Power conversion device

Abstract

To provide a power conversion device that suppresses voltage fluctuations in an AC power distribution network while maintaining the inertia of the AC power distribution network to suppress frequency fluctuations.SOLUTION: The power conversion device includes a main circuit for performing power conversion and a control unit for controlling the main circuit, and includes a function to impart inertia to an AC power distribution network to which the power conversion device is connected. The control unit receives an excess or deficiency amount of inertia or a command value corresponding to the excess or deficiency amount in the AC power distribution network from a control device controlling the AC power distribution network, and the control unit adjusts the response speed of the main circuit on the basis of the excess or deficiency amount of inertia or the command value corresponding to the excess or deficiency amount in the AC power distribution network.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power conversion device that contributes to stabilizing the frequency and voltage of an AC power grid. [Background technology]

[0002] In AC power distribution networks such as electric power systems, when a power source trips, the inertia provided by synchronous generators such as thermal power plants suppresses changes in the power system's frequency. In the future, as renewable energy generation such as solar power generation increases and becomes the main power source, the number of synchronous generators decreases, and the inertia provided by the synchronous generators decreases, causing the frequency of the AC power distribution network to become unstable. In order to maintain the stability of the AC power distribution network's frequency, a grid-forming inverter (GFI), which is a power conversion device with the function of supplying inertia, is being considered.

[0003] Patent Document 1 discloses a power supply device that controls operation by changing parameters such as the inertia constant of a power conversion device that has a function of supplying inertia to quickly stabilize the system frequency when a disturbance such as a sudden load change occurs. The document shows an example in which parameters are changed depending on whether the system is on-grid or off-grid. Since inertia is large when on-grid and small when off-grid, the document can be said to show a power conversion device with a function of supplying inertia that changes parameters depending on the magnitude of the inertia.

[0004] Patent Document 2 discloses a distributed power system that adjusts the output change rate of a distributed power source to a predetermined value by controlling a power converter according to the inertia of the power grid so that the frequency of the AC power grid falls within an acceptable range when renewable energy power generation suddenly changes. In this system, the magnitude of the inertia of the AC power grid is determined depending on whether it is connected to the power grid or in islanding operation. Furthermore, there is no mention of a function for supplying inertia to the power converter.

[0005] One method for quantitatively understanding the inertia of an AC power distribution network is to use a phasor measurement unit (PMU) to acquire data such as voltage, current, and phase time-synchronized with the Global Positioning System (GPS) at multiple points in the network, and then use that data to estimate the inertia of the network.Another method is to estimate the inertia of an AC power distribution network by integrating the individual inertias shared by devices such as synchronous generators and synchronous motors connected to the network. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2024-016572 [Patent Document 2] Japanese Patent Publication No. 2024-017513 Summary of the Invention [Problem to be solved by the invention]

[0007] A quantitative understanding of inertia is important to ensure frequency stability in AC power distribution networks. In the future, when renewable energy generation becomes the main power source, it is predicted that the inertia of the power system will be quantitatively understood every hour of every day. Furthermore, as GFIs powered by renewable energy generation become more widespread, it is predicted that the inertia of AC power distribution networks will fluctuate more greatly depending on the time of day. When the inertia fluctuations of AC power distribution networks increase, there is a greater risk of the inertia falling below the required level, resulting in greater frequency fluctuations, while at the same time, it is thought that there will be times when the inertia is unnecessarily large.

[0008] While GFIs make it harder for the frequency of AC power distribution networks to change, they also have the problem of slower response times for power output and voltage control due to their function of making it harder for frequency changes to occur. Generally, the greater the inertia supplied by a power conversion device, the slower the response time. A slower response time means that the GFI is slower to restore voltage to the AC power distribution network in the event of an accident. Increasing the response time of the GFI will speed up the restoration of voltage in the AC power distribution network, but the inertia supplied by the GFI to the system will decrease, resulting in greater fluctuations in the system frequency.

[0009] An object of the present invention is to provide a power conversion device that suppresses voltage fluctuations in an AC power distribution network while ensuring the inertia of the AC power distribution network and suppressing frequency fluctuations. [Means for solving the problem]

[0010] The present application includes a number of means for solving the above problems. Representative means are as follows:

[0011] 1. A power conversion device comprising: a main circuit for converting DC power and AC power; and a control unit for controlling the main circuit; and having a function of imparting inertia to a connected AC power distribution network, wherein the control unit receives a command value corresponding to an excess or deficiency of the inertia of the AC power distribution network from a control device that controls the AC power distribution network, and the control unit adjusts the response speed of the main circuit based on the command value corresponding to the excess or deficiency of the inertia of the AC power distribution network. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a power conversion device that suppresses voltage fluctuations in an AC power distribution network while ensuring the inertia of the AC power distribution network and suppressing frequency fluctuations. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram showing the configuration of a power conversion device and an inertia control device connected to an AC wiring network in an embodiment of the present invention. [Figure 2]4 is a flowchart showing the processing of the inertia control device according to the embodiment of the present invention. [Figure 3] 1 is a graph illustrating an example of the change in estimated inertia, required inertia, and adjusted inertia of an AC power distribution network over three days in an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing the voltage recovery speed at each point in an AC power distribution network in an embodiment of the present invention. [Figure 5] FIG. 2 is a diagram illustrating a control block of a control unit of a power conversion device according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram illustrating a control block of an inertia conversion unit of a control unit of a power conversion device according to an embodiment of the present invention. [Figure 7] FIG. 2 is a diagram illustrating a control block of an angular frequency command generating unit of a control unit of a power conversion device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to FIGS. 1 to 7, an embodiment of a power conversion device of the present invention will be described in detail with reference to the drawings.

[0015] FIG. 1 is a block diagram showing the configuration of a power conversion device connected to an AC power distribution network and an inertia control device that controls the inertia of the power conversion device according to an embodiment of the present invention.

[0016] A power conversion equipment (GFI) 101 is connected to an AC power distribution network 111, and the power conversion equipment 101 is composed of a main circuit 102 that converts DC power to AC power and a control unit 103 that controls the main circuit. A solar power generator (PV) 104, a battery (BAT) 105, or a renewable energy power source such as a wind power generator (not shown) is connected to the power conversion equipment 101. One or more power conversion equipment (GFI) 101 are connected to the AC power distribution network 111. The power conversion equipment 101 is a grid-forming inverter that can supply inertia to the AC power distribution network 111. The AC power distribution network 111 is a power distribution network within a power system or a microgrid. The power distribution network within a microgrid also includes a power distribution network within a business or factory.

[0017] An inertia control device 106 that controls the AC power distribution network 111 is connected to the control unit 103 of the power conversion device 101 via a control signal line 110. The control signal line 110 may be wired or wireless. The inertia control device 106 includes an inertia estimation unit 107, an utilized inertia surplus / deficiency determination unit 108, and an utilized inertia surplus / deficiency transmission unit 109. The inertia control device 106 is implemented by a computer equipped with a CPU (Central Processing Unit), a main memory device, an external memory device, and an input / output unit. In this embodiment, an example is described in which the inertia control device 106 is implemented by a standalone computer, but it may also be implemented as a server on the cloud. The inertia control device 106 may be incorporated into a power utility's grid command device or a microgrid's EMS (Energy Management System). Furthermore, if the AC power distribution network 111 is small or if only one power conversion device is connected to the AC power distribution network 111, the inertia control device 106 may be incorporated into the power conversion device 101. In this case, the control signal line 110 is not required, and the system configuration can be simplified.

[0018] 2 shows a flow of processing executed by the inertia estimation unit 107, the utilized inertia surplus / deficiency determination unit 108, and the utilized inertia surplus / deficiency transmission unit 109 of the inertia control device 106. The inertia estimation unit 107 executes step S1, the utilized inertia surplus / deficiency determination unit 108 executes steps S1 to S6, and the utilized inertia surplus / deficiency transmission unit 109 executes step S7.

[0019] In step S1, the inertia of the AC power distribution network 111 is estimated. One of the following two methods is used to estimate the inertia. One method is to use a phasor measurement unit (PMU) to acquire data such as voltage, current, and phase time-synchronized with a global positioning system (GPS) at multiple locations on the AC power distribution network 111, and estimate the inertia using that data. The other method is to estimate the inertia of the AC power distribution network 111 by understanding the operating status of synchronous generators, synchronous motors, and other devices connected to the AC power distribution network 111, accumulating the inertia supplied by each of them. The former method is more suitable for large-scale power systems in which it is easy to install PMUs at multiple locations and there are many devices that supply inertia. The latter method is more suitable for small-scale microgrid power distribution networks in which it is difficult to install PMUs at multiple locations and there are few devices that supply inertia. In addition, the former method collects operating status data in real time every 30 minutes or every hour to estimate the inertia. In the latter method, the operation plans of the synchronous generators, synchronous motors, etc. are obtained in advance, and the inertia is estimated on a daily basis. If necessary, information on changes in the plans is received and the estimated inertia is corrected.

[0020] Figure 3 shows an example of estimated inertia (hereafter referred to as estimated inertia) for a case where GFI, photovoltaic power generation (PV), and storage batteries (BAT) are widely used. The solid line in the figure is the estimated inertia, showing changes over three days. This inertia is inertial energy, and its unit is pu·s. The dashed line in the figure also represents the inertia (hereafter referred to as required inertia) required to keep the grid frequency within a predetermined tolerance range in the event of a predicted accident, such as a power source failure. The required inertia includes a margin for error in the estimated inertia.

[0021] Day 1 in Figure 3 is a sunny weekday. During the day, PV power generation increases, and the inertia supplied by the GFI connected to the PV also increases, causing the estimated inertia to significantly exceed the required inertia. Even after sunset, because it is a weekday and power demand is high, many synchronous generators, such as thermal and hydroelectric power plants, are operating, so the estimated inertia continues to exceed the required inertia. Day 2 is a cloudy weekday. During the day, PV power generation is low, and the estimated inertia supplied by the GFI connected to the PV does not increase. Because it is a weekday, power demand increases, and the inertia from the synchronous generators operating to meet that demand increases, causing the estimated inertia to exceed the required inertia. Day 3 is a sunny holiday. During the day, PV power generation increases, and the inertia supplied by the GFI connected to the PV also increases, causing the estimated inertia to exceed the required inertia. However, because power demand is low on the holiday, the inertia supplied by synchronous generators and synchronous motors is low, and after sunset, the estimated inertia falls below the required inertia. There is a method of operating a synchronous generator to supply inertia when the estimated inertia falls below the required inertia, thereby ensuring the required inertia, but operating a synchronous generator requires a large cost.

[0022] In steps S2 and S3, the inertia estimation is judged to be excessive or insufficient. In step S2, the inertia estimation is compared with the required estimation. If the inertia estimation is smaller, i.e., if the inertia is insufficient, proceed to step 5. If not, proceed to step S2. The case after sunset on the third day in Figure 3 corresponds to a case where inertia is insufficient. In step S3, the inertia estimation is compared with the required estimation + α. If the inertia estimation is larger, i.e., if the inertia is excessive, proceed to step 4. If not excessive, the inertia excess or deficiency is not utilized and the processing flow in Figure 2 ends. α is a preset inertia band in which inertia excess or deficiency is not utilized. This sets an inertia range in which inertia excess or deficiency is not utilized, preventing frequent changes in the control of the power conversion device 101 due to inertia utilization. If frequent control changes are not a problem, there is no need to set α.

[0023] In step S4, the voltage recovery speed of the AC distribution network 111 is calculated to confirm the voltage stability of the AC distribution network 111. Specifically, a simulation of the AC distribution network 111 is performed using the substation (SS) 112, GFI response speed, and impedance of the distribution line, and the like, to calculate the voltage recovery speed in the event of a fault. Since the voltage recovery speed varies depending on the location of the AC distribution network 111, it is calculated at multiple locations if the AC distribution network 111 is not small. Figure 4 shows an example of the results of calculating the voltage recovery speed. The numbers in the figure (1.24 pu / s, 1.42 pu / s, 0.92 pu / s, 0.86 pu / s) are the voltage recovery speeds at those locations. The unit of voltage recovery speed is pu / s, which represents the amount of voltage recovery per unit time. The power recovery speed may be used instead of the voltage recovery speed. A required range of the voltage recovery speed is determined in advance. Here, the required range is 1.00 pu / s or more.

[0024] In step S5, a power conversion device that utilizes the inertial excess or deficiency is selected using the voltage recovery speed calculated in step S4. If the voltage recovery speed at all points meets the required range, the voltage stability of the AC power distribution network 111 is sufficient and the inertial excess or deficiency is not utilized. If there is a point where the voltage recovery speed does not meet the required range, the voltage stability of the AC power distribution network 111 is insufficient, and a power conversion device 101 connected near the point where the voltage recovery speed does not meet the required range is selected. Power conversion devices that are not operating, such as power conversion devices connected to PV at night, are excluded.

[0025] In step S6, the amount of inertia surplus or deficiency to be allocated to each of the power electronics devices selected in step S4 is determined. To determine the amount of inertia surplus or deficiency to be allocated, the inertia control device 106 stores data on the maximum amount of inertia that can be utilized for each power electronics device 101. Because inertia cannot be reduced beyond the inertia supplied by the power electronics device 101, the maximum amount of excess inertia that can be utilized by the power electronics device 101 is equal to the inertia supplied by the power electronics device 101. Because inertia cannot be increased beyond the increment of power that the power electronics device 101 can output, the maximum amount of inertia deficiency that can be utilized by the power electronics device 101 is a value determined by the increment of power that the power electronics device 101 can output. The amount of inertia surplus or deficiency calculated in step S1 from the estimated inertia of the AC power distribution network and the required inertia is allocated to each of the power electronics devices 101 selected in step S4 so that it falls within the maximum amount of usable inertia. If the inertia surplus or deficiency is smaller than the total maximum usable inertia of the target, the power is preferentially allocated to the power electronics device 101 that has the greatest effect of increasing the voltage recovery speed due to inertia, or allocated equally to the power electronics devices.

[0026] In step S7, a signal indicating the inertia surplus or deficiency allocated to the power electronics device 101 determined in step S6 is transmitted to each power electronics device 101 via the control signal line 110.

[0027] Next, the control unit 103 of the power conversion device 101 will be described.

[0028] 5 shows a control block of the control unit 103 of the power conversion device 101. There are many types of control methods for GFI, and the control block shown here employs a droop control type that uses an angular frequency droop.

[0029] The main circuit 102 includes a power conversion module 2 that converts DC power and AC power, an AC filter 4 located on the AC distribution network 111 side of the power conversion module 2, a current sensor located between the power conversion module 2 and the AC filter 4, and a voltage sensor located on the AC distribution network 111 side of the AC filter 4.

[0030] The control unit 103 receives AC voltage measurement values ​​and AC current measurement values ​​from the sensors of the main circuit 102, and sends a PWM (Pulse Width Modulation) signal to the power conversion module 2 of the main circuit 102 to control the switching elements of the power conversion module 2. The control unit 103 also receives a signal indicating the allocated inertia surplus or deficiency from the inertia control device 106.

[0031] The control unit 103 includes a measurement unit 301, a power calculation unit 302, an active power command unit 303, an inertia conversion unit 304, an angular frequency command generation unit 305, a phase command generation unit 306, a reactive power command unit 307, a first voltage command generation unit 308, a current command generation unit 309, a current command constraint unit 310, a second voltage command generation unit 311, and a main circuit control unit 312.

[0032] The measurement unit 301 converts the AC voltage measurement value and AC current measurement value received from the sensor of the main circuit into V out , I out When outputting, measurement noise can be removed using a low-pass filter or the like.

[0033] The power calculation unit 302 calculates the V output from the measurement unit 301. out , I out The active power P output from out and reactive power Q out For example, calculate the three-phase voltage and current V out , I out can be calculated from the voltage and current values ​​in the α-β coordinate system obtained by three-phase to two-phase conversion.

[0034] The active power command unit 303 outputs an active power command P0 based on an active power command P0' given from outside the power conversion device 1. ′ can be received from a higher-level command device for the power conversion device (for example, an energy management system) that is external to the power conversion device 1 via wired communication or wireless communication.

[0035] The inertia conversion unit 304 converts the inertia surplus / deficiency ΔI given from the utilized inertia surplus / deficiency transmission unit 109 of the inertia control device 106.ner0 The delay time constant of the filter is the manipulated variable ΔT do FIG. 6 shows the control block of the inertia conversion unit 304. First, the inertia I ner , rated frequency ω0, moment of inertia J o The following equation shows the relationship between

[0036]

number

[0037] Using this, the inertia surplus or deficiency ΔI ner moment of inertia operation amount ΔJ o Next, the droop coefficient Kp of the active power-angular frequency change command and the rated frequency ω0 are used to calculate the moment of inertia operation amount ΔJ o The delay time constant is the manipulated variable ΔT do Convert to. The angular frequency command generator 305 generates an active power command P0 and an active power P out The angular frequency command ω is calculated by droop control from the deviation of * 7 shows the control block of the angular frequency command generator 305. The angular frequency command generator 305 generates an active power command P0 and an active power P out The deviation is multiplied by the droop coefficient Kp of the active power-angular frequency change command, and passed through a first-order lag-lead filter to obtain the angular frequency command ω * The first-order lag-lead filter has a lead time constant T α0 and delay time constant T do The delay time constant operation amount ΔT do When is given, the original delay time constant T do Delay time constant operation amount ΔT do The value obtained by subtracting is used as the delay time constant.

[0038] The phase command generator 306 generates the angular frequency command ω * is integrated to obtain the phase command θ * Generate. The reactive power command unit 307 outputs an external reactive power command Q 01 and V, which is the output of the measurement unit 301out Enter the reactive power command Q 02 Generates and outputs reactive power command Q 02 is the rated voltage V0 (for example, 200 V) and the output of the measuring unit 301, V out Deviation V0-V out is generated by droop control by multiplying it by a proportional gain Kq (Kq>0). The reactive power command unit 307 receives not the output of this droop control but an external reactive power command Q given from outside the power conversion device 101. 01 is used as the reactive power command Q 02 It may be output as reactive power command Q 02 Behavior equivalent to power factor control is possible by determining the reactive power command Q0 from the active power command P0' given from outside the power conversion device 101, the rated power of the power conversion device 101, and the desired power factor. Also, the reactive power command unit 307 may determine the reactive power command Q0 from the active power command P0 output by the active power command unit 303, the rated power of the power conversion device 101, and the desired power factor.

[0039] The first voltage command generator 308 generates a reactive power command Q0 and a reactive power Q out The first voltage command V1 is calculated by calculating the deviation of the voltage V1 and performing PI control.

[0040] The current command generator 309 calculates the first voltage command V1 and the AC voltage measurement value V OUT and impedance Z, calculate the AC current that flows when the AC terminal voltage of the power conversion module 2 is the first voltage command V1, and obtain the current command I * The current command I * is the d-axis component I in the dq transformation d * and the q-axis component I q * Calculate each.

[0041] The current command constraint unit 310 constrains the current command I generated by the current command generation unit 309. * For example, the d-axis component I d * and the q-axis component I q *For each, limiters are set so that the upper and lower threshold currents are the upper and lower limits.

[0042] The second voltage command generator 311 generates the current command I constrained by the current command constraint unit 310 for each of the d-axis component and the q-axis component. * and AC current measurement value I out The deviation of the proportional gain K vp , integral gain K vi PI control is performed to obtain the second voltage command V * Calculate the following.

[0043] The main circuit control unit 312 outputs a second voltage command V * Phase command θ * Then, an inverse dq transformation is performed, and an inverse three-phase to two-phase transformation is performed to generate voltage commands for each of the three phases. Based on this, gate waveforms for the switching elements of the power conversion module 2 are generated, and the power conversion module 2 of the main circuit 102 is driven.

[0044] As a result of the above, the control unit 103 of the power conversion device 101 calculates the inertia surplus / deficiency ΔI nero The delay time constant T of the filter, which is related to the response speed, is calculated by using do and changes the control of the power conversion device 101. When the inertia of the AC power distribution network 111 is excessive, the inertia excess / deficiency amount ΔI nero When is positive, the delay time constant T do As a result, the speed of voltage recovery by the power conversion device 101 increases, improving the stability of the voltage of the AC power distribution network 111. When the inertia of the AC power distribution network 111 is insufficient, the inertia surplus / deficiency ΔI nero When is negative, the delay time constant T do As a result, the inertia provided by the power conversion device 101 increases, improving the stability of the frequency of the AC power distribution network 111.

[0045] The inertia after applying the present invention is shown by the dashed line in Figure 3. Compared to the estimated inertia, the excess inertia has been reduced and the insufficiency of inertia has been eliminated.

[0046] In the above embodiment, the utilized inertia surplus / deficiency transmission unit 109 of the inertia control device 106 transmits the inertia surplus / deficiency I nero The signal is sent through the control signal line 110, but the inertia surplus / deficiency ΔI nero Instead of this, the delay time constant T of the filter according to the inertial excess or deficiency is do The control unit 103 of the power conversion device 101 receives the parameter according to the inertia surplus / deficiency and calculates the inertia surplus / deficiency ΔI nero Change the response speed in the same way as in

[0047] In the above embodiment, a droop control type using an angular frequency droop is adopted as the control method of the control unit 103, but other droop control types may be adopted, or a synchronous machine simulation control type such as a VSM (Virtual Synchronous Machine) or other control types may be adopted. If another method is adopted and a delay time constant is not used, the same effect as in the above embodiment can be obtained by controlling parameters related to both the response speed and inertia instead of the delay time constant.

[0048] Furthermore, one example of the invention disclosed in the above-mentioned specification of the present application can also be expressed as follows.

[0049] <Part 1> A power conversion device that includes a main circuit that performs power conversion and a control unit that controls the main circuit and has a function of imparting inertia to an AC power distribution network connected thereto, the control unit receives an excess or deficiency amount of inertia of the AC power distribution network or a command value corresponding to the excess or deficiency amount from an inertia control device that controls the AC power distribution network; The power conversion device, wherein the control unit adjusts the response speed of the main circuit based on a command value corresponding to the excess or deficiency of inertia of the AC power distribution network.

[0050] <Part 2> The power conversion device according to <Item 1>, characterized in that when the inertia of the AC power distribution network is excessive, the response speed of the main circuit is adjusted by increasing the response speed.

[0051] <Part 3> The power conversion device according to <Item 1>, characterized in that when the inertia of the AC power distribution network is insufficient, the response speed of the main circuit is adjusted by slowing down the response speed.

[0052] <Part 4> The power conversion device described in <Item 1>, characterized in that the excess or deficiency of inertia is the difference between the inertia of the AC power distribution network and the inertia required to keep the frequency of the AC power distribution network within a predetermined range.

[0053] <Part 5> The power conversion device according to <Item 4>, wherein the inertia of the AC power distribution network is estimated by integrating the inertia of devices that supply inertia to the AC power distribution network.

[0054] <Part 6> The power conversion device according to <Item 1>, wherein the command value according to the excess or deficiency is a time constant of a filter.

[0055] <Part 7> The power conversion device according to <Item 1>, wherein the inertia control device has a function of allocating the excess or deficiency of the inertia to the plurality of power conversion devices.

[0056] <Part 8> The power conversion device described in <No. 7>, characterized in that the function of allocating the excess or deficiency of inertia to the plurality of power conversion devices allocates the excess or deficiency of inertia based on the recovery speed of the voltage of the AC power distribution network.

[0057] <No. 9> The power conversion device according to <Item 1>, wherein the AC power distribution network is a power system or a microgrid AC power distribution network.

[0058] <Part 10> The power conversion device according to <Item 1>, wherein the inertia control device is provided in a system command device or an EMS.

[0059] <Part 11> The power conversion device according to <Item 1>, wherein the inertia control device is provided in the power conversion device.

[0060] <Part 12> The power conversion device according to <No. 7>, wherein the inertia control device estimates the inertia of the AC power distribution network from data obtained from a phasor information measurement device. [Explanation of symbols]

[0061] 101: Power conversion equipment (GFI) 102: Main circuit 103: Control unit 104: Photovoltaic power generator (PV) 105: Storage battery 106: Inertial control device 107:Inertia estimation section 108: Utilization inertia excess / deficiency determination unit 109: Utilization inertia excess / deficiency amount transmitter 110: Control signal line 111: AC power distribution network 112: Substation 301:Measurement part 302: Power calculation section 303: Active power command unit 304: Inertial conversion unit 305: Angular frequency command generation unit 306: Phase command generation section 307: Reactive power command unit 308: First voltage command generation unit 309: Current command generation section 310: Current command restriction section 311: Second voltage command generation unit 312: Main circuit control unit

Claims

1. A power conversion device that includes a main circuit that performs power conversion and a control unit that controls the main circuit and has a function of imparting inertia to an AC power distribution network connected thereto, the control unit receives an excess or deficiency amount of inertia of the AC power distribution network or a command value corresponding to the excess or deficiency amount from an inertia control device that controls the AC power distribution network; The power conversion device, wherein the control unit adjusts the response speed of the main circuit based on a command value corresponding to the excess or deficiency of inertia of the AC power distribution network.

2. 2. The power conversion device according to claim 1, wherein when the inertia of the AC power distribution network is excessive, the response speed of the main circuit is adjusted by increasing the response speed.

3. 2. The power conversion device according to claim 1, wherein when the inertia of the AC power distribution network is insufficient, the response speed of the main circuit is adjusted by slowing down the response speed.

4. 2. The power conversion device according to claim 1, wherein the excess or deficiency of inertia is a difference between the inertia of the AC power distribution network and the inertia required to keep the frequency of the AC power distribution network within a predetermined range.

5. 5. The power conversion device according to claim 4, wherein the inertia of the AC power distribution network is estimated by integrating inertia of devices that supply inertia to the AC power distribution network.

6. 2. The power conversion device according to claim 1, wherein the command value according to the excess or deficiency is a time constant of a filter.

7. 2. The power conversion device according to claim 1, wherein the inertia control device has a function of allocating the excess or deficiency of the inertia to the plurality of power conversion devices.

8. 8. The power conversion device according to claim 7, wherein the function of allocating the excess or shortage of inertia to the plurality of power conversion devices allocates the excess or shortage of inertia based on a recovery speed of voltage of the AC power distribution network.

9. 2. The power conversion device according to claim 1, wherein the AC power distribution network is a power system or a microgrid AC power distribution network.

10. 2. The power conversion device according to claim 1, wherein the inertia control device is provided in a power system command system or an EMS.

11. 2. The power converter according to claim 1, wherein the inertia control device is provided in the power converter.

12. 8. The power conversion device according to claim 7, wherein the inertia control device estimates the inertia of the AC power distribution network from data obtained from a phasor information measurement device.

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