Control method, control device and grid-forming inverter of virtual synchronous generator

Abstract

The embodiment of the application discloses a control method and device of a virtual synchronous generator and a grid-connected inverter, and is used for the field of electrical control technology. In the embodiment of the application, a damping gain coefficient of the virtual synchronous generator in transient fluctuation is acquired; the damping coefficient of an active ring in the virtual synchronous generator is adjusted based on the damping gain coefficient, and a gain after-transient damping coefficient is obtained; when the virtual synchronous generator is in a steady state and the grid frequency changes, the change of active power in the active ring is suppressed based on the transient damping coefficient. That is, the transient damping coefficient can make the active power not change, that is, not perform primary frequency modulation, when the grid frequency only has a steady state change, decouple the damping coefficient in the active ring and a primary frequency modulation coefficient, and ensure the accuracy of primary frequency modulation of the virtual synchronous generator.

Description

Technical Field

[0001] This application relates to the field of electrical control technology, and in particular to a control method and control device for a virtual synchronous generator, as well as a grid-type inverter. Background Technology

[0002] With the application of distributed renewable energy systems, more and more inverters are being connected to the grid, resulting in a significant reduction in the total damping and total inertia provided by traditional generators in the grid. This causes the grid to experience faster frequency changes and a decrease in its anti-interference capability when facing disturbances. To address this issue, the concept of virtual synchronous generator (VSG) control technology has been proposed. This control technology can mimic the operating mechanism of a synchronous generator, suppress frequency and output power fluctuations, and enable grid-connected inverters corresponding to the VSG to possess grid support, inertial response, and damping characteristics, thereby improving grid voltage amplitude and frequency fluctuations.

[0003] In existing virtual synchronous generators, a second-order excitation swing equation is used. When the virtual synchronous generator performs primary frequency regulation in the active power loop, the damping coefficient in the active power loop is coupled with the primary frequency regulation coefficient, which affects the accuracy of the primary frequency regulation of the virtual synchronous generator. Summary of the Invention

[0004] This application provides a control method, control device, and grid-type inverter for a virtual synchronous generator, which can decouple the damping coefficient in the active power loop from the primary frequency regulation coefficient, thereby ensuring the accuracy of the primary frequency regulation of the virtual synchronous generator.

[0005] This application provides a control method for a virtual synchronous generator, including:

[0006] Obtain the damping gain coefficient of the virtual synchronous generator during transient fluctuations;

[0007] Based on the damping gain coefficient, the damping coefficient of the active loop in the virtual synchronous generator is adjusted to obtain the transient damping coefficient after gain.

[0008] When the virtual synchronous generator is in a steady state and the grid frequency changes, the change in active power in the active power loop is suppressed based on the transient damping coefficient.

[0009] Furthermore, obtaining the damping gain coefficient of the virtual synchronous generator during transient fluctuations includes:

[0010] Based on the decay time constant of the virtual winding in the virtual synchronous generator, the damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined.

[0011] Furthermore, obtaining the damping gain coefficient of the virtual synchronous generator during transient fluctuations further includes:

[0012] Obtain the cutoff frequency of damping attenuation;

[0013] The gain value of the damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined based on the cutoff frequency.

[0014] Furthermore, adjusting the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain the gained transient damping coefficient includes:

[0015] Multiply the damping gain coefficient by the damping coefficient of the active loop in the virtual synchronous generator to obtain the gained transient damping coefficient.

[0016] Furthermore, the method also includes:

[0017] Obtain the frequency difference between the grid angular frequency and the rated angular frequency of the virtual synchronous generator;

[0018] If the frequency difference is not zero, then it is determined that the power grid frequency has changed;

[0019] If the frequency difference is zero, then it is determined that the power grid frequency has not changed.

[0020] Furthermore, the method of suppressing changes in active power in the active power loop based on the transient damping coefficient includes:

[0021] The damping power in the virtual synchronous generator is controlled to be zero based on the transient damping coefficient, so as to suppress the change of active power in the active power loop.

[0022] Furthermore, the method of suppressing changes in active power in the active power loop based on the transient damping coefficient includes:

[0023] Based on the transient damping coefficient in the transfer function of active power and grid frequency, the active power in the active power loop is controlled to remain consistent with the given active power of the virtual synchronous generator after the grid frequency changes.

[0024] This application also provides a control device for a virtual synchronous generator, including:

[0025] The acquisition unit is used to acquire the damping gain coefficient of the virtual synchronous generator during transient fluctuations;

[0026] An adjustment unit is used to adjust the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient, so as to obtain the transient damping coefficient after gain.

[0027] The suppression unit is used to suppress changes in active power in the active power loop based on the transient damping coefficient when the virtual synchronous generator is in a steady state and the grid frequency corresponding to the virtual synchronous generator changes.

[0028] This application also provides a control device for a virtual synchronous generator, including:

[0029] Central processing unit, memory, input / output interface, wired or wireless network interface, power supply;

[0030] The memory is either a short-term storage memory or a persistent storage memory;

[0031] The central processing unit is configured to communicate with the memory and execute instructions in the memory on a control plane functional entity to perform the methods described above.

[0032] This application embodiment also provides a grid-connected inverter. When the grid-connected inverter is in grid-connected state, a virtual synchronous generator obtained by the above-described virtual synchronous generator control method is used to control the grid-connected inverter.

[0033] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0034] In this embodiment, the damping gain coefficient of the virtual synchronous generator during transient fluctuations is obtained; the damping coefficient of the active power loop in the virtual synchronous generator is adjusted based on the damping gain coefficient to obtain the gained transient damping coefficient; when the virtual synchronous generator is in a steady state and the grid frequency changes, the change in active power in the active power loop is suppressed based on the transient damping coefficient. That is, the transient damping coefficient ensures that when the grid frequency only has a steady-state frequency difference (i.e., when the grid frequency only has a steady-state change), the active power remains unchanged, i.e., primary frequency regulation is not performed, thus decoupling the damping coefficient in the active power loop from the primary frequency regulation coefficient and ensuring the accuracy of the primary frequency regulation of the virtual synchronous generator. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0036] Figure 1 This is a control block diagram of rotor motion in an active power loop disclosed in an embodiment of this application;

[0037] Figure 2 This is a control block diagram of primary frequency regulation in an active power loop disclosed in an embodiment of this application;

[0038] Figure 3 This is a control flowchart of a virtual synchronous generator disclosed in an embodiment of this application;

[0039] Figure 4 This is a control block diagram of rotor motion based on transient damping coefficient disclosed in an embodiment of this application;

[0040] Figure 5 This is a control block diagram of a primary frequency modulation based on transient damping coefficient disclosed in an embodiment of this application;

[0041] Figure 6 This is a response diagram of an existing virtual synchronous generator disclosed in an embodiment of this application as the grid frequency decreases;

[0042] Figure 7 This is a response diagram of a virtual synchronous generator disclosed in an embodiment of this application as the grid frequency decreases;

[0043] Figure 8 This is a response diagram of an existing virtual synchronous generator as the grid frequency rises, as disclosed in an embodiment of this application.

[0044] Figure 9 This is a response diagram of a virtual synchronous generator disclosed in an embodiment of this application as the grid frequency increases;

[0045] Figure 10 This is a response diagram of a superimposed single-frequency modulation disclosed in an embodiment of this application;

[0046] Figure 11 This is a diagram of a control device for a virtual synchronous generator disclosed in an embodiment of this application;

[0047] Figure 12 This is a diagram of a control device for another virtual synchronous generator disclosed in an embodiment of this application. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0049] In the description of the embodiments of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0050] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0051] Virtual synchronous generator (VSG) control technology controls grid-connected inverters by mimicking the operating mechanism of a synchronous generator. Existing VSGs employ the second-order excitation swing equations (i.e., the second-order classical model of a synchronous generator) of a synchronous generator, including the rotor motion equations reflecting the mechanical characteristics of the synchronous generator; these rotor motion equations are as follows:

[0052]

[0053] Where J is the inertia constant, T m T is the mechanical torque. e Where ω is the electromagnetic torque, D is the damping torque coefficient, ω is the grid angular frequency, Δω=ω-ω0, Δω is the angular frequency deviation, and ω0 is the rated angular frequency of the synchronous generator, which is also the rated angular frequency of the virtual synchronous generator.

[0054] The corresponding power form expression is:

[0055]

[0056] Among them, P m P is the rotor mechanical power. e This refers to electromagnetic power; the corresponding rotor motion control in the virtual synchronous generator is as follows: Figure 1 As shown, where P ref The given active power of the virtual synchronous generator is equivalent to P m P represents the actual active power output of the virtual synchronous generator, equivalent to P0. e; s is the complex frequency in the Laplace transform.

[0057] The virtual synchronous generator can perform primary frequency regulation in the active power loop, meaning its active power adaptively adjusts with changes in grid frequency. The corresponding primary frequency regulation is as follows: Figure 2 As shown, T f Given the first-order filtering time constant for the actual sampling frequency, the transfer function of active power to grid frequency (the transfer function of active power-frequency characteristics) can be obtained as follows:

[0058]

[0059] Where f is the real-time power grid frequency, ω = 2πf, f n Let ω0 be the rated frequency of the virtual synchronous generator (i.e., the rated frequency of the power grid), and ω0 = 2πf n The transfer function of the virtual synchronous generator in steady state is:

[0060]

[0061] When the grid frequency changes, that is, when there is a deviation between the grid frequency and the rated frequency of the virtual synchronous generator, i.e., when the angular frequency deviation Δω≠0, the damping power P of the virtual synchronous generator... D =Dω0Δω≠0, perform one frequency modulation.

[0062] The primary frequency modulation coefficient is defined as:

[0063]

[0064] Where, ΔP=PP ref Δf=ff n P n Given the rated active power of the virtual synchronous generator, the primary frequency regulation coefficient can be obtained as:

[0065]

[0066] It can be seen that the primary frequency regulation coefficient is affected by the damping coefficient, meaning that the damping coefficient of the virtual synchronous generator is coupled with the primary frequency regulation coefficient. Since the primary frequency regulation function requires setting a frequency dead zone, the active power corresponding to the dead zone portion needs to be subtracted when the frequency exceeds the dead zone range. This indicates a nonlinear control relationship between active power and frequency, and the coupled damping coefficient affects the accuracy of the primary frequency regulation of the virtual synchronous generator. Therefore, this application provides a control method for a virtual synchronous generator that decouples the damping coefficient in the active power loop from the primary frequency regulation coefficient, ensuring the accuracy of the primary frequency regulation of the virtual synchronous generator. Figure 3 As shown, the specific steps include the following:

[0067] 301. Obtain the damping gain coefficient of the virtual synchronous generator during transient fluctuations.

[0068] In this embodiment, the damping gain coefficient of the virtual synchronous generator during transient fluctuations can be obtained. This virtual synchronous generator is used to control a grid-connected inverter. The transient fluctuations of the virtual synchronous generator can be understood as fluctuations in the grid power supply to the grid-connected inverter, or fluctuations in the load of the grid-connected inverter; the specifics are not limited here.

[0069] Understandably, the damping of existing synchronous generators includes mechanical damping, electromagnetic damping generated by damping windings, and damping provided by the PSS (Power System Static Stabilizer). Among these, mechanical damping is related to the relative speed of the synchronous generator and only manifests during transient fluctuations. During transient fluctuations, the damping characteristics of a synchronous generator exhibit a certain gain, i.e., a degree of attenuation. Therefore, the damping characteristics of a virtual synchronous generator during transient fluctuations can be simulated to improve the damping characteristics of the active power loop.

[0070] The damping gain coefficient with transient damping characteristics can be obtained based on the damping decay characteristics during transient fluctuations. Specifically, the damping gain coefficient G of the virtual synchronous generator during transient fluctuations can be determined based on the decay time constant of the virtual winding in the virtual synchronous generator. d (s), the corresponding expression is as follows:

[0071]

[0072] Among them, T c This is the decay time constant of the virtual winding.

[0073] Furthermore, the cutoff frequency for damping attenuation can be obtained; this cutoff frequency indicates that damping is gaining between this cutoff frequency and attenuating after this cutoff frequency. This cutoff frequency can be selected to be less than 1Hz, taking into account the damping attenuation characteristics of the synchronous generator under transient fluctuations and the amplitude-frequency characteristics in digital filtering. Based on the cutoff frequency, the gain value of the damping gain coefficient of the virtual synchronous generator under transient fluctuations is determined. It can be understood that, generally, the higher the cutoff frequency, the higher the gain value of the damping gain coefficient, and the lower the cutoff frequency, the lower the gain value of the damping gain coefficient. When the cutoff frequency is less than 1Hz, the corresponding gain value of the damping gain coefficient is less than -5dB, i.e.:

[0074]

[0075] The decay time constant T of the virtual winding can be obtained. c It is 0.108.

[0076] 302. Adjust the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain the transient damping coefficient after gain.

[0077] After obtaining the damping gain coefficient, the damping coefficient of the active power loop in the virtual synchronous generator can be adjusted based on the damping gain coefficient to obtain the amplified transient damping coefficient. Specifically, the damping gain coefficient can be multiplied by the damping coefficient of the active power loop in the virtual synchronous generator to obtain the amplified transient damping coefficient. Figure 4 As shown, the damping coefficient D of the active loop in the virtual synchronous generator is replaced with the transient damping coefficient D·G after gain. d (s) can be used to obtain a virtual synchronous generator with transient damping characteristics.

[0078] 303. When the virtual synchronous generator is in steady state and the grid frequency changes, suppress the change in active power in the active power loop based on the transient damping coefficient.

[0079] When the virtual synchronous generator is in steady state and the grid frequency changes, the change in active power in the active power loop can be suppressed based on the transient damping coefficient. Specifically, the frequency difference Δω between the grid angular frequency and the rated angular frequency of the virtual synchronous generator can be obtained; if this frequency difference Δω is not zero, it is determined that the grid frequency has changed; if the frequency difference Δω is zero, it is determined that the grid frequency has not changed.

[0080] This method simulates a synchronous generator in steady state. The transient damping coefficient can be used for bandpass filtering in the active power loop. When the grid frequency changes, it eliminates the effect of the original damping coefficient on the change in active power caused by the grid frequency change in steady state, thus eliminating primary frequency regulation and decoupling the damping coefficient from the primary frequency regulation coefficient. Specifically, addressing the coupling relationship between the primary frequency regulation coefficient and the damping coefficient in existing virtual synchronous generators, and based on the transient and steady-state characteristics of the damping winding in a synchronous generator, a virtual transient damping coefficient is introduced. This bandpass filtering eliminates the influence of the damping coefficient on primary frequency regulation in steady state, achieving decoupling of the damping coefficient and the primary frequency regulation coefficient in the virtual synchronous generator (i.e., decoupling of damping characteristics from primary frequency regulation characteristics).

[0081] As can be seen, in this embodiment, the damping gain coefficient of the virtual synchronous generator during transient fluctuations is obtained; based on the damping gain coefficient, the damping coefficient of the active power loop in the virtual synchronous generator is adjusted to obtain the gained transient damping coefficient; when the virtual synchronous generator is in a steady state and the grid frequency undergoes a steady-state change, the change in active power in the active power loop is suppressed based on the transient damping coefficient. That is, this transient damping coefficient ensures that when the grid frequency only undergoes a steady-state change, the active power remains unchanged, i.e., primary frequency regulation is not performed, thus decoupling the damping coefficient in the active power loop from the primary frequency regulation coefficient, ensuring the accuracy of the primary frequency regulation of the virtual synchronous generator.

[0082] Furthermore, when the virtual synchronous generator is in steady state and the grid frequency changes (i.e., Δω≠0), the damping power in the virtual synchronous generator can be controlled to be zero based on the transient damping coefficient to suppress changes in active power in the active power loop. Specifically, when in steady state, the value of the damping power can be obtained according to the final value theorem; where the final value theorem is used in steady state, the time-domain behavior is calculated by directly taking the limit of the frequency domain expression. That is, the corresponding damping power is:

[0083]

[0084] At this point, the damping power is zero, meaning that when the grid frequency only has steady-state changes, no active power changes are generated, and no primary frequency regulation is performed, thus achieving decoupling of the damping coefficient and the primary frequency regulation coefficient.

[0085] Furthermore, the control of a virtual synchronous generator with transient damping coefficients, such as... Figure 5 As shown, based on the transient damping coefficient in the transfer function of active power and grid frequency, the active power in the active power loop can be controlled to remain consistent with the given active power of the virtual synchronous generator after a change in grid frequency, thus ensuring that the active power does not change. The transfer function of active power and grid frequency is:

[0086]

[0087] In steady state, based on the final value theorem, we can obtain:

[0088]

[0089] At this point, P≈P ref That is, the active power in the active power loop remains consistent with the given active power of the virtual synchronous generator after the steady-state change of the grid frequency, without causing changes in active power, thus achieving decoupling of the damping coefficient from the primary frequency regulation.

[0090] Furthermore, in this embodiment of the application, the primary frequency modulation coefficient K can be... fSetting it to 0 will allow a virtual synchronous generator with transient damping characteristics to operate under the same control parameters and conditions as a traditional virtual synchronous generator without transient damping characteristics (i.e., 1P can be set). n Power, rated active power P n =1250K), the response graphs of these two types of virtual synchronous generators to changes in grid frequency (frequency step) can be analyzed. For example, the response of a traditional virtual synchronous generator is as follows: Figure 6 As shown in the figure, Freq is the grid frequency, P is the active power of the virtual synchronous generator, and Q is the reactive power of the virtual synchronous generator. The grid frequency drops from 50Hz to 49Hz in 15 seconds, and the active power changes accordingly. The response of the virtual synchronous generator with transient damping characteristics is as follows: Figure 7 As shown, the grid frequency drops from 50Hz to 49Hz in a step transition at 15s, while the active power remains unchanged. An example of the response of a conventional virtual synchronous generator is as follows: Figure 8 As shown, the grid frequency increases from 50Hz to 51Hz in 15s, and the active power changes; while the response of the virtual synchronous generator with transient damping characteristics is as follows: Figure 9 As shown, the grid frequency increases from 50Hz to 51Hz in 15 seconds, while the active power remains unchanged. Correspondingly, when a virtual synchronous generator with transient damping characteristics is superimposed with the previous frequency regulation, the grid frequency increases from 50Hz to 51Hz in 15 seconds, as shown. Figure 10 As shown in the figure. It can be seen that, in the embodiments of this application, the virtual synchronous generator with transient damping characteristics can achieve decoupling of the damping coefficient and the primary frequency regulation.

[0091] This application also provides a control device for a virtual synchronous generator, such as... Figure 11 As shown, it includes:

[0092] Acquisition unit 1101 is used to acquire the damping gain coefficient of the virtual synchronous generator during transient fluctuations;

[0093] Adjustment unit 1102 is used to adjust the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient, so as to obtain the transient damping coefficient after gain.

[0094] The suppression unit 1103 is used to suppress the change in active power in the active power loop based on the transient damping coefficient when the virtual synchronous generator is in a steady state and the grid frequency corresponding to the virtual synchronous generator changes.

[0095] This application embodiment also provides a control device 1200 for a virtual synchronous generator, such as... Figure 12As shown, the control device 1200 of this application embodiment may include one or more central processing units (CPUs) 1201 and a memory 1202, wherein the memory 1202 stores one or more application programs or data.

[0096] The memory 1202 can be volatile or persistent storage. The program stored in the memory 1202 can include one or more modules, each module including a series of instruction operations on the electronic device. Furthermore, the central processing unit 1201 can be configured to communicate with the memory 1202, and the control device 1200 can execute the series of instruction operations stored in the memory 1202.

[0097] The control device 1200 may also include one or more power supplies 1205, one or more wired or wireless network interfaces 1204, one or more input / output interfaces 1203, and / or one or more operating systems, such as Windows Server™, Mac OS X™, Unix™, Linux™, FreeBSD™, etc.

[0098] The central processing unit 1201 can perform the operations performed in any of the aforementioned specific method embodiments, which will not be described in detail here.

[0099] This application embodiment also provides a grid-connected inverter. When the grid-connected inverter is in grid-connected state, a virtual synchronous generator obtained by the above-described virtual synchronous generator control method is used to control the grid-connected inverter.

[0100] This application also provides a computer-readable storage medium including instructions that, when executed on a computer, cause the computer to perform the method described above.

[0101] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0102] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0103] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0105] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A control method for a virtual synchronous generator, characterized in that, include: Obtain the damping gain coefficient of the virtual synchronous generator during transient fluctuations; The step of obtaining the damping gain coefficient of the virtual synchronous generator during transient fluctuations includes: Based on the decay time constant of the virtual winding in the virtual synchronous generator, the damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined, and the corresponding expression is: ,in, The damping gain coefficient is... The decay time constant of the virtual winding, The complex frequency in the Laplace transform; Based on the damping gain coefficient, the damping coefficient of the active loop in the virtual synchronous generator is adjusted to obtain the transient damping coefficient after gain. The step of adjusting the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain the gained transient damping coefficient includes: Multiply the damping gain coefficient by the damping coefficient of the active loop in the virtual synchronous generator to obtain the amplified transient damping coefficient; When the virtual synchronous generator is in a steady state and the grid frequency changes, the change in active power in the active power loop is suppressed based on the transient damping coefficient. The method of suppressing changes in active power in the active power loop based on the transient damping coefficient includes: Bandpass filtering is implemented in the active power loop based on the transient damping coefficient to suppress changes in active power caused by grid frequency variations in the damping coefficient of the active power loop in the virtual synchronous generator during steady state.

2. The control method according to claim 1, characterized in that, The step of obtaining the damping gain coefficient of the virtual synchronous generator during transient fluctuations further includes: Obtain the cutoff frequency of damping attenuation; The gain value of the damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined based on the cutoff frequency.

3. The control method according to claim 1, characterized in that, The method further includes: Obtain the frequency difference between the grid angular frequency and the rated angular frequency of the virtual synchronous generator; If the frequency difference is not zero, then it is determined that the power grid frequency has changed; If the frequency difference is zero, then it is determined that the power grid frequency has not changed.

4. The control method according to claim 1, characterized in that, The method of suppressing changes in active power in the active power loop based on the transient damping coefficient includes: The damping power in the virtual synchronous generator is controlled to be zero based on the transient damping coefficient, so as to suppress the change of active power in the active power loop.

5. The control method according to claim 1, characterized in that, The method of suppressing changes in active power in the active power loop based on the transient damping coefficient includes: Based on the transient damping coefficient in the transfer function of active power and grid frequency, the active power in the active power loop is controlled to remain consistent with the given active power of the virtual synchronous generator after the grid frequency changes.

6. A control device for a virtual synchronous generator, characterized in that, include: The acquisition unit is used to acquire the damping gain coefficient of the virtual synchronous generator during transient fluctuations; The acquisition unit is specifically used to determine the damping gain coefficient of the virtual synchronous generator during transient fluctuations based on the decay time constant of the virtual winding in the virtual synchronous generator. The corresponding expression is: ,in, The damping gain coefficient is... The decay time constant of the virtual winding, The complex frequency in the Laplace transform; An adjustment unit is used to adjust the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient, so as to obtain the transient damping coefficient after gain. The adjustment unit is specifically used to multiply the damping gain coefficient by the damping coefficient of the active loop in the virtual synchronous generator to obtain the gained transient damping coefficient. The suppression unit is used to suppress the change in active power in the active power loop based on the transient damping coefficient when the virtual synchronous generator is in a steady state and the grid frequency corresponding to the virtual synchronous generator changes. The suppression unit is specifically used to implement bandpass filtering in the active power loop based on the transient damping coefficient, so as to suppress the change in active power caused by the change in grid frequency in the active power loop of the virtual synchronous generator during steady state.

7. A control device for a virtual synchronous generator, characterized in that, include: Central processing unit, memory, input / output interface, wired or wireless network interface, power supply; The memory is either a short-term storage memory or a persistent storage memory; The central processing unit is configured to communicate with the memory and execute instructions in the memory on a control plane functional entity to perform the method described in any one of claims 1 to 5.

8. A grid-connected inverter, characterized in that, When the grid-connected inverter is in grid-connected state, the virtual synchronous generator obtained by the control method of the virtual synchronous generator according to any one of claims 1 to 5 is used to control the grid-connected inverter.

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