JP2023086352A - Power converter controller and control method - Google Patents

Abstract

To provide a power converter controller and a control method that can switch between the isolated operation and the grid-connected operation without changing a control method, continues the grid-connected operation even when a momentary voltage drop occurs during the grid-connected operation, and can quickly recover from the voltage drop state at the time of voltage recovery.SOLUTION: A controller of a power converter calculates a frequency target value on the basis of the calculation of multiplying a value based on the deviation of the active power from an active power command value by a coefficient indicating the first drooping characteristic, calculates an internal phase difference angle from the frequency target value, calculates a current target value by using the internal phase difference angle, generates a current command value by limiting the current target value within a predetermined first range, calculates a power correction value on the basis of the deviation of the current command value from the current target value, corrects the frequency target value by the power correction value, generates a limit voltage obtained by limiting the voltage in the AC wiring within a predetermined limit range, and generates a drive signal for the power converter by using the deviation of the current output to the AC wiring with respect to the current command value, and the limit voltage.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to a power converter controller and control method.

In a power supply system in which an AC power system and storage equipment are interconnected, such as a microgrid, the AC power of the AC power supply system is converted to DC power between the AC power supply system and the storage equipment, and the DC power of the storage equipment is converted to DC power. A power converter is connected to convert electrical power to AC power.

If a problem occurs in part of such a power supply system, there is a possibility that a momentary voltage drop will occur in the AC wiring between the AC power supply system and the power storage equipment. Even if such a momentary voltage drop occurs, it is possible to continue grid-connected operation and quickly restore the power output from the power converter to the AC wiring when the voltage in the AC power supply system recovers from the voltage drop. Desired. For example, in the grid interconnection regulations (JEAC9701-2019), which is an approved standard of the Japan Electrotechnical Standards Committee, one of the FRT (Fault Ride Through) requirements is that if the residual voltage is 20% or more, the phase will continue without a change. It is stipulated that the operation should be continued for a voltage drop of 0.3 seconds, and that the output should be restored to 80% or more of the voltage before the voltage drop within 0.1 seconds after the voltage recovery in the AC power system. there is

On the other hand, in Patent Document 1 below, in a power converter used in such a power supply system, the power storage equipment can be separated from the AC power supply system and switched to self-sustained operation without changing the control method. A power converter has been proposed that can be switched from isolated operation to grid-connected operation by reconnecting an electricity storage facility to an AC power supply system.

Specifically, the power converter in Patent Document 1 estimates a current to be output by the virtual prime mover-generator when it is assumed that a virtual prime mover-generator is connected instead of the power converter, and estimates It is controlled by a virtual generator model control that determines the calculated current as the current target value output by the power converter.

WO2013/008413

In the control mode of a power converter that simulates a virtual prime mover generator as in Patent Document 1 above, when a momentary voltage drop occurs in the AC wiring, the interconnected operation is continued and the voltage in the AC power supply system is restored. Sometimes there is room for improvement in order to quickly recover from a brownout condition.

The present disclosure is intended to solve the above problems, it is possible to switch between isolated operation and grid-connected operation without changing the control method, and even if a momentary voltage drop occurs during grid-connected operation It is an object of the present invention to provide a power converter controller and control method capable of continuing grid-connected operation and recovering quickly from a voltage drop state when the voltage in an AC power supply system recovers.

A controller for a power converter according to one aspect of the present disclosure is a controller for a power converter that performs power conversion between a power storage facility and an AC power system, wherein the AC power system and the power converter are The voltage and frequency in the AC wiring to be connected and the current output from the power converter to the AC wiring are obtained, and the relationship between the frequency and the active power of the power converter output by the power converter to the AC wiring is determined by a predetermined number. A frequency target including an operation of multiplying a value based on a first deviation, which is a deviation of the power converter active power from a predetermined active power command value, by a coefficient indicative of the first droop characteristic so as to have a droop characteristic of 1. A frequency target value is calculated by value calculation processing, a second deviation that is a deviation of the frequency in the AC wiring with respect to the frequency target value is integrated to calculate an internal phase difference angle, and the AC wiring for a predetermined reactive power command value is calculated. An internal electromotive voltage target value is calculated by adding a predetermined reference voltage to a value based on a third deviation, which is a deviation of the reactive power of the power converter output by the power converter, and the internal phase difference angle and the internal electromotive force are calculated. A current target value is calculated from the voltage target value and the voltage in the AC wiring, the current target value is limited within a predetermined first range to generate a current command value, and the current command value for the current target value is generated. A power correction value is calculated from a fourth deviation that is a deviation of the value and the voltage in the AC wiring, and the first deviation is corrected by the power correction value to correct the frequency target value, and the AC wiring A limit voltage is generated by limiting the voltage in a predetermined limit range, and the limit voltage is added to a value based on a fifth deviation that is the deviation of the current output to the AC wiring from the current command value to the voltage command value to generate a drive signal for the power converter.

A control method for a power converter according to another aspect of the present disclosure is a control method for a power converter that performs power conversion between a power storage facility and an AC power system, wherein the AC power system and the power converter obtain the voltage and frequency in the AC wiring that connects the AC wiring, and the current output from the power converter to the AC wiring, and the relationship between the frequency and the active power of the power converter output by the power converter to the AC wiring is a predetermined A frequency including an operation of multiplying a value based on a first deviation, which is a deviation of the power converter active power from a predetermined active power command value, by a coefficient indicating the first drooping characteristic so as to have the first drooping characteristic. A frequency target value is calculated by a target value calculation process, a second deviation that is a frequency deviation in the AC wiring with respect to the frequency target value is integrated to calculate an internal phase difference angle, and the AC wiring with respect to a predetermined reactive power command value. A predetermined reference voltage is added to a value based on a third deviation, which is a deviation of the power converter reactive power output by the power converter, to calculate an internal electromotive voltage target value, and the internal phase difference angle and the internal A current target value is calculated from the electromotive voltage target value and the voltage in the AC wiring, a current command value is generated by limiting the current target value within a predetermined first range, and the current command value is generated with respect to the current target value. A power correction value is calculated from a fourth deviation, which is a deviation of the command value, and the voltage in the AC wiring, and the frequency target value is corrected by correcting the first deviation with the power correction value. A limit voltage is generated by limiting the voltage in the wiring within a predetermined second range, and the limit voltage is added to a value based on a fifth deviation, which is the deviation of the current output to the AC wiring from the current command value, to obtain a voltage A drive signal for the power converter is generated by generating the command value.

According to the present disclosure, it is possible to switch between isolated operation and grid-connected operation without changing the control method, and even if a momentary voltage drop occurs during grid-connected operation, grid-connected operation is continued, When the voltage in the AC power supply system recovers, it is possible to quickly recover from the voltage drop state.

FIG. 1 is a block diagram showing a schematic configuration of a power supply system including a power converter controller according to an embodiment of the present disclosure. FIG. 2 is a block diagram showing a configuration of a frequency target value calculation section in the controller shown in FIG. 1; 3 is a block diagram showing the configuration of an internal phase difference angle calculator in the controller shown in FIG. 1. FIG. 4 is a block diagram showing a configuration of an internal electromotive voltage target value calculation section in the controller shown in FIG. 1. FIG. FIG. 5 is a block diagram showing the configuration of a current command value calculator in the controller shown in FIG. FIG. 6 is a block diagram showing a configuration of a drive signal generator in the controller shown in FIG. 1; FIG. 7 is a graph showing temporal changes in output power in the first simulation. FIG. 8 is a graph showing temporal changes in frequency in the first simulation. FIG. 9 is a graph showing temporal changes in the internal retardation angle in the first simulation. FIG. 10 is a graph showing temporal changes in the d-axis current command value and the d-axis current of the example in the first simulation. FIG. 11 is a graph showing temporal changes in the d-axis current command value and the d-axis current of the comparative example in the first simulation. FIG. 12 is a graph showing temporal changes in the output current from the power converter in the first simulation. FIG. 13 is a graph showing temporal changes in AC voltage and frequency in AC wiring based on the results of the second simulation for the example. 14 is a graph showing temporal changes in AC voltage and frequency in AC wiring based on the result of the second simulation for Comparative Example 1. FIG. FIG. 15 is a graph showing temporal changes in AC voltage and frequency in AC wiring, based on the results of the second simulation for Comparative Example 2. FIG.

Embodiments of the present disclosure will be described below with reference to the drawings. Elements that are the same or have the same function are denoted by the same reference numerals throughout the drawings, and duplicate descriptions thereof will be omitted.

[System configuration]
FIG. 1 is a block diagram showing a schematic configuration of a power supply system including a power converter controller according to an embodiment of the present disclosure. As shown in FIG. 1 , the power supply system 1 in the present embodiment includes an AC power supply system 2 such as a commercial power supply system, an electricity storage device 3 and a power converter 4 . AC power supply system 2 and power converter 4 are connected by AC wiring 5 . The power storage equipment 3 and the power converter 4 are connected by DC wiring 6 . In this embodiment, the case where the AC power supply system 2 is a three-phase AC system is exemplified.

The power storage equipment 3 includes a secondary battery, an electric double layer capacitor, a fuel cell, and the like. The power converter 4 includes a plurality of power semiconductor elements, and by switching the power semiconductor elements on and off at high speed, converts the DC power from the power storage equipment 3 into AC power and outputs it to the AC wiring 5. Alternatively, the AC power from the AC power supply system 2 is converted into DC power and stored in the power storage equipment 3 . A controller 10 is connected to the power converter 4 for controlling on/off of the power semiconductor device.

The power supply system 1 has a voltage detector 7 and a current detector 8 . Voltage detector 7 detects the voltage in AC wiring 5 . Current detector 8 detects the current output from power converter 4 to AC wiring 5 . For example, the voltage detector 7 is a transformer known as a PT (Potential Transformer) and the current detector 8 is a current transformer known as a CT (Current Transformer). The detected voltage and current are input to controller 10 .

A state detector 9 is connected to the power storage equipment 3 to detect the state of the power storage equipment 3, such as voltage, current, temperature, and pressure. The output of state detector 9 is input to state monitor 11 . The state monitor 11 monitors the state of the power storage equipment and also calculates the SOC (State Of Charge) indicating the charging rate of the power storage equipment 3 . The state monitor 11 is connected to the controller 10 , and transmits an abnormality signal to the controller 10 when an abnormality in the state of the power storage equipment 3 is detected. The controller 10 stops the operation of the power converter 4 when receiving the abnormal signal from the state monitor 11 .

The controller 10 comprises a computer such as a microcontroller or a personal computer. For example, the controller 10 includes a CPU, a main memory such as a RAM, a communication interface, and the like.

It should be noted that the functionality of the elements disclosed herein may be achieved by general purpose processors, special purpose processors, integrated circuits, Application Specific Integrated Circuits (ASICs), conventional circuits, or any combination thereof configured or programmed to perform the disclosed functions. can be implemented using a circuit or processing circuit that includes a combination of A processor is considered a processing circuit or circuit because it includes transistors and other circuits. As used herein, a circuit, unit, or means is hardware that performs or is programmed to perform the recited functions. The hardware may be the hardware disclosed herein, or other known hardware programmed or configured to perform the recited functions. A circuit, unit, means, or part is a combination of hardware and software, where the hardware is a processor, which is considered a type of circuit, and the software is used to configure the hardware or the processor.

The controller 10 includes a voltage calculation unit 71, a current calculation unit 72, a power calculation unit 73, a frequency target value calculation unit 80, an internal phase difference angle calculation unit 82, an internal electromotive force target value calculation unit 83, a current command value calculation unit 84 and Each control block of the drive signal generator 85 is provided. As noted above, each of these control blocks is considered a processing circuit or circuitry, respectively. The controller 10 performs the processing in each control block, so that when it is assumed that a virtual generator is connected to the AC wiring 5 instead of the power converter 4, the virtual generator is output to the AC wiring 5. A virtual power generator model control is performed to control the power that the power converter 4 outputs to the AC wiring 5 by simulating the power that is generated. Each control block will be described in detail below.

[Voltage calculation part]
Voltage calculator 71 calculates AC voltage Vac from the instantaneous voltages _va , _vb , and _vc of the phases detected by voltage detector 7 using the following equation.

The voltage calculator 71 also calculates the frequency fac and the phase _φac in the AC wiring 5 by a known PLL (Phase Lock Loop) calculation. In addition, the voltage calculator 71 calculates the d-axis, which is the voltage on each coordinate _axis of the rotating coordinate system of the AC voltage, that is, the dq coordinate system, from the instantaneous voltages v _a , v _b , v _c of each phase and the phase φ ac according to the following equation. Voltage Vd and q-axis voltage Vq are calculated. Thus, in the present embodiment, controller 10 obtains voltages _Vd , Vq and frequency fac in AC wiring 5 from instantaneous voltages va, _vb , _vc detected by voltage detector 7 .

[Current calculation part]
The current calculator 72 calculates an AC current Iac output from the power converter 4 to the AC wiring 5 from the instantaneous currents _ia , _ib , and _ic of each phase detected by the current detector 8 according to the following equation.

Further, the current calculator 72 uses the instantaneous current i _a , i _b , i _c of each phase detected by the current detector 8 and the phase φac calculated by the voltage calculator 71 to calculate the rotating coordinate system of the alternating current by the following equation. A d-axis current Id and a q-axis current Iq, which are currents on each coordinate axis of , are calculated. Thus, in the present embodiment, the controller 10 obtains the currents Id and Iq in the AC wiring 5 from the instantaneous currents i _a , i _b and i _c detected by the current detector 8 .

[Power calculation part]
Power calculator 73 calculates corresponding power converter active power Pac and power converter reactive power Qac from the voltages Vd and Vq calculated by voltage calculator 71 and the currents Id and Iq calculated by current calculator 72 by the following equations: Calculate Note that, hereinafter, the power converter active power Pac and the power converter reactive power Qac may be simply referred to as the active power Pac and the reactive power Qac.

In this embodiment, as described above, the active power Pac and the reactive power Qac are calculated from the voltages Vd, Vq and the currents Id, Iq obtained from the voltage detector 7 and the current detector 8. However, it is not limited to this. For example, instead of this, power supply system 1 may include a power detector that detects active power Pac and reactive power Qac in AC wiring 5 . That is, controller 10 may acquire active power Pac and reactive power Qac from the outside. For example, the power detector may consist of a known power meter. In the following, the voltages Vd and Vq in the AC wiring 5 obtained by the voltage calculation unit 71 may be referred to as system voltages, and are output from the power converter 4 obtained by the current calculation unit 72 to the AC wiring 5. The currents Id and Iq are sometimes referred to as system currents.

[Frequency target value calculator]
FIG. 2 is a block diagram showing a configuration of a frequency target value calculation section in the controller shown in FIG. 1; As shown in FIG. 2, the frequency target value calculation unit 80 performs frequency target value calculation processing. In the frequency target value calculation process, the frequency target value calculation unit 80 calculates the frequency target value fac_ref such that the relationship between the active power Pac and the frequency fac has a predetermined first drooping characteristic. The first drooping characteristic means a characteristic such that the frequency fac decreases as the active power Pac increases, and the frequency fac increases as the active power Pac decreases.

Specifically, the frequency target value calculation unit 80 subtracts a power correction value Pac_cmp, which will be described later, from the first deviation D1=Pac_cmd−Pac, which is the deviation of the active power Pac from the predetermined active power command value Pac_cmd, A value multiplied by a droop coefficient Dr_p that indicates the drooping characteristic of 1 is calculated.

In the present embodiment, the frequency target value calculator 80 inputs the calculated value to the first-order lag calculator 86 to perform first-order lag calculation. This simulates the moment of inertia that occurs in a real generator in the virtual generator model. Note that the moment of inertia generated in the generator may be simulated by computation processing other than the first-order lag computation.

Furthermore, the value output from the first-order lag calculator 86 is input to the upper/lower limiter 87 . The upper/lower limiter 87 limits the value output from the first-order lag calculator 86 between a predetermined upper limit value and a predetermined lower limit value, and outputs a frequency reference value Δfac_ref. Note that the frequency reference value Δfac_ref may be calculated without providing the first-order lag calculator 86, the upper/lower limiter 87, or both in the frequency target value calculator 80. FIG.

The frequency target value calculator 80 adds a predetermined frequency command value fac_cmd to the frequency reference value Δfac_ref output from the upper/lower limiter 87 to calculate the frequency target value fac_ref.

When the power consumption of the load connected to the AC wiring 5 increases and the frequency fac in the AC wiring 5 decreases, the leading phase of the AC voltage in the AC wiring 5 with respect to the AC voltage output by the power converter 4 increases. . In response to this, the controller 10 lowers the frequency target value fac_ref in order to cancel out the lead phase. As a result, the active power Pac output by the power converter 4 increases.

Conversely, when the power consumption of the load connected to the AC wiring 5 decreases and the frequency fac in the AC wiring 5 increases, the AC voltage in the AC wiring 5 lags behind the AC voltage output by the power converter 4. increases. In response to this, the controller 10 increases the frequency target value fac_ref in order to cancel out the lag phase. As a result, the active power Pac output by the power converter 4 decreases.

[Internal phase difference angle calculator]
3 is a block diagram showing the configuration of an internal phase difference angle calculator in the controller shown in FIG. 1. FIG. As shown in FIG. 3, the internal phase difference angle calculator 82 calculates a second deviation D2=fac_ref−fac, which is the deviation of the frequency fac in the AC wiring 5 from the frequency target value fac_ref calculated by the frequency target value calculator 80. and input it to the integrator 88 for integration. The integrator 88 calculates the internal phase difference angle θ in the virtual generator by integrating the rotation speed of the virtual generator obtained by multiplying the second deviation D2 by the unit conversion coefficient Kw.

[Internal electromotive force target value calculator]
4 is a block diagram showing a configuration of an internal electromotive voltage target value calculation section in the controller shown in FIG. 1. FIG. As shown in FIG. 4 , internal electromotive voltage target value calculator 83 calculates AC voltage target value Vac_ref based on reactive power Qac calculated by power calculator 73 . Here, internal electromotive voltage target value calculation unit 83 calculates AC voltage target value Vac_ref such that the relationship of AC voltage Vac to reactive power Qac has a predetermined second drooping characteristic. The second drooping characteristic means a characteristic such that as the reactive power Qac increases, the AC voltage Vac decreases, and as the reactive power Qac decreases, the AC voltage Vac increases.

Specifically, the internal electromotive voltage target value calculation unit 83 calculates the droop coefficient Dr_q corresponding to the second drooping characteristic to the third deviation D3=Qac_cmd−Qac, which is the deviation of the reactive power Qac from the predetermined reactive power command value Qac_cmd. and an AC voltage command value Vac_cmd, which is a predetermined reference voltage, is added to that value to calculate an AC voltage target value Vac_ref.

Internal electromotive voltage target value calculation unit 83 generates internal electromotive voltage target value Ef_ref by performing a proportional integration operation on the deviation of AC voltage Vac from AC voltage target value Vac_ref. A transfer function in the proportional-integral calculation is expressed by, for example, Kp+Ki/s, where Kp is the proportional gain and Ki is the integral gain. Thus, by giving the second drooping characteristic to the third deviation D3, which is the deviation of the reactive power Qac from the reactive power command value Qac_cmd, the automatic voltage regulation (AVR) using the reactive power Qac in the virtual generator A control mode simulating control can be easily realized.

Like frequency target value calculator 80, internal electromotive voltage target value calculator 83 may perform first-order lag calculation on the result of proportional-integral calculation of the deviation of AC voltage Vac from AC voltage target value Vac_ref. Further, the internal electromotive voltage target value calculation section 83 may apply the upper and lower limit limiters to the result of the proportional integral calculation or the result of the temporary delay calculation of the deviation of the AC voltage Vac from the AC voltage target value Vac_ref.

[Current command value calculator]
FIG. 5 is a block diagram showing the configuration of a current command value calculator in the controller shown in FIG. As shown in FIG. 5, in the current command value calculator 84, the internal phase difference angle θ calculated by the internal phase difference angle calculator 82, the internal electromotive voltage target value Ef_ref calculated by the internal electromotive voltage target value calculator 83, and the , the d-axis voltage Vd and the q-axis voltage Vq calculated by the voltage calculator 71 are input to the function calculator 89 . The function calculator 89 performs calculations shown in the following equations to calculate current target values Id_ref and Iq_ref.

The current target values Id_ref and Iq_ref obtained by the above equations are determined by the total impedance r+jx between the power supply that outputs the same voltage as the AC voltage Vac in the AC wiring 5 and the power supply that outputs the same voltage as the internal electromotive voltage target value Ef_ref. It is the value of the current that flows through the total impedance when it is assumed that they are connected.

By the way, the total impedance r+jx is defined as the sum of the internal impedance r _s +jx _s of the power storage equipment 3 and the external impedance r _l +jx _l between the power storage equipment 3 and the AC power supply system 2 . However, the internal impedance r _s +jx _s in the actual power storage equipment 3 is substantially equal to zero, and the overall impedance r+jx is substantially equal to the external impedance r _l +jx _l between the power storage equipment 3 and the AC wiring 5 . However, as described above, in the present embodiment, when calculating the current target values Id_ref and Iq_ref, the internal impedance r _s +jx _s of the power storage equipment 3 and the external impedance between the power storage equipment 3 and the AC power supply system 2 We decided to use the total impedance r+jx, which is the sum of r _l +jx _l .

In particular, by virtually increasing the internal impedance r _s +jx _s of the power storage equipment 3 to obtain the overall impedance r + jx, and using this virtual impedance to calculate the current target values Id_ref and Iq_ref, stable operation is possible. . This is because when a plurality of power converters 4 are operated in parallel, even a slight voltage difference between the power converters 4 causes the output balance to be greatly disturbed because the impedance of the power converters 4 is low. Virtually increasing the internal impedance of the power storage equipment 3 increases the impedance of the power converter 4, which can prevent the output balance from becoming unstable due to the voltage difference. For example, when the internal impedance r _s +jx _s is practically almost zero, considerable stabilization can be achieved by setting the total impedance to 0.1 PU for the resistance component and 0.4 PU for the reactance component.

That is, the current command value calculation unit 84 assumes that the virtual generator is connected to the AC wiring 5 instead of the power converter 4, and the virtual generator is connected to the internal electromotive voltage target value calculation unit 83 and the internal phase difference angle The current value output to the AC wiring 5 is estimated when the internal electromotive force obtained by the calculation unit 82 is generated. As a result, the apparent impedance of the power converter 4 rises, and the system is prevented from becoming unstable during interconnected operation with the AC power supply system 2 or parallel operation between the power converters 4 .

Furthermore, the current command value calculator 84 limits the current target values Id_ref and Iq_ref to within a predetermined first range to generate the current command values Id_cmd and Iq_cmd. That is, the current target values Id_ref and Iq_ref that are the outputs of the function calculator 89 are input to the limiters 90 and 91, respectively.

When the d-axis current target value Id_ref is equal to or greater than the upper limit value of the first range, the limiter 90 outputs the upper limit value as the d-axis current command value Id_cmd. When the d-axis current target value Id_ref is equal to or less than the lower limit value of the first range, the limiter 90 outputs the lower limit value as the d-axis current command value Id_cmd. The limiter 90 outputs the d-axis current target value Id_ref as the d-axis current command value Id_cmd when the d-axis current target value Id_ref is within the first range. The limiter 91 performs the same limiting process as the limiter 90 on the q-axis current target value Iq_ref. The upper limit value and lower limit value set in the limiters 90 and 91 may be mutually different values or may be the same value. The current command values Id_cmd and Iq_cmd output by the limiters 90 and 91 are input to the drive signal generator 85 .

Furthermore, the current command value calculation unit 84 calculates current deviations Id_cmp and Iq_cmp obtained as fourth deviations D4d and D4q, which are deviations of the current command values Id_cmd and I_cmd from the current target values Id_ref and Iq_ref, and the system voltages Vd and Vq. A power correction value Pac_cmp is calculated.

More specifically, the current command value calculator 84 subtracts the d-axis current command value Id_cmd, which is the output of the limiter 90, from the d-axis current target value Id_ref, which is the input of the limiter 90, to obtain the d-axis current deviation Id_cmp=D4d= Generate Id_ref-Id_cmd. Similarly, the current command value calculator 84 subtracts the q-axis current command value Iq_cmd, which is the output of the limiter 91, from the q-axis current target value Iq_ref, which is the input of the limiter 91, to obtain the q-axis current deviation Iq_cmp=D4q=Iq_ref-Iq_cmd. to generate Current deviations Id_cmp, Iq_cmp and system voltages Vd, Vq are input to electric power correction value calculator 92 .

The power correction value calculator 92 calculates the power correction value Pac_cmp by adding the value obtained by multiplying the d-axis voltage Vd by the d-axis current deviation Id_cmp and the value obtained by multiplying the q-axis voltage Vq by the q-axis current deviation Iq_cmp. That is, the power correction value Pac_cmp is represented by Pac_cmp=Vd*Id_cmp+Vq*Iq_cmp.

The current command value calculator 84 calculates the current command values Id_cmd and Iq_cmd so that the power converter 4 does not trip with respect to the current target values Id_ref and Iq_ref, which are the theoretical current outputs calculated from the virtual generator model. It is limited within the first range. The power correction value Pac_cmp corresponds to the power that could not be output due to the above restrictions of the power converter 4 with respect to the theoretical current output calculated from the virtual generator model.

The power correction value Pac_cmp is input to the frequency target value calculator 80 as described above. As shown in FIG. 2, the frequency target value calculator 80 subtracts the power correction value Pac_cmp from the first deviation D1, which is the deviation of the active power Pac from the predetermined active power command value Pac_cmd. Accordingly, the frequency target value calculator 80 corrects the frequency target value fac_ref by correcting the first deviation D1=Pac_cmd−Pac with the power correction value Pac_cmp.

In this way, when the current command values Id_cmd and Iq_cmd are limited to the theoretical current output calculated from the virtual generator model, power converter 4 does not output power corresponding to the virtual generator model. Even so, the frequency target value fac_ref is calculated in the frequency target value calculation unit 80 on the assumption that the electric power corresponding to the virtual generator model is output from the power converter 4 . Therefore, it is possible to prevent the target frequency value fac_ref from becoming excessive due to the restriction of the current command values Id_cmd and Iq_cmd.

[Drive signal generator]
FIG. 6 is a block diagram showing a configuration of a drive signal generator in the controller shown in FIG. 1; As shown in FIG. 6, the drive signal generator 85 receives the currents Id and Iq, the phase φac and the current command values Id_cmd and Iq_cmd in the AC wiring 5 . The drive signal generator 85 generates a drive signal So that makes the system currents Id and Iq equal to the current command values Id_cmd and Iq_cmd, and outputs the drive signal So to the power converter 4 .

Specifically, the drive signal generator 85 performs proportional integral calculation of fifth deviations D5d=Id_cmd−Id and D5q=Iq_cmd−Iq, which are the deviations of the system currents Id and Iq from the current command values Id_cmd and Iq_cmd. Furthermore, the drive signal generator 85 generates a limit voltage that limits the system voltage within a predetermined limit range. The limit voltage is a voltage that allows at least the d-axis voltage Vd or the q-axis voltage Vq to vary within a predetermined limit range.

In this embodiment, the d-axis voltage Vd is input to the drive signal generator 85 . The d-axis voltage Vd input to the drive signal generator 85 is input to the limiter 93 . The limiter 93 outputs a d-axis limit voltage Vdl that limits the d-axis voltage Vd to a predetermined second range. In the present embodiment, the magnitude of the d-axis limiting voltage Vdl is 0 or more and 1 or less, where 1 is the rated voltage of the d-axis voltage Vd. The drive signal generator 85 adds the d-axis limit voltage Vdl to the result of the proportional integral calculation for the fifth deviation D5d with respect to the d-axis current Id. That is, the d-axis limit voltage Vdl added to the result of the proportional integral calculation for the fifth deviation D5d with respect to the d-axis current Id is the d-axis voltage Vd at that time when the magnitude of the d-axis voltage Vd is equal to or less than the rated voltage. can vary depending on

Note that in the present embodiment, the q-axis limiting voltage is not added to the result of the proportional integral calculation for the fifth deviation D5q with respect to the q-axis current Iq. This is equivalent to adding a fixed value of 0 as a conventional q-axis voltage additive term.

Further, the drive signal generation unit 85 subtracts the interference component from the result of the proportional integral calculation for the fifth deviations D5d and D5q regarding the current in the AC wiring 5. In the virtual generator, there is interference between the d-axis current Id and the q-axis current Iq, such that when the d-axis current Id changes, the q-axis current Iq changes, and when the q-axis current Iq changes, the d-axis current Id changes. occur. The drive signal generator 85 performs non-interference processing to remove such interference components from the voltage command values Vd_cmd and Vq_cmd based on the current command values Id_cmd and Iq_cmd.

Specifically, the drive signal generation unit 85 subtracts the q-axis interference component XqIq obtained by multiplying the q-axis current Iq by a predetermined gain Xq from the result of the proportional integral calculation for the fifth deviation D5d with respect to the d-axis current Id. Similarly, the drive signal generator 85 adds a d-axis interference component XdId obtained by multiplying the d-axis current Id by a predetermined gain Xd to the result of the proportional-integral operation for the fifth deviation D5q with respect to the q-axis current Iq.

As described above, the drive signal generator 85 calculates the voltage command values Vd_cmd and Vq_cmd from the current command values Id_cmd and Iq_cmd by the following equations. Here, Kd, Kq, Xd and Xq represent predetermined gains, and Tid and Tiq represent predetermined time constants.

The drive signal generator 85 calculates the target values va_ref, vb_ref, _{vc_ref} of the instantaneous voltages _va , _vb , _vc of each phase of the AC _wiring 5, which is a three-phase AC, from the voltage command values Vd_cmd, _{Vq_cmd} . . Specifically, the voltage command values Vd_cmd and Vq_cmd are input to the dq-abc converter 94 . The dq-abc converter 94 calculates the target values v _{a_ref} , v _{b_ref} , and v _{c_ref} of the instantaneous voltages of the respective phases of the AC wiring 5 from the voltage command values Vd_cmd, Vq_cmd based on the following equations.

The calculated instantaneous voltage target values v _{a — ref} , v _{b — ref} , and v _{c — ref} are input to the signal converter 95 . The signal converter 95 generates a drive signal So for switching the power converter 4 based on the instantaneous voltage target values _{va_ref} , _{vb_ref} , and _{vc_ref} . For example, the drive signal So is a PWM control signal. The drive signal generator 85 outputs the drive signal So generated in this way. The drive signal So is input to the power converter 4, and the output voltage to the AC wiring 5 is controlled based on the drive signal So.

[effect]
According to the present embodiment, assuming that a virtual generator is connected to the AC wiring 5 instead of the power converter 4, in order to simulate the power that the virtual generator outputs to the AC wiring 5, The internal electromotive voltage target value Ef_ref and the internal phase difference angle θ of the generator are calculated, and the current output from the virtual generator is estimated from the internal electromotive voltage target value Ef_ref, the internal phase difference angle θ, and the voltages Vd and Vq in the AC wiring 5. ing. If a system fault or the like occurs in the power supply system 1 and a momentary voltage drop occurs, the estimated value of this current becomes an excessive value. Therefore, if the power converter 4 is driven using the estimated value of the current as it is as the current command value, the power converter 4 may be tripped or damaged due to overcurrent. As a result, it becomes impossible to continue the operation in the event of a momentary voltage drop and to quickly recover from the voltage drop state when the voltage in the AC power supply system 2 recovers.

Therefore, in the present embodiment, the current command values Id_cmd and Iq_cmd obtained by limiting the current target values Id_ref and Iq_ref estimated as the current output from the virtual generator to within the first range by the limiters 90 and 91 are used. Power converter 4 is driven. As a result, it is possible to suppress overcurrent when the voltage drops momentarily. Furthermore, since the d-axis limit voltage Vdl, which limits the d-axis voltage Vd within the second range, is added to the feedback loop of the d-axis current command value Id_cmd, the responsiveness of current control during an instantaneous voltage drop is enhanced. It is possible to prevent tripping due to overcurrent.

As described above, in the present embodiment, the estimated value of the current output from the virtual power generator is limited by the limiters 90 and 91, so the power output from the power converter 4 is also limited. In the present embodiment, the frequency target value fac_ref in the virtual generator is estimated from the first deviation D1, which is the deviation of the active power Pac from the predetermined active power command value Pac_cmd, and the internal phase difference angle θ is calculated from the frequency target value fac_ref. be done.

Therefore, when the active power Pac is limited during a momentary voltage drop, the first deviation D1 increases and the frequency target value fac_ref also increases. As a result, the internal phase difference angle .theta. becomes larger than the theoretical value when the voltage drops instantaneously, causing a large power fluctuation in the power supply system 1 when recovering from the voltage drop. Therefore, when the voltage in the AC power supply system 2 recovers, it may not be possible to quickly recover from the voltage drop state.

Therefore, in the present embodiment, power correction is performed based on the fourth deviation D4d=Id_cmp, D4q=Iq_cmp, which is the deviation of the current command values Id_cmd, I_cmd from the current target values Id_ref, Iq_ref, and the voltages Vd, Vq in the AC wiring 5. A value Pac_cmp is calculated. The calculated power correction value Pac_cmp is subtracted from the first deviation D1 for calculating the frequency target value fac_ref. As a result, an increase in the frequency target value fac_ref accompanying a decrease in power output due to the limitation by the limiters 90 and 91 is suppressed, and an increase in the internal phase difference angle θ that occurs during an instantaneous voltage drop is suppressed. Therefore, when the voltage in the AC power supply system 2 recovers, the occurrence of power fluctuation is suppressed, and the interconnection operation in the power converter 4 can be quickly restored from the voltage drop state.

In the conventional virtual generator model control, in order to switch between grid-connected operation and isolated operation without changing the control method, current feedback is performed by PI control in the drive signal generation unit, and the system voltage As additional terms of , the voltage command values Vd_cmd and Vq_cmd are calculated by adding the d-axis voltage Vd=1 and the q-axis voltage Vq=0. This makes it possible to switch between grid-connected operation and isolated operation without changing the control method, but on the other hand, if there is a momentary voltage drop, the follow-up is delayed and there is a risk of a transient excessive current flow. There is

On the other hand, in the present embodiment, in the drive signal generator 85, a voltage obtained by limiting the voltage in the AC wiring 5 is added as an addition term of the system voltage. That is, the drive signal generator 85 adds the d-axis limiting voltage Vdl to the result of the proportional integral calculation for the fifth deviation D5d=Id_cmd−Id regarding the d-axis current. This makes it possible to switch between grid-connected operation and isolated operation without changing the control method in the same way as the conventional virtual generator model control, while improving the responsiveness of current control when a momentary voltage drop occurs. can be enhanced.

In addition, as another method for realizing continuation of operation and quick recovery from the voltage drop state at the moment of voltage drop, it is possible to detect the momentary voltage drop and temporarily switch the control method. Conceivable. However, in this case, additional equipment is required to detect the occurrence of a momentary voltage drop. On the other hand, according to the present embodiment, there is no need to change the control method even when a momentary voltage drop occurs. Therefore, since it is not necessary to detect the occurrence of a momentary voltage drop, there is no need for additional equipment in the power supply system 1 to continue operation at the moment of the momentary voltage drop and the voltage drop at the time of voltage recovery in the AC power system. Rapid recovery from the state can be realized.

[simulation result]
(1) Simulation Regarding Occurrence of Instantaneous Voltage Drop As a first simulation, the results of a simulation in which an instantaneous voltage drop occurs in the power supply system 1 of the above-described embodiment are shown below. In the first simulation, as an example, for the power supply system 1 shown in FIG. was carried out and compared with the comparative example. In the first simulation, a momentary voltage drop occurs 5 seconds after the start of the simulation, and the voltage in the AC power supply system 2 recovers 0.3 seconds later.

In the comparative example, the correction by the power correction value Pac_cmp is not performed in the power supply system 1 shown in FIG. , and XdId are not subtracted, and the PI control is performed for the fifth deviations D5d and D5q regarding the current in the AC wiring 5 . Also in the comparative example, the current is limited by the limiters 90 and 91 in the current command value calculator 84 shown in FIG.

FIG. 7 is a graph showing temporal changes in output power in the first simulation. According to the graph of the output power Pc in the comparative example, after the voltage recovery in the AC power supply system 2 5.3 seconds after the start of the simulation, the output power Pc of the power converter largely swings into the negative region. As can be seen from the simulation results of the internal phase difference angle, which will be described later, it is considered that the increase in the internal phase difference angle that occurred during the momentary voltage drop became excessive and the step-out phenomenon occurred. For this reason, for example, one of the FRT requirements stipulated in the grid interconnection regulations (JEAC9701) is that after voltage recovery in the AC power system, the output must be restored to 80% or more of the output before the voltage drop within 0.1 seconds. can't satisfy you.

On the other hand, according to the graph of the output power Pe in the example, the step-out phenomenon does not occur, and the power fluctuation after voltage recovery is kept low. As a result, the above FRT requirements are satisfied. This is probably because the power compensation control using the power correction value Pac_cmp suppresses increases in the frequency target value fac_ref and the internal phase difference angle θ during an instantaneous voltage drop.

FIG. 8 is a graph showing temporal changes in frequency in the first simulation. The frequency in the graph of FIG. 8 is a value corresponding to the frequency fac obtained by the voltage calculator 71 . According to the graph of the frequency frc in the comparative example, when the voltage drops momentarily, the output power is suppressed by limiting the current command value, so the frequency frc rises. Furthermore, after the voltage recovery, a step-out phenomenon occurred, resulting in a further increase in the frequency frc.

On the other hand, according to the graph of the frequency fre in the example, an increase in the frequency fre is suppressed by the power compensation control using the power correction value Pac_cmp. The step-out phenomenon does not occur even after the voltage recovery, and although the frequency fre once decreases, it returns to a value close to the original frequency in a short period of time thereafter.

FIG. 9 is a graph showing temporal changes in the internal retardation angle in the first simulation. Comparing the graph of the internal phase difference angle θc in the comparative example with the graph of the internal phase difference angle θe in the example, the internal phase difference angle θc in the comparative example changes more greatly at the time of the instantaneous voltage drop. Furthermore, in the comparative example, the positive value instantaneously changes to a negative value after the voltage recovery. This indicates that the inclination of the change in the internal phase difference angle θc in the comparative example at the time of the momentary voltage drop was large, so the phase difference could not be restored at the time of the voltage recovery, and the step-out state occurred as it was. .

On the other hand, according to the graph of the internal phase difference angle θe in Example, the internal phase difference angle θe returns to its original state after the voltage recovery. This is considered to be due to the effect of power compensation control using the power correction value Pac_cmp.

FIG. 10 is a graph showing temporal changes in the d-axis current command value and the d-axis current of the example in the first simulation. FIG. 11 is a graph showing temporal changes in the d-axis current command value and the d-axis current of the comparative example in the first simulation. Also, FIG. 12 is a graph showing temporal changes in the output current from the power converter in the first simulation. The output current in the graph of FIG. 12 is a value corresponding to the alternating current Iac output from the power converter 4 to the alternating current wiring 5 obtained by the above equation (3).

According to the graph of the comparative example shown in FIG. 11, the d-axis current Idc cannot follow the d-axis current command value Idcc during the momentary voltage drop. That is, although the d-axis current command value Idcc is limited by the limiter, the d-axis current Idc exceeds the d-axis current command value Idcc. In contrast, according to the graph of the embodiment shown in FIG. 10, the d-axis current Ide can substantially follow the d-axis current command value Idce. This is considered to be due to the addition of the d-axis limit voltage Vdl, which is a limit voltage addition term, to the current feedback loop.

Regarding the current command value shown in FIG. 12, according to the graph of the current command value Ic in the comparative example, the current command value Ic exceeds 2.5 times the rated current immediately after the momentary voltage drop. Therefore, the power converter may trip due to overcurrent at this point. On the other hand, according to the graph of the current command value Ie in the example, it can be seen that the current command value Ie is appropriately limited even during an instantaneous voltage drop.

(2) Simulation on transition from grid-connected operation to isolated operation Below, as a second simulation, the results of a simulation when switching from grid-connected operation to isolated operation in the power supply system 1 of the above embodiment are shown below. shown in In the second simulation, using the same example and comparative example (hereinafter referred to as comparative example 1) as in the first simulation, switching from grid-connected operation to isolated operation realized in comparative example 1 is also performed in the example. It was verified whether it can be realized without inferiority. Furthermore, in the power supply system 1 of the above-described embodiment, a simulation of switching from grid-connected operation to isolated operation was performed as a comparative example 2 in which the voltage addition term added to the current feedback loop was not limited. rice field. In both examples, the simulation is performed when the grid-connected operation is switched to the isolated operation at a timing of 5 seconds from the start of the simulation.

FIG. 13 is a graph showing temporal changes in AC voltage and frequency in AC wiring based on the results of the second simulation for the example. FIG. 14 is a graph showing temporal changes in AC voltage and frequency in AC wiring based on the results of the second simulation for Comparative Example 1. In FIG. The AC voltages in these graphs are values corresponding to the AC voltage Vac obtained by the above equation (1). Further, the frequencies in these graphs are values corresponding to the frequency fac obtained by the voltage calculator 71 .

According to the graph of the AC voltage Vc1 and the frequency fc1 of Comparative Example 1 shown in FIG. The frequency fc1 fluctuates slightly. This is the expected response in virtual generator model control. The graph of the AC voltage Ve and the frequency fe of the example shown in FIG. 13 also shows the same result as the graph of the comparative example 1 shown in FIG. Therefore, in the power supply system 1 of the embodiment, similarly to the comparative example 1, it is considered that the switching from the grid-connected operation to the isolated operation can be realized without any problem.

FIG. 15 is a graph showing temporal changes in AC voltage and frequency in AC wiring, based on the results of the second simulation for Comparative Example 2. FIG. In Comparative Example 2, after 5 seconds from the start of the simulation, after parallel-off between the AC power supply system 2 and the power converter 4, both the AC voltage Vc2 and the frequency fc2 became abnormal values, and self-sustained operation was not possible. I understand.

(3) Summary of simulation From the results of the above two simulations, according to the control mode of the power supply system 1 in the above embodiment, it is possible to switch between isolated operation and grid-connected operation without changing the control method. In addition, even if a momentary voltage drop occurs during grid-connected operation, grid-connected operation can be continued, and when the voltage in the AC power supply system 2 recovers, the voltage drop can be rapidly recovered.

[Other embodiments]
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various improvements, changes, and modifications are possible without departing from the scope of the present disclosure.

For example, in the above embodiment, the case where the AC wiring 5 in the power supply system 1 is a three-phase system has been described, but the present invention is not limited to this. For example, even if the AC wiring 5 is a single-phase two-wire system or a single-phase three-wire system, the same power supply system 1 can be constructed except that the method of various calculations differs depending on the system system.

Further, in the above-described embodiment, the drive signal generator 85 exemplifies a mode in which the d-axis limit voltage Vdl is added to the feedback loop of the d-axis current Id. A q-axis limiting voltage Vql may be added to the feedback loop of the current Iq. That is, the drive signal generator 85 limits the q-axis voltage Vq as a limit voltage within a predetermined third range to a value based on the deviation D5q of the q-axis current Iq from the q-axis current command value Iq_cmd=Iq_cmd−Iq. The q-axis voltage command value Vq_ref may be generated by adding the axis limiting voltage Vql.

Further, in the above embodiment, the second range, which is the limit range of the d-axis voltage Vd for generating the d-axis limit voltage Vd1, is 0 or more and 1 or less when the rated voltage of the d-axis voltage Vd is 1. However, it is not limited to this. However, when the rated voltage of the d-axis voltage Vd is 1, the second range is preferably a range of 1 or less. When the q-axis limiting voltage Vql is added to the feedback loop of the q-axis current Iq, the d-axis limiting voltage Vdl may be a fixed value such as 1 when the rated voltage of the d-axis voltage Vd is 1, for example. Further, the third range, which is the limit range of the q-axis voltage Vq for generating the q-axis limit voltage Vq1, can be appropriately set according to the power supply system 1. However, the third range is preferably a range including 0 when the rated voltage of the q-axis voltage Vq is 1.

In the above embodiment, the interference component XqIq is subtracted from the fifth deviation D5d related to the d-axis current Id in order to perform non-interference processing between the d-axis and the q-axis in the drive signal generator 85, and Although an example of adding the interference component XdId to the fifth deviation D5q has been shown, the subtraction of the interference component XqIq and the addition of the interference component XdId may be omitted.

[Summary of this disclosure]
A controller for a power converter according to one aspect of the present disclosure is a controller for a power converter that performs power conversion between a power storage facility and an AC power system, wherein the AC power system and the power converter are The voltage and frequency in the AC wiring to be connected and the current output from the power converter to the AC wiring are obtained, and the relationship between the frequency and the active power of the power converter output by the power converter to the AC wiring is determined by a predetermined number. A frequency target including an operation of multiplying a value based on a first deviation, which is a deviation of the power converter active power from a predetermined active power command value, by a coefficient indicative of the first droop characteristic so as to have a droop characteristic of 1. A frequency target value is calculated by value calculation processing, a second deviation that is a deviation of the frequency in the AC wiring with respect to the frequency target value is integrated to calculate an internal phase difference angle, and the AC wiring for a predetermined reactive power command value is calculated. An internal electromotive voltage target value is calculated by adding a predetermined reference voltage to a value based on a third deviation, which is a deviation of the reactive power of the power converter output by the power converter, and the internal phase difference angle and the internal electromotive force are calculated. A current target value is calculated from the voltage target value and the voltage in the AC wiring, the current target value is limited within a predetermined first range to generate a current command value, and the current command value for the current target value is generated. A power correction value is calculated from a fourth deviation that is a deviation of the value and the voltage in the AC wiring, and the first deviation is corrected by the power correction value to correct the frequency target value, and the AC wiring A limit voltage is generated by limiting the voltage in a predetermined limit range, and the limit voltage is added to a value based on a fifth deviation that is the deviation of the current output to the AC wiring from the current command value to the voltage command value to generate a drive signal for the power converter.

According to the above configuration, the electric power converter is driven using the current command value obtained by limiting the current target value estimated as the current output from the virtual generator to within the first range. As a result, it is possible to suppress overcurrent when the voltage drops instantaneously. Furthermore, since a limit voltage that limits the voltage in the AC wiring to within a predetermined limit range is added to the feedback loop of the current command value, the responsiveness of the current control during momentary voltage drops can be improved. Tripping due to current can be prevented.

Furthermore, in the above configuration, the power correction value is calculated from the fourth deviation, which is the deviation of the current command value from the current target value, and the voltage in the AC wiring. The calculated power correction value is subtracted from the first deviation for calculating the frequency target value. As a result, the current command value is limited with respect to the current target value estimated as the current output from the virtual power generator, and the output power is determined based on the limited current command value, thereby reducing the power output. is suppressed. As a result, an increase in the internal phase difference angle that occurs during an instantaneous voltage drop is suppressed. Therefore, when the voltage in the AC power supply system recovers, the occurrence of power fluctuation is suppressed, and the voltage drop state can be quickly restored.

Further, in the above configuration, a voltage obtained by limiting the voltage in the AC wiring to within a predetermined limit range is added as an addition term of the voltage applied to the current feedback loop for generating the drive signal. This makes it possible to switch between grid-connected operation and isolated operation without changing the control method in the same way as the conventional virtual generator model control, while improving the responsiveness of current control when a momentary voltage drop occurs. can be enhanced.

The current command value includes a d-axis current command value and a q-axis current command value, and the controller calculates the d-axis voltage and the q-axis voltage from the instantaneous value of the voltage in the AC wiring, The d-axis current and the q-axis current are calculated from the instantaneous values of , and the d-axis voltage is limited within a predetermined second range as the limit voltage to a value based on the deviation of the d-axis current from the d-axis current command value. A d-axis voltage command value may be generated by adding the d-axis limiting voltage, and a value based on the deviation of the q-axis current from the q-axis current command value may be generated as the q-axis voltage command value.

The magnitude of the d-axis limiting voltage may be 0 or more and 1 or less, where 1 is the rated voltage of the d-axis voltage.

2 AC power supply system 3 Power storage equipment 4 Power converter 10 Controller 71 Voltage calculator 72 Current calculator 80 Frequency target value calculator 82 Internal phase difference angle calculator 83 Internal electromotive force target value calculator 84 Current command value calculator 85 Drive Signal generator

Claims (4)

A controller for a power converter that performs power conversion between a power storage facility and an AC power supply system,
Obtaining the voltage and frequency in the AC wiring connecting the AC power supply system and the power converter and the current output from the power converter to the AC wiring,
It is a deviation of the power converter active power from a predetermined active power command value so that the relationship of the frequency with respect to the power converter active power output from the power converter to the AC wiring has a predetermined first drooping characteristic. calculating a frequency target value by a frequency target value calculation process including a calculation of multiplying a value based on the first deviation by a coefficient indicating the first drooping characteristic;
calculating an internal phase difference angle by integrating a second deviation that is a deviation of the frequency in the AC wiring from the frequency target value;
An internal electromotive voltage target value is calculated by adding a predetermined reference voltage to a value based on a third deviation, which is a deviation of the power converter reactive power output from the power converter to the AC wiring with respect to a predetermined reactive power command value. death,
calculating a current target value from the internal phase difference angle, the internal electromotive voltage target value, and the voltage in the AC wiring;
generating a current command value by limiting the current target value within a predetermined first range;
calculating a power correction value from a fourth deviation, which is a deviation of the current command value from the current target value, and the voltage in the AC wiring;
correcting the frequency target value by correcting the first deviation with the power correction value;
A limit voltage is generated by limiting the voltage in the AC wiring within a predetermined limit range, and the limit voltage is added to a value based on a fifth deviation that is a deviation of the current output to the AC wiring from the current command value. A controller that generates a drive signal for the power converter by generating a voltage command value. the current command value includes a d-axis current command value and a q-axis current command value;
The controller is
calculating the d-axis voltage and the q-axis voltage from the instantaneous value of the voltage in the AC wiring;
calculating a d-axis current and a q-axis current from the instantaneous value of the current in the AC wiring;
A d-axis voltage command value is generated by adding a d-axis limit voltage obtained by limiting the d-axis voltage within a predetermined second range as the limit voltage to a value based on the deviation of the d-axis current from the d-axis current command value. ,
2. The controller according to claim 1, wherein a value based on a deviation of said q-axis current from said q-axis current command value is generated as a q-axis voltage command value. 3. The controller according to claim 2, wherein the magnitude of said d-axis limiting voltage is 0 or more and 1 or less, where 1 is the rated voltage of said d-axis voltage. A control method for a power converter that performs power conversion between a power storage facility and an AC power supply system,
Obtaining the voltage and frequency in the AC wiring connecting the AC power supply system and the power converter and the current output from the power converter to the AC wiring,
It is a deviation of the power converter active power from a predetermined active power command value so that the relationship of the frequency with respect to the power converter active power output from the power converter to the AC wiring has a predetermined first drooping characteristic. calculating a frequency target value by a frequency target value calculation process including a calculation of multiplying a value based on the first deviation by a coefficient indicating the first drooping characteristic;
calculating an internal phase difference angle by integrating a second deviation that is a deviation of the frequency in the AC wiring from the frequency target value;
An internal electromotive voltage target value is calculated by adding a predetermined reference voltage to a value based on a third deviation, which is a deviation of the power converter reactive power output from the power converter to the AC wiring with respect to a predetermined reactive power command value. death,
calculating a current target value from the internal phase difference angle, the internal electromotive voltage target value, and the voltage in the AC wiring;
generating a current command value by limiting the current target value within a predetermined first range;
calculating a power correction value from a fourth deviation, which is a deviation of the current command value from the current target value, and the voltage in the AC wiring;
correcting the frequency target value by correcting the first deviation with the power correction value;
A limit voltage is generated by limiting the voltage in the AC wiring within a predetermined second range, and the limit voltage is added to a value based on a fifth deviation that is a deviation of the current output to the AC wiring from the current command value. and generating a voltage command value to generate a drive signal for the power converter.

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