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

Abstract

The embodiment of the invention discloses a control method and a control device of a virtual synchronous generator, and a network-forming inverter, which are used in the technical field of electrical control. According to the embodiment of the invention, the method comprises the steps: obtaining a damping gain coefficient of a virtual synchronous generator during transient fluctuation; adjusting a damping coefficient of an active ring in the virtual synchronous generator based on the damping gain coefficient to obtain a transient damping coefficient after gain; and when the virtual synchronous generator is in a steady state and the power grid frequency is changed, suppressing the change of the active power in the active loop based on the transient damping coefficient. The transient damping coefficient can control the active power not to change when the power grid frequency only has steady-state change, that is, primary frequency modulation is not carried out, so that the damping coefficient in an active ring is decoupled from a primary frequency modulation coefficient, and the accuracy of the primary frequency modulation of the virtual synchronous generator is ensured.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of electrical control technology, and in particular to a control method and a control device for a virtual synchronous generator and a grid-connected inverter. Background Art

[0002] With the application of distributed new energy systems, more and more inverters are connected to the power grid, resulting in a significant reduction in the total damping and total inertia provided by traditional generators in the power grid, which makes the frequency change faster and the anti-interference ability decrease when the power grid faces disturbances. In order to solve this problem, the concept of virtual synchronous generator (VSG) control technology is proposed. This control technology can imitate the operation mechanism of synchronous generators, suppress the fluctuation of frequency and output power, and enable the grid-connected inverter corresponding to the virtual synchronous generator to have grid support, inertia response and damping characteristics, thereby improving the voltage amplitude and frequency fluctuation of the power grid.

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

[0004] The embodiments of the present application provide a control method, a control device and a grid-type inverter for a virtual synchronous generator, which can decouple the damping coefficient in the active loop from the primary frequency modulation coefficient, thereby ensuring the accuracy of the primary frequency modulation of the virtual synchronous generator.

[0005] The embodiment of the present application provides a control method for a virtual synchronous generator, including:

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

[0007] Adjusting the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain a transient damping coefficient after gain;

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

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

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

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

[0012] Get the cutoff frequency of damping attenuation;

[0013] A gain value of a damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined based on the cut-off frequency.

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

[0015] The damping gain coefficient is multiplied by the damping coefficient of the active loop in the virtual synchronous generator to obtain a transient damping coefficient after gain.

[0016] Furthermore, the method further comprises:

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

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

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

[0020] Further, suppressing the change of active power in the active loop based on the transient damping coefficient includes:

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

[0022] Further, suppressing the change of active power in the active 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 loop is controlled to be consistent with the given active power of the virtual synchronous generator after the grid frequency changes.

[0024] The embodiment of the present application also provides a control device for a virtual synchronous generator, comprising:

[0025] An acquisition unit, used for acquiring a damping gain coefficient of the virtual synchronous generator during transient fluctuations;

[0026] An adjusting unit, configured to adjust the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain a transient damping coefficient after gain;

[0027] A suppression unit is used to suppress the change of active power in the active 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] The embodiment of the present application also provides a control device for a virtual synchronous generator, comprising:

[0029] CPU, memory, input and output interface, wired or wireless network interface, power supply;

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

[0031] The central processor is configured to communicate with the memory, and execute the instruction operation in the memory on the control plane function entity to perform the above method.

[0032] The embodiment of the present application further provides a grid-connected inverter. When the grid-connected inverter is in a grid-connected state, a virtual synchronous generator obtained by the above-mentioned control method of a virtual synchronous generator is used to control the grid-connected inverter.

[0033] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0034] In the embodiment of the present application, the damping gain coefficient of the virtual synchronous generator during transient fluctuations is obtained; the damping coefficient of the active loop in the virtual synchronous generator is adjusted based on the damping gain coefficient to obtain the transient damping coefficient after gain; when the virtual synchronous generator is in a steady state and the grid frequency changes, the change of active power in the active loop is suppressed based on the transient damping coefficient. That is, the transient damping coefficient can control the active power not to change when there is only a steady-state frequency difference in the grid frequency, that is, when there is only a steady-state change in the grid frequency, that is, no primary frequency modulation is performed, so that the damping coefficient in the active loop is decoupled from the primary frequency modulation coefficient, and the accuracy of the primary frequency modulation of the virtual synchronous generator is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0036] Figure 1 A control block diagram of the rotor motion in an active ring disclosed in an embodiment of the present application;

[0037] Figure 2 A control block diagram of a primary frequency modulation in an active loop disclosed in an embodiment of the present application;

[0038] Figure 3 A control flow chart of a virtual synchronous generator disclosed in an embodiment of the present application;

[0039] Figure 4 A control block diagram of rotor motion based on transient damping coefficient disclosed in an embodiment of the present application;

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

[0041] Figure 6 A response diagram of an existing virtual synchronous generator disclosed in an embodiment of the present application when the grid frequency decreases;

[0042] Figure 7 A response diagram of a virtual synchronous generator disclosed in an embodiment of the present application when the grid frequency decreases;

[0043] Figure 8 A response diagram of an existing virtual synchronous generator disclosed in an embodiment of the present application when the grid frequency rises;

[0044] Fig. 9 A response diagram of a virtual synchronous generator disclosed in an embodiment of the present application when the grid frequency rises;

[0045] Fig.10 A response diagram of a superimposed primary frequency modulation disclosed in an embodiment of the present application;

[0046] Fig.11 A control device diagram of a virtual synchronous generator disclosed in an embodiment of the present application;

[0047] Fig.12 A diagram of a control device of another virtual synchronous generator disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] In the description of the embodiments of the present application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present application.

[0050] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0051] The virtual synchronous generator (VSG) control technology controls the grid-connected inverter by imitating the operation mechanism of the synchronous generator. The existing virtual synchronous generator uses the second-order excitation swing equation of the synchronous generator (i.e., the second-order classical model of the synchronous generator), including the rotor motion equation reflecting the mechanical characteristics of the synchronous generator; the rotor motion equation of the mechanical characteristics is:

[0052]

[0053] Where J is the inertia constant, T m is the mechanical torque, T e 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, ω0 is the rated angular frequency of the synchronous generator, that is, the rated angular frequency of the virtual synchronous generator;

[0054] The corresponding expression in power form is:

[0055]

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

[0057] Among them, the virtual synchronous generator can perform primary frequency modulation in the active loop, that is, the active power of the virtual synchronous generator is adaptively adjusted as the grid frequency changes. The corresponding primary frequency modulation is as follows: Figure 2 As shown, where T f is the first-order filtering time constant of the actual sampling frequency, and the transfer function of active power and grid frequency (transfer function of active power-frequency characteristic) can be obtained as follows:

[0058]

[0059] Where f is the real-time grid frequency, ω=2πf, f n is the rated frequency of the virtual synchronous generator (i.e. the rated frequency of the power grid), ω0=2πf n ; When the virtual synchronous generator is in steady state, the transfer function 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, that is, when the angular frequency deviation Δω≠0, the damping power P of the virtual synchronous generator D =Dω0Δω≠0, a frequency modulation effect is performed.

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

[0063]

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

[0065]

[0066] It can be seen that the primary frequency modulation coefficient is affected by the damping coefficient, that is, there is a coupling between the damping coefficient of the virtual synchronous generator and the primary frequency modulation coefficient. Since the primary frequency modulation function requires the setting of a frequency dead zone, the active power corresponding to the frequency dead zone part needs to be deducted when it exceeds the frequency dead zone range, that is, the active power and frequency have a nonlinear control relationship. The coupled damping coefficient affects the accuracy of the primary frequency modulation of the virtual synchronous generator. Therefore, an embodiment of the present application provides a control method for a virtual synchronous generator, which can decouple the damping coefficient in the active power loop from the primary frequency modulation coefficient, thereby ensuring the accuracy of the primary frequency modulation of the virtual synchronous generator. Figure 3 As shown, the specific steps include:

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

[0068] In the embodiment of the present application, the damping gain coefficient of the virtual synchronous generator during transient fluctuations can be obtained. The virtual synchronous generator is used to control the grid-connected inverter, and the transient fluctuation of the virtual synchronous generator can be understood as the fluctuation of the grid of the grid-connected inverter, or the fluctuation of the load of the grid-connected inverter, which is not limited here.

[0069] It is understandable that the damping of existing synchronous generators includes mechanical damping, electromagnetic damping generated by damping windings, damping provided by PSS (power system static stabilizer), etc., among which mechanical damping is related to the relative speed of the synchronous generator and is only manifested in the transient fluctuation process of the synchronous generator. The damping characteristics of the synchronous generator will have a certain gain, that is, the degree of attenuation, during the transient fluctuation process; at this time, the damping characteristics of the synchronous generator during the transient fluctuation process can be simulated to improve the damping characteristics of the active loop in the virtual synchronous generator.

[0070] Based on the damping attenuation characteristics during transient fluctuations, a damping gain coefficient with transient damping characteristics can be obtained. The damping gain coefficient G of the virtual synchronous generator during transient fluctuations can be determined based on the attenuation 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 is the decay time constant of the virtual winding.

[0073] Furthermore, the cutoff frequency of damping attenuation can also be obtained; the cutoff frequency is used to indicate that damping is gain between the cutoff frequency and is attenuated after the cutoff frequency. Among them, the cutoff frequency can be selected to be less than 1HZ in combination with the damping attenuation characteristics of the synchronous generator under transient fluctuations and the amplitude-frequency characteristics in digital filtering. The gain value of the damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined based on the cutoff frequency. It can be understood that, in general, the higher the cutoff frequency, the higher the gain value of the corresponding 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, that is:

[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 a transient damping coefficient after gain.

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

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

[0079] When the virtual synchronous generator is in a steady state and the grid frequency changes, the change of active power in the active loop can be suppressed based on the transient damping coefficient. Among them, the frequency difference Δω between the grid angular frequency and the rated angular frequency of the virtual synchronous generator can be obtained; if the 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] That is, when the synchronous generator is in steady state, the transient damping coefficient can realize bandpass filtering in the active loop. When the grid frequency changes, the original damping coefficient can be removed. The active power changes due to the grid frequency change in steady state, that is, no primary frequency modulation is performed, and the damping coefficient is decoupled from the primary frequency modulation coefficient. That is, according to the coupling relationship between the primary frequency modulation coefficient and the damping coefficient in the existing virtual synchronous generator, according to the transient characteristics and steady-state characteristics of the damping winding in the synchronous generator, a virtual transient damping coefficient is introduced on the basis of the existing virtual synchronous generator, that is, a bandpass filtering link is introduced to eliminate the influence of the damping coefficient on the primary frequency modulation in steady state, and the decoupling of the damping coefficient and the primary frequency modulation coefficient in the virtual synchronous generator (that is, the decoupling of the damping characteristics and the primary frequency modulation characteristics) can be realized.

[0081] It can be seen. In the embodiment of the present application, the damping gain coefficient of the virtual synchronous generator during transient fluctuations is obtained; the damping coefficient of the active loop in the virtual synchronous generator is adjusted based on the damping gain coefficient to obtain the transient damping coefficient after gain; 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 loop is suppressed based on the transient damping coefficient. That is, the transient damping coefficient can control the active power not to change when the grid frequency only undergoes a steady-state change, that is, no primary frequency modulation is performed, so that the damping coefficient in the active loop is decoupled from the primary frequency modulation coefficient, thereby ensuring the accuracy of the primary frequency modulation 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 the change of active power in the active loop. Specifically, when in steady state, the value of the damping power can be obtained according to the final value theorem; wherein, the final value theorem is used in steady state, and the frequency domain expression is directly limited to calculate the time domain behavior. That is, the corresponding damping power is:

[0083]

[0084] At this time, the damping power is zero, that is, when the grid frequency only has steady-state changes, no active power changes are generated, and no primary frequency modulation is performed, that is, the damping coefficient and the primary frequency modulation coefficient are decoupled.

[0085] Furthermore, the control of the virtual synchronous generator with transient damping coefficient is as follows 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 loop can be controlled to be consistent with the given active power of the virtual synchronous generator after the grid frequency changes, so that the active power does not change. Among them, the transfer function of active power and grid frequency is:

[0086]

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

[0088]

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

[0090] Furthermore, in the embodiment of the present application, the primary frequency modulation coefficient K can be fSet to 0, and use the same control parameters and operating conditions (i.e., 1P n Power, rated active power P n =1250K), the response diagrams of these two virtual synchronous generators to changes in grid frequency (frequency step) can be analyzed. For example, the response of the 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, Q is the reactive power of the virtual synchronous generator, the grid frequency drops from 50Hz to 49Hz at 15s, and the active power changes; the response of the virtual synchronous generator with transient damping characteristics is as follows Figure 7 As shown in Figure 1, the grid frequency drops from 50 Hz to 49 Hz at 15 s, and the active power does not change. For example, the response of a traditional virtual synchronous generator is as follows: Figure 8 As shown in Figure 1, the grid frequency increases from 50 Hz to 51 Hz at 15 s, and the active power changes. The response of the virtual synchronous generator with transient damping characteristics is shown in Figure 1. Fig. 9 As shown in the figure, the grid frequency increases from 50 Hz to 51 Hz at 15 s, and the active power does not change; correspondingly, the virtual synchronous generator with transient damping characteristics superimposes the previous frequency modulation, and the grid frequency increases from 50 Hz to 51 Hz at 15 s, as shown in the figure. Fig.10 It can be seen that in the embodiment of the present application, the virtual synchronous generator with transient damping characteristics can achieve the decoupling of the damping coefficient and the primary frequency modulation.

[0091] The present application also provides a control device for a virtual synchronous generator, such as Fig.11 As shown, including:

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

[0093] An adjusting unit 1102 is used to adjust the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain a transient damping coefficient after gain;

[0094] The suppression unit 1103 is used to suppress the change of active power in the active 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] The present application also provides a control device 1200 for a virtual synchronous generator. Fig.12As shown, the control device 1200 of the embodiment of the present application may include one or more central processing units (CPU) 1201 and a memory 1202 , and the memory 1202 stores one or more application programs or data.

[0096] The memory 1202 may be a volatile storage or a persistent storage. The program stored in the memory 1202 may include one or more modules, each of which may include a series of instruction operations in the electronic device. Furthermore, the central processor 1201 may be configured to communicate with the memory 1202, and the control device 1200 may execute a series of instruction operations 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 and output interfaces 1203, and / or one or more operating systems, such as Windows ServerTM, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM, etc.

[0098] The central processing unit 1201 can execute the operations performed by any of the aforementioned specific method embodiments, and the details will not be repeated here.

[0099] The embodiment of the present application further provides a grid-connected inverter. When the grid-connected inverter is in a grid-connected state, a virtual synchronous generator obtained by the above-mentioned control method of a virtual synchronous generator is used to control the grid-connected inverter.

[0100] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium includes instructions. When the instructions are executed on a computer, the computer executes the method described above.

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

[0102] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

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

[0104] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0105] If the integrated unit is implemented in the form of 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 the present application is essentially 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, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, read-only memory), random access memory (RAM, random access memory), disk or optical disk and other media that can store program code.

Claims

1. A control method for a virtual synchronous generator, characterized in that: include: Obtaining a damping gain coefficient of the virtual synchronous generator during transient fluctuations; Adjusting the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain a transient damping coefficient after gain; When the virtual synchronous generator is in a steady state and the grid frequency changes, the change of active power in the active loop is suppressed based on the transient damping coefficient.

2. The control method according to claim 1, characterized in that: The obtaining of the damping gain coefficient of the virtual synchronous generator during transient fluctuations comprises: Based on the attenuation time constant of the virtual winding in the virtual synchronous generator, a damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined.

3. The control method according to claim 1, characterized in that: The obtaining of the damping gain coefficient of the virtual synchronous generator during transient fluctuations further includes: Get the cutoff frequency of damping attenuation; A gain value of a damping gain coefficient of the virtual synchronous generator during transient fluctuations is determined based on the cut-off frequency.

4. The control method according to claim 1, characterized in that: The step of adjusting the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain a transient damping coefficient after gain includes: The damping gain coefficient is multiplied by the damping coefficient of the active loop in the virtual synchronous generator to obtain a transient damping coefficient after gain.

5. The control method according to claim 1, characterized in that: The method further comprises: Acquire a frequency difference between a grid angular frequency and a rated angular frequency of the virtual synchronous generator; If the frequency difference is not zero, it is determined that the grid frequency has changed; If the frequency difference is zero, it is determined that the grid frequency has not changed.

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

7. The control method according to claim 1, characterized in that: The step of suppressing the change of active power in the active 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 loop is controlled to be consistent with the given active power of the virtual synchronous generator after the grid frequency changes.

8. A control device for a virtual synchronous generator, characterized in that: include: An acquisition unit, used for acquiring a damping gain coefficient of the virtual synchronous generator during transient fluctuations; An adjustment unit, configured to adjust the damping coefficient of the active loop in the virtual synchronous generator based on the damping gain coefficient to obtain a transient damping coefficient after gain; A suppression unit is used to suppress the change of active power in the active 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.

9. A control device for a virtual synchronous generator, characterized in that: include: CPU, memory, input and output interface, wired or wireless network interface, power supply; The memory is a short-term storage memory or a persistent storage memory; The central processor is configured to communicate with the memory, and execute instruction operations in the memory on a control plane function entity to perform the method according to any one of claims 1 to 7.

10. A grid-connected inverter, characterized in that: When the grid-connected inverter is in a grid-connected state, a virtual synchronous generator obtained by the control method of a virtual synchronous generator according to any one of claims 1 to 7 is used to control the grid-connected inverter.

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