JP2015198487A - Voltage control device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide voltage control device and method for stabilizing the DC voltage of a DC wire connected to each converter of plural dispersion type power sources.SOLUTION: Converters 21 to 26 are connected to each dispersion type power source 10. The converters 21 to 26 are connected to a bus voltage control device 40 through a communication line L2. A controller 41 of the bus voltage control device 40 detects the bus voltage of a DC bus L1, and detects a ripple voltage having a bus voltage waveform. When the amplitude of the ripple voltage is determined to be not less than a threshold value, the controller 41 of the bus voltage control device 40 determines a compensation voltage for offsetting ripple, and executes control instruction processing of offsetting the ripple voltage on the converters 21 to 26.

Description

  The present invention relates to a voltage control apparatus and a voltage control method for controlling a DC voltage of a DC wiring connected to each converter of a plurality of distributed power sources.

  In recent years, distributed power supply devices using distributed power sources such as solar power generation and fuel cells are becoming popular. The distributed power supply device converts DC power generated by the distributed power supply into AC power using, for example, a power conditioner and outputs the AC power to a commercial power system.

  In the power converter of this power conditioner, the converter and the inverter are connected by a DC bus (DC wiring). Then, the inverter converts the DC input voltage into an AC voltage having the same frequency as the system voltage. In this case, a large ripple current having a frequency twice the system frequency is superimposed on the DC bus. Therefore, a technique for suppressing the ripple current has been studied (for example, see Patent Document 1). In the technique of Patent Document 1, the power conversion device includes a boost chopper circuit that boosts an input voltage from a distributed power supply, and an inverter circuit that converts an output voltage of the boost chopper circuit into an alternating current. Furthermore, a first control circuit for controlling the output voltage and a second control circuit for controlling the chopper input current are provided. The first control circuit has a low-pass filter that removes a ripple component contained in the output voltage.

WO2011 / 090210

  As described in Patent Document 1, in order to suppress this ripple, it is necessary to provide a large number of DC bus capacitors in the DC bus. Furthermore, this ripple tends to shorten the life of the capacitor. When a large number of long-life capacitors are used, the size of the DC bus capacitor increases, and as a result, the size of the power conditioner also increases.

  The present invention has been made in view of such problems, and an object thereof is to provide a voltage control device for stabilizing the DC voltage of DC wiring connected to each converter of a plurality of distributed power sources, and The object is to provide a voltage control method.

  (1) A voltage control device that solves the above problems is connected to a converter that converts DC power of a distributed power source and an inverter that is connected to the converter via DC wiring, and performs output control on the converter. A control unit for instructing is provided. And the said control part specifies the ripple voltage in the DC voltage of the said DC wiring, and transmits the control command which produces | generates the electric power of the reverse phase for negating the said ripple voltage to the said converter, It is characterized by the above-mentioned. .

(2) In the voltage control apparatus, it is preferable that the control unit detects a DC voltage of the DC wiring and specifies a ripple voltage in the DC voltage.
(3) In the voltage control device, the control unit measures a discrete value of a DC voltage of the DC wiring, and generates a control command for generating an antiphase power for canceling a ripple voltage in the discrete value. Is preferably transmitted.

  (4) In the voltage control device, the control unit detects a system voltage waveform, predicts a ripple voltage in a DC voltage based on the system voltage waveform, and has an antiphase for canceling the predicted ripple voltage. It is preferable to transmit a control command for generating electric power to the converter.

  (5) In the voltage control device, the control unit obtains a power status of the energy storage means in the distributed power source connected to the DC wiring, and issues a control command for charging or discharging according to the power status. It is preferable to transmit to the converter connected to the energy storage means.

  (6) In the voltage control device, the control unit obtains a power status of the energy storage means in a distributed power source connected to the DC wiring, and time-divides charging and discharging according to the power status. It is preferable to transmit the control command to be performed to the converter connected to the energy storage means.

  (7) In the voltage control apparatus, the control unit is connected to a converter that converts DC power of each distributed power source in a plurality of distributed power sources, acquires a power status of the distributed power source, and It is preferable to specify a converter that transmits a control command according to a power supply state and transmit the converter to the converter.

  (8) In the voltage control device, when a plurality of converters that transmit a control command are specified in accordance with the power supply status, power of opposite phase for canceling the ripple voltage is distributed, and the control command is sent to each converter. Is preferably transmitted.

  (9) In the voltage control device, the control unit obtains power statuses of a plurality of energy storage units in a distributed power source connected to the DC wiring, and in accordance with the power status, each control unit stores each power storage unit. It is preferable to transmit a control command for charging or discharging to each connected converter.

  ADVANTAGE OF THE INVENTION According to this invention, the DC voltage of the DC wiring connected to each converter of a some distributed power supply can be stabilized.

Explanatory drawing of the structure of the voltage control apparatus in 1st Embodiment. Explanatory drawing of the process sequence in 1st Embodiment. The timing chart about the discharge control in 1st Embodiment. The timing chart about the charge control in 1st Embodiment. The timing chart about the charging / discharging control in 1st Embodiment. Explanatory drawing of the process sequence in 2nd Embodiment. The timing chart about control of the energy creation means in 2nd Embodiment. The timing chart about the equalization control in the some energy storage means in 2nd Embodiment. The timing chart about the time division control in the some energy storage means in 2nd Embodiment. Explanatory drawing of the process sequence in 3rd Embodiment. The timing chart in 3rd Embodiment. Explanatory drawing of the process sequence in 4th Embodiment. The timing chart in 4th Embodiment.

<First Embodiment>
The first embodiment will be described with reference to FIGS.
As shown in FIG. 1, in the first embodiment, a power control system U <b> 1 is used in order to effectively use energy creation and energy storage. The power control system U1 includes a plurality of power conversion devices such as a converter unit 20 and an inverter 30. Here, converter unit 20 and inverter 30 are connected via a DC wiring (DC bus L1). The converter unit 20 is connected to the distributed power source 10 and the inverter 30 is connected to a system power source 50 that is a commercial power source. In the present embodiment, the DC voltage (bus voltage) of the DC bus L1 is stabilized.

In the present embodiment, it is assumed that the solar cell panels 11, 12, 13, the fuel cell 14, the storage battery 15, and the electric vehicle 16 are used as the distributed power source 10.
The solar cell panels 11, 12, and 13 are power generation devices that convert solar energy into DC power, and function as energy creation means. Each of the solar battery panels 11, 12, 13 includes a solar battery panel formed by connecting a plurality of solar battery cells as a main part.

  The fuel cell 14 is a power generator that obtains DC power by chemically reacting hydrogen and oxygen using a fuel gas containing hydrogen such as natural gas and an oxidant gas containing oxygen such as air. Function as.

The storage battery 15 is a battery that charges electric power and supplies this electric power as required, and is an energy storage means that can be used repeatedly.
The electric vehicle 16 includes an in-vehicle charging device and is driven by an electric motor, and functions as an energy storage unit that supplies electric power stored in the vehicle to a house. The electric vehicle 16 includes a gasoline engine and includes a plug-in hybrid car that can be supplied and charged directly from a household power source using a plug (plug-in device).

  The converter unit 20 includes converters 21 to 26 connected to the respective distributed power sources 10. Each converter 21 to 26 performs chopper control for generating a necessary DC voltage (for example, DC 350 V) by turning on / off the switching element (switching control).

  Converters 21 to 23 are connected to solar cell panels 11 to 13, respectively, and perform maximum power point tracking control (MPPT control) according to the generated power that is affected by the solar radiation condition. And the output of the solar cell panels 11-13 is converted into a bus voltage value, and it outputs to DC bus L1.

The converter 24 is connected to the fuel cell 14, converts the output (direct current) of the fuel cell 14 into a bus voltage value, and outputs it to the DC bus L1.
The converter 25 is connected to the storage battery 15, converts the output (direct current) of the storage battery 15 into a bus voltage value and outputs it to the DC bus L 1, or supplies power supplied from the DC bus L 1 to the storage battery 15. .

  The converter 26 is connected to the electric vehicle 16, converts the output (direct current) of the electric vehicle 16 into a bus voltage value and outputs it to the DC bus L 1, or supplies electric power supplied from the DC bus L 1 to the electric vehicle 16. To do.

  Here, the converters 25 and 26 connected to the energy storage means are charged when the bus voltage value rises, and are charged and discharged when the bus voltage value falls, thereby making the bus voltage value constant. Control to be.

  Each converter 21-26 is connected to inverter 30 via DC bus L1. In the present embodiment, a single inverter 30 is used.

  The inverter 30 includes a control unit that performs switching control. The control unit of the inverter 30 performs conversion between direct current and alternating current by performing switching control of the switching element of the inverter 30. Here, the DC power is converted into AC power having a voltage and frequency that can be linked to the system power supply 50 (for example, AC 202V, 50 Hz).

  The inverter 30 supplies AC power to the system power supply 50 via a distribution board (not shown). The amount of AC power is measured by a power meter provided between the distribution board and the commercial system. The distribution board is connected to a home load that supplies AC power.

  Further, a bus voltage control device 40 is provided in the power control system U1. The bus voltage control device 40 includes a control unit 41 that controls the bus voltage. The control unit 41 includes a voltage detection unit 411 and an output instruction unit 412.

  The voltage detection unit 411 is connected to a sensor that measures the bus voltage of the DC bus L1. Then, the voltage detection unit 411 executes processing for acquiring information on the measured bus voltage from the sensor and supplying the information to the output instruction unit 412.

  The output instruction unit 412 is connected to each control unit of the converters 21 to 26 via the communication line L2. The output instruction unit 412 holds information related to the reference value (reference voltage) of the bus voltage. Then, the output instruction unit 412 calculates a ripple voltage waveform by subtracting the reference voltage from the bus voltage. Further, the output instruction unit 412 calculates the amplitude, period, and phase of the ripple waveform by waveform analysis of the calculated ripple voltage waveform. Then, output instruction unit 412 executes processing for instructing each control unit of converters 21 to 26 to adjust the output voltage based on the ripple voltage waveform. Furthermore, the output instruction unit 412 holds data relating to the threshold value for the ripple voltage in order to determine whether or not the converter needs to be controlled. In this embodiment, the output control of the converter is instructed when the amplitude of the ripple voltage becomes equal to or greater than the threshold value.

Next, the bus voltage control process will be described with reference to FIG.
Here, the control unit 41 of the bus voltage control device 40 executes a bus voltage detection process (step S01). Specifically, the voltage detection unit 411 of the control unit 41 measures (samples) the bus voltage of the DC bus L1 using a sensor. Then, the voltage detection unit 411 supplies the measurement result (bus detection voltage) to the output instruction unit 412. In this case, a value sufficiently shorter than the period of the ripple voltage waveform is used as the sampling period of the bus voltage measurement. For example, since the ripple voltage waveform has a period twice that of the system voltage waveform, a value smaller than twice the Nyquist period of the system voltage waveform is used as the sampling period.

  Next, the control part 41 of the bus voltage control apparatus 40 performs a ripple voltage detection process (step S02). Specifically, the output instruction unit 412 of the control unit 41 generates a bus voltage waveform by associating the bus detection voltage acquired from the voltage detection unit 411 with the acquisition time, and records it in the memory. Then, the output instruction unit 412 calculates a ripple voltage waveform by subtracting the reference voltage from the bus voltage waveform stored in the memory. Further, the output instruction unit 412 calculates the amplitude, period, and phase of the ripple waveform by waveform analysis of the calculated ripple voltage waveform.

  Next, the control part 41 of the bus voltage control apparatus 40 performs the determination process about whether it is more than a threshold value (step S03). Specifically, the output instruction unit 412 of the control unit 41 compares the calculated ripple voltage amplitude with a threshold value.

  When it is determined that the amplitude of the ripple voltage is not equal to or greater than the threshold value (in the case of “NO” in step S03), the control unit 41 of the bus voltage control device 40 returns to the bus voltage detection process (step S01).

  On the other hand, when it is determined that the amplitude of the ripple voltage is equal to or greater than the threshold (in the case of “YES” in step S03), the control unit 41 of the bus voltage control device 40 executes a compensation voltage determination process for ripple cancellation (step S03). S04). Specifically, the output instruction unit 412 of the control unit 41 specifies an antiphase waveform whose phase is shifted by 180 degrees in order to cancel (cancel) the calculated ripple voltage waveform. Here, the amplitude (compensation voltage value) and period of the antiphase waveform are set to the same value as the ripple voltage waveform.

Next, the control unit 41 of the bus voltage control device 40 executes a control instruction process (step S05). Here, the output instruction unit 412 of the control unit 41 supplies an instruction to generate an antiphase waveform for canceling the ripple voltage waveform to the converter connected to the distributed power source of the energy storage means. Specifically, the output instruction unit 412 detects the charge amount (power supply status) of the storage battery 15 that is an energy storage means. And according to this charge amount, a control command is transmitted to converter 25 connected to storage battery 15. This control command includes information (compensation voltage value, period, phase) for generating an antiphase waveform. Here, the following three types of output control are performed according to the state of charge of the storage battery 15.
First state: a state where the charge amount is larger than the first reference value, for example, a state close to a fully charged state.
Second state: a state where the charge amount is smaller than the second reference value (less than the first reference value), for example, close to complete discharge
Third state: A state in which the amount of charge is equal to or less than the first reference value and equal to or greater than the second reference value and is close to, for example, about half the charge state.

As shown in FIGS. 3 to 5, it is assumed that a ripple voltage having a period T is generated as the bus detection voltage.
As shown in FIG. 3, in the first state, the bus voltage control device 40 instructs the converter 25 to control the discharge voltage. In this case, the control unit of the converter 25 that has acquired the control command outputs an antiphase discharge voltage for canceling the ripple voltage waveform.

  Further, as shown in FIG. 4, in the second state, the bus voltage control device 40 instructs the converter 25 to control the charging voltage. In this case, the control unit of the converter 25 that has acquired the control command stores the charge with a reverse phase charging voltage for canceling the ripple voltage waveform.

  Further, as shown in FIG. 5, in the third state, the bus voltage control device 40 instructs the converter 25 to control the charge / discharge voltage. In this case, the control unit of the converter 25 that has acquired the control command repeats charging and discharging at an opposite phase for canceling the ripple voltage waveform.

According to this embodiment, the following effects can be obtained.
(1) In the present embodiment, the control unit 41 of the bus voltage control device 40 performs a bus voltage detection process (step S01). And the control part 41 of the bus voltage control apparatus 40 performs a control instruction | indication process (step S05). In this case, the control unit 41 of the bus voltage control device 40 supplies an instruction to generate an antiphase waveform for canceling the ripple voltage waveform. Thereby, the bus voltage of the DC bus L1 can be stabilized. Although a capacitor is connected to the DC bus L1, the life of the capacitor can be extended. Furthermore, a small-sized capacitor can be employed in the DC bus L1.

  (2) In this embodiment, the control part 41 of the bus voltage control apparatus 40 controls the discharge in the converter 25, charge, and charging / discharging according to the charge amount of the storage battery 15 which is an energy storage means. Thereby, suppression of a ripple voltage can be aimed at according to the condition of a distributed power supply. Therefore, the charge amount of the storage battery 15 can be adjusted while stabilizing the bus voltage.

<Second Embodiment>
Next, a second embodiment will be described with reference to FIGS. In the first embodiment, the converter 25 connected to the storage battery 15 performs output control of the converter connected to the distributed power source of the energy storage means. In the second embodiment, the control target device is specified according to the state of the distributed power source, and detailed description of the same parts is omitted.

  First, as shown in FIG. 6, the control unit 41, like steps S01 to S03, performs a bus voltage detection process (step S11), a ripple voltage detection process (step S12), and a determination process as to whether or not the threshold value is exceeded. (Step S13) is executed.

  When it is determined that the amplitude of the ripple voltage is not equal to or greater than the threshold (in the case of “NO” in step S13), the control unit 41 of the bus voltage control device 40 returns to the bus voltage detection process (step S11).

  On the other hand, when it is determined that the amplitude of the ripple voltage is equal to or greater than the threshold value (in the case of “YES” in step S13), the control unit 41 of the bus voltage control device 40 executes a converter state specifying process (step S14). Specifically, the output instruction unit 412 of the control unit 41 acquires operating status information from each of the converters 21 to 26.

  Next, the control part 41 of the bus voltage control apparatus 40 performs the converter specific process of a control object based on an operation condition (step S15). Specifically, the output instruction unit 412 of the control unit 41 specifies a converter capable of canceling the ripple voltage based on the operating status. For example, in the converter connected to the energy storage unit, when it is determined that the ripple voltage can be canceled, the converter connected to the energy storage unit is specified as a control target. On the other hand, when it is determined that the ripple voltage cannot be canceled by the energy storage means, the converter connected to the energy creation means is specified as a control target. When it is determined that the ripple voltage can be canceled using a plurality of converters, the output instruction unit 412 specifies these converters as control targets.

  Next, the control part 41 of the bus voltage control apparatus 40 performs the compensation voltage determination process for ripple cancellation (step S16). Specifically, the output instruction unit 412 of the control unit 41 specifies the calculated amplitude of the ripple voltage waveform as the compensation voltage value.

  Next, the control unit 41 of the bus voltage control device 40 executes compensation voltage distribution processing (step S17). Specifically, the output instruction unit 412 of the control unit 41 allocates all compensation voltage values to this converter when canceling the ripple voltage in one converter. On the other hand, when the ripple voltage is canceled by a plurality of converters, the compensation voltage value is divided and assigned to each converter. For example, a controllable compensation voltage value is determined based on the operating status of each converter.

  Next, the control unit 41 of the bus voltage control device 40 executes a control instruction process (step S18). Specifically, the output instruction unit 412 of the control unit 41 transmits a control command for output of an antiphase waveform for canceling the ripple voltage to the specified converter to be controlled. This control command includes information regarding the distributed compensation voltage value, the same period as the ripple voltage waveform, and the reverse phase of the ripple voltage waveform.

FIG. 7 shows an embodiment in which an output of an antiphase waveform for canceling a ripple voltage is instructed by using a converter 21 connected to a solar cell panel 11 which is an energy generating means.
FIG. 8 shows an embodiment in which the storage battery 15 and the electric vehicle 16 are instructed to output an antiphase waveform for canceling the ripple voltage by using converters 25 and 26 respectively connected thereto. Here, the control unit 41 of the bus voltage control device 40 divides the compensation voltage value for canceling the ripple voltage into two, and instructs each converter (25, 26) to output each antiphase waveform.

  FIG. 9 shows an example in which the storage battery 15 and the electric vehicle 16 are instructed to output an antiphase waveform for canceling the ripple voltage using converters 25 and 26 respectively connected thereto. Here, the antiphase waveform is time-divided every half cycle, and the output of the antiphase waveform by the discharge voltage in the converter 25 and the charge voltage in the converter 26 is instructed.

According to this embodiment, the following effects can be obtained.
(3) In this embodiment, the control part 41 of the bus voltage control apparatus 40 performs the specific process of the state of a converter (step S14). The control part 41 of the bus voltage control apparatus 40 performs the converter specific process of a control object based on an operation condition (step S15). Thereby, stabilization of the bus voltage of DC bus L1 can be aimed at according to the connection condition and operation condition of an energy creation means or an energy storage means. For example, in the energy creation means using natural energy such as the solar cell panels 11 to 13, the output varies depending on the natural environment. In addition, the fuel cell 14 is less responsive when the output fluctuates than the energy storage means. In consideration of the characteristics of each distributed power source, the bus voltage of the DC bus L1 can be stabilized.

  (4) In this embodiment, when a plurality of converters can be used, the output instruction unit 412 identifies these converters as control targets. The control unit 41 of the bus voltage control device 40 executes compensation voltage distribution processing (step S17). Thereby, the load of the output control for stabilizing the bus voltage can be distributed. Therefore, even when one distributed power supply 10 cannot cope with the problem, the bus voltage can be stabilized by using a plurality of distributed power supplies 10.

<Third Embodiment>
Next, a third embodiment will be described with reference to FIGS. 10 and 11. In the first embodiment, the control unit 41 of the bus voltage control device 40 uses a value that is sufficiently shorter for the sampling period of the bus voltage measurement than the period of the ripple voltage waveform. In the third embodiment, the bus voltage is measured using a longer sampling period, and output control is performed based on the measurement result (discrete value), and detailed description of similar parts is omitted.

In this case, the voltage detection unit 411 measures the bus voltage using a voltmeter side sensor at a predetermined sampling frequency.
The output instruction unit 412 detects a ripple voltage by subtracting a reference value (reference voltage) of the bus voltage from the measured bus voltage (discrete value).

  Here, as shown in FIG. 10, the control unit 41 executes a bus voltage detection process (step S <b> 21). Specifically, the voltage detection unit 411 of the control unit 41 measures the bus voltage of the DC bus L1 using a voltmeter side sensor at a predetermined sampling frequency. Then, the voltage detection unit 411 supplies the measurement result (sampling value) to the output instruction unit 412.

  Next, the control part 41 of the bus voltage control apparatus 40 performs a ripple voltage calculation process (step S22). Specifically, the output instruction unit 412 of the control unit 41 calculates the ripple voltage by subtracting the reference value (reference voltage) of the bus voltage from the bus voltage (discrete value) acquired from the voltage detection unit 411.

Next, the control part 41 of the bus voltage control apparatus 40 performs the determination process about whether it is more than a threshold value similarly to step S03 (step S23).
When it is determined that the amplitude of the ripple voltage is not equal to or greater than the threshold value (in the case of “NO” in step S23), the control unit 41 of the bus voltage control device 40 returns to the bus voltage detection process (step S21).

  On the other hand, when it is determined that the amplitude of the ripple voltage is greater than or equal to the threshold value (in the case of “YES” in step S23), the control unit 41 of the bus voltage control device 40 determines the compensation voltage for ripple cancellation similarly to step S04. Processing is executed (step S24). Furthermore, the control part 41 of the bus voltage control apparatus 40 performs a control instruction | indication process similarly to step S05 (step S25).

  In FIG. 11, the bus voltage is measured at the sampling period [T / 4] in the bus voltage waveform indicated by the broken line. For this measurement result (discrete value), a control command for an antiphase waveform for canceling the ripple voltage by subtracting the reference voltage from the bus voltage is transmitted to the converter 25. Here, a control command for outputting an anti-phase waveform approximated by a straight line is transmitted.

According to this embodiment, the following effects can be obtained.
(5) In this embodiment, the control part 41 of the bus voltage control apparatus 40 performs a ripple voltage calculation process (step S22). Furthermore, the control unit 41 of the bus voltage control device 40 executes compensation voltage determination processing (step S24) and control instruction processing (step S25) for ripple cancellation. As a result, the bus voltage can be stabilized while reducing the processing load on the control unit 41.

<Fourth Embodiment>
Next, a fourth embodiment will be described with reference to FIGS. In the first to third embodiments, the bus voltage is measured and a control command is output. In the fourth embodiment, a ripple voltage waveform is predicted based on the system voltage waveform, and a control command for canceling the ripple voltage waveform is transmitted, and detailed description of similar parts is omitted.

  In the present embodiment, the voltage detection unit 411 acquires a system voltage waveform from the system power supply 50 connected to the inverter 30. Furthermore, the output instruction unit 412 retains amplitude determination information for determining the amplitude of the ripple voltage in accordance with the fluctuation amount of the system voltage.

  Here, as shown in FIG. 12, the control unit 41 of the bus voltage control device 40 executes a system voltage fluctuation acquisition process (step S <b> 31). Specifically, the voltage detection unit 411 of the control unit 41 acquires a system voltage waveform from the system power supply 50 connected to the inverter 30.

  Next, the control unit 41 of the bus voltage control device 40 executes a DC bus ripple prediction process (step S32). Specifically, the output instructing unit 412 of the control unit 41 generates a predicted waveform having a cycle twice and a phase delayed by 1/4 cycle with respect to the system voltage waveform. Further, the output instruction unit 412 specifies the amplitude of the ripple voltage waveform according to the fluctuation of the system voltage using the amplitude determination information.

Next, the control part 41 of the bus voltage control apparatus 40 performs the determination process about whether it is more than a threshold value similarly to step S03, S13, S23 (step S33).
If it is determined that the amplitude of the ripple voltage is not equal to or greater than the threshold value (in the case of “NO” in step S33), the control unit 41 of the bus voltage control device 40 returns to the system voltage fluctuation acquisition process (step S31).

  On the other hand, when it is determined that the amplitude of the ripple voltage is greater than or equal to the threshold value (in the case of “YES” in step S33), the control unit 41 of the bus voltage control device 40 executes a compensation voltage determination process for ripple cancellation (step S33). S34). Specifically, the output instruction unit 412 of the control unit 41 specifies the calculated amplitude of the ripple voltage waveform as the compensation voltage value.

  Next, the control part 41 of the bus voltage control apparatus 40 performs a control instruction process (step S35). Specifically, the output instruction unit 412 of the control unit 41 transmits a control command to the control target. This control command includes information on an antiphase waveform (compensation voltage value, period, phase) for canceling the predicted waveform. A predetermined value is used as the compensation voltage value.

  For example, as shown in FIG. 13, the ripple waveform of the bus voltage is predicted based on the AC waveform of the system voltage. Then, the converter 25 is instructed to output an antiphase waveform for canceling the ripple waveform.

According to this embodiment, the following effects can be obtained.
(6) In this embodiment, the control part 41 of the bus voltage control apparatus 40 performs the acquisition process of a system voltage fluctuation | variation (step S31). Further, the control unit 41 of the bus voltage control device 40 executes a DC bus ripple prediction process (step S32). As a result, the bus voltage can be stabilized without a load for detecting the bus voltage of the DC bus L1.

In addition, you may change the said embodiment as follows.
In the above embodiments, the control units of the converters 21 to 26 are connected via the communication line L2. The communication method is not limited to the configuration using the communication line L2, and wireless communication or power line communication can also be used.

  In each of the above embodiments, it is assumed that solar cell panels 11, 12, 13, fuel cell 14, storage battery 15, and electric vehicle 16 are used as distributed power source 10. Each distributed power source 10 is connected to converters 21 to 26. The type of the distributed power source is not limited to this. It is also possible to use other distributed power sources or to configure a combination of some of these.

  Further, converters 21 to 26 as power converters do not need to be independent devices. For example, the voltage control device of the present invention can be provided in a distributed power supply system (power conditioner) in which a plurality of converters and a single inverter are provided in one housing.

  In each of the above embodiments, the bus voltage control device 40 is provided separately from the inverter 30 and the converters 21 to 26. Instead of this, the bus voltage control device 40 may be provided in any one of the inverter 30 and the converters 21 to 26.

  In the first embodiment, the control unit 41 of the bus voltage control device 40 performs a control instruction process (step S05). In this case, the charge amount (power supply status) of the storage battery 15 which is an energy storage means is detected. And according to this charge amount, the control command regarding charge, discharge, or charge / discharge is transmitted to the converter 25 connected to the storage battery 15. Here, the converter 25 may determine whether to perform charge, discharge, or charge / discharge control. In this case, converter 25 detects the charge amount of storage battery 15 and determines charge, discharge or charge / discharge based on this charge amount.

  In the second embodiment, the control unit 41 of the bus voltage control device 40 executes a converter specifying process to be controlled based on the operating status (step S15). Here, when the ripple voltage is canceled using a plurality of converters, the compensation voltage is distributed. In this case, the combination of the converters is arbitrary as long as an antiphase waveform for canceling the ripple voltage can be generated. For example, it is possible to use a combination of three or more converters, a combination of energy creation means and energy storage means, a combination of time division using charge / discharge and division of the compensation voltage value.

  In the third embodiment, the output instruction unit 412 calculates the ripple voltage by subtracting the reference value (reference voltage) of the bus voltage from the measured bus voltage (discrete value). Here, the output instruction unit 412 may detect the ripple voltage by pattern matching between the bus voltage waveform and the ripple voltage waveform pattern. In this case, the output instruction unit 412 stores a ripple waveform pattern having a cycle twice that of the system voltage. Then, the ripple voltage is predicted by pattern matching.

  DESCRIPTION OF SYMBOLS 10 ... Distributed type | mold power supply 11, 12, 13 ... Solar cell panel, 14 ... Fuel cell, 15 ... Storage battery, 16 ... Electric vehicle, 20 ... Converter part, 21-26 ... Converter, 30 ... Inverter, 50 ... System power supply, U1 ... Power control system, L1 ... DC bus, L2 ... Communication line, 40 ... Bus voltage control device, 41 ... Control unit, 411 ... Voltage detection unit, 412 ... Output instruction unit.

Claims (10)

A voltage control device including a converter that converts DC power of a distributed power source and an inverter that is connected to the converter via a DC wiring and includes a control unit that instructs output control to the converter. ,
The control unit specifies a ripple voltage in a DC voltage of the DC wiring, and transmits a control command for generating an electric power of an opposite phase for canceling the ripple voltage to the converter. apparatus.   The voltage control device according to claim 1, wherein the control unit detects a DC voltage of the DC wiring and specifies a ripple voltage in the DC voltage.   The control unit measures a discrete value of a DC voltage of the DC wiring, and transmits a control command to generate an antiphase power for canceling a ripple voltage at the discrete value to the converter. The voltage control device according to claim 2.   The control unit detects a system voltage waveform, predicts a ripple voltage in a DC voltage based on the system voltage waveform, and generates a control command for generating an electric power in an antiphase for canceling the predicted ripple voltage, The voltage control device according to claim 1, wherein the voltage control device transmits the voltage to a converter.   The control unit acquires the power status of the energy storage means in the distributed power source connected to the DC wiring, and a control command for charging or discharging is connected to the energy storage means according to the power status. The voltage control device according to claim 1, wherein the voltage control device transmits the voltage to a converter.   The control unit acquires a power status of the energy storage means in the distributed power source connected to the DC wiring, and according to the power status, performs a control command to perform charging and discharging in a time-sharing manner. The voltage control apparatus according to claim 1, wherein the voltage control apparatus transmits the signal to a converter connected to the converter. The control unit is connected to a converter that converts DC power of each distributed power source in a plurality of distributed power sources,
The power supply status of the distributed power supply is acquired, a converter that transmits a control command is specified according to the power supply status, and the converter is transmitted to the converter. The voltage control apparatus described in 1.   When a plurality of converters that transmit a control command are specified in accordance with the power supply status, power of an opposite phase for canceling the ripple voltage is distributed and the control command is transmitted to each converter. The voltage control device according to claim 7.   The control unit acquires the power status of a plurality of energy storage means in a distributed power source connected to the DC wiring, and according to the power status, for each converter connected to each energy storage means, The voltage control apparatus according to claim 7, wherein a control command for charging or discharging is transmitted to. Using a voltage control device including a converter that converts DC power of a distributed power source and an inverter that is connected to the converter via a DC wiring and includes a control unit that instructs output control to the converter A method for controlling the DC voltage of the DC wiring,
The control unit specifies a ripple voltage in a DC voltage of the DC wiring, and transmits a control command for generating an electric power of an opposite phase for canceling the ripple voltage to the converter. Method.

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