Power conversion device and control device

Abstract

Provided is a power conversion device comprising: a main circuit unit that has a power conversion unit for converting power and converts input power into AC power corresponding to a power system; and a control device that calculates an instantaneous value voltage output command value for the AC power output from the power conversion unit and controls the operation of the power conversion unit so that a voltage corresponding to the instantaneous value voltage output command value is output from the power conversion unit, wherein the control device has a command value calculation unit whereby a phase voltage phase command value for the AC power output from the main circuit unit and a phase voltage amplitude command value for the AC power output from the main circuit unit are calculated, and a command value generation unit whereby an instantaneous value voltage output command value is calculated on the basis of the phase voltage phase command value and the phase voltage amplitude command value, and the command value calculation unit has a power synchronization control unit that calculates the phase voltage phase command value of the AC power output from the main circuit unit on the basis of the measured value of active power at the output terminal of the main circuit and a corrected active power command value obtained by correcting an active power command value in accordance with at least one of the frequency of the AC voltage output from the main circuit unit and the frequency of the AC voltage of the power system. As a result, it is possible to provide a power conversion device that can attenuate power fluctuation phenomena as quickly as possible and obtain desired frequency-effective power output droop characteristics, and a control device for the power conversion device.

Description

Power conversion device and control device

[0001] Embodiments of the present invention relate to a power conversion device and a control device thereof.

[0002] Voltage-source, voltage-controlled power converters (Grid forming inverters) are known. Compared to voltage-source, current-controlled power converters (Grid following inverters), voltage-source, voltage-controlled power converters can achieve a seamless transition between grid-connected operation and standalone operation.

[0003] However, voltage source voltage control type power converters can potentially generate power fluctuations, which cause fluctuations in the active power output, due to their interaction with the power grid. Power fluctuations can have adverse effects on the power grid. Therefore, measures are being considered to reduce power fluctuations as quickly as possible when they occur in voltage source voltage control type power converters.

[0004] On the other hand, power converters connected to power grids have a predetermined frequency-active power output droop characteristic that changes the magnitude of the output active power in response to changes in the power grid frequency. Countermeasures against power fluctuations are in a trade-off relationship with the frequency-active power output droop characteristic; if power fluctuations are to be attenuated quickly, it may become impossible to obtain the desired frequency-active power output droop characteristic.

[0005] Therefore, in voltage source voltage control type power converters and their control devices, it is desirable to attenuate power fluctuation phenomena as quickly as possible and to obtain the desired frequency-active power output droop characteristics.

[0006] Ryotaro Hirakawa, et al., "Basic Research on Power Oscillation Damping Control in Grid-Forming Inverters," Central Research Institute of Electric Power Industry Report, Central Research Institute of Electric Power Industry, September 2023, Research Report: GD22018

[0007] Embodiments of the present invention provide a power converter and a control device that can attenuate power fluctuation phenomena as quickly as possible and obtain desired frequency-active power output droop characteristics.

[0008] According to an embodiment of the present invention, the present invention includes a power conversion unit that performs power conversion, a main circuit unit that converts input power into AC power corresponding to a power system, and outputs the converted AC power to the power system, and a control device that controls the power conversion by the main circuit unit by calculating an instantaneous voltage output command value of the AC power output from the power conversion unit and controlling the operation of the power conversion unit so that a voltage corresponding to the instantaneous voltage output command value is output from the power conversion unit, wherein the control device includes a command value calculation unit that calculates a phase voltage phase command value of the AC power output from the main circuit unit and a phase voltage amplitude command value of the AC power output from the main circuit unit, and based on the phase voltage phase command value and the phase voltage amplitude command value, the instantaneous voltage output command A power converter is provided, comprising: a command value generation unit for calculating command values, the command value calculation unit calculates the phase voltage phase command value of the AC power output from the main circuit unit based on a corrected active power command value obtained by correcting the active power command value according to at least one of the frequency of the AC voltage output from the main circuit unit and the frequency of the AC voltage of the power system, and a measured value of active power at the output terminal of the main circuit unit; and a voltage amplitude control unit for calculating the phase voltage amplitude command value of the AC power output from the main circuit unit based on the deviation between the reactive power command value and the measured value of reactive power at the output terminal of the main circuit unit, or the deviation between the instantaneous voltage output command value and the measured value of the phase voltage of the AC power output from the main circuit unit.

[0009] According to embodiments of the present invention, a power converter and its control device are provided that can attenuate power fluctuation phenomena as quickly as possible and obtain desired frequency-active power output droop characteristics.

[0010] It is a block diagram schematically showing a power conversion device according to an embodiment. It is a block diagram schematically showing an example of a command value calculation unit according to an embodiment. It is a block diagram schematically showing an example of a command value generation unit according to an embodiment. FIGS. 4(a) and 4(b) are graphs schematically showing an example of the operation of a reference power conversion device. FIGS. 5(a) and 5(b) are graphs schematically showing an example of the operation of a reference power conversion device. It is a graph schematically showing an example of the operation of a power conversion device according to an embodiment. It is a block diagram schematically showing a modified example of a power synchronization control unit according to an embodiment. It is a block diagram schematically showing a modified example of a power synchronization control unit according to an embodiment. It is a block diagram schematically showing a modified example of a power synchronization control unit according to an embodiment. It is a block diagram schematically showing a modified example of a voltage amplitude control unit according to an embodiment.

[0011] Hereinafter, each embodiment will be described with reference to the drawings. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc. are not necessarily the same as those in reality. Also, even when representing the same part, the dimensions and ratios may be shown differently in the drawings. In the specification of the present application and each figure, the same reference numerals are given to the same elements as those described above with respect to the already shown figures, and detailed descriptions are appropriately omitted.

[0012] FIG. 1 is a block diagram schematically showing a power conversion device according to an embodiment. As shown in FIG. 1, the power conversion device 10 includes a main circuit unit 12, a control device 14, a first measurement device 16, and a second measurement device 18. The main circuit unit 12 converts electric power. The control device 14 controls the conversion of electric power by the main circuit unit 12.

[0013] The main circuit unit 12 is connected to the power grid 2 and the power supply device 4. The power grid 2 is an AC power grid. The AC power of the power grid 2 is, for example, three-phase AC power. However, the AC power of the power grid 2 may be single-phase AC power or the like. The power supply device 4 is, for example, a power storage device using a storage battery or the like. The power supply device 4 outputs DC power to the main circuit unit 12.

[0014] The main circuit section 12, for example, converts the DC power input from the power supply device 4 into AC power corresponding to the power system 2, outputs the converted AC power to the power system 2, and charges the power supply device 4 by converting the AC power input from the power system 2 into DC power. Thereby, the main circuit section 12 connects the power supply device 4 to the power system 2.

[0015] The power supply device 4 is not limited to a power storage device, and may be, for example, a solar panel or the like. In this case, the main circuit section 12 may not have the function of converting the AC power input from the power system 2 into DC power.

[0016] Also, the power supply device 4 may be, for example, another generator such as a wind power generator or a gas turbine generator. The power input from the power supply device 4 to the main circuit section 12 is not limited to DC power and may be AC power. The main circuit section 12 may be configured to convert the AC power input from the power supply device 4 into another AC power corresponding to the power system 2. The power supply device 4 may be, for example, another power system different from the power system 2. The main circuit section 12 may be, for example, a frequency conversion device that connects two power systems with different frequencies.

[0017] Thus, the power conversion by the main circuit section 12 is not limited to the conversion from DC to AC, and may be any conversion that converts the power of the power supply device 4 into AC power corresponding to the power system 2.

[0018] The main circuit section 12 includes a power conversion section 20 and a filter circuit 22. The power conversion section 20 performs power conversion. The power conversion section 20, for example, has a plurality of switching elements and performs power conversion by switching the plurality of switching elements. The power conversion section 20, for example, has a plurality of switching elements connected in a three-phase bridge. The configuration of the power conversion section 20 may be any configuration that can convert the input power into AC power corresponding to the power system 2 by switching a plurality of switching elements or the like.

[0019] The filter circuit 22 is installed on the AC side of the power conversion unit 20. In other words, the filter circuit 22 is installed between the power conversion unit 20 and the power system 2. The filter circuit 22 brings the AC power output from the power conversion unit 20 closer to a sine wave. For example, the filter circuit 22 brings the AC power output from the power conversion unit 20 closer to a sine wave by suppressing high-frequency components contained in the AC power output from the power conversion unit 20.

[0020] The filter circuit 22 includes, for example, a reactor 24 connected in series with the AC output point of the power conversion unit 20, and a capacitor 26 connected in parallel with the AC output point of the power conversion unit 20. The reactor 24 and the capacitor 26 are provided for each phase of the AC power output from the power conversion unit 20.

[0021] However, the configuration of the filter circuit 22 is not limited to this, and may be any configuration that can make the AC power output from the power conversion unit 20 closer to a sine wave. Also, the configuration of the main circuit unit 12 is not limited to the above, and may be any configuration that has at least a power conversion unit 20, converts the input power into AC power corresponding to the power system 2, and outputs the converted AC power to the power system 2.

[0022] The first measuring device 16 measures the phase voltages Va(INV), Vb(INV), Vc(INV) and the line currents Ia(INV), Ib(INV), Ic(INV) of each phase of the AC power output from the power conversion unit 20, and inputs the measurement results to the control device 14.

[0023] The second measuring device 18 measures the phase voltages Va (PCS), Vb (PCS), and Vc (PCS) of each phase of the AC power output from the main circuit unit 12 (filter circuit 22), the line currents Ia (PCS), Ib (PCS), and Ic (PCS) of each phase, the active power P (PCS) at the output terminal of the main circuit unit 12, and the reactive power Q (PCS) at the output terminal of the main circuit unit 12, and inputs the measurement results to the control device 14.

[0024] The control device 14 controls the power conversion by the main circuit 12 by controlling the operation of the power conversion unit 20. In other words, the control device 14 controls the switching of the multiple switching elements of the power conversion unit 20.

[0025] The control device 14 receives the measurement results from the first measuring device 16 and the second measuring device 18, as well as the active power command value and reactive power command value of the AC power output from the main circuit unit 12, which are input from a higher-level controller or the like.

[0026] The control device 14 controls the operation of the power conversion unit 20 based on the measurement results input from the first measuring device 16 and the second measuring device 18, and the active power command value and reactive power command value input from a higher-level controller or the like.

[0027] More specifically, the control device 14 calculates the instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref) for each phase of the AC power output from the power conversion unit 20 based on the input measurement results, active power command value, and reactive power command value, and controls the operation of the power conversion unit 20 so that voltages corresponding to the calculated instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref) are output from the power conversion unit 20.

[0028] In this manner, the control device 14 controls the output voltage of the main circuit unit 12. The control device 14 performs voltage control operation of the main circuit unit 12. Note that the measurement results are not limited to being directly input to the control device 14 from the first measuring device 16 and the second measuring device 18, but may also be input to the control device 14 via, for example, a higher-level controller.

[0029] Furthermore, the measured values ​​of the active power P (PCS) and the reactive power Q (PCS) at the output terminal of the main circuit section 12 are not limited to being input from the second measuring device 18 to the control device 14. For example, they may be calculated within the control device 14 based on the measured values ​​of the phase voltages Va (PCS), Vb (PCS), Vc (PCS) and the line currents Ia (PCS), Ib (PCS), Ic (PCS) for each phase. The second measuring device 18 does not necessarily have to measure the active power P (PCS) and the reactive power Q (PCS).

[0030] The control device 14 includes a command value calculation unit 30 and a command value generation unit 32. The command value calculation unit 30 receives active power command values ​​and reactive power command values ​​input from a higher-level controller, as well as measured values ​​of active power P (PCS) and reactive power Q (PCS) measured by the second measuring device 18.

[0031] The command value calculation unit 30 calculates the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the active power command value and the measured value of active power P (PCS). Then, the command value calculation unit 30 calculates the phase voltage amplitude command value |V| of the AC power output from the main circuit unit 12 based on the reactive power command value and the measured value of reactive power Q (PCS). The command value calculation unit 30 inputs the calculated phase voltage phase command value θ and phase voltage amplitude command value |V| to the command value generation unit 32.

[0032] The command value generation unit 32 receives the phase voltage phase command value θ and the phase voltage amplitude command value |V| from the command value calculation unit 30, as well as the measured values ​​of the phase voltages Va(INV), Vb(INV), Vc(INV), line currents Ia(INV), Ib(INV), Ic(INV) measured by the first measuring device 16, and the phase voltages Va(PCS), Vb(PCS), Vc(PCS), line currents Ia(PCS), Ib(PCS), Ic(PCS) measured by the second measuring device 18.

[0033] The command value generation unit 32 calculates instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref) using the input information of the phase voltage phase command value θ, phase voltage amplitude command value |V|, phase voltages Va(INV), Vb(INV), Vc(INV), line currents Ia(INV), Ib(INV), Ic(INV), phase voltages Va(PCS), Vb(PCS), Vc(PCS), and line currents Ia(PCS), Ib(PCS), and Ic(PCS).

[0034] The command value generation unit 32 calculates instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref) based on each input information to suppress overcurrent at the output terminal of the main circuit unit 12. The command value generation unit 32 may also be called, for example, an overcurrent suppression control unit.

[0035] Figure 2 is a schematic block diagram showing an example of a command value calculation unit according to the embodiment. As shown in Figure 2, the command value calculation unit 30 includes a power synchronization control unit 40 and a voltage amplitude control unit 42.

[0036] The power synchronization control unit 40 calculates the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the corrected active power command value Pref', which is obtained by correcting the active power command value Pref according to the frequency of the AC voltage output from the main circuit unit 12, and the measured value of the active power P (PCS).

[0037] The power synchronization control unit 40 includes, for example, a low-pass filter 50, a subtractor 51, an arithmetic unit 52, an adder 53, and an integrator 54.

[0038] The low-pass filter 50 receives the measured value of the active power P (PCS). The low-pass filter 50 processes the measured value of the active power P (PCS) to attenuate components above a predetermined frequency, and inputs the processed measured value of the active power P (PCS) to the subtractor 51. This suppresses noise components, such as temporary measurement anomalies, included in the measured value of the active power P (PCS). Note that the power synchronization control unit 40 does not necessarily have a low-pass filter 50. For example, the measured value of the active power P (PCS) may be input directly to the subtractor 51.

[0039] The subtractor 51 receives the measured value of the active power P (PCS) after processing, as well as the corrected active power command value Pref'. The subtractor 51 subtracts the measured value of the active power P (PCS) from the corrected active power command value Pref' to calculate the deviation between the corrected active power command value Pref' and the measured value of the active power P (PCS), and inputs the calculated deviation to the arithmetic unit 52.

[0040] Based on the input deviation, the arithmetic unit 52 outputs a correction value Δf of the frequency of the AC voltage from the main circuit unit 12 to bring the measured value of the active power P (PCS) closer to the corrected active power command value Pref'. ＧＦＭ The calculator performs the calculation. The calculator unit 52 calculates the correction value Δf of the calculated frequency. ＧＦＭ This is input to the adder 53.

[0041] When the measured value of the active power P(PCS) is smaller than the corrected active power command value Pref', the arithmetic unit 52 calculates the correction value Δf so as to increase the frequency according to the magnitude of the difference between the corrected active power command value Pref' and the measured value of the active power P(PCS). ＧＦＭ Thereby, the measured value of the active power P(PCS) can be increased and brought closer to the corrected active power command value Pref'. Conversely, when the measured value of the active power P(PCS) is larger than the corrected active power command value Pref', the arithmetic unit 52 calculates the correction value Δf so as to decrease the frequency according to the magnitude of the difference between the corrected active power command value Pref' and the measured value of the active power P(PCS). ＧＦＭ Thereby, the measured value of the active power P(PCS) can be decreased and brought closer to the corrected active power command value Pref'.

[0042] The arithmetic unit 52 calculates the correction value Δf of the frequency based on the deviation of the active power by, for example, proportional-integral control. However, the calculation method of the correction value Δf of the frequency by the arithmetic unit 52 is not limited to the above, and any method that can appropriately calculate the correction value Δf of the frequency based on the deviation of the active power may be used. In other words, the configuration of the arithmetic unit 52 may be any configuration that can calculate the deviation between the target value of the frequency of the AC voltage output from the main circuit unit 12 and the reference value (rated frequency) of the frequency based on the deviation between the corrected active power command value Pref' and the measured value of the active power P(PCS). ＧＦＭ However, the correction value Δf of the frequency by the arithmetic unit 52 ＧＦＭ The calculation method is not limited to the above, and any method that can appropriately calculate the correction value Δf of the frequency based on the deviation of the active power may be used. ＧＦＭ In other words, the configuration of the arithmetic unit 52 may be any configuration that can calculate the deviation between the target value of the frequency of the AC voltage output from the main circuit unit 12 and the reference value (rated frequency) of the frequency based on the deviation between the corrected active power command value Pref' and the measured value of the active power P(PCS).

[0043] The adder 53 receives the correction value Δf of the frequency and the reference value of the frequency of the AC voltage output from the main circuit unit 12. The adder 53 adds the correction value Δf of the frequency to the reference value of the frequency of the AC voltage output from the main circuit unit 12 to calculate the command value of the frequency of the AC voltage output from the main circuit unit 12, and inputs the calculated command value of the frequency to the integrator 54. ＧＦＭ is input, and the reference value of the frequency of the AC voltage output from the main circuit unit 12 is input. The adder 53 adds the correction value Δf of the frequency to the reference value of the frequency of the AC voltage output from the main circuit unit 12 to calculate the command value of the frequency of the AC voltage output from the main circuit unit 12, and inputs the calculated command value of the frequency to the integrator 54. ＧＦＭ By adding, the command value of the frequency of the AC voltage output from the main circuit unit 12 is calculated, and the calculated command value of the frequency is input to the integrator 54.

[0044] The reference value of the frequency of the AC voltage output from the main circuit unit 12 is represented by, for example, 1. The correction value Δf of the frequency ＧＦＭThis is a correction value expressed as a proportional ratio, for example, when the reference frequency is set to 1.

[0045] The integrator 54 integrates the frequency command value of the AC voltage output from the main circuit unit 12, which is input from the adder 53, and multiplies the integration result by 2π to calculate the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the frequency command value.

[0046] As a result, the power synchronization control unit 40 calculates the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the corrected active power command value Pref' and the measured value of the active power P (PCS).

[0047] Thus, the power synchronization control unit 40 adjusts the frequency of the AC voltage output from the main circuit unit 12 to bring the measured value of the active power P (PCS) closer to the corrected active power command value Pref'. ＧＦＭ The frequency correction value Δf is applied to the reference value of the frequency of the AC voltage output from the main circuit section 12. ＧＦＭ By adding these values, the command value for the frequency of the AC voltage output from the main circuit section 12 is calculated. The command value for the frequency is then integrated, and the phase voltage phase command value θ is calculated by multiplying the integration result by 2π.

[0048] The power synchronization control unit 40 further includes, for example, an arithmetic unit 55, a subtractor 56, and an arithmetic unit 57.

[0049] The arithmetic unit 55 receives the frequency correction value Δf calculated by the arithmetic unit 52. ＧＦＭ The input is received. The arithmetic unit 55 calculates the correction value Δf of the input frequency. ＧＦＭ A predetermined constant D ｏｕｔｅｒ By multiplying by this, the correction value of the active power command value Pref corresponding to the frequency of the AC voltage output from the main circuit unit 12 is calculated. The arithmetic unit 55 inputs the calculated correction value to the subtractor 56.

[0050] The subtractor 56 receives a correction value of the active power command value Pref calculated by the arithmetic unit 55, as well as the measured value of the active power command value Pref and the processed active power P (PCS) calculated by the low-pass filter 50.

[0051] The subtractor 56 subtracts the measured value of active power P (PCS) from the active power command value Pref, and also subtracts the correction value calculated by the arithmetic unit 55, and inputs the subtraction result to the arithmetic unit 57. The subtractor 56 may be configured to subtract only the correction value calculated by the arithmetic unit 55 from the active power command value Pref, for example.

[0052] Based on the input subtraction result, the arithmetic unit 57 calculates an active power command value Pref' by correcting the active power command value Pref according to the frequency of the AC voltage output from the main circuit unit 12. The arithmetic unit 57 inputs the calculated corrected active power command value Pref' to the subtractor 51.

[0053] The arithmetic unit 57 calculates the corrected active power command value Pref' based on the subtraction result, for example, by proportional-integral control. However, the method by which the arithmetic unit 57 calculates the corrected active power command value Pref' is not limited to the above, and any method that can appropriately calculate the corrected active power command value Pref' based on the subtraction result is acceptable.

[0054] Thus, the power synchronization control unit 40 sets the frequency correction value Δf ＧＦＭ A predetermined constant D ｏｕｔｅｒ By multiplying by this, a correction value for the active power command value Pref corresponding to the frequency of the AC voltage output from the main circuit unit 12 is calculated, and the corrected active power command value Pref' is calculated by correcting the active power command value Pref based on the correction value.

[0055] The configuration of the power synchronization control unit 40 is not limited to the above, and may be any configuration that can appropriately calculate the phase voltage phase command value θ based on the corrected active power command value Pref' and the measured value of the active power P (PCS).

[0056] The voltage amplitude control unit 42 calculates the phase voltage amplitude command value |V| of the AC power output from the main circuit unit 12 based on the reactive power command value Qref and the measured value of reactive power Q (PCS). The voltage amplitude control unit 42 includes, for example, a low-pass filter 60, a subtractor 61, an arithmetic unit 62, and an adder 63.

[0057] The low-pass filter 60 receives the measured value of reactive power Q (PCS). The low-pass filter 60 processes the measured value of reactive power Q (PCS) to attenuate components above a predetermined frequency, and inputs the processed measured value of reactive power Q (PCS) to the subtractor 61. This suppresses noise components, such as temporary measurement anomalies, included in the measured value of reactive power Q (PCS). Note that the voltage amplitude control unit 42 does not necessarily have a low-pass filter 60. For example, the measured value of reactive power Q (PCS) may be input directly to the subtractor 61.

[0058] The subtractor 61 receives the measured value of the reactive power Q (PCS) after processing, as well as the reactive power command value Qref. The subtractor 61 subtracts the measured value of the reactive power Q (PCS) from the reactive power command value Qref, and inputs the subtraction result to the arithmetic unit 62.

[0059] Based on the input subtraction result, the arithmetic unit 62 calculates a correction value ΔV for the magnitude (amplitude) of the AC voltage output from the main circuit unit 12 in order to bring the measured value of reactive power Q (PCS) closer to the reactive power command value Qref. The arithmetic unit 62 inputs the calculated correction value ΔV for the magnitude of the AC voltage to the adder 63.

[0060] If the measured value of reactive power Q (PCS) is smaller than the reactive power command value Qref, the arithmetic unit 62 calculates a correction value ΔV to reduce the magnitude of the AC voltage according to the magnitude of the difference between the reactive power command value Qref and the measured value of reactive power Q (PCS). This increases the measured value of reactive power Q (PCS) and brings it closer to the reactive power command value Qref. Conversely, if the measured value of reactive power Q (PCS) is larger than the reactive power command value Qref, the arithmetic unit 62 calculates a correction value ΔV to increase the magnitude of the AC voltage according to the magnitude of the difference between the reactive power command value Qref and the measured value of reactive power Q (PCS). This decreases the measured value of reactive power Q (PCS) and brings it closer to the reactive power command value Qref.

[0061] The arithmetic unit 62 calculates a correction value ΔV for the magnitude of the AC voltage based on the subtraction result, for example, by proportional-integral control. However, the method by which the arithmetic unit 62 calculates the correction value ΔV for the magnitude of the AC voltage is not limited to the above, and any method that can appropriately calculate the correction value ΔV for the magnitude of the AC voltage based on the subtraction result is acceptable.

[0062] The adder 63 receives a correction value ΔV for the magnitude of the AC voltage, as well as a reference value for the magnitude of the AC voltage output from the main circuit unit 12. The adder 63 calculates the phase voltage amplitude command value |V| of the AC power output from the main circuit unit 12 by adding the correction value ΔV for the magnitude of the AC voltage to the reference value for the magnitude of the AC voltage output from the main circuit unit 12.

[0063] The reference value for the magnitude of the AC voltage output from the main circuit section 12 is, for example, represented by 1. The correction value ΔV for the magnitude of the AC voltage is, for example, a correction value expressed as a proportional ratio when the reference value for the magnitude of the AC voltage is set to 1.

[0064] As a result, the voltage amplitude control unit 42 calculates the phase voltage amplitude command value |V| of the AC power output from the main circuit unit 12 based on the reactive power command value Qref and the measured value of reactive power Q (PCS).

[0065] In this way, the voltage amplitude control unit 42 calculates a correction value ΔV for the magnitude of the AC voltage output from the main circuit unit 12 in order to bring the measured value of the reactive power Q (PCS) closer to the reactive power command value Qref, and calculates the phase voltage amplitude command value |V| by adding the correction value ΔV for the magnitude of the AC voltage to the reference value of the magnitude of the AC voltage output from the main circuit unit 12.

[0066] However, the configuration of the voltage amplitude control unit 42 is not limited to the above, and may be any configuration that can appropriately calculate the phase voltage amplitude command value |V|.

[0067] Figure 3 is a schematic block diagram showing an example of a command value generation unit according to the embodiment. As shown in Figure 3, the command value generation unit 32 includes, for example, a subtractor 70, arithmetic units 71 and 72, an adder 73, a limiter 74, a subtractor 75, arithmetic units 76 and 77, a subtractor 78, an adder 79, a subtractor 80, arithmetic units 81 and 82, an adder 83, a limiter 84, a subtractor 85, arithmetic units 86 and 87, adders 88 and 89, and an inverse converter 90.

[0068] The subtractor 70 receives the phase voltage amplitude command value |V| calculated by the command value calculation unit 30, as well as the voltage signal Vod of the d-axis component of the AC power output from the main circuit unit 12. The voltage signal Vod of the d-axis component of the AC power output from the main circuit unit 12 is calculated, for example, by performing a dq conversion (Park conversion) on the phase voltages Va (PCS), Vb (PCS), and Vc (PCS) of each phase of the AC power output from the main circuit unit 12.

[0069] The subtractor 70 subtracts the voltage signal Vod from the phase voltage amplitude command value |V| and inputs the subtraction result to the arithmetic unit 71.

[0070] The arithmetic unit 71 calculates a correction value for the magnitude of the d-axis component of the AC current output from the power conversion unit 20, based on the input subtraction result, in order to bring the voltage signal Vod closer to the phase voltage amplitude command value |V|. The arithmetic unit 71 inputs the calculated correction value to the adder 73. The arithmetic unit 71 calculates the correction value based on the subtraction result, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 71 is not limited to this, and any method that can appropriately calculate the correction value based on the subtraction result is acceptable.

[0071] The arithmetic unit 72 receives the voltage signal Voq, which is the q-axis component of the AC power output from the main circuit unit 12. The voltage signal Voq, which is the q-axis component of the AC power output from the main circuit unit 12, is calculated, for example, by performing a dq conversion (Park conversion) on the phase voltages Va (PCS), Vb (PCS), and Vc (PCS) of each phase of the AC power output from the main circuit unit 12, similar to the voltage signal Vod of the d-axis component.

[0072] The arithmetic unit 72 calculates a correction value for the magnitude of the d-axis component of the AC current output from the power conversion unit 20, based on the input q-axis component voltage signal Voq. The arithmetic unit 72 calculates the correction value based on the voltage signal Voq, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 72 is not limited to this, and any method that can appropriately calculate the correction value based on the voltage signal Voq may be used. The arithmetic unit 72 inputs the calculated correction value to the adder 73.

[0073] The adder 73 receives correction values ​​calculated by the arithmetic units 71 and 72, as well as the current signal Igd of the d-axis component of the AC power output from the power conversion unit 20. The current signal Igd of the d-axis component of the AC power output from the power conversion unit 20 is calculated, for example, by performing a dq conversion (Park conversion) on the line currents Ia (INV), Ib (INV), and Ic (INV) of each phase of the AC power output from the power conversion unit 20.

[0074] The adder 73 adds the correction value calculated by the arithmetic unit 71 and the correction value calculated by the arithmetic unit 72 to the current signal Igd of the d axis component, thereby generating the current command value Icd of the d axis component of the AC current output from the main circuit unit 12. ＊ The adder 73 calculates the current command value Icd of the calculated d-axis component. ＊ Input this into limiter 74.

[0075] The limiter 74 controls the current command value Icd of the d-axis component. ＊ The value of is restricted to a predetermined range, and the current command value Icd of the d-axis component after processing is performed. ＊ Input this into the subtractor 75.

[0076] The subtractor 75 receives the current command value Icd for the d-axis component. ＊ Along with the input, the current signal Icd, which is the d-axis component of the AC power output from the main circuit unit 12, is also input. The current signal Icd, which is the d-axis component of the AC power output from the main circuit unit 12, is calculated, for example, by performing a dq conversion (Park conversion) on the line currents Ia (PCS), Ib (PCS), and Ic (PCS) of each phase of the AC power output from the main circuit unit 12.

[0077] The subtractor 75 controls the current command value Icd of the d-axis component. ＊ The current signal Icd of the d-axis component is subtracted from the signal, and the subtraction result is calculated by the arithmetic unit 76.

[0078] The arithmetic unit 76 calculates the current signal Icd based on the input subtraction result, and sets the current command value Icd ＊ The power conversion unit 20 calculates a correction value for the magnitude of the d-axis component of the AC voltage output to approximate the target value. The arithmetic unit 76 inputs the calculated correction value to the subtractor 78. The arithmetic unit 76 calculates the correction value based on the subtraction result, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 76 is not limited to this, and any method that can appropriately calculate the correction value based on the subtraction result may be used.

[0079] The arithmetic unit 77 receives the current signal Icq, which is the q-axis component of the AC power output from the main circuit unit 12. The current signal Icq, which is the q-axis component of the AC power output from the main circuit unit 12, is calculated by performing a dq conversion (Park conversion) on the line currents Ia (PCS), Ib (PCS), and Ic (PCS) of each phase of the AC power output from the main circuit unit 12, similar to the current signal Icd, which is the d-axis component.

[0080] The arithmetic unit 77 calculates a correction value for the magnitude of the d-axis component of the AC voltage output from the power conversion unit 20, based on the input q-axis component current signal Icq. The arithmetic unit 77 inputs the calculated correction value to the subtractor 78. The arithmetic unit 77 calculates the correction value based on the current signal Icq, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 77 is not limited to this, and any method that can appropriately calculate the correction value based on the subtraction result is acceptable.

[0081] The subtractor 78 subtracts the correction value input from the arithmetic unit 77 from the correction value input from the arithmetic unit 76, and inputs the subtraction result to the adder 79.

[0082] The adder 79 receives a correction value calculated by the subtractor 78, as well as the voltage signal Vgd of the d-axis component of the AC power output from the power conversion unit 20. The voltage signal Vgd of the d-axis component of the AC power output from the power conversion unit 20 is calculated, for example, by performing a dq conversion (Park conversion) on the phase voltages Va(INV), Vb(INV), and Vc(INV) of each phase of the AC power output from the power conversion unit 20.

[0083] The adder 79 calculates the voltage command value of the d-axis component of the AC power output from the power conversion unit 20 by adding a correction value to the input d-axis component voltage signal Vgd. The adder 79 inputs the calculated d-axis component voltage command value to the inverse converter 90.

[0084] The subtractor 80 receives a voltage command value for the q-axis component of the AC power output from the main circuit unit 12, as well as a voltage signal Voq for the q-axis component of the AC power output from the main circuit unit 12. The voltage command value for the q-axis component of the AC power output from the main circuit unit 12 is set to, for example, 0.

[0085] The subtractor 80 subtracts the voltage signal Voq from the voltage command value of the q-axis component and inputs the subtraction result to the arithmetic unit 81.

[0086] The arithmetic unit 81 calculates a correction value for the magnitude of the q-axis component of the AC current output from the power conversion unit 20, which brings the voltage signal Voq closer to the voltage command value of the q-axis component, based on the input subtraction result. The arithmetic unit 81 inputs the calculated correction value to the adder 83. The arithmetic unit 81 calculates the correction value based on the subtraction result, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 81 is not limited to this, and any method that can appropriately calculate the correction value based on the subtraction result is acceptable.

[0087] The arithmetic unit 82 receives the voltage signal Vod, which is the d-axis component of the AC power output from the main circuit unit 12. Based on the input voltage signal Vod of the d-axis component, the arithmetic unit 82 calculates a correction value for the magnitude of the q-axis component of the AC current output from the power conversion unit 20. The arithmetic unit 82 inputs the calculated correction value to the adder 83. The arithmetic unit 82 calculates the correction value based on the voltage signal Vod, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 82 is not limited to this, and any method that can appropriately calculate the correction value based on the voltage signal Vod may be used.

[0088] The adder 83 receives correction values ​​calculated by the arithmetic units 81 and 82, as well as the current signal Igq of the q-axis component of the AC power output from the power conversion unit 20. The current signal Igq of the q-axis component of the AC power output from the power conversion unit 20 is calculated, for example, by performing a dq conversion (Park conversion) on the line currents Ia(INV), Ib(INV), and Ic(INV) of each phase of the AC power output from the power conversion unit 20.

[0089] The adder 83 adds the correction value calculated by the arithmetic unit 81 and the correction value calculated by the arithmetic unit 82 to the current signal Igq of the q-axis component, thereby obtaining the current command value Icq of the q-axis component of the AC current output from the main circuit unit 12. ＊ The adder 83 calculates the current command value Icq of the calculated q-axis component. ＊ Input this into limiter 84.

[0090] The limiter 84 controls the current command value Icq of the q-axis component. ＊ The value of is restricted to a predetermined range, and the current command value Icq of the q-axis component after processing is obtained. ＊ This is input to the subtractor 85.

[0091] The subtractor 85 receives the current command value Icq for the q-axis component. ＊ Along with the input, the current signal Icq of the q-axis component of the AC power output from the main circuit unit 12 is input. The subtractor 85 takes the current command value Icq of the q-axis component as input. ＊ The current signal Icq of the q-axis component is subtracted from the signal, and the subtraction result is calculated by the arithmetic unit 86.

[0092] The arithmetic unit 86 determines the current command value Icq based on the input subtraction result. ＊ The power conversion unit 20 calculates a correction value for the magnitude of the q-axis component of the AC voltage output to approximate the target value. The arithmetic unit 86 inputs the calculated correction value to the adder 88. The arithmetic unit 86 calculates the correction value based on the subtraction result, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 86 is not limited to this, and any method that can appropriately calculate the correction value based on the subtraction result is acceptable.

[0093] The arithmetic unit 87 receives the current signal Icd, which is the d-axis component of the AC power output from the main circuit unit 12. Based on the input current signal Icd, the arithmetic unit 87 calculates a correction value for the magnitude of the q-axis component of the AC voltage output from the power conversion unit 20. The arithmetic unit 87 inputs the calculated correction value to the adder 88. The arithmetic unit 87 calculates the correction value based on the current signal Icd, for example, by proportional control or proportional-integral control. However, the calculation method by the arithmetic unit 87 is not limited to this, and any method that can appropriately calculate the correction value based on the current signal Icd may be used.

[0094] The adder 88 adds the correction value input from the arithmetic unit 86 and the correction value input from the arithmetic unit 87, and inputs the sum to the adder 89.

[0095] The adder 89 receives the correction value calculated by the adder 88, as well as the voltage signal Vgq of the q-axis component of the AC power output from the power conversion unit 20. The voltage signal Vgq of the q-axis component of the AC power output from the power conversion unit 20 is calculated, for example, by performing a dq conversion (Park conversion) on the phase voltages Va(INV), Vb(INV), and Vc(INV) of each phase of the AC power output from the power conversion unit 20.

[0096] The adder 89 calculates the voltage command value of the q-axis component of the AC power output from the power conversion unit 20 by adding a correction value to the input q-axis component voltage signal Vgq. The adder 89 inputs the calculated q-axis component voltage command value to the inverse converter 90.

[0097] The inverse converter 90 receives the voltage command value of the d-axis component and the voltage command value of the q-axis component as input, as well as the phase voltage phase command value θ calculated by the command value calculation unit 30. The inverse converter 90, for example, performs an inverse dq conversion (inverse Park conversion) on the voltage command value of the d-axis component and the voltage command value of the q-axis component based on the phase voltage phase command value θ, thereby calculating instantaneous voltage output command values ​​Va (ref), Vb (ref), and Vc (ref) corresponding to the phase voltage phase command value θ from the voltage command value of the d-axis component and the voltage command value of the q-axis component.

[0098] As a result, the command value generation unit 32 calculates the instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref). However, the configuration of the command value generation unit 32 is not limited to the above. The configuration of the command value generation unit 32 can be any configuration that can appropriately calculate the instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref) based on each input information.

[0099] Figures 4(a) and 4(b) are schematic graphs illustrating an example of the operation of a reference power converter. Figures 4(a) and 4(b) schematically illustrate an example of the operation of a reference power converter in which the power synchronization control unit 40 calculates the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the active power command value Pref and the measured value of the active power P (PCS). In other words, Figures 4(a) and 4(b) schematically illustrate an example of the operation of a reference power converter in which the input of the subtractor 51 is replaced from the corrected active power command value Pref' to the active power command value Pref.

[0100] In Figure 4(a), the horizontal axis represents time (seconds), and the vertical axis represents the magnitude of active power (Per-Unit: PU). Figure 4(a) schematically represents an example of the active power command value Pref and the active power P (PCS) at the output terminal of the main circuit unit 12. In other words, Figure 4(a) schematically represents an example of the target magnitude of active power for the main circuit unit 12 and the magnitude of active power output from the main circuit unit 12.

[0101] In Figure 4(b), the horizontal axis represents time (seconds), and the vertical axis represents the magnitude of the frequency (Hz). Figure 4(b) schematically shows an example of the frequency f (GRID) of the AC voltage of power system 2 and the frequency f (PCS) of the AC voltage output from the main circuit section 12.

[0102] As shown in Figure 4(a), the reference power converter may generate power fluctuations that cause the active power P (PCS) to oscillate. Power fluctuations occur due to interaction with the power system 2. Power fluctuations can be triggered by various factors, such as changes in command values.

[0103] Furthermore, as shown in Figure 4(b), in the reference power converter, when a power fluctuation phenomenon occurs, the frequency f(PCS) also oscillates in accordance with the oscillation of the active power P(PCS), and the deviation between the frequency f(PCS) of the main circuit section 12 and the frequency f(GRID) of the power system 2 also increases.

[0104] Figures 5(a) and 5(b) are schematic graphs illustrating an example of the operation of a reference power converter. Figure 5(a) schematically shows an example of the active power P (PCS) at the output terminal of the main circuit section 12. Figure 5(b) schematically shows an example of the frequency f (GRID) of the AC voltage of the power system 2 and the frequency f (PCS) of the AC voltage output from the main circuit section 12.

[0105] Figures 5(a) and 5(b) show a reference power converter similar to those in Figures 4(a) and 4(b), where the frequency correction value Δf calculated by the calculator 52 is used to suppress the occurrence of power fluctuation phenomena. ＧＦＭ Figures 5(a) and 5(b) schematically illustrate an example of another operation in which the calculations are adjusted. For example, Figures 5(a) and 5(b) schematically illustrate an example of another operation in which the proportional-integral control parameters of the calculator 52 are adjusted to suppress the occurrence of power fluctuation phenomena.

[0106] As shown in Figures 5(a) and 5(b), adjusting the operation of the arithmetic unit 52 can suppress fluctuations in active power P (PCS) and frequency f (PCS), but it may also increase the fluctuation of active power P (PCS) in response to fluctuations in the frequency f (GRID) of the power system 2. For example, in the examples shown in Figures 5(a) and 5(b), the active power P (PCS) of the main circuit section 12 fluctuates by approximately 1.0 PU in response to a 0.5 Hz fluctuation in the frequency f (GRID) of the power system 2.

[0107] In a power converter connected to power system 2, a frequency-active power output droop characteristic is predetermined, which changes the magnitude of the output active power P (PCS) in response to changes in the frequency f (GRID) of power system 2. The droop characteristic is sometimes called the governor characteristic. For example, the frequency-active power output droop characteristic is set so that the active power P (PCS) of the main circuit section 12 changes by 1.0 PU in response to a 5 Hz fluctuation in the frequency f (GRID) of power system 2. In this case, as shown in the examples in Figures 5(a) and 5(b), the active power P (PCS) of the main circuit section 12 fluctuates excessively in response to changes in the frequency f (GRID) of power system 2, making it impossible to obtain the desired frequency-active power output droop characteristic.

[0108] Thus, in the power converter shown in the reference, countermeasures against power fluctuations are in a trade-off relationship with the frequency-active power output droop characteristics. If the power fluctuations are to be attenuated quickly, it may become impossible to obtain the desired frequency-active power output droop characteristics.

[0109] Figure 6 is a schematic graph illustrating an example of the operation of the power converter according to the embodiment. Figure 6 schematically shows an example of the active power command value Pref and the active power P (PCS) at the output terminal of the main circuit section 12.

[0110] In the power converter 10 according to this embodiment, the power synchronization control unit 40 calculates the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the corrected active power command value Pref' obtained by correcting the active power command value Pref according to the frequency of the AC voltage output from the main circuit unit 12, and the measured value of the active power P (PCS).

[0111] As a result, the power converter 10 can relatively quickly dampen the oscillation of the active power P (PCS) (power oscillation phenomenon) even when a power oscillation phenomenon occurs, as shown in Figure 6, and can also converge the active power P (PCS) toward the target active power command value Pref.

[0112] In the power converter 10, by adjusting the operation of the arithmetic unit 52, the oscillations of the active power P (PCS) and the oscillations of the frequency f (PCS) can be suppressed, similar to the example shown in Figure 5. Furthermore, in the power converter 10, the constant D of the arithmetic unit 55 ｏｕｔｅｒ By adjusting the value of , the magnitude of the target active power command value Pref can be adjusted in accordance with the change in the frequency f (PCS) of the AC voltage output from the main circuit section 12. In other words, in the power converter 10, the constant D of the arithmetic unit 55 ｏｕｔｅｒ By adjusting this value, the magnitude of the active power P (PCS) output from the main circuit unit 12 can be adjusted in accordance with the change in the frequency f (PCS) of the AC voltage output from the main circuit unit 12. As a result, the power converter 10 can obtain the desired frequency-active power output droop characteristics.

[0113] Thus, the power converter 10 and its control device 14 according to this embodiment can attenuate power fluctuation phenomena as quickly as possible and obtain the desired frequency-active power output droop characteristics.

[0114] In this example, the frequency correction value Δf calculated by the arithmetic unit 52 is used. ＧＦＭ The value is input to the calculator 55, and the frequency correction value Δf ＧＦＭ The constant D ｏｕｔｅｒ By multiplying by , the correction value of the active power command value Pref is calculated. However, the value input to the arithmetic unit 55 is the frequency correction value Δf ＧＦＭ It is not limited to this, and any value corresponding to the frequency of the AC voltage output from the main circuit unit 12 is acceptable. For example, the command value of the frequency of the AC voltage output from the main circuit unit 12 calculated by the adder 53 is input to the arithmetic unit 55, and a constant D is applied to the frequency command value. ｏｕｔｅｒThe correction value for the active power command value Pref may be calculated by multiplying by .

[0115] The method for correcting the corrected active power command value Pref' is not limited to the above, and any method is acceptable in which the active power command value Pref is appropriately corrected according to the frequency of the AC voltage output from the main circuit section 12, thereby obtaining the desired frequency-active power output droop characteristics.

[0116] Figure 7 is a schematic block diagram showing a modified example of the power synchronization control unit according to the embodiment. As shown in Figure 7, the power synchronization control unit 40a further includes an arithmetic unit 58. In addition, in the power synchronization control unit 40a, the subtractor 51 and the arithmetic unit 52 are replaced by the subtractor 51a and the arithmetic unit 52a, respectively. Components that are substantially the same in function and configuration as those in the above embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0117] The arithmetic unit 52a, similar to the arithmetic unit 52 in the above embodiment, adjusts the frequency correction value Δf of the AC voltage output from the main circuit unit 12 based on the deviation input from the subtractor 51a. ＧＦＭ Perform the calculation.

[0118] The arithmetic unit 58 receives the frequency correction value Δf calculated by the arithmetic unit 52a. ＧＦＭ The input is received. The arithmetic unit 58 calculates the correction value Δf of the input frequency. ＧＦＭ By multiplying by a predetermined constant D, the corrected value of the corrected active power command value Pref' corresponding to the frequency of the AC voltage output from the main circuit unit 12 is calculated. The arithmetic unit 58 inputs the calculated corrected value to the subtractor 51a.

[0119] The subtractor 51a receives the correction value of the corrected active power command value Pref', along with the measured value of the processed active power P (PCS) and the corrected active power command value Pref'. The subtractor 51a subtracts the measured value of the active power P (PCS) and the correction value of the corrected active power command value Pref' from the corrected active power command value Pref'. As a result, the subtractor 51a further corrects the corrected active power command value Pref' with the correction value and calculates the deviation between the corrected active power command value Pref' after correction with the correction value and the measured value of the active power P (PCS). The subtractor 51a inputs the calculated deviation to the arithmetic unit 52a.

[0120] Based on the deviation input from the subtractor 51a, the arithmetic unit 52a adjusts the frequency correction value Δf of the AC voltage output from the main circuit unit 12 so that the measured value of the active power P (PCS) approaches the command value which has been further corrected based on the correction value calculated by the arithmetic unit 58 to correct the corrected active power command value Pref'. ＧＦＭ Perform the calculation.

[0121] This power synchronization control unit 40a is sometimes called a VSG (Virtual Synchronous Generators) system. In a VSG-type power synchronization control unit 40a, the rate of damping of power fluctuations can be adjusted by adjusting the value of the constant D of the arithmetic unit 58 (the value of the damping term).

[0122] In the VSG-type power synchronization control unit 40a, if the value of the constant D of the arithmetic unit 58 is reduced, the oscillation of the active power P (PCS) output from the main circuit unit 12 becomes larger when a power oscillation phenomenon occurs, as shown in Figure 4(a).

[0123] On the other hand, the value of the constant D in the arithmetic unit 58 is also a parameter that determines the frequency-active power output droop characteristics. For this reason, if the input of the subtractor 51 is replaced from the corrected active power command value Pref' to the active power command value Pref, as in the power converter shown in the reference above, and the value of the constant D in the arithmetic unit 58 is made excessively large, then, as shown in the examples in Figures 5(a) and 5(b), while the oscillations of the active power P (PCS) and frequency f (PCS) can be suppressed, the fluctuations of the active power P (PCS) may become larger in response to the fluctuations of the frequency f (GRID) of the power system 2.

[0124] In response, the power synchronization control unit 40a has a subtractor 51a that further corrects the corrected active power command value Pref' with the correction value, calculates the deviation between the corrected active power command value Pref' after correction with the correction value and the measured value of active power P (PCS), and the calculator 52a calculates the frequency correction value Δf based on the deviation calculated by the subtractor 51a. ＧＦＭ Perform the calculation.

[0125] As a result, the power synchronization control unit 40a sets the value of the constant D of the arithmetic unit 58 to a relatively large value that can suppress the power fluctuation phenomenon, while the constant D of the arithmetic unit 55 ｏｕｔｅｒ By adjusting the value of , the frequency-active power output droop characteristics can be adjusted. Therefore, in the power synchronization control unit 40a, as in the above embodiment, the power fluctuation phenomenon can be attenuated as quickly as possible, and the desired frequency-active power output droop characteristics can be obtained.

[0126] Thus, the configuration of the power synchronization control unit is not limited to the configuration of the power synchronization control unit 40 shown in Figure 2, but may also be the configuration of a VSG type power synchronization control unit 40a.

[0127] Figure 8 is a schematic block diagram showing a modified example of the power synchronization control unit according to the embodiment. As shown in Figure 8, the power synchronization control unit 40b further includes a frequency calculation unit 100 and a subtractor 102. In addition, in the power synchronization control unit 40b, the arithmetic unit 55 is replaced by the arithmetic unit 55b.

[0128] The frequency calculation unit 100 receives, for example, the phase voltages Va (PCS), Vb (PCS), and Vc (PCS) of each phase of the AC power output from the main circuit unit 12, which are measured by the second measuring device 18.

[0129] The frequency calculation unit 100 calculates the measured value of the frequency f (GRID) of the AC voltage of power system 2 based on the input phase voltages Va (PCS), Vb (PCS), and Vc (PCS), for example, by measuring the zero-crossing period of the input phase voltages Va (PCS), Vb (PCS), and Vc (PCS). The frequency calculation unit 100 inputs the calculated measured value of the frequency f (GRID) of the AC voltage of power system 2 to the subtractor 102.

[0130] The subtractor 102 receives the measured value of the frequency f (GRID) of the AC voltage of power system 2, as well as the rated frequency f of the AC voltage of power system 2. ０ The following is input. The subtractor 102 calculates the rated frequency f from the measured value of the AC voltage frequency f (GRID) of the power system 2. ０ By subtracting this, the measured value of the AC voltage frequency f (GRID) of power system 2 and the rated frequency f ０ The deviation Δf ｍｅａｓｕｒｅｄ The subtractor 102 calculates the deviation Δf of the calculated frequency. ｍｅａｓｕｒｅｄ This is input to the arithmetic unit 55b.

[0131] The arithmetic unit 55b calculates the deviation Δf of the input frequency. ｍｅａｓｕｒｅｄ A predetermined constant D ｏｕｔｅｒ By multiplying by this, a correction value for the active power command value Pref corresponding to the frequency f (GRID) of the AC voltage of power system 2 is calculated. The arithmetic unit 55b inputs the calculated correction value to the subtractor 56.

[0132] As a result, in the power synchronization control unit 40b, the corrected active power command value Pref' is equal to the frequency deviation Δf ｍｅａｓｕｒｅｄ The calculation is performed based on the following. In other words, in the power synchronization control unit 40b, the corrected active power command value Pref' is calculated based on the frequency f (GRID) of the AC voltage of the power system 2.

[0133] Thus, the power synchronization control unit 40b uses the measured value of the frequency f (GRID) of the AC voltage of the power system 2 and the rated frequency f of the AC voltage of the power system 2. ０ And the deviation Δf ｍｅａｓｕｒｅｄ Calculate the deviation Δf ｍｅａｓｕｒｅｄ A predetermined constant D ｏｕｔｅｒ By multiplying by this, a correction value for the active power command value Pref corresponding to the frequency f (GRID) of the AC voltage of power system 2 is calculated, and the corrected active power command value Pref' is calculated by correcting the active power command value Pref based on this correction value.

[0134] The power synchronization control unit 40b calculates an active power command value Pref' by correcting the active power command value Pref according to the frequency f (GRID) of the AC voltage of the power system 2. Then, the power synchronization control unit 40b calculates the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the corrected active power command value Pref' obtained by correcting the active power command value Pref according to the frequency f (GRID) of the AC voltage of the power system 2, and the measured value of the active power P (PCS).

[0135] Thus, the corrected active power command value Pref' may be calculated by correcting the active power command value Pref according to the frequency f (GRID) of the AC voltage of the power system 2, rather than being limited to the frequency of the AC voltage output from the main circuit unit 12. In this case as well, as in the above embodiments, the power fluctuation phenomenon can be attenuated as quickly as possible, and the desired frequency-active power output droop characteristics can be obtained.

[0136] The corrected active power command value Pref' may be calculated by correcting the active power command value Pref according to the frequency of the AC voltage output from the main circuit unit 12 and the frequency f(GRID) of the AC voltage of the power system 2. The method for calculating the corrected active power command value Pref' can be any calculation method that can appropriately calculate the corrected active power command value Pref' by correcting the active power command value Pref according to at least one of the frequency of the AC voltage output from the main circuit unit 12 and the frequency f(GRID) of the AC voltage of the power system 2.

[0137] The configuration of the power synchronization control unit 40b can be any configuration that can appropriately calculate the phase voltage phase command value θ of the AC power output from the main circuit unit 12 based on the corrected active power command value Pref' obtained by correcting the active power command value Pref according to at least one of the frequency of the AC voltage output from the main circuit unit 12 and the frequency f (GRID) of the AC voltage of the power system 2, and the measured value of the active power P (PCS).

[0138] In the example shown in Figure 8, the frequency deviation Δf calculated by the subtractor 102 is... ｍｅａｓｕｒｅｄ The value is input to the arithmetic unit 55b, and the frequency deviation Δf ｍｅａｓｕｒｅｄ The constant D ｏｕｔｅｒ By multiplying by this, the correction value for the active power command value Pref is calculated. However, the value input to the arithmetic unit 55b is the frequency deviation Δf ｍｅａｓｕｒｅｄ It is not limited to this, and any value corresponding to the frequency f(GRID) of the AC voltage of power system 2 is acceptable. For example, the measured value of the frequency f(GRID) of the AC voltage of power system 2 calculated by the frequency calculation unit 100 is input to the calculator 55b, and the constant D is applied to the measured value of frequency f(GRID). ｏｕｔｅｒ The correction value for the active power command value Pref may be calculated by multiplying by .

[0139] The method for correcting the corrected active power command value Pref' is not limited to the above, and any method is acceptable in which the active power command value Pref is appropriately corrected according to at least one of the frequency of the AC voltage output from the main circuit unit 12 and the frequency f (GRID) of the AC voltage of the power system 2, thereby obtaining the desired frequency-active power output droop characteristics.

[0140] Furthermore, in the example shown in Figure 8, the frequency calculation unit 100 calculates the measured frequency f (GRID) of the AC voltage of power system 2 based on the input phase voltages Va (PCS), Vb (PCS), and Vc (PCS) by measuring the zero-crossing period of the input phase voltages Va (PCS), Vb (PCS), and Vc (PCS). The method of calculating the measured frequency f (GRID) by the frequency calculation unit 100 is not limited to the above, and may also be a frequency calculation method using a PLL (Phase Locked Loop), for example.

[0141] Furthermore, the power synchronization control unit 40b may obtain the measured frequency f(GRID) of the AC voltage of the power system 2 from an external frequency measuring instrument connected to the power system 2, for example, without internally calculating the measured frequency f(GRID). The method for obtaining the measured frequency f(GRID) is not limited to the above, and any method that allows the power synchronization control unit 40b to appropriately obtain the measured frequency f(GRID) may be used.

[0142] Figure 9 is a schematic block diagram showing a modified example of the power synchronization control unit according to the embodiment. As shown in Figure 9, in the power synchronization control unit 40c, the arithmetic unit 55b (arithmetic unit 55), subtractor 56, arithmetic unit 57, frequency calculation unit 100, and subtractor 102 are omitted.

[0143] The power synchronization control unit 40c (control device 14) communicates with the external device 6 and receives the corrected active power command value Pref' from the external device 6. The power synchronization control unit 40c inputs the corrected active power command value Pref' received from the external device 6 to the subtractor 51a.

[0144] Thus, the power synchronization control unit 40c may obtain the corrected active power command value Pref' from an external device 6 without internally calculating it. The external device 6 is, for example, a higher-level controller. Communication between the power synchronization control unit 40c and the external device 6 may be via a wired connection or wireless connection.

[0145] In this example, the calculation of the corrected active power command value Pref' is performed, for example, by an external device 6. In this case, each component such as the arithmetic unit 55b (arithmetic unit 55), subtractor 56, arithmetic unit 57, frequency calculation unit 100, and subtractor 102 is provided in, for example, the external device 6.

[0146] Figure 10 is a schematic block diagram showing a modified example of the voltage amplitude control unit according to the embodiment. As shown in Figure 10, in the voltage amplitude control unit 42a, the reactive power command value Qref is replaced with instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref), and the measured value of reactive power Q(PCS) is replaced with the measured values ​​of the phase voltages Va(PCS), Vb(PCS), and Vc(PCS) of the AC power output from the main circuit unit 12. In addition, in the voltage amplitude control unit 42a, the low-pass filter 60, subtractor 61, and arithmetic unit 62 are replaced with the low-pass filter 60a, subtractor 61a, and arithmetic unit 62a, respectively.

[0147] The voltage amplitude control unit 42a calculates the phase voltage amplitude command value |V| of the AC power output from the main circuit unit 12 based on the instantaneous voltage output command values ​​Va(ref), Vb(ref), Vc(ref) and the measured values ​​of the phase voltages Va(PCS), Vb(PCS), Vc(PCS) of the main circuit unit 12.

[0148] The low-pass filter 60a performs a process to attenuate components above a predetermined frequency included in the measured values ​​of the phase voltages Va(PCS), Vb(PCS), and Vc(PCS) of the main circuit section 12, and inputs the processed measured values ​​of the phase voltages Va(PCS), Vb(PCS), and Vc(PCS) to the subtractor 61a. This makes it possible to suppress noise components such as temporary measurement anomalies included in the measured values ​​of the phase voltages Va(PCS), Vb(PCS), and Vc(PCS). Note that the voltage amplitude control section 42a does not necessarily have a low-pass filter 60a. For example, the measured values ​​of the phase voltages Va(PCS), Vb(PCS), and Vc(PCS) may be input directly to the subtractor 61a.

[0149] The subtractor 61a receives the measured values ​​of the processed phase voltages Va(PCS), Vb(PCS), and Vc(PCS), as well as the instantaneous voltage output command values ​​Va(ref), Vb(ref), and Vc(ref). The subtractor 61a subtracts the measured value of the phase voltage Va(PCS) from the instantaneous voltage output command value Va(ref), subtracts the measured value of the phase voltage Vb(PCS) from the instantaneous voltage output command value Vb(ref), and subtracts the measured value of the phase voltage Vc(PCS) from the instantaneous voltage output command value Vc(ref). The subtractor 61a inputs each subtraction result to the arithmetic unit 62a.

[0150] Based on the input subtraction results, the arithmetic unit 62a calculates a correction value ΔV for the magnitude (amplitude) of the AC voltage output from the main circuit unit 12, which brings each of the measured values ​​of the phase voltages Va (PCS), Vb (PCS), and Vc (PCS) closer to the respective instantaneous voltage output command values ​​Va (ref), Vb (ref), and Vc (ref). The arithmetic unit 62a inputs the calculated AC voltage magnitude correction value ΔV to the adder 63.

[0151] As a result, the voltage amplitude control unit 42a calculates the phase voltage amplitude command value |V| of the AC power output from the main circuit unit 12 based on the instantaneous voltage output command values ​​Va(ref), Vb(ref), Vc(ref) and the measured values ​​of the phase voltages Va(PCS), Vb(PCS), Vc(PCS) of the main circuit unit 12.

[0152] Thus, the method for calculating the phase voltage amplitude command value |V| is not limited to a method based on the reactive power command value Qref and the measured value of reactive power Q(PCS). It may also be a method based on the instantaneous voltage output command values ​​Va(ref), Vb(ref), Vc(ref) and the measured values ​​of the phase voltages Va(PCS), Vb(PCS), Vc(PCS) of the main circuit section 12.

[0153] The configuration of the voltage amplitude control unit 42a is not limited to the above, and can be any configuration that can appropriately calculate the phase voltage amplitude command value |V| based on the instantaneous voltage output command values ​​Va(ref), Vb(ref), Vc(ref) and the measured values ​​of the phase voltages Va(PCS), Vb(PCS), Vc(PCS) of the main circuit unit 12.

[0154] The voltage amplitude control unit can be configured in any way that allows for the appropriate calculation of the phase voltage amplitude command value |V| of the AC power output from the main circuit unit 12, based on the deviation between the reactive power command value Qref and the measured value of reactive power Q(PCS), or the deviation between the instantaneous voltage output command values ​​Va(ref), Vb(ref), Vc(ref) and the measured values ​​of phase voltages Va(PCS), Vb(PCS), Vc(PCS).

[0155] This embodiment includes the following aspects: (Note 1) A main circuit unit having a power conversion unit that converts power, converts input power into AC power corresponding to a power system, and outputs the converted AC power to the power system; A control device that controls the power conversion by the main circuit unit by calculating an instantaneous voltage output command value of the AC power output from the power conversion unit and controlling the operation of the power conversion unit so that a voltage corresponding to the instantaneous voltage output command value is output from the power conversion unit; The control device comprises: a command value calculation unit that calculates a phase voltage phase command value of the AC power output from the main circuit unit and a phase voltage amplitude command value of the AC power output from the main circuit unit; a command value generation unit that calculates the instantaneous voltage output command value based on the phase voltage phase command value and the phase voltage amplitude command value; The command value calculation unit A power converter comprising: a power synchronization control unit that calculates the phase voltage phase command value of AC power output from a main circuit unit based on a corrected active power command value obtained by correcting the active power command value according to at least one of the frequency of the AC voltage output from the main circuit unit and the frequency of the AC voltage of the power system, and a measured value of the active power at the output terminal of the main circuit unit; and a voltage amplitude control unit that calculates the phase voltage amplitude command value of AC power output from a main circuit unit based on the deviation between the reactive power command value and the measured value of the reactive power at the output terminal of the main circuit unit, or the deviation between the instantaneous voltage output command value and the measured value of the phase voltage of AC power output from the main circuit unit.

[0156] (Note 2) The power synchronization control unit calculates the deviation between the corrected active power command value and the measured value of the active power; calculates a correction value for the frequency of the AC voltage output from the main circuit unit to bring the measured value of the active power closer to the corrected active power command value based on the deviation; calculates a command value for the frequency of the AC voltage output from the main circuit unit by adding the frequency correction value to a reference value for the frequency of the AC voltage output from the main circuit unit; and calculates the phase voltage phase command value by integrating the frequency command value and multiplying the integration result by 2π, as described in Note 1.

[0157] (Note 3) The power synchronization control unit calculates a correction value for the corrected active power command value by multiplying the frequency correction value by a predetermined constant, further corrects the corrected active power command value by the correction value, and calculates the deviation between the corrected active power command value after correction by the correction value and the measured value of the active power, as described in Note 2.

[0158] (Note 4) The power synchronous control unit calculates a correction value for the active power command value corresponding to the frequency of the AC voltage output from the main circuit unit by multiplying the frequency correction value by a predetermined constant, and calculates the corrected active power command value by correcting the active power command value based on the correction value, as described in Note 2 or 3.

[0159] (Note 5) The power conversion device according to any one of Notes 1 to 3, wherein the power synchronization control unit calculates the difference between the measured value of the frequency of the AC voltage of the power system and the rated frequency of the AC voltage of the power system, calculates a correction value for the active power command value corresponding to the frequency of the AC voltage of the power system by multiplying the difference by a predetermined constant, and calculates the corrected active power command value by correcting the active power command value based on the correction value.

[0160] (Note 6) The power synchronization control unit is a power conversion device according to any one of Notes 1 to 3 that receives the corrected active power command value from an external device.

[0161] (Note 7) A control device for use in a power conversion device having a power conversion unit that performs power conversion, a main circuit unit that converts input power into AC power corresponding to a power system, and outputs the converted AC power to the power system, which controls the power conversion by the main circuit unit by calculating an instantaneous value voltage output command value of the AC power output from the power conversion unit and controlling the operation of the power conversion unit so that a voltage corresponding to the instantaneous value voltage output command value is output from the power conversion unit, comprising: a command value calculation unit that calculates a phase voltage phase command value of the AC power output from the main circuit unit and a phase voltage amplitude command value of the AC power output from the main circuit unit; and a command value generation unit that calculates the instantaneous value voltage output command value based on the phase voltage phase command value and the phase voltage amplitude command value, wherein the command value calculation unit A control device comprising: a power synchronization control unit that calculates the phase voltage phase command value of AC power output from a main circuit unit based on a corrected active power command value obtained by correcting the active power command value according to at least one of the frequency of the AC voltage output from the main circuit unit and the frequency of the AC voltage of the power system, and a measured value of active power at the output terminal of the main circuit unit; and a voltage amplitude control unit that calculates the phase voltage amplitude command value of AC power output from a main circuit unit based on the deviation between the reactive power command value and the measured value of reactive power at the output terminal of the main circuit unit, or the deviation between the instantaneous voltage output command value and the measured value of the phase voltage of AC power output from the main circuit unit.

[0162] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention and in the scope of the invention and its equivalents as described in the claims.

[0163] 2...Power system, 4...Power supply unit, 6...External equipment, 10...Power converter, 12...Main circuit section, 14...Control device, 16...First measuring device, 18...Second measuring device, 20...Power conversion section, 22...Filter circuit, 24...Reactor, 26...Capacitor, 30...Command value calculation unit, 32...Command value generation unit, 40, 40a-40c...Power synchronization control unit, 42, 42a...Voltage amplitude control unit, 50...Low-pass filter, 51, 51a...Subtractor, 52, 52a...Arithmetic unit, 53...Adder, 54...Integrator, 55, 55b...Arithmetic unit, 56...Subtractor, 57...Arithmetic unit, 58...Arithmetic unit, 60, 60a...Low-pass filter, 61, 61a...Subtractor, 62, 62a...Arithmetic unit, 63...Adder, 70...Subtractor, 71, 72...Arithmetic unit, 73...Adder, 74...Limiter, 75...Subtractor, 76, 77...Arithmetic unit, 78...Subtractor, 79...Adder, 80...Subtractor, 81, 82...Arithmetic unit, 83...Adder, 84...Limiter, 85...Subtractor, 86, 87...Arithmetic unit, 88, 89...Adder, 90...Inverse converter, 100...Frequency calculation unit, 102...Subtractor

Claims

1. A power conversion unit that performs power conversion, converts input power into AC power corresponding to a power system, and outputs the converted AC power to the power system; a control device that controls the power conversion by the main circuit unit by calculating an instantaneous voltage output command value of the AC power output from the power conversion unit and controlling the operation of the power conversion unit so that a voltage corresponding to the instantaneous voltage output command value is output from the power conversion unit; the control device comprises a command value calculation unit that calculates a phase voltage phase command value of the AC power output from the main circuit unit and a phase voltage amplitude command value of the AC power output from the main circuit unit; a command value generation unit that calculates the instantaneous voltage output command value based on the phase voltage phase command value and the phase voltage amplitude command value; the command value calculation unit A power converter comprising: a power synchronization control unit that calculates the phase voltage phase command value of AC power output from a main circuit unit based on a corrected active power command value obtained by correcting the active power command value according to at least one of the frequency of the AC voltage output from the main circuit unit and the frequency of the AC voltage of the power system, and a measured value of the active power at the output terminal of the main circuit unit; and a voltage amplitude control unit that calculates the phase voltage amplitude command value of AC power output from a main circuit unit based on the deviation between the reactive power command value and the measured value of the reactive power at the output terminal of the main circuit unit, or the deviation between the instantaneous voltage output command value and the measured value of the phase voltage of AC power output from the main circuit unit.

2. The power synchronization control unit calculates the deviation between the corrected active power command value and the measured value of the active power; calculates a correction value for the frequency of the AC voltage output from the main circuit unit to bring the measured value of the active power closer to the corrected active power command value based on the deviation; calculates a command value for the frequency of the AC voltage output from the main circuit unit by adding the frequency correction value to a reference value for the frequency of the AC voltage output from the main circuit unit; and calculates the phase voltage phase command value by integrating the frequency command value and multiplying the integration result by 2π.

3. The power synchronization control unit calculates a correction value for the corrected active power command value by multiplying the frequency correction value by a predetermined constant, further corrects the corrected active power command value by the correction value, and calculates the deviation between the corrected active power command value after correction by the correction value and the measured value of the active power, according to claim 2.

4. The power conversion device according to claim 2, wherein the power synchronization control unit calculates a correction value for the active power command value corresponding to the frequency of the AC voltage output from the main circuit unit by multiplying the frequency correction value by a predetermined constant, and calculates the corrected active power command value by correcting the active power command value based on the correction value.

5. The power conversion device according to claim 1, wherein the power synchronization control unit calculates the difference between a measured value of the frequency of the AC voltage of the power system and the rated frequency of the AC voltage of the power system, calculates a correction value for the active power command value corresponding to the frequency of the AC voltage of the power system by multiplying the difference by a predetermined constant, and calculates the corrected active power command value by correcting the active power command value based on the correction value.

6. The power conversion device according to claim 1, wherein the power synchronization control unit receives the corrected active power command value from an external device.

7. A control device used in a power conversion device having a power conversion unit that performs power conversion, a main circuit unit that converts input power into AC power corresponding to a power system, and outputs the converted AC power to the power system, the control device for controlling power conversion by the main circuit unit by calculating an instantaneous voltage output command value of the AC power output from the power conversion unit, and controlling the operation of the power conversion unit so that a voltage corresponding to the instantaneous voltage output command value is output from the power conversion unit, comprising: a command value calculation unit that calculates a phase voltage phase command value of the AC power output from the main circuit unit and a phase voltage amplitude command value of the AC power output from the main circuit unit; and a command value generation unit that calculates the instantaneous voltage output command value based on the phase voltage phase command value and the phase voltage amplitude command value, wherein the command value calculation unit A control device comprising: a power synchronization control unit that calculates the phase voltage phase command value of AC power output from a main circuit unit based on a corrected active power command value obtained by correcting the active power command value according to at least one of the frequency of the AC voltage output from the main circuit unit and the frequency of the AC voltage of the power system, and a measured value of active power at the output terminal of the main circuit unit; and a voltage amplitude control unit that calculates the phase voltage amplitude command value of AC power output from a main circuit unit based on the deviation between the reactive power command value and the measured value of reactive power at the output terminal of the main circuit unit, or the deviation between the instantaneous voltage output command value and the measured value of the phase voltage of AC power output from the main circuit unit.

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