Power converter control device, control method of power converter, and control program of power converter

Abstract

A power converter control device controls a voltage output from a power converter connected to a power line for supplying power from a power system to a load, the power converter control device including: a counter voltage calculation section that calculates a counter voltage that is in phase and has the same amplitude as a voltage of the power system; a voltage variation calculation section that acquires an output current command value of a current output from the power converter and calculates a voltage variation when the power converter outputs the output current command value through open-loop control based on the output current command value; and a voltage command value output section that outputs a voltage command value that is a voltage in which the counter voltage and the voltage variation are synthesized to the power converter.

Description

Technical Field

[0001] This invention relates to a power converter control device, a power converter control method, and a power converter control program. Background Technology

[0002] Due to power fluctuations from loads or distributed power sources connected to the power lines of a power system, the voltage or frequency of the power system may fluctuate. A power converter control device is used to control the output voltage of a power system by connecting a power converter that converts DC power from solar cells or batteries into AC power and controlling the output voltage to suppress voltage or frequency fluctuations in the power system.

[0003] As a power converter control device, for example as shown in Non-Patent Document 1, there exists a device comprising: a phase control unit that calculates the phase of the voltage output by the power converter based on the deviation between the active power command value and the active power output value; and an amplitude control unit that calculates the amplitude of the voltage output by the power converter based on the deviation between the reactive power command value and the reactive power output value. The power converter control device determines the control amount of the voltage output by the power converter based on the output values ​​of the phase control unit and the amplitude control unit.

[0004] Existing technical documents

[0005] Patent documents

[0006] Non-Patent Document 1: "Relevant Measures on the Practical Application of Countermeasures Against Inertia Decline in Renewable Energy Power Sources," Journal of the Chinese Institute of Electrical Engineering, Vol. 143, No. 4, April 1, 2023 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, when the voltage of a power line drops due to a short circuit or other accident in the power system, the active and reactive power output values ​​of the traditional power converter control device decrease, thus increasing the control quantity of the voltage output by the power converter and posing a risk of a current flowing through the converter that is larger than the commanded value.

[0009] Furthermore, with the recent shift towards renewable energy as the primary power source, a scenario is envisioned where multiple distributed power sources are connected to the same bus via power converters. Here, as with the power converter control device described, when feedback control is applied to the voltage output of the power converter, the feedback control quantity may fluctuate due to the control quantity of another power converter, potentially causing instability phenomena such as flicker.

[0010] Therefore, the present invention was made in view of the aforementioned problems, and its main objective is to enable the power converter to output a current that conforms to the command value regardless of voltage fluctuations in the power system.

[0011] Technical means to solve the problem

[0012] That is, the power converter control device of the present invention is a power converter control device for controlling the voltage output by a power converter connected to a power line, characterized in that it includes: a counter voltage calculation unit, which calculates a voltage that is in phase and has the same amplitude as the voltage of the power system, namely the counter voltage; a voltage change calculation unit, which acquires an output current command value and calculates the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value; and a voltage command value output unit, which outputs a voltage command value synthesized from the counter voltage and the voltage change to the power converter.

[0013] In this configuration, the opposing voltage is in phase and has the same amplitude as the power system voltage. The voltage command output unit synthesizes the opposing voltage and the voltage change, and outputs the voltage command value to the power converter. Therefore, the power system voltage is canceled out by the opposing voltage, and only the voltage change is applied to the grid-connected transformer and grid-connected reactor of the power converter. Thus, regardless of the voltage fluctuations in the power system, the power converter can output a current that meets the output current command value.

[0014] Furthermore, since the voltage change calculation unit calculates the voltage change through open-loop control, the voltage change will not fluctuate due to the control inputs of other distributed power sources even if multiple distributed power sources are connected to the same bus. Therefore, even when multiple distributed power sources are connected to the same bus, instability phenomena such as flicker can be prevented.

[0015] Preferably, the output current command value is at least one of the fundamental positive phase active current, fundamental positive phase reactive current, fundamental reverse phase current, and non-fundamental frequency current.

[0016] With this structure, if the fundamental positive-phase active current and fundamental positive-phase reactive current are obtained in the voltage change calculation unit, voltage or frequency fluctuations in the power system can be suppressed. Furthermore, if the fundamental reverse-phase current is obtained in the voltage change calculation unit, imbalances in the fundamental voltage or current can be suppressed. Moreover, if non-fundamental frequency currents are obtained in the voltage change calculation unit, harmonic voltage distortion can be suppressed.

[0017] Voltage-controlled inverters that supply inertia to power lines (hereinafter also known as grid-forming (GFM) inverters) are particularly prone to overcurrent due to voltage fluctuations in the power system compared to other power converters.

[0018] Therefore, the power converter that is preferably controlled by the power converter control device is a voltage-controlled inverter that supplies inertia to the power line.

[0019] With this structure, regardless of the voltage fluctuations in the power system, the current output from the power converter will always be the output current command value, thus suppressing overcurrent in the GFM inverter.

[0020] The voltage change calculation unit may include the following components: it further includes a positive phase voltage calculation unit that calculates the positive phase voltage as the voltage change amount. The positive phase voltage calculation unit obtains the output current command value and the phase of the power system, and calculates the positive phase voltage through open-loop control based on the output current command value so that it is synchronized with the phase of the power system.

[0021] If this structure is used, the power converter outputs a voltage that combines the opposing voltage and the positive phase voltage. Therefore, the voltage of the power system is canceled out by the opposing voltage, allowing the power converter to output only the positive phase voltage equivalent to the output current command value.

[0022] Preferably, the positive phase voltage calculation unit calculates the instantaneous voltage values ​​of active power and reactive power respectively through open-loop control based on the active current command value and the reactive current command value, and calculates the positive phase voltage by synthesizing the instantaneous voltage values ​​of active power and reactive power.

[0023] With this structure, since the positive phase voltage calculation unit calculates the instantaneous voltage values ​​of active power and reactive power, it can simultaneously suppress frequency fluctuations and voltage fluctuations.

[0024] Specifically, since the positive phase voltage calculation unit calculates the instantaneous voltage value of active power, it supplies active power to the power system when the power system frequency decreases and supplies active power to the power converter when the power system frequency increases. Therefore, frequency fluctuations can be suppressed.

[0025] Furthermore, since the positive phase voltage calculation unit calculates the instantaneous voltage value of reactive power, reactive power is supplied to the power system when the connection point voltage, which is the voltage at the connection between the power system and the power converter, drops, and reactive power is supplied to the power converter when the connection point voltage rises. Therefore, voltage fluctuations can be suppressed.

[0026] For example, if a large number of non-rotating generators, such as current-controlled solar generators, which lack inertia, are connected to the power system in order to make it the main power source, the inertia of rotating generators will be insufficient for supply and demand adjustment, and the power system may become unstable.

[0027] Therefore, it is preferable that the output current command value obtained by the positive phase voltage calculation unit is an active current command value including inertia and a reactive current command value including inertia.

[0028] With this structure, when the power converter converts DC power from the non-rotating generator into AC power, sufficient inertia can be supplied to the load, stabilizing the power system. Furthermore, "including inertia" refers to the generator supplying power to the load having the ability to autonomously reduce frequency variations in the power system.

[0029] The voltage change calculation unit may include the following components: it further includes a reverse phase voltage calculation unit that calculates the reverse phase voltage as the voltage change amount. The reverse phase voltage calculation unit obtains the phase command value of the reverse phase voltage and the output current command value, and calculates the reverse phase voltage through open-loop control based on the phase command value of the reverse phase voltage and the output current command value.

[0030] In addition, the voltage change calculation unit may include the following components: it also includes a non-fundamental component calculation unit, which calculates the non-fundamental component of the power system at a frequency different from the fundamental frequency as the voltage change, and obtains the phase command value of the non-fundamental component and the output current command value, and calculates the non-fundamental component through open-loop control based on the phase command value of the non-fundamental component and the output current command value.

[0031] With this structure, the current output from the power converter to compensate for voltage imbalances or non-fundamental components can suppress the generator's equivalent reverse current, prevent winding burn-out, or improve generator utilization. Furthermore, since it can output any reverse voltage or non-fundamental component, it can suppress harmonic voltage distortion or voltage imbalance caused by single-phase loads or rectifier loads, thereby improving power quality.

[0032] Furthermore, because the power converter outputs a reverse voltage or non-fundamental component, and the voltage is synthesized by the opposing voltage, the voltage of the power system is canceled out by the opposing voltage, and only the reverse voltage or non-fundamental component is output to the power system. Therefore, regardless of how the voltage of the power system fluctuates, the power converter can reliably output only the reverse voltage or non-fundamental component.

[0033] A control method for a power converter is disclosed, which controls the voltage output by the power converter connected to a power line, the power line being used to supply power from a power system to a load. The control method is characterized by calculating a voltage in phase and with the same amplitude as the voltage of the power system, i.e., a counter voltage; obtaining a current that causes the power converter to output, i.e., an output current command value; and calculating, through open-loop control, the voltage at which the power converter outputs the output current command value, i.e., the voltage change, so that the power converter outputs a voltage that combines the counter voltage and the voltage change.

[0034] Additionally, a control program for a power converter controls the voltage output by the power converter connected to a power line used to supply power from a power system to a load. The control program is characterized by enabling a computer to: function as a counter-voltage calculation unit, which calculates a counter-voltage that is in phase and has the same amplitude as the voltage of the power system; function as a voltage change calculation unit, which acquires an output current command value that causes the power converter to output the current, and calculates the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value; and function as a voltage command unit, which causes the power converter to output a voltage that combines the counter-voltage and the voltage change.

[0035] If this structure is used, the same effect as the power converter control device can be achieved.

[0036] The effects of the invention

[0037] According to the present invention configured in this way, the power converter can output a current that conforms to the command value regardless of the voltage fluctuation of the power system. Attached Figure Description

[0038] [ Figure 1 [Illustration 1] is a schematic diagram showing the structure of the power system in this embodiment.

[0039] [ Figure 2 [Illustration 1] is a diagram showing the functional blocks of the power converter control device in the described embodiment.

[0040] [ Figure 3 [Image 1] shows the simulation results of the output waveform of the power converter in the described embodiment.

[0041] [ Figure 4 [Image 1] shows the simulation results of the output waveform of the power converter during a short circuit in the described embodiment.

[0042] [ Figure 5[Image] shows the simulation results of the voltage waveform output by the power converter and the voltage waveform of the power system during a short circuit in the described embodiment.

[0043] [ Figure 6 [Illustration 1] is a diagram showing the functional blocks of a power converter control device in another embodiment. Detailed Implementation

[0044] Hereinafter, an embodiment of the power system of the present invention will be described with reference to the accompanying drawings. Furthermore, in any of the figures shown below, schematic depictions may be appropriately omitted or exaggerated for ease of understanding. Identical components are labeled with the same symbols, and descriptions are appropriately omitted.

[0045] <System Architecture>

[0046] In this embodiment, the power system 100 is connected to power line B, which supplies power from the power system 10 to the load 20, and supplies AC power to the load 20. Specifically, the power system 100 includes: a DC power supply 30, which supplies DC power; a power converter 40, which converts the DC power to AC power and supplies AC power to power line B; a measuring unit 50, which measures the current flowing through power line B or the voltage of power line B; and a power converter control device 60, which controls the voltage output by power converter 40. Furthermore, in this embodiment, a distributed power source 70 is connected in parallel with the power system 100 to power line B. Each part will be described below.

[0047] The DC power supply 30 is, for example, a non-rotating generator such as a solar generator or a wind turbine, or an electrical storage device such as a battery or a secondary battery.

[0048] The power converter 40 converts the DC power supplied from the DC power source 30 into AC power and supplies it to power line B. Specifically, the power converter 40 can supply inertia to power line B and is a voltage-controlled inverter, i.e., a GFM inverter (grid forming inverter). Additionally, as... Figure 1 As shown, viewed from the B side of the power line, the power converter 40 is connected to the power line B from the high-voltage side via the circuit breaker S, the grid-connected transformer T, and the grid-connected reactor L.

[0049] The measuring unit 50 has the functions of: a voltage measuring unit that measures the voltage of power line B using a transformer with a known instrument, for example; and a current measuring unit that measures the current flowing through power line B using a converter with a known instrument, for example. Specifically, as... Figure 1 As shown, the measuring unit 50 measures the current and voltage between the circuit breaker S and the grid-connected transformer T. Here, the voltage measured by the measuring unit 50 is equivalent to the voltage of the power system 10.

[0050] The power converter control device 60 is a dedicated or general-purpose computer equipped with a central processing unit (CPU), internal memory, input / output interface, analog / digital (A / D) converter, etc., which controls the voltage output by the power converter 40 based on predetermined instruction values. Specifically, the power converter control device 60 includes: a counter voltage calculation unit 61, which calculates the counter voltage Vabc, which is in phase and has the same amplitude as the voltage of the power system 10; a voltage change calculation unit 62, which calculates the voltage change when the power converter 40 outputs a current, i.e., an output current instruction value; and a voltage instruction value output unit 63, which outputs the instruction value Vref, which causes the power converter 40 to output a voltage. Furthermore, the power converter control device 60 can be integrated with the power converter 40, or it can be a separate device different from the power converter 40.

[0051] The counter-voltage calculation unit 61 acquires the voltage measured by the measurement unit 50, calculates the voltage that is in phase and has the same amplitude as the voltage measured by the measurement unit 50, and sets the calculated voltage as the counter-voltage Vabc. Furthermore, the phase used by the counter-voltage calculation unit 61 in calculating the counter-voltage Vabc can be obtained from the voltage measured by the measurement unit 50, or from phase information input via an external input mechanism (not shown).

[0052] The voltage change calculation unit 62 acquires the output current command value that causes the power converter 40 to output, and calculates the voltage change when the power converter 40 outputs the output current command value through open-loop control based on the output current command value. Open-loop control, as referred to here, means that the voltage change is calculated based on the output current command value without feedback of the voltage output by the power converter 40, using a known calculation method.

[0053] In this embodiment, the so-called output current command value includes at least one of the following command values: the active current command value i, which is the command value for the current used to suppress voltage fluctuations in the power system 10. p ref and reactive current command value i q ref; the command value for the reverse current used to suppress the imbalance of fundamental voltage and fundamental current, i.e., the reverse current command value I2ref; and the command value for the non-fundamental current used to suppress harmonic voltage distortion, i.e., the non-fundamental current command value I. n ref.

[0054] In this embodiment, the voltage change includes at least one of the following changes: the active current command value i output by the power converter 40. p ref and reactive current command value i qThe voltage change at ref is the positive phase voltage change ΔV1abc; the voltage change at ref is the reverse phase voltage change ΔV2abc; and the non-fundamental current command value I2 of the power converter 40 is the output voltage of the reverse phase current command I2. n The voltage change at ref is the change in the non-fundamental component ΔV. n abc.

[0055] Specifically, the voltage change calculation unit 62 includes: a positive phase voltage calculation unit 621, which calculates the positive phase voltage change ΔV1abc; a reverse phase voltage calculation unit 622, which calculates the reverse phase voltage change ΔV2abc; and a non-fundamental component calculation unit 623, which calculates the non-fundamental component change ΔV n abc.

[0056] The positive phase voltage calculation unit 621 acquires the output current command value and the phase of the power system 10, and calculates the positive phase voltage change ΔV1abc based on the output current command value through open-loop control to synchronize it with the phase of the power system 10. Specifically, the positive phase voltage calculation unit 621 calculates the positive phase voltage change ΔV1abc based on the active current command value i p ref and reactive current command value i q The instantaneous voltage value ΔV of the active power is calculated by open-loop control. p The instantaneous voltage values ​​ΔV of abc and reactive power q abc, through the instantaneous voltage value ΔV of synthesized active power. p The instantaneous voltage values ​​ΔV of abc and reactive power q The method for calculating the positive phase voltage change ΔV1abc using abc is explained below.

[0057] The positive phase voltage calculation unit 621 obtains the active current command value i from an external input mechanism (not shown). p ref and reactive current command value i q ref. Here, the active current command value i p ref and reactive current command value i q The reference includes inertia. Furthermore, "including inertia" means that the power converter 40 has the ability to autonomously reduce frequency variations in the power system 100.

[0058] Then, the positive phase voltage calculation unit 621 multiplies the active current gain Kp corresponding to the active current and the reactive current gain Kq corresponding to the reactive current by the active current command value i. p ref and reactive current command value i qThe voltage amplitude command values ​​ΔEp for active power and ΔEq for reactive power are calculated. In this embodiment, the voltage amplitude command values ​​ΔEp for active power and ΔEq for reactive power are actual values. Here, the active current gain Kp and reactive current gain Kq are determined by the impedance of the equipment that connects the power converter 40 to the power line B, i.e., the grid connection impedance. Furthermore, the grid connection impedance is determined to be approximately 10% to 15% of the capacity of the equipment connected to the grid. The capacity of the equipment connected to the grid here includes, for example, the capacity of the grid-connected transformer T and the capacity of the harmonic filter reactor inside the power converter 40.

[0059] Furthermore, the positive phase voltage calculation unit 621 obtains the phase of the power system 10 from the voltage measured by the measurement unit 50. Then, the positive phase voltage calculation unit 621 calculates the phase that is the same as the phase of the power system 10, namely the first phase θp, and the phase that lags behind the phase of the power system 10 by 90 degrees, namely the second phase θq. In addition, the positive phase voltage calculation unit 621 can also obtain the phase of the power system 10 from phase information input via an external input mechanism (not shown).

[0060] Then, the positive phase voltage calculation unit 621 controls the conversion of the actual voltage value into the instantaneous voltage value, i.e., positive phase instantaneous voltage control, and calculates the instantaneous voltage value ΔV in the active power based on the voltage amplitude command value ΔEp of the active power and the first phase θp. p abc. Furthermore, the positive phase voltage calculation unit 621, through positive phase instantaneous voltage control, calculates the instantaneous voltage value ΔV of the reactive power based on the voltage amplitude command value ΔEq of the reactive power and the second phase θq. q abc. Then, the positive phase voltage calculation unit 621 calculates the instantaneous voltage value ΔV of the synthesized active power. p The instantaneous voltage values ​​ΔV of abc and reactive power q The change in positive phase voltage ΔV1abc can be calculated using abc.

[0061] The reverse-phase voltage calculation unit 622 acquires the phase command value θ2ref and the reverse-phase current command value I2ref of the reverse-phase voltage, and calculates the reverse-phase voltage change ΔV2abc through open-loop control based on the phase command value θ2ref and the reverse-phase current command value I2ref of the reverse-phase voltage. The method by which the reverse-phase voltage calculation unit 622 calculates the reverse-phase voltage change ΔV2abc is described below.

[0062] The reverse phase voltage calculation unit 622 obtains the phase command value θ2ref of the reverse phase voltage and the reverse phase current command value I2ref from an external input mechanism (not shown).

[0063] Next, the reverse phase voltage calculation unit 622 calculates the voltage amplitude command value ΔE2 of the reverse phase voltage by multiplying the predetermined gain K2 by the reverse phase current command value I2ref. Furthermore, the gain K2, like the active current gain Kp and reactive current gain Kq, is determined by the grid impedance.

[0064] Then, the reverse phase voltage calculation unit 622 calculates the reverse phase voltage change ΔV2abc based on the reverse phase instantaneous voltage control, according to the reverse phase voltage amplitude command value ΔE2 and the reverse phase voltage phase command value θ2ref.

[0065] The non-fundamental component calculation unit 623 acquires the phase command value θn and the non-fundamental current command value I of the non-fundamental component. n ref, and based on the phase command value θn and the non-fundamental current command value I of the non-fundamental component. n The non-fundamental component variation ΔV is calculated using open-loop control. n abc. The non-fundamental frequency component in this embodiment refers to, for example, harmonic components or interharmonics. The following describes how the non-fundamental frequency component calculation unit 623 calculates the change in non-fundamental frequency component ΔV. n abc's method.

[0066] The non-fundamental component calculation unit 623 acquires the phase command value θn and the non-fundamental current command value I of the non-fundamental component via an external input mechanism (not shown). n ref. Here, the phase command value θn and the non-fundamental current command value I are... n The value of ref is determined by the order of the non-fundamental component.

[0067] Next, the non-fundamental component calculation unit 623 calculates the non-fundamental component by multiplying the specified gain Kn by the non-fundamental current command value I. n ref, calculate the voltage amplitude command value ΔEn for the non-fundamental component. Furthermore, when the inductive component of the grid impedance is dominant (i.e., the resistive component is negligible relative to the inductive component), the gain Kn is determined by multiplying the order of the non-fundamental component by the grid impedance.

[0068] Then, the non-fundamental component calculation unit 623 calculates the voltage amplitude command value ΔEn and the phase command value θ of the non-fundamental component. n The change in non-fundamental component ΔV is calculated through instantaneous voltage control. n abc.

[0069] The voltage command value output unit 63 calculates the voltage command value Vref by synthesizing the opposing voltage Vabc and the voltage change, and outputs the voltage command value Vref to the power converter 40. Specifically, the voltage command value output unit 63 calculates the voltage command value Vref by synthesizing the positive phase voltage change ΔV1abc, the reverse phase voltage change ΔV2abc, and the non-fundamental component change ΔV n The voltage change is calculated using abc. Then, the voltage command value output unit 63 synthesizes the opposing voltage Vabc and the voltage change to calculate the voltage command value Vref. When the voltage command value output unit 63 outputs the voltage command value Vref, the power converter 40 controls the output voltage to the load 20 according to the voltage command value Vref, for example, through pulse width modulation (PWM).

[0070] <Simulation Results>

[0071] The following simulation shows the output waveform of the power converter 40 when the power converter control device 60 of this embodiment controls the voltage of the power converter 40.

[0072] Figure 3 Under the condition of no abnormalities in the power system 10, such as a short circuit, the voltage waveform, current waveform, active power waveform, and reactive power waveform are output by the power converter 40 under the control of the power converter control device 60. Figure 3 In the simulation, 1.5 seconds after the simulation began, the power converter 40 applied a voltage change. As per... Figure 3 It can be confirmed that the current output from the power converter 40 is 0 before the voltage change is applied. Furthermore, it can be confirmed that when the power converter 40 applies a voltage change, the active power and reactive power increase accordingly to the amplitude of the applied voltage change.

[0073] Figure 4 These are the voltage and current waveforms output by the power converter 40 when a voltage change is applied by the power converter 40 under the control of the power converter control device 60, and an abnormality occurs in the power system 10, such as a short circuit. Figure 4 In the simulation, the power converter 40 applied a voltage change 1.5 seconds after the simulation started, and a two-phase short circuit occurred between 2.0 and 2.2 seconds after the simulation started. (As per...) Figure 4 It can be seen that the phase and amplitude of the current output from the power converter 40 did not fluctuate before and after the two-phase short circuit occurred. Therefore, it can be confirmed that regardless of voltage fluctuations in the power system 10, overcurrent can be prevented from flowing through the power converter 40. Furthermore, as... Figure 5As shown, it can be confirmed that under any circumstances before or after a short circuit, the phase and amplitude of the voltage output by the power converter 40 are consistent with the phase and amplitude of the voltage of the power system 10.

[0074] <Effects of this implementation method>

[0075] According to the power converter control device 60 in this embodiment, the opposing voltage Vabc is a voltage with the same phase and amplitude as the voltage of the power system 10. The power converter 40 outputs a voltage command value Vref, which is a synthesis of the opposing voltage Vabc and the voltage change. As a result, the voltage of the power system 10 is canceled out by the opposing voltage Vabc, and only the voltage change is applied to the grid-connected transformer T and grid-connected reactor L of the power converter 40. Therefore, regardless of how the voltage of the power system 10 fluctuates, the power converter 40 can output a current that conforms to the output current command value.

[0076] Furthermore, since the voltage change calculation unit 62 calculates the voltage change through open-loop control, the voltage change will not fluctuate due to the control amount of the distributed power source 70 even if the distributed power source 70 is connected to the same power line B. Therefore, even when the DC power source 30 and the distributed power source 70 are connected to the same power line B, instability phenomena such as flicker can be prevented.

[0077] <Other Implementation Methods>

[0078] Furthermore, the present invention is not limited to the embodiments described.

[0079] For example, Figure 6 As shown, the non-fundamental component calculation unit 623 can also calculate non-fundamental components of different orders. Specifically, the non-fundamental component calculation unit 623 may also include: a first non-fundamental component calculation unit 623a, which calculates the change ΔV of the first non-fundamental component corresponding to the first order number n1. n1 abc; and the second non-fundamental component calculation unit 623b, calculates the change ΔV of the second non-fundamental component corresponding to the second number n2. n2 abc. Here, the order n1 of the first non-fundamental component and the order n2 of the second non-fundamental component are different from each other. Furthermore, the change ΔV of the first non-fundamental component... n1 The changes ΔV of abc and the second non-fundamental component n2 The method for calculating abc is similar to the change in non-fundamental component ΔV in the described embodiment. n The method for calculating abc is the same.

[0080] In this case, such as Figure 6 As shown, the voltage command value output unit 63 outputs the positive phase voltage change ΔV1abc, the negative phase voltage change ΔV2abc, and the first non-fundamental component change ΔVn1 The changes ΔV of abc and the second non-fundamental component n2 The voltage change is calculated by combining the abc values. Then, the voltage command value output unit 63 combines the opposing voltage Vabc and the voltage change to calculate the voltage command value Vref. In addition, the non-fundamental component calculation unit 623 can also calculate three or more non-fundamental components of different orders.

[0081] In the described embodiment, the positive phase voltage calculation unit 621, the negative phase voltage calculation unit 622, and the non-fundamental component calculation unit 623 acquire the phase command value of the voltage change and the output current command value via an external input mechanism (not shown), but are not limited thereto. For example, the phase command value of the voltage change and the output current command value may be stored in the internal memory of the power converter control device 60, and the positive phase voltage calculation unit 621, the negative phase voltage calculation unit 622, and the non-fundamental component calculation unit 623 may acquire each command value from the internal memory.

[0082] In the embodiment described above, the voltage change calculation unit 62 includes a positive phase voltage calculation unit 621, a negative phase voltage calculation unit 622, and a non-fundamental component calculation unit 623. However, the voltage change calculation unit 62 may include at least one of these three calculation units.

[0083] In the described embodiment, the active current command value and the reactive current command value include inertia, but if sufficient inertia is supplied to the load 20, the active current command value and the reactive current command value may not include inertia.

[0084] Furthermore, the present invention is not limited to the described embodiments, and various modifications can be made without departing from its spirit. For example, those skilled in the art will understand that the various exemplary embodiments are specific examples of the following approaches.

[0085] (Method 1) A power converter control device for controlling the voltage output by a power converter connected to a power line, the power line being used to supply power from a power system to a load, the power converter control device comprising: a counter voltage calculation unit for calculating a voltage that is in phase and has the same amplitude as the voltage of the power system, i.e., a counter voltage; a voltage change calculation unit for acquiring a current that causes the power converter to output, i.e., an output current command value, and calculating the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value; and a voltage command value output unit for outputting a voltage command value, i.e., a voltage command value, synthesized from the counter voltage and the voltage change value, to the power converter.

[0086] (Method 2) The power converter control device according to Method 1, wherein the output current command value is at least one of fundamental positive phase active current, fundamental positive phase reactive current, fundamental reverse phase current and non-fundamental frequency current.

[0087] (Method 3) The power converter control device according to Method 1 or 2, wherein the power converter is a voltage-controlled inverter that supplies inertia to the power line.

[0088] (Method 4) The power converter control device according to any one of Methods 1 to 3, wherein the voltage change calculation unit further includes a positive phase voltage calculation unit, the positive phase voltage calculation unit calculates a positive phase voltage as a voltage change amount to compensate for the active power of the load, the positive phase voltage calculation unit acquires the output current command value and the phase of the power system, and calculates the positive phase voltage according to the output current command value through open-loop control to synchronize it with the phase of the power system.

[0089] (Method 5) The power converter control device according to Method 4, wherein the output current command value obtained by the positive phase voltage calculation unit is an active current command value including inertia and a reactive current command value including inertia.

[0090] (Method 6) The power converter control device according to Method 4 or 5, wherein the positive phase voltage calculation unit calculates the instantaneous voltage value of active power and the instantaneous voltage value of reactive power respectively through open-loop control based on the active current command value and the reactive current command value, and calculates the positive phase voltage by synthesizing the instantaneous voltage value of active power and the instantaneous voltage value of reactive power.

[0091] (Method 7) The power converter control device according to any one of Methods 1 to 6, wherein the voltage change calculation unit further includes a reverse phase voltage calculation unit, the reverse phase voltage calculation unit calculates a reverse phase voltage as a voltage change amount to compensate for the voltage imbalance of the load, the reverse phase voltage calculation unit acquires the phase command value of the reverse phase voltage and the output current command value, and calculates the reverse phase voltage through open-loop control based on the phase command value of the reverse phase voltage and the output current command value.

[0092] (Method 8) The power converter control device according to any one of Methods 1 to 7, wherein the voltage change calculation unit further includes a non-fundamental component calculation unit, the non-fundamental component calculation unit calculates the non-fundamental component of the power system at a frequency different from the fundamental frequency as the voltage change, the non-fundamental component calculation unit obtains the phase command value of the non-fundamental component and the output current command value, and calculates the non-fundamental component through open-loop control based on the phase command value of the non-fundamental component and the output current command value.

[0093] (Method 9) A control method for a power converter, wherein the voltage output by the power converter connected to a power line is controlled, the power line being used to supply power from a power system to a load, the control method for the power converter includes calculating a voltage that is in phase and has the same amplitude as the voltage of the power system, i.e., a counter voltage, obtaining a current that causes the power converter to output, i.e., an output current command value, and calculating the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value, so that the power converter outputs a voltage that combines the counter voltage and the voltage change.

[0094] (Method 10) A control program for a power converter controls the voltage output by the power converter connected to a power line used to supply power from a power system to a load. The control program for the power converter enables a computer to: function as a counter voltage calculation unit, which calculates a voltage that is in phase and has the same amplitude as the voltage of the power system, i.e., a counter voltage; function as a voltage change calculation unit, which acquires the current that causes the power converter to output, i.e., an output current command value, and calculates the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value; and function as a voltage command unit, which causes the power converter to output a voltage that combines the counter voltage and the voltage change.

[0095] Industrial availability

[0096] According to the present invention, the power converter can output a current that conforms to the command value regardless of the voltage fluctuation of the power system.

[0097] Explanation of icon numbers

[0098] 100: Power System

[0099] 10: Power System

[0100] 20: Load

[0101] 30: DC power supply

[0102] 40: Power Converter

[0103] 50: Measurement Department

[0104] 60: Power converter control device

[0105] 61: Counter-voltage calculation section

[0106] 62: Voltage Change Calculation Section

[0107] 621: Non-phase voltage calculation section

[0108] 622: Reverse phase voltage calculation section

[0109] 623: Non-fundamental component calculation part

[0110] 70: Distributed Power Generation

[0111] B: Power line

[0112] S: Circuit breaker

[0113] T: Injection Transformer

[0114] L: Grid-connected reactor

Claims

1. A power converter control device for controlling the voltage output of a power converter connected to a power line, the power line being used to supply power from a power system to a load, the power converter control device comprising: The counter-voltage calculation unit calculates the counter-voltage, which is in phase and has the same amplitude as the voltage of the power system. The voltage change calculation unit acquires the current that causes the power converter to output, i.e., the output current command value, and calculates the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value. as well as The voltage command value output unit outputs the voltage command value, which is the voltage synthesized from the opposing voltage and the voltage change, to the power converter.

2. The power converter control device according to claim 1, wherein, The output current command value is at least one of the fundamental positive phase active current, fundamental positive phase reactive current, fundamental reverse phase current, and non-fundamental frequency current.

3. The power converter control device according to claim 1, wherein, The power converter is a voltage-controlled inverter that supplies inertia to the power line.

4. The power converter control device according to claim 1, wherein, The voltage change calculation unit further includes a positive phase voltage calculation unit that calculates the positive phase voltage as the voltage change. The positive phase voltage calculation unit acquires the output current command value and the phase of the power system, and calculates the positive phase voltage based on the output current command value through open-loop control to synchronize it with the phase of the power system.

5. The power converter control device according to claim 4, wherein, The output current command value obtained by the positive phase voltage calculation unit is an active current command value including inertia and a reactive current command value including inertia.

6. The power converter control device according to claim 4, wherein, The positive phase voltage calculation unit calculates the instantaneous voltage values ​​of active power and reactive power respectively through open-loop control based on the active current command value and the reactive current command value, and calculates the positive phase voltage by synthesizing the instantaneous voltage values ​​of active power and reactive power.

7. The power converter control device according to claim 1, wherein, The voltage change calculation unit further includes an inverse phase voltage calculation unit that calculates the inverse phase voltage as the voltage change. The reverse phase voltage calculation unit acquires the phase command value of the reverse phase voltage and the output current command value, and calculates the reverse phase voltage through open-loop control based on the phase command value of the reverse phase voltage and the output current command value.

8. The power converter control device according to any one of claims 1 to 7, wherein, The voltage change calculation unit further includes a non-fundamental component calculation unit, which calculates the non-fundamental component of the power system at a frequency different from the fundamental frequency as the voltage change. The non-fundamental component calculation unit acquires the phase command value of the non-fundamental component and the output current command value, and calculates the non-fundamental component through open-loop control based on the phase command value of the non-fundamental component and the output current command value.

9. A control method for a power converter, comprising controlling the voltage output by the power converter connected to a power line, the power line being used to supply power from a power system to a load, wherein the control method for the power converter, Calculate the voltage that is in phase and has the same amplitude as the voltage of the power system, i.e., the opposing voltage; The system acquires the output current command value that causes the power converter to output the current, and calculates the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value; and The power converter outputs a voltage that combines the opposing voltage and the voltage change.

10. A control program for a power converter, controlling the voltage output by the power converter connected to a power line for supplying power from a power system to a load, the control program of the power converter enabling a computer to: As a function of the counter voltage calculation unit, the counter voltage calculation unit calculates the voltage that is in phase and has the same amplitude as the voltage of the power system, namely the counter voltage. As a function of the voltage change calculation unit, the voltage change calculation unit acquires the current that causes the power converter to output, i.e., the output current command value, and calculates the voltage change when the power converter outputs the output current command value through open-loop control based on the output current command value. as well as As a function of the voltage command unit, the voltage command unit causes the power converter to output a voltage that combines the opposing voltage and the voltage change.

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