JP2007020361A - System stabilizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a parallel operation device that is constituted so as to suppress the load variation of an autonomous power supply system, constituted of a power storage device using DC power for storing the power of a current control type self-excitated inverter and a synchronous generator cannot sufficiently cope with abrupt changes in the load and imbalance load. <P>SOLUTION: An active current set value is obtained, by inputting a signal composed of a frequency set value and a negative correction amount obtained from the drooping properties of the frequency of the autonomous system to a frequency controller. A reactive current set value is obtained, by inputting a signal composed of a voltage set value and a negative correction amount obtained from the drooping properties of the voltage to the difference of actual values of the autonomous system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a system stabilization device during parallel operation of a self-sustained power supply system composed of a power storage device using a self-excited inverter and an engine generator using a synchronous generator, and in particular, a sudden change in load or an unbalanced load. It is related with the control apparatus which can respond to.

As a power source for supplying power to a load independently from the system, there are an engine generator using a synchronous generator and an uninterruptible power supply device using a self-excited inverter. In the case of an engine generator using a synchronous generator, the system voltage is kept constant by the excitation current of the exciter and the system frequency is kept constant by a governor that controls the torque input to the engine. When operating a synchronous generator, the system voltage and system frequency are given drooping characteristics in order to suppress the cross current between the generators and keep the load sharing properly.

  When the load is relatively large with respect to the power supply device, a plurality of units are operated. However, when a plurality of synchronous generators are operated, a cross current is generated between the generators. In order to suppress this cross current and keep the load sharing properly, the system voltage and system frequency have drooping characteristics, but if the load fluctuation is steep, the output control of the engine generator can not sufficiently follow, The amount of power generation and load power are not balanced, resulting in frequency fluctuations and voltage fluctuations.

  In addition, when multiple uninterruptible power supply units using self-excited inverters are connected, parallel operation is possible by synchronizing the magnitude and phase of the voltage generated between the uninterruptible power supply units. When the secondary battery is used as the DC power source, there is a problem that the power supply time is limited.

In consideration of these problems, when the synchronous generator and the uninterruptible power supply are operated in parallel, the cross current generated between the two becomes a problem. Also, if the uninterruptible power supply is a voltage-controlled type and generates an AC voltage with a constant voltage and constant frequency, the uninterruptible power supply will bear the load power fluctuation, and the load sharing with the synchronous generator will be appropriate. Can't keep up. For example, Patent Document 1 discloses that stabilization at the time of system connection is achieved as parallel operation of a synchronous generator and an inverter. In this document, a short-period component of system power fluctuation is extracted in a wind power generation system and compensated on the self-excited inverter side.
JP 2000-4541 A

When the parallel operation of the synchronous generator and the self-excited inverter is controlled by the conventional method, the load fluctuation is borne by the self-excited inverter and a large power storage capacity is required. Note that the above-described Patent Document 1 does not disclose a technique for correcting according to the output amount of the power storage device with a correction amount having drooping characteristics when generating a control signal of the inverter.

  An object of the present invention is to provide a control device that can supply high-quality power with a smaller power storage capacity by appropriately sharing the fluctuation of the load between the two.

A first aspect of the present invention is a parallel operation apparatus configured to suppress load fluctuations of a self-sustained power system composed of a power storage device using a DC power source and a synchronous generator for power storage of a current-controlled self-excited inverter,
Three-phase two-phase conversion means for detecting an effective current component and a reactive current component by converting a three-phase current into a three-phase two-phase with reference to the phase of the output voltage of the inverter, and a frequency setting value and a detected detection value Frequency control means for generating an active current set value from a deviation signal, voltage control means for generating a reactive current set value from a deviation signal between the voltage set value and the detected detection value, and the generated active current set value The deviation signal from the detected effective current by the three-phase to two-phase conversion means, and the deviation between the generated reactive current set value and the detected detected reactive current are obtained and input separately for each of the effective voltage components. A current control means for obtaining a reactive voltage component; a means for inputting an output of each current control means; and a means for generating a PWM control signal by performing two-phase to three-phase conversion based on the detected voltage phase; and 3 phase 2 A first proportional calculation unit that inputs an effective current component by the conversion means and multiplies the proportional constant is provided, and the output of the proportional calculation unit is added to the deviation signal between the frequency set value and the detected detection value with a reverse polarity. And a second proportional operation unit that multiplies the proportional constant by inputting the reactive current component from the three-phase / two-phase conversion unit, and outputs the output of the proportional operation unit to the voltage set value. Is added to the deviation signal between the detected value and the detected value with the opposite polarity, and is input to the voltage control means.

  A second aspect of the present invention is characterized in that a current limiter circuit is connected in series with each of the current control means.

  According to a third aspect of the present invention, a low-pass filter is connected in series to the input side of each proportional calculation unit.

  According to a fourth aspect of the present invention, an electric double layer capacitor is used as the DC power source, and a deviation signal between a DC voltage detection value of the electric double layer capacitor and a preset DC voltage setting value is obtained, and at least a proportional / integral function is obtained. DC voltage control means having a DC voltage control means, a deviation signal between the DC voltage detection value and the DC voltage setting value is input to the DC voltage control means, and the output signal is added to the polarity opposite to the generated effective current setting value. The current control means for obtaining the effective voltage is input to the current control means.

  The fifth aspect of the present invention is characterized in that the output from the DC voltage control means is added to the polarity opposite to the frequency set value and input to the frequency control means.

A sixth aspect of the present invention is a parallel operation apparatus configured to suppress load fluctuations of a self-sustained power system composed of a power generator using a DC power source and a synchronous generator for power storage of a voltage-controlled self-excited inverter,
The droop calculation means for detecting the reactive power of the inverter output and executing the droop calculation according to the detected reactive power, the deviation signal input between the calculation output by the droop calculation means and the preset set value, and the valid Two-phase three-phase conversion means fixed at voltage 0, and frequency phase conversion means for inputting the detected frequency of the independent power supply system through a low-pass filter and converting it into a phase signal are provided. The means is characterized in that after the two-phase / three-phase conversion based on the voltage phase detected by the frequency phase conversion means, the gate signal of the inverter is output via the PWM control signal generation means. .

  According to a seventh aspect of the present invention, the DC power source is an electric double layer capacitor, and a deviation between the detected value of the DC voltage and a preset DC voltage setting value is input to a DC voltage control means having at least a proportional / integral function. A difference signal between the output signal and the voltage phase from the frequency phase conversion means is obtained and output as a voltage phase reference signal to the two-phase / three-phase conversion means.

The eighth aspect of the present invention is a parallel operation device configured to suppress load fluctuations of a self-sustained power system configured by a power storage device using a DC power source and a synchronous generator for power storage of a voltage-controlled self-excited inverter,
A power calculation unit that detects reactive power and active power of the inverter output, a droop calculation unit that executes droop calculation according to the reactive power detected by the calculation unit, and a calculation output by the droop calculation unit are preset. Deviation signal input to the set voltage value and two-phase three-phase conversion means fixed to the effective voltage 0, droop calculation means for executing droop calculation according to the active power detected by the power calculation section, and the droop A phase control unit that inputs a deviation signal between a calculation output from the calculation means and a preset frequency setting value to generate a phase signal and outputs the phase signal to the two-phase / three-phase conversion means; After the two-phase / three-phase conversion with the phase signal as a reference, the inverter gate signal is output via the PWM control signal generating means.

  According to a ninth aspect of the present invention, the DC power source is an electric double layer capacitor, and a deviation between the detected value of the DC voltage and a preset DC voltage setting value is input to a DC voltage control means having at least a proportional / integral function. The output of the DC voltage control means and the output of the droop calculation means for executing the droop calculation according to the active power are added.

  As described above, according to the present invention, it is possible to stabilize the system by suppressing frequency fluctuations and voltage fluctuations by appropriately sharing the load between the synchronous generator and the self-excited inverter. Moreover, energy can be always stored by controlling the capacitor voltage to be constant, and an output capable of coping with load fluctuation can be maintained in a state where it can always be supplied from the inverter side. Furthermore, by making the inverter a voltage control type, a part of the reverse phase current can be compensated to reduce the share of the synchronous generator, and the synchronous generator can be prevented from being heated by an eddy current or the like.

Embodiments of the present invention are described in detail below.

  FIG. 1 is a configuration diagram showing a first embodiment of the present invention. Reference numeral 1 is a synchronous generator driven by an engine or the like, 2 is a variable load, 3 is a current-controlled self-excited inverter, and a self-extinguishing type switch igniter element is used and PWM control is performed by the control device 50. The self-excited inverter 3 has a DC power supply 4 and constitutes a power storage device together with the DC power supply 4. The power storage device is connected in parallel to the synchronous generator 1 and supplies power to the variable load 2.

  5 is a current transformer, 6 is a transformer, and the output voltage of the self-excited inverter 3 detected by the transformer 6 is output to the effective value detection circuit 7 and the phase synchronization circuit 8. The effective value detection circuit 7 detects the effective voltage value, and the phase synchronization circuit 8 detects the phase and frequency. Reference numeral 9 denotes a three-phase to two-phase converter, which receives the phase signal detected by the phase synchronization circuit 8 and the self-excited inverter output current from the current transformer 5, and uses the voltage phase as a reference to detect the self-excited inverter detected by the current transformer 5. The output current is converted by the three-phase two-phase converter 9 to obtain an effective current and a reactive current.

  The voltage effective value obtained by the effective value detection circuit 7 is obtained as a deviation signal from the voltage set value VS in the adder AD1, and the frequency obtained by the phase synchronization circuit 8 is obtained by the frequency set value FS in the adder AD2. The deviation signal is obtained. The reactive current converted by the three-phase / two-phase converter 9 is applied to the adder AD6 and the proportional operation circuit 11, and the active current is applied to the adder AD5 and the proportional operation circuit 15, respectively. In the proportional calculation circuit 15, the active current is multiplied by a fixed value and applied to the adder AD3 as a correction value of the active current. The deviation from the deviation signal obtained by the adder AD2 is obtained and input to the frequency controller 14. To obtain the effective current set value. In the proportional calculation circuit 11, the reactive current is multiplied by a fixed value and applied to the adder AD4, and the voltage deviation signal obtained by the adder AD2 is obtained and input to the current controller 10 to obtain the reactive current set value. .

  FIG. 2A is a frequency drooping characteristic diagram, which is obtained by subtracting a correction amount proportional to the effective current. By setting it as such a characteristic, the effect of reducing a frequency is acquired, so that an effective current increases. FIG. 2B is a voltage drooping characteristic diagram. The voltage drooping characteristic is obtained by subtracting a correction amount proportional to the reactive current. That is, the effect of lowering the voltage is obtained as the reactive power output increases.

  A current controller 17 obtains a deviation between the effective current set value obtained by the frequency controller 14 and the detected effective current by the adder AD5 and inputs it to the current controller 17 to obtain an effective voltage. A current controller 13 obtains a deviation between the reactive current set value obtained by the voltage controller 10 and the detected reactive current by the adder AD6 and inputs it to the current controller 13 to obtain a reactive voltage. Reference numeral 18 denotes a two-phase / three-phase converter, which converts the obtained effective voltage and invalid voltage and the voltage phase detected by the phase synchronization circuit 8 by the two-phase / three-phase converter 18 to generate a PWM control signal generator. In 19, an inverter gate signal is generated, and a desired inverter output is obtained. Here, the frequency controller 14, the voltage controller 10, and the current controllers 13 and 17 are configured by PI, PID, or the like. In some cases, an inverter overcurrent can be prevented by providing the current limiter circuits 12 and 16 in series with the current controllers 13 and 17, respectively.

  According to this embodiment, by having a drooping characteristic that lowers the frequency as the active power of the current-controlled self-excited inverter output increases and decreases the voltage as the reactive power increases, the synchronous generator and the self-excited Even if a sudden load change occurs during parallel operation of the inverter, the load sharing with the synchronous generator having the drooping characteristics similar to that of the self-excited inverter is effectively performed, and the voltage and frequency of the system can be stabilized. . That is, the synchronous generator shares the gradual fluctuation component of the power load, and the power storage device bears the steep fluctuation component, thereby improving the power quality of the self-sustained system by utilizing the high-speed response of the self-excited inverter. It becomes possible. Further, since the self-excited inverter is a current control type, the overcurrent prevention of the inverter can be easily realized by the current limiter circuit.

  FIG. 3 is a block diagram showing a second embodiment of the present invention. 3 is different from FIG. 1 in that a low-pass filter 20 and a low-pass filter 21 are additionally connected to the input sides of the proportional calculation circuit 11 and the proportional calculation circuit 15, respectively.

  If the low-pass filter is connected in series to the proportional calculation circuits 11 and 15, the proportional constant of each proportional calculation circuit is apparently small at the start of load fluctuation, and the original droop proportional constant in the steady state after time has passed. Match. That is, the drooping characteristic can be changed from time t1 to time t2 with time as shown in FIG. 4A shows active power output characteristics, and FIG. 4B shows reactive power output characteristics. FIG. 6C shows the load sharing characteristics, where the solid line indicates the synchronous generator and the dotted line indicates the inverter side sharing. As shown in FIG. 4, when a steep fluctuation of the load occurs at time t1, the inverter with quick response is mainly responsible for the load until the time t2, and the synchronous generator bears the load as time passes. Therefore, according to this embodiment, it is possible to make the fluctuations in voltage and frequency smaller than in the first embodiment, and there is an advantage that the inverter can be miniaturized with a small power storage capacity.

  In other words, in the first embodiment, the synchronous generator shares the gentle fluctuation component of the power load, and the power storage device bears the steep fluctuation component, so that the high-speed response performance of the self-excited inverter is utilized. Quality can be improved. However, in the case of Example 1, since the drooping characteristic is proportional to the active power output and reactive power output of the power storage device, the synchronous generator and the power storage device also share steep power load fluctuation components. In other words, there may be cases where the power quality related to voltage fluctuation and frequency fluctuation cannot be satisfied. On the other hand, in the second embodiment, the drooping characteristic is dynamically changed in order to load the power storage device with a steep fluctuation component of the power load. Slow fluctuation components of the active power output and reactive power output of the power storage device are detected by the first-order lag filters 20 and 21, and the frequency setting value is lowered as the active power output increases, and the voltage setting value as the reactive power output increases. It has a drooping characteristic that lowers As a result, the power storage device absorbs steep fluctuation components of frequency fluctuations and voltage fluctuations due to sudden changes in the load, and the synchronous generator can bear gradual fluctuations.

  FIG. 5 is a block diagram showing a third embodiment of the present invention. 5 differs from FIG. 1 and FIG. 3 in an embodiment in which the DC power supply 4 is an electric double layer capacitor 24. In the electric double layer capacitor 24, the stored energy is determined by a DC voltage, and a control function for keeping the DC voltage constant is added.

  In FIG. 5, a deviation between the DC voltage set value DVS of the electric double layer capacitor 24 and the detected value is obtained by the adder AD 7, and the deviation signal is input to the DC voltage controller 25. The DC voltage controller 25 is composed of PI, PID, etc., like the current controller 17, but prioritizes the response to load fluctuations by setting parameters so as to respond more slowly than the current controller 17. Yes. Deviation of the output of the DC voltage controller 25 from the active current set value is obtained in the adder AD8, and the deviation signal is added to the input of the current controller 17 to keep the DC voltage of the electric double layer capacitor 24 constant. It is said.

  In addition, the drooping operation circuits 22 and 23 for obtaining the drooping characteristic use either the first embodiment or the second embodiment. In this way, by controlling the DC voltage to be substantially constant, even an electric double layer capacitor having a small stored energy can cope with load fluctuations.

  FIG. 6 is a block diagram showing a fourth embodiment of the present invention. 6 is different from FIG. 5 in that the output of the DC voltage controller 26 is added to the input of the frequency controller 14 in order to control the DC voltage of the electric double layer capacitor 24 to be constant.

  Again, the DC voltage controller 26 is composed of PI, PID, and the like, similar to the frequency controller 14, but the parameters are set so as to respond more slowly than the frequency controller to cope with load fluctuations. Prioritize. Even if it is such a structure, the same effect as Example 3 is acquired.

  FIG. 7 is a block diagram showing a fifth embodiment of the present invention. 7 is different from FIG. 1 in that a voltage-controlled self-excited inverter 27 that can generate a harmonic current or a negative phase current due to an unbalanced load is used as the self-excited inverter.

  When the voltage level and frequency are controlled using a self-excited inverter as a current control type, the current generated by the self-excited inverter becomes a three-phase balanced current source only for the positive phase, so there is no harmonic load or noise in the independent system. In the case where balanced loads exist, the negative phase current required by these loads is mainly borne by the synchronous generator. When a negative phase current flows through the synchronous generator, there is a problem that the operation cannot be stably continued due to heating of the winding or the like.

  By making the self-excited inverter voltage control type, not only the synchronous generator but also the power storage device can be used as the source of the negative phase current, and the burden on the negative phase current of the synchronous generator can be reduced. It becomes. However, when a synchronous generator, which is a voltage source, and a voltage-controlled self-excited inverter are operated in parallel, it is necessary to synchronize the two, so the phase of the voltage generated by the self-excited inverter is set to AC of the independent system. Synchronize with voltage phase. This phase synchronization is performed by a PLL circuit.

  In addition, the LPF is used to detect the voltage phase of the autonomous system, and the power storage device operates so as to suppress the frequency fluctuation with respect to the steep active power load fluctuation. It is possible to supply a load fluctuation of active power from the power storage device. The magnitude of the voltage is determined from the drooping characteristic that drops the voltage according to the reference value and the output reactive power of the self-excited inverter. The drooping characteristic uses a proportionality constant similar to that of the first embodiment or a proportionality constant with LPF similar to that of the second embodiment. By using the drooping characteristic with the LPF, the power storage device bears the voltage fluctuation with respect to the steep load fluctuation, and then the reactive power burden of the power storage apparatus and the synchronous generator can be appropriately maintained according to the drooping characteristic.

  That is, reactive power is calculated by the reactive power calculator 28 from the inverter output current detected by the current transformer 5 and the voltage detected by the transformer 6, and is fed back to the voltage reference value VS through the droop calculation circuit 22 to obtain a reactive voltage. Reference numeral 30 denotes a two-phase / three-phase converter. An invalid voltage is input to one input terminal, but an effective voltage is set to zero. The voltage phase input to the two-phase / three-phase converter 30 is input via the frequency detection circuit 31, the low-pass filter 32, and the frequency / phase converter 33, and is converted by the two-phase / three-phase converter 30. The PWM control signal generator generates a PWM control signal and outputs it to the gate of the self-excited inverter 27. Here, by using the low-pass filter 32, there is an effect that the self-excited inverter supplies the active power so as to suppress the voltage phase change due to the rapid fluctuation of the load to stabilize the fluctuation of the frequency.

  The magnitude of the voltage in phase with the system voltage generated by the self-excited inverter is given as the voltage setting value. The voltage setting value is determined from the difference between the voltage reference value (fixed value) and the drooping characteristic corresponding to the magnitude of the output reactive power of the self-excited inverter. The drooping characteristic is a proportional constant or a proportional constant with LPF. The magnitude of the voltage delayed by 90 deg with respect to the system voltage generated by the self-excited inverter is fixed at zero. The AC voltage generated by the self-excited inverter is obtained by two-phase and three-phase conversion of the in-phase voltage provided as the two-phase DC component and the magnitude of the 90 deg delay voltage. The phase used for the two-phase / three-phase conversion is a phase synchronized with the voltage phase of the independent system. The voltage phase of the autonomous system is detected by the PLL and processed by the detected LPF so that the voltage phase generated by the self-excited inverter does not rapidly follow the phase of the autonomous system, and the frequency in the autonomous system is stabilized. Plan. By adopting such a configuration, it is possible to supply from the inverter also about the harmonic current and the negative phase current caused by the unbalanced load that were all borne by the synchronous generator, and the burden on the synchronous generator can be reduced. .

  FIG. 8 is a block diagram showing a sixth embodiment of the present invention. 8 differs from FIG. 7 in an embodiment in which the DC power source 4 is an electric double layer capacitor 24. In FIG. In the electric double layer capacitor 24, the stored energy is determined by a DC voltage, and a control function for keeping the DC voltage constant is added.

  When the self-excited inverter is voltage controlled, the active power output is determined by the phase difference between the voltage phase of the self-sustained system and the voltage phase generated by the self-excited inverter, and LPF is used to detect the voltage phase of the self-supported system and When stabilization is achieved, a steep fluctuation of the active power load in the self-supporting system is supplied from the self-excited inverter. In order to keep the storage capacity constant, it is necessary to gently control the amount of active power supplied from the electric double layer capacitor.

  In order to control the amount of active power supplied, the basic circuit configuration is the same as in Example 4, and a DC voltage controller that operates so that the deviation between the DC voltage of the electric double layer capacitor and the DC voltage setting value is zero is added. The voltage phase used for the two-phase / three-phase conversion of the self-excited inverter is corrected. When the DC voltage detection value rises above the DC voltage set value, the DC voltage can be kept constant by operating the electric double layer capacitor in the discharging direction. Therefore, when the DC voltage rises, the power storage device can be operated in the discharge direction by operating the voltage phase generated by the self-excited inverter in the advance direction with respect to the voltage phase of the independent system. The DC voltage controller includes proportional control (P control), lead / lag compensation (ST1 + 1) / (ST2 + 1), and the like.

  In FIG. 8, the DC voltage set value DVS of the electric double layer capacitor and the detected value are added to the opposite polarity in the adding unit to obtain a deviation value, and the deviation value is input to the DC voltage controller 34 to perform PI control or PID control. The output of the controller 34 is input to the two-phase / three-phase converter 30, and the voltage phase used in the converter 30 is corrected. Also in this case, the response of the DC voltage controller 34 is set so as to be gentle, and priority is given to the response to the load fluctuation. In this way, by controlling the DC voltage to be substantially constant, even an electric double layer capacitor having a small stored energy can cope with load fluctuations.

  FIG. 9 shows a seventh embodiment of the present invention. In FIG. 9, the difference from FIG. 7 is how to create a phase signal to be input to the two-phase / three-phase converter 30. The self-excited inverter is operated as a voltage control type and controlled so as to keep the frequency and the voltage magnitude constant. In this case, if the frequency generated by the self-excited inverter is constant, the power storage device bears almost all the fluctuation of the active power generated in the self-supporting system. The oscillation frequency of the voltage to be dropped is lowered.

  Since this method does not explicitly synchronize the voltage phase of the self-excited inverter with the voltage phase of the self-sustained system in normal operation, the voltage generated by the self-excited inverter is larger than the self-sustained system voltage established by the synchronous generator at startup. The frequency is controlled, and when the magnitude, frequency and phase of both voltages are detected to coincide with each other, the self-excited inverter circuit breaker is turned on. During normal operation after synchronization, only the oscillation frequency and voltage magnitude of the generated voltage are adjusted. The oscillation frequency is determined by the drooping characteristic for the active power output generated by the self-excited inverter, and the magnitude of the voltage is determined by the drooping characteristic for the reactive power output generated by the self-excited inverter. As the drooping characteristic, either Example 1 or Example 2 is adopted.

  When starting up the power storage device, the frequency deviation of the voltage of the self-sustained system bus on the primary side of the circuit breaker (not shown) and the voltage generated by the self-excited inverter on the secondary side of the circuit breaker are detected and set to zero. The frequency control and voltage control of the self-excited inverter are performed. The frequency reference value of the voltage generated by the self-excited inverter is corrected by the output of the frequency controller, and the phase is generated by the phase controller. Further, the voltage reference value of the voltage generated by the self-excited inverter is corrected by the output of the voltage controller. The magnitude of the voltage delayed by 90 deg with respect to this voltage is fixed at zero, and two-phase three-phase conversion is performed to determine the AC voltage generated by the self-excited inverter.

  At the same time, the synchronous verification circuit compares the voltage level, frequency, and phase of the primary and secondary side of the circuit breaker, and generates a synchronization signal when all absolute values are below the threshold value. And the control mode of the self-excited inverter is switched to the control mode of normal operation. After switching to the normal operation control mode, the frequency reference value is corrected by the drooping characteristic that lowers the frequency reference value according to the active power output of the power storage device, and the drooping characteristic that lowers the voltage reference value according to the reactive power output. The voltage reference value is corrected to control the magnitude and phase of the voltage generated by the self-excited inverter.

  That is, in FIG. 9, the active power is calculated by the power calculator 35 and the deviation from the frequency reference value is input to the phase controller 36 through the droop calculation circuit 23 to obtain the phase signal of the two-phase / three-phase converter. Yes. By adopting such a configuration, the same effect as in the fifth embodiment can be obtained.

  FIG. 10 is a block diagram showing an eighth embodiment of the present invention. 10 is different from FIG. 9 in an embodiment in which the DC power source 4 is an electric double layer capacitor 24. In the electric double layer capacitor 24, the stored energy is determined by a DC voltage, and a control function for keeping the DC voltage constant is added.

  The basic circuit configuration is the same as in Example 7, and a DC voltage controller that operates to make the deviation between the DC voltage of the electric double layer capacitor and the DC voltage set value zero is added to correct the oscillation frequency of the self-excited inverter. To do. Since the capacitance control of the electric double layer capacitor is performed only during normal operation, the correction amount adding unit is provided at the output unit of the frequency drooping characteristic during normal operation. When the oscillation frequency of the self-excited inverter is increased, the active power output is increased (discharge direction), and when the oscillation frequency is decreased, the active power output is decreased (charge direction).

  When the detected DC voltage value of the electric double layer capacitor is higher than the DC voltage set value, the capacitance can be kept constant by operating the electric double layer capacitor in the discharging direction. When the DC voltage detection value rises above the DC voltage setting value, the DC voltage deviation input to the DC voltage controller becomes negative. In this case, in order to operate the electric double layer capacitor in the discharge direction, the oscillation frequency Operate to raise.

  In other words, the input of the phase controller 36 is corrected by the output of the DC voltage controller 37 to which the deviation between the DC voltage set value and the detected value of the electric double layer capacitor is input. The DC voltage controller 37 is set with parameters so as to have a more gradual response, and priority is given to dealing with load fluctuations. By adopting such a configuration, the same effect as in the seventh embodiment can be obtained.

The block diagram which shows the 1st Example of this invention. The drooping characteristic of an inverter output is shown, (a) is active power, (b) is a reactive power characteristic diagram. The block diagram which shows the 2nd Example of this invention. It is a time change figure of drooping characteristics, (a) is active power, (b) is reactive power, (c) is a load sharing explanatory view. The block diagram which shows the 3rd Example of this invention. The block diagram which shows the 4th Example of this invention. The block diagram which shows the 5th Example of this invention. The block diagram which shows the 6th Example of this invention. The block diagram which shows the 7th Example of this invention. The block diagram which shows the 8th Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Synchronous generator 2 ... Variable load 3 ... Current control type inverter 4 ... DC power supply 5 ... Current transformer 6 ... Transformer 7 ... Effective value detection circuit 8 ... Phase synchronous circuit 9 ... Three-phase two-phase converter 10 ... Voltage control 11 ... Proportional arithmetic circuit 12 ... Current limiter 13 ... Current controller 14 ... Frequency controller 15 ... Proportional arithmetic circuit 16 ... Current limiter circuit 17 ... Current controller 18 ... Two-phase three-phase converter 19 ... PWM control signal generator DESCRIPTION OF SYMBOLS 20 ... Low pass filter 21 ... Low pass filter 22 ... Droop operation circuit 23 ... Droop operation circuit 24 ... Electric double layer capacitor 25 ... DC voltage controller 26 ... DC voltage controller 27 ... Voltage control type inverter 28 ... Reactive power calculator 30 ... Two-phase / three-phase converter 31 ... Frequency detector 32 ... Low pass filter 33 ... Frequency / phase converter 34 ... DC voltage controller 35 ... Power calculator 36 ... Phase controller 37 ... DC voltage controller 50 ... Control device

Claims (9)

In a parallel operation device configured to suppress load fluctuations of a self-sustained power system composed of a power storage device using a DC power source and a synchronous generator for power storage of a current-controlled self-excited inverter,
Three-phase two-phase conversion means for detecting an effective current component and a reactive current component by converting a three-phase current into a three-phase two-phase with reference to the phase of the output voltage of the inverter, and a frequency setting value and a detected detection value Frequency control means for generating an active current set value from a deviation signal, voltage control means for generating a reactive current set value from a deviation signal between the voltage set value and the detected detection value, and the generated active current set value The deviation signal from the detected effective current by the three-phase to two-phase conversion means, and the deviation between the generated reactive current set value and the detected detected reactive current are obtained and input separately for each of the effective voltage components. A current control means for obtaining a reactive voltage component; a means for inputting an output of each current control means; and a means for generating a PWM control signal by performing two-phase to three-phase conversion based on the detected voltage phase; and 3 phase 2 A first proportional calculation unit that inputs an effective current component by the conversion means and multiplies the proportional constant is provided, and the output of the proportional calculation unit is added to the deviation signal between the frequency set value and the detected detection value with a reverse polarity. And a second proportional operation unit that multiplies the proportional constant by inputting the reactive current component from the three-phase / two-phase conversion unit, and outputs the output of the proportional operation unit to the voltage set value. A system stabilizing device characterized by being added to the deviation signal between the detected value and the detected value and having the opposite polarity and inputting it to the voltage control means. 2. The system stabilizing device according to claim 1, wherein a current limiter circuit is connected in series with each of the current control means. 3. The system stabilizing device according to claim 1, wherein a low pass filter is connected in series to each input side of each proportional calculation unit. An electric double layer capacitor is used as the DC power source, a deviation signal between a DC voltage detection value of the electric double layer capacitor and a preset DC voltage setting value is obtained, and a DC voltage control means having at least a proportional / integral function A deviation signal between the DC voltage detection value and the DC voltage setting value is input to the DC voltage control means, and the output signal is added to the polarity opposite to the generated effective current setting value to obtain the effective voltage component. 4. The system stabilizing device according to claim 1, wherein the system stabilizing device is configured to input to the current control means to be obtained. 5. The system stabilizing device according to claim 4, wherein an output from the DC voltage control means is added to a polarity opposite to the frequency set value and input to the frequency control means. In a parallel operation device configured to suppress load fluctuations of a self-sustained power system composed of a power storage device using a DC power source and a synchronous generator for power storage of a voltage-controlled self-excited inverter,
The droop calculation means for detecting the reactive power of the inverter output and executing the droop calculation according to the detected reactive power, the deviation signal input between the calculation output by the droop calculation means and the preset set value, and the valid Two-phase three-phase conversion means fixed at voltage 0, and frequency phase conversion means for inputting the detected frequency of the independent power supply system through a low-pass filter and converting it into a phase signal are provided. The system stabilization is characterized in that after the two-phase / three-phase conversion based on the voltage phase detected by the frequency phase conversion means, the gate signal of the inverter is output via the PWM control signal generation means. apparatus. The DC power supply is an electric double layer capacitor, and a deviation between the detected value of the DC voltage and a preset DC voltage set value is input to a DC voltage control means having at least a proportional / integral function, the output signal and the frequency 7. The system stabilizing device according to claim 6, wherein a difference signal from the voltage phase from the phase conversion means is obtained and output to the two-phase / three-phase conversion means as a voltage phase reference signal. In a parallel operation device configured to suppress load fluctuations of a self-sustained power system composed of a power storage device using a DC power source and a synchronous generator for power storage of a voltage-controlled self-excited inverter,
A power calculation unit that detects reactive power and active power of the inverter output, a droop calculation unit that executes droop calculation according to the reactive power detected by the calculation unit, and a calculation output by the droop calculation unit are preset. Deviation signal input to the set voltage value and two-phase three-phase conversion means fixed to the effective voltage 0, droop calculation means for executing droop calculation according to the active power detected by the power calculation section, and the droop A phase control unit that inputs a deviation signal between a calculation output from the calculation means and a preset frequency setting value to generate a phase signal and outputs the phase signal to the two-phase / three-phase conversion means; A system stabilization device configured to output a gate signal of the inverter via a PWM control signal generation means after performing two-phase / three-phase conversion with the phase signal as a reference. The DC power supply is an electric double layer capacitor, and a deviation between the detected value of the DC voltage and a preset DC voltage set value is input to a DC voltage control means having at least a proportional / integral function, and the DC voltage control means 9. The system stabilization apparatus according to claim 8, wherein the output is added to an output of a drooping operation means for executing a drooping operation according to the active power.

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