that is a product of the effective value of the output voltage and the effective value of the output current from the power converter,
The amount of change in the output value from the power converter used for detecting disconnection and welding of the grid interconnection switch by the disconnection welding detection means is the amount of change in the apparent power detected by the apparent power change amount detection means. The power conversion device according to claim 1, wherein:   The disconnection welding detection means is based on the apparent power change detected by the apparent power change detection means when the grid connection switch is switched from the disconnected state to the connected state. Disconnection of the interconnection switch is detected, and from the state in which both of the interconnection switches are not connected to the commercial power system, only one of the interconnection switches is connected. Based on the change amount of the apparent power detected by the apparent power change amount detecting means when switching to the state connected to the commercial power system, the commercial power system of the pair of grid interconnection switches The power conversion device according to claim 2, wherein welding of a grid connection switch that is not connected is detected. Output voltage amplitude instantaneous value detecting means for detecting an instantaneous value of the amplitude of the output voltage from the power converter;
An output current amplitude instantaneous value detecting means for detecting an instantaneous value of the amplitude of the output current from the power converter,
The apparent power change amount detecting means is based on the instantaneous value of the output voltage amplitude detected by the output voltage amplitude instantaneous value detecting means and the instantaneous value of the output current amplitude detected by the output current amplitude instantaneous value detecting means. The power converter according to claim 2, wherein the change amount of the apparent power is calculated. The apparent power change amount detecting means is
When detecting disconnection of the system interconnection switch by the disconnection welding detection means,
An average value of the instantaneous value of the amplitude of the output voltage for a predetermined number of times detected by the output voltage amplitude instantaneous value detecting means with the grid interconnection switch in the disconnected state, and the grid interconnection switch with the interconnection A first instantaneous voltage amplitude difference that is an absolute value of a voltage amplitude difference from the instantaneous value of the amplitude of the output voltage detected by the output voltage amplitude instantaneous value detection means in a state;
An average value of an instantaneous value of the output current amplitude for a predetermined number of times detected by the output current amplitude instantaneous value detecting means with the grid interconnection switch in the disconnected state, and the grid interconnection switch with the interconnection Based on the first instantaneous current amplitude difference that is the absolute value of the current amplitude difference from the instantaneous value of the amplitude of the output current detected by the output current amplitude instantaneous value detecting means in the state, the change amount of the apparent power is calculated. Calculate
When detecting the welding of the grid connection switch that is not connected to the commercial power system among the pair of grid connection switches by the disconnection welding detection means,
Among the pair of grid interconnection switches, the average of the instantaneous values of the amplitudes of the output voltage for a predetermined number of times detected by the output voltage amplitude instantaneous value detection means in a state where both switches are not connected to the commercial power system A second instantaneous value that is the absolute value of the voltage amplitude difference between the value and the instantaneous value of the output voltage amplitude detected by the output voltage amplitude instantaneous value detecting means in a state where only one switch is connected to the commercial power system. Voltage amplitude difference,
Among the pair of grid interconnection switches, the average of the instantaneous values of the amplitudes of the output currents for a predetermined number of times detected by the output current amplitude instantaneous value detection means in a state where both switches are not connected to the commercial power system A second instantaneous value that is an absolute value of a current amplitude difference between the value and an instantaneous value of the output current amplitude detected by the output current amplitude instantaneous value detecting means in a state where only one switch is connected to the commercial power system. The power converter according to claim 4, wherein a change amount of the apparent power is calculated based on a current amplitude difference. The output voltage amplitude instantaneous value detecting means includes a first low-pass filter for removing noise from the output voltage from the power converter,
The output current amplitude instantaneous value detecting means includes a second low-pass filter for removing noise of the output current from the power converter,
The cutoff frequency of the first low-pass filter and the second low-pass filter is set to a commercial system frequency when the disconnection and welding of the grid interconnection switch is detected by the disconnection and welding detection means. The power conversion device according to claim 4 or 5. Output current value detecting means for detecting an output current value from the inverter;
A passing current value estimating means for estimating a capacitor passing current value which is a value of a current flowing through the capacitor;
Based on the output current value from the inverter detected by the output current value detection means and the capacitor passing current value estimated by the passing current value estimation means, the output current value from the power converter is calculated. A device output current value calculating means for
The disconnection welding detection means is based on the output current value calculated by the device output current value calculation means in a state where both of the pair of grid connection switches are not connected to the commercial power system. The power conversion device according to claim 1, wherein welding of both switches of the pair of grid interconnection switches is detected. A power converter for converting DC power from a distributed power source into AC power and supplying the converted AC power to a self-supporting load,
An inverter that converts DC power based on power input from at least one of the distributed power source and a power storage device that stores power output from the distributed power source into AC power;
Amplitude adjustment means during stand-alone operation in which the amplitude of the output voltage from the power converter is increased stepwise from 0 to match the command value of the amplitude of the stand-alone system voltage that is the voltage during stand-alone operation;
A pair of independent system switches for switching between a connected state and a disconnected state of the self-supporting load and the power converter;
Based on the amount of change in the output value from the power converter when the switch for the independent system is switched, a switch disconnection detection means for detecting disconnection and welding of the switch for the independent system,
When autonomous operation is performed at the time of startup of the device, the amplitude of the output voltage from the power conversion device is adjusted to the command value of the amplitude of the autonomous system voltage by the amplitude adjustment means during autonomous operation, and then the autonomous system An activation control means for controlling the power converter to connect to the self-supporting load and to start the self-sustaining operation after detecting the disconnection and welding of the switch for the self-supporting system by the switch disconnection welding detection means. A power converter provided. Apparent power change amount detecting means for detecting a change amount of the apparent power that is a product of the effective value of the output voltage and the effective value of the output current from the power converter,
The amount of change in the output value from the power converter used for detecting the disconnection and welding of the switch for the independent system by the switch disconnection welding detection unit for the independent system is the apparent power detected by the apparent power change detection unit. The power conversion device according to claim 8, wherein the power conversion device is an amount of change.   Based on the amount of change in apparent power detected by the amount of apparent power change detected by the means for detecting the amount of apparent power change when the switch for welding of the independent system is switched from the disconnected state to the connected state. A disconnection of the switch for the independent system is detected, and from the state where both of the switches for the independent system are not connected to the self-supporting load, only one switch for the independent system is connected to the self-supporting load. Based on the change amount of the apparent power detected by the apparent power change amount detecting means when switching to the connected state, the one of the pair of independent power system switches not connected to the self-supporting load The power converter according to claim 9, wherein the welding of the switch for a self-supporting system is detected. Output voltage amplitude instantaneous value detecting means for detecting an instantaneous value of the amplitude of the output voltage from the power converter;
An output current amplitude instantaneous value detecting means for detecting an instantaneous value of the amplitude of the output current from the power converter,
The apparent power change amount detecting means is based on the instantaneous value of the output voltage amplitude detected by the output voltage amplitude instantaneous value detecting means and the instantaneous value of the output current amplitude detected by the output current amplitude instantaneous value detecting means. The power converter according to claim 9 or 10, wherein the change amount of the apparent power is calculated. The apparent power change amount detecting means is
By detecting the disconnection of the switch for the self-supporting system by the switch disconnection welding detection means for the self-supporting system,
An average value of the instantaneous value of the amplitude of the output voltage for a predetermined number of times detected by the output voltage amplitude instantaneous value detecting means with the independent system switch in the disconnected state and the independent system switch in the connected state A third instantaneous voltage amplitude difference which is an absolute value of a voltage amplitude difference from an instantaneous value of the amplitude of the output voltage detected by the output voltage amplitude instantaneous value detection means;
An average value of the instantaneous value of the output current amplitude for a predetermined number of times detected by the output current amplitude instantaneous value detecting means with the independent system switch in the disconnected state, and the independent system switch in the connected state. Based on the third instantaneous current amplitude difference that is the absolute value of the current amplitude difference from the instantaneous value of the amplitude of the output current detected by the output current amplitude instantaneous value detection means, the change amount of the apparent power is calculated,
When detecting the welding of the switch for the self-supporting system that is not connected to the self-supporting load among the pair of switches for the self-supporting system by the switch disconnection welding detection means for the self-supporting system,
Among the pair of independent power system switches, the average value of the instantaneous values of the output voltage amplitude for a predetermined number of times detected by the output voltage amplitude instantaneous value detection means in a state where both switches are not connected to the independent load; The fourth instantaneous voltage amplitude difference which is the absolute value of the voltage amplitude difference from the instantaneous value of the output voltage amplitude detected by the output voltage amplitude instantaneous value detecting means with only one switch connected to the self-supporting load. When,
Among the pair of independent power system switches, the average value of the instantaneous values of the amplitudes of the output current for a predetermined number of times detected by the output current amplitude instantaneous value detection means in a state where both switches are not connected to the self-supporting load; The fourth instantaneous current amplitude difference which is the absolute value of the current amplitude difference from the instantaneous value of the output current amplitude detected by the output current amplitude instantaneous value detecting means with only one switch connected to the self-supporting load The power conversion device according to claim 11, wherein a change amount of the apparent power is calculated based on The output voltage amplitude instantaneous value detecting means includes a first low-pass filter for removing noise from the output voltage from the power converter,
The output current amplitude instantaneous value detecting means includes a second low-pass filter for removing noise of the output current from the power converter,
At the time of detecting disconnection and welding of the switch for the independent system by the disconnection welding detection unit for the independent system, the cutoff frequency of the first low-pass filter and the second low-pass filter is determined from the power conversion device during the independent operation. The power conversion device according to claim 11, wherein the power conversion device is set to a self-supporting system frequency that is a frequency of the output voltage and the output current. A capacitor connected between the inverter and the self-supporting load;
Output current value detecting means for detecting an output current value from the inverter;
A passing current value estimating means for estimating a capacitor passing current value which is a value of a current flowing through the capacitor;
Based on the output current value from the inverter detected by the output current value detection means and the capacitor passing current value estimated by the passing current value estimation means, the output current value from the power converter is calculated. A device output current value calculating means for
The self-standing system switch disconnection welding detecting means is configured to output the current value calculated by the device output current value calculating means in a state where both of the pair of self-supporting system switches are not connected to the self-supporting load. 14. The power conversion device according to claim 8, wherein welding of both of the pair of independent system switches is detected based on the switch. 14. Commercial voltage phase angle detection means for detecting the phase angle of the commercial grid voltage;
Phase angle adjusting means for adjusting the phase angle of the output voltage from the power converter to the phase angle of the commercial system voltage detected by the commercial voltage phase angle detecting means,
When starting up the apparatus, the start control means adjusts the phase angle of the output voltage from the power converter to the phase angle of the commercial system voltage by the phase angle adjusting means when performing grid connection operation. The power conversion device according to claim 1, wherein the power conversion device is connected to the commercial power system and controlled to start grid connection operation. apparatus.   The start control means performs a self-sustained operation control before shifting to the grid interconnection operation when performing the grid interconnection operation at the start-up of the device, and at the time of the self-sustained operation control, the output voltage of the power conversion device is controlled. The power converter according to any one of claims 1 to 7, wherein the amplitude is adjusted to the amplitude before the grid connection operation by the amplitude adjusting unit.   The amplitude adjustment means increases the amplitude of the output voltage from the power converter in a stepwise manner from the amplitude of the independent power system voltage output from the power converter during independent operation, or 0, and The power conversion device according to claim 1, wherein the power conversion device is adjusted to an amplitude before operation.

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