Grid-connected converter based on virtual synchronous generator technology and control method

Abstract

The invention discloses a grid-connected converter based on a virtual synchronous generator technology and a control method. The grid-connected converter comprises a power conversion circuit, a filter circuit, a first state observer, a second expansion state observer and a controller, the direct-current side of the power conversion circuit is connected with a direct-current source, the alternating-current side of the power conversion circuit is connected with the first end of the filter circuit, and the second end of the filter circuit is connected with a power grid; the first extended state observer is used for acquiring a first coupling disturbance quantity related to reactive power in the active power; the second extended state observer is used for acquiring a second coupling disturbance quantity related to the active power in the reactive power; and the controller is used for decoupling the active power and the reactive power according to the first coupling disturbance quantity and the second coupling disturbance quantity. In the embodiment of the invention, the active power and the reactive power are decoupled according to the obtained first coupling disturbance quantity and the second coupling disturbance quantity, the method is simple, and the robustness of power decoupling can be improved.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a grid-connected converter and a control method based on virtual synchronous generator technology. Background Art

[0002] In recent years, virtual synchronous generator (VSG) technology has gradually attracted widespread attention, which can provide inertia and damping support for the power grid. In the current low-voltage weak power grid, the line impedance ratio is relatively large, resulting in obvious coupling problems between active power and reactive power.

[0003] In the related art, the decoupling between active power and reactive power is achieved by using virtual power method, virtual impedance method, feedforward compensation method, etc. However, none of the above methods considers the change of grid impedance. If the grid impedance deviates from the nominal value, the power decoupling performance will deteriorate and the power decoupling will not be robust. Summary of the invention

[0004] Based on the above problems, the present application provides a grid-connected converter and a control method based on virtual synchronous generator technology to improve the power decoupling performance and robustness of the grid-connected inverter.

[0005] The embodiments of the present application disclose the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a grid-connected converter based on virtual synchronous generator technology, comprising: a power conversion circuit, a filter circuit, a first extended state observer, a second extended state observer, and a controller;

[0007] The DC side of the power conversion circuit is used to connect to a DC source, the AC side of the power conversion circuit is connected to a first end of the filter circuit, and the second end of the filter circuit is used to connect to a power grid;

[0008] A first extended state observer is used to obtain a first coupled disturbance amount of active power with respect to reactive power;

[0009] A second extended state observer is used to obtain a second coupled disturbance amount with respect to the active power in the reactive power;

[0010] The controller is used to decouple the active power and the reactive power according to the first coupling disturbance amount and the second coupling disturbance amount.

[0011] Optionally, the controller is also used to obtain the active power and reactive power of the grid-connected converter based on the output voltage and output current of the power conversion circuit; wherein the active power includes a first coupling disturbance amount related to the reactive power, and the reactive power includes a second coupling disturbance amount related to the active power.

[0012] Optionally, the controller is specifically used for using active power as feedback active power; obtaining a small signal component Δω about angular frequency by using a first transfer function to obtain a difference between the reference active power, the feedback active power and the first coupling disturbance; Δω obtains a small signal component Δδ about phase by using a second transfer function; Δδ obtains a small signal component Δδ about phase by using the first power small signal transfer function H Pδ The first active power component is obtained, Δδ is obtained through the third power small signal transfer function H Qδ The second reactive power component is obtained; the reactive power is used as the feedback reactive power, and the difference between the reference reactive power, the feedback reactive power and the first coupling disturbance is obtained through the third transfer function to obtain the small signal component ΔE about the effective value of the electromotive force; ΔE is obtained through the second power small signal transfer function H PE The second component of active power is obtained, ΔE, through the fourth power small signal transfer function H QE A first reactive power component is obtained; wherein the active power includes a first active power component and a second active power component, and the reactive power includes a first reactive power component and a second reactive power component.

[0013] Optionally, the first extended state observer is specifically used to obtain according to the active power, the reference active power and the estimated value of the active power, wherein the active power includes a first coupled disturbance amount about the reactive power;

[0014] The second extended state observer is specifically used to obtain, according to the reactive power, the reference reactive power and the estimated value of the reactive power, the reactive power including a second coupling disturbance amount related to the active power.

[0015] Optionally, the first extended state observer is further used to use the active power estimate as the feedback active power estimate, obtain a first coupling disturbance amount by using a difference between the active power and the estimated value of the feedback active power through a fourth transfer function and a fifth transfer function, obtain a first parameter by using a sixth transfer function, and obtain a second parameter by using a seventh transfer function; and obtain the active power estimate according to the reference active power, the active power, the first coupling disturbance amount, the first parameter, and the second parameter;

[0016] The second extended state observer is also used for the reactive power estimate as the feedback reactive power estimate. The difference between the reactive power and the estimated value of the feedback reactive power is used to obtain the second coupling disturbance through the eighth transfer function and the ninth transfer function, and the third parameter is obtained through the tenth transfer function; the reactive power estimate is obtained according to the reference reactive power, the reactive power, the second coupling disturbance and the third parameter.

[0017] Optionally, the controller is specifically used to perform Clarke transformation on the output voltage of the power conversion circuit to obtain a first output voltage Eα and a second output voltage Eβ, and to perform Clarke transformation on the output current of the power conversion circuit to obtain a first output current Iα and a second output current Iβ; the product of the first output voltage Eα and the first output current Iα plus the product of the second output voltage Eβ and the second output current Iβ obtains active power; the product of the second output voltage Eβ and the first output current Iα plus the product of the first output voltage Eα and the second output current Iβ obtains reactive power.

[0018] In a second aspect, an embodiment of the present application provides a control method for a grid-connected inverter based on a virtual synchronous generator technology, wherein the grid-connected inverter based on the virtual synchronous generator technology includes: a power conversion circuit and a filter circuit; wherein the DC side of the power conversion circuit is used to connect to a DC source, the AC side of the power conversion circuit is connected to a first end of the filter circuit, and the second end of the filter circuit is used to connect to a power grid;

[0019] Methods include:

[0020] Acquire a first coupled disturbance amount of active power with respect to reactive power, and a second coupled disturbance amount of reactive power with respect to active power;

[0021] Active power and reactive power are decoupled according to the first coupling disturbance amount and the second coupling disturbance amount.

[0022] Optionally, the method further comprises:

[0023] According to the output voltage and output current of the power conversion circuit, the active power and reactive power of the grid-connected converter are obtained; wherein the active power includes a first coupling disturbance amount related to the reactive power, and the reactive power includes a second coupling disturbance amount related to the active power.

[0024] Optionally, decoupling active power and reactive power according to the first coupling disturbance amount and the second coupling disturbance amount includes:

[0025] The active power is used as the feedback active power; the difference between the reference active power, the feedback active power and the first coupling disturbance is obtained through the first transfer function to obtain a small signal component Δω about the angular frequency; Δω is obtained through the second transfer function to obtain a small signal component Δδ about the phase; Δδ is obtained through the first power small signal transfer function H Pδ The first active power component is obtained, Δδ is obtained through the third power small signal transfer function H Qδ Obtaining a second reactive power component;

[0026] Reactive power is used as feedback reactive power, and the difference between the reference reactive power, the feedback reactive power and the first coupling disturbance is obtained through the third transfer function to obtain a small signal component ΔE about the effective value of the electromotive force; ΔE is obtained through the second power small signal transfer function H PE The second component of active power is obtained, ΔE, through the fourth power small signal transfer function H QE A first reactive power component is obtained; wherein the active power includes a first active power component and a second active power component, and the reactive power includes a first reactive power component and a second reactive power component.

[0027] Optionally, the active power is obtained according to the active power and the reference active power, and the active power includes a first coupling disturbance amount about the reactive power; the reactive power is obtained according to the reactive power and the reference reactive power, and the active power includes a second coupling disturbance amount about the active power, including:

[0028] According to the active power, the reference active power and the estimated value of the active power, the active power includes a first coupling disturbance amount about the reactive power; according to the reactive power, the reference reactive power and the estimated value of the reactive power, the reactive power includes a second coupling disturbance amount about the active power.

[0029] In the embodiment of the present application, a first coupled disturbance amount about reactive power in active power is obtained by a first extended state observer, and a second coupled disturbance amount about active power in reactive power is obtained by a second extended state observer; and active power and reactive power are decoupled according to the first coupled disturbance amount and the second coupled disturbance amount. The method is simple and can improve the robustness of power decoupling. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 A schematic diagram of the structure of a grid-connected converter provided in an embodiment of the present application;

[0032] Figure 2 A control schematic diagram of a first extended state observer provided in an embodiment of the present application;

[0033] Figure 3 A control schematic diagram of a second extended state observer provided in an embodiment of the present application;

[0034] Figure 4A control schematic diagram of power decoupling provided in an embodiment of the present application;

[0035] Figure 5 A schematic diagram of obtaining active power and reactive power provided in an embodiment of the present application;

[0036] Figure 6 A flowchart of a control method for a grid-connected inverter based on virtual synchronous generator technology provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] It should be noted that the embodiments described in this application are only part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0038] The terms "first" and "second" in the specification and claims of this application are used to distinguish different objects rather than to describe a specific order of objects. For example, first data and second data are used to distinguish different data rather than to describe a specific order of data.

[0039] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0040] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. For example, multiple processing units refer to two or more processing units, etc.; multiple elements refer to two or more elements, etc.

[0041] See also Figure 1 , which is a schematic diagram of the structure of a grid-connected converter provided in an embodiment of the present application.

[0042] like Figure 1 As shown, the grid-connected converter includes: a power conversion circuit 10, a filter circuit 200, a first state expansion observer ( Figure 1 Not shown), the second state expansion observer ( Figure 1 ) and a controller ( Figure 1 not shown).

[0043] The DC side of the power conversion circuit 100 is used to connect to a DC source, the AC side of the power conversion circuit 100 is connected to a first end of the filter circuit 200 , and the second end of the filter circuit 200 is used to connect to a power grid.

[0044] It should be noted that Figure 1 Where Ls represents filter inductance, Rs represents damping resistance, C represents filter capacitance and Lg represents grid-side filter inductance.

[0045] The embodiment of the present application models the active power P and reactive power Q in the dq axis, where the d axis is positioned according to the grid voltage Ug, and δ represents the phase difference between the output voltage e of the power conversion circuit and the grid voltage Ug. The following transfer function matrix can be obtained:

[0046]

[0047] Among them, Δδ represents the small signal component of the phase, ΔE represents the small signal component of the effective value of the electromotive force, ΔP represents the small signal component of the active power, and ΔQ represents the small signal component of the reactive power; H Pδ represents the first power small signal transfer function, H PE represents the second power small signal transfer function, H Qδ represents the third power small signal transfer function and H QE Denotes the fourth power small signal transfer function.

[0048] It should be noted that the first power small signal transfer function H described in the embodiment of the present application is Pδ , the second power small signal transfer function H PE 、The third power small signal transfer function H Qδ And the fourth power small signal transfer function H QE All of them can be obtained by Matlab calculation. Since obtaining the power small signal transfer function by Matlab calculation is a mature technical means in this field, it will not be described here.

[0049] The first extended state observer is used to obtain a first coupled disturbance amount of active power with respect to reactive power.

[0050] Among them, the purpose of the extended state observer (ESO) is to estimate the extended state of the output based on the output of the system.

[0051] In a possible implementation manner, the first extended state observer is specifically configured to obtain a first coupled disturbance amount related to reactive power in the active power according to the active power, the reference active power and the estimated value of the active power.

[0052] For example, Figure 2As shown in FIG. 1 , this figure is a control schematic diagram of a first expanded observer provided in an embodiment of the present application. Figure 2 In the example, first, the difference between the active power P and the estimated value of the active power Pes is obtained; secondly, the difference is respectively passed through the fourth transfer function w 0 2 The first coupling disturbance Pd is obtained by the fifth transfer function 1 / s, and the difference is passed through the sixth transfer function 3w 0 2 The first parameter is obtained, and the difference is passed through the seventh transfer function 3w 0 The second parameter is obtained; again, the difference between the input Uin-P of ESO1 and the first coupling disturbance is added to the first parameter to obtain the fourth parameter; then, the difference between the fourth parameter and the fifth parameter is obtained by the eleventh transfer function 1 / s to obtain the sixth parameter, and the sixth parameter is obtained by the twelfth transfer function D / J to obtain the fifth parameter; finally, the sum of the sixth parameter and the second parameter is obtained by the twelfth transfer function 1 / s to obtain the estimated value Pes of the active power.

[0053] Wherein, Wo is the bandwidth of the extended state observer, and the input Uin-P of ESO1 is the difference between the reference active power Pref, the active power P and the first coupled disturbance Pd.

[0054] The second extended state observer is used to obtain a second coupled disturbance amount with respect to the active power in the reactive power.

[0055] In a possible implementation manner, the second extended state observer is specifically configured to obtain a second coupled disturbance amount related to active power in the reactive power according to the reactive power, the reference reactive power and the estimated value of the reactive power.

[0056] like Figure 3 As shown in FIG. 1 , this figure is a control schematic diagram of a second expanded observer provided in an embodiment of the present application. Figure 3 In the example, first, the reactive power Q and the estimated value of the active power Qes are subtracted to obtain the difference; secondly, the difference is respectively passed through the eighth transfer function w 0 2 The first coupling disturbance Qd is obtained by the ninth transfer function 1 / s. The difference is passed through the tenth transfer function 2w 0 The third parameter is obtained; then, the difference between the input Uin-Q of ESO2 and the second coupling disturbance is added to the third parameter to obtain the seventh parameter; finally, the seventh parameter is obtained by the thirteenth transfer function 1 / s and the fourteenth transfer function 1 / k to obtain the estimated value Qes of the reactive power.

[0057] The input Uin-Q of ESO2 is the difference between the reference active power Qref, the active power Q and the first coupling disturbance Qd.

[0058] The controller is used to decouple the active power and the reactive power according to the first coupling disturbance amount and the second coupling disturbance amount.

[0059] It should be understood that the embodiments of the present application do not specifically limit the type of controller. For example, the controller may be a digital signal processor (DSP) or a field programmable gate array (FPGA).

[0060] In a possible implementation, in a decoupling control loop of active power and reactive power, a corresponding first coupling disturbance interference amount is deducted for active power control; and a corresponding second coupling disturbance interference amount is deducted for reactive power control.

[0061] For example, Figure 4 As shown, this figure is a control schematic diagram of power decoupling provided in an embodiment of the present application.

[0062] exist Figure 4 In the example, the active power P is used as the feedback active power; the difference between the reference active power Pref, the feedback active power and the first coupling disturbance Pd is obtained through the first transfer function 1 / (Js+D) to obtain the small signal component Δω about the angular frequency; Δω is obtained through the second transfer function 1 / s to obtain the small signal component Δδ about the phase; Δδ is obtained through the first power small signal transfer function H Pδ The first active power component is obtained, Δδ is obtained through the third power small signal transfer function H Qδ The second reactive power component is obtained; the reactive power Q is used as the feedback reactive power, and the difference between the reference reactive power Qref, the feedback reactive power and the first coupling disturbance Qd is obtained through the third transfer function 1 / Ks to obtain the small signal component ΔE about the effective value of the electromotive force; ΔE is obtained through the second power small signal transfer function H PE The second component of active power is obtained, ΔE, through the fourth power small signal transfer function H QE A first reactive power component is obtained; wherein the active power includes the first active power component and the second active power component, and the reactive power includes the first reactive power component and the second reactive power component.

[0063] The embodiment of the present application obtains the first coupling disturbance amount about reactive power in active power through the first extended state observer ESO1, and deducts it in the decoupled active power loop; obtains the second coupling disturbance amount about active power in reactive power through the second extended state observer ESO2, and deducts it in the decoupled reactive power loop, thereby realizing the decoupling between active power and reactive power and improving the robustness of power decoupling.

[0064] In addition, the controller is also used to obtain active power and reactive power according to the output voltage of the power conversion circuit and the output current of the power conversion circuit.

[0065] In one possible implementation, Figure 5 (a) and Figure 5 As shown in (b), the controller performs Clarke transformation on the output voltage (ea, eb and ec) of the power conversion circuit to obtain a first output voltage eα and a second output voltage eβ, and performs Clarke transformation on the output current (Ia, Ib and Ic) of the power conversion circuit to obtain a first output current Iα and a second output current Iβ; the product of the first output voltage eα and the first output current Iα plus the product of the second output voltage eβ and the second output current Iβ obtains the active power P; the product of the second output voltage eβ and the first output current Iα plus the product of the first output voltage eα and the second output current Iβ obtains the reactive power Q.

[0066] The output voltage of the power conversion circuit may be the voltage across the filter capacitor, and the output current of the power conversion circuit may be the current on the filter inductor.

[0067] It should be noted that "3s / 2s" refers to the Clarke transform.

[0068] See also Figure 6 , the modified figure is a flow chart of a control method for a grid-connected inverter based on virtual synchronous generator technology provided in an embodiment of the present application.

[0069] The grid-connected converter based on the virtual synchronous generator technology includes: a power conversion circuit and a filter circuit; wherein the DC side of the power conversion circuit is used to connect to a DC source, the AC side of the power conversion circuit is connected to a first end of the filter circuit, and the second end of the filter circuit is used to connect to a power grid;

[0070] like Figure 6 As shown, the method includes:

[0071] S610: Obtain a first coupled disturbance amount of active power with respect to reactive power, and a second coupled disturbance amount of reactive power with respect to active power;

[0072] S620: Decouple the active power and the reactive power according to the first coupling disturbance amount and the second coupling disturbance amount.

[0073] Optionally, the method further comprises:

[0074] According to the output voltage and output current of the power conversion circuit, the active power and reactive power of the grid-connected converter are obtained; wherein the active power includes a first coupling disturbance amount related to the reactive power, and the reactive power includes a second coupling disturbance amount related to the active power;

[0075] Obtaining a first coupled disturbance amount of active power with respect to reactive power, and a second coupled disturbance amount of reactive power with respect to active power, specifically includes:

[0076] The active power is obtained according to the active power and the reference active power, and the active power includes a first coupling disturbance amount about the reactive power; the reactive power is obtained according to the reactive power and the reference reactive power, and the reactive power includes a second coupling disturbance amount about the active power.

[0077] Optionally, decoupling active power and reactive power according to the first coupling disturbance amount and the second coupling disturbance amount includes:

[0078] The active power is used as the feedback active power; the difference between the reference active power, the feedback active power and the first coupling disturbance is obtained through the first transfer function to obtain a small signal component Δω about the angular frequency; Δω is obtained through the second transfer function to obtain a small signal component Δδ about the phase; Δδ is obtained through the first power small signal transfer function H Pδ The first active power component is obtained, Δδ is obtained through the third power small signal transfer function H Qδ Obtaining a second reactive power component;

[0079] Reactive power is used as feedback reactive power, and the difference between the reference reactive power, the feedback reactive power and the first coupling disturbance is obtained through the third transfer function to obtain a small signal component ΔE about the effective value of the electromotive force; ΔE is obtained through the second power small signal transfer function H PE The second component of active power is obtained, ΔE, through the fourth power small signal transfer function H QE A first reactive power component is obtained; wherein the active power includes a first active power component and a second active power component, and the reactive power includes a first reactive power component and a second reactive power component.

[0080] Optionally, the active power is obtained according to the active power and the reference active power, and the active power includes a first coupling disturbance amount about the reactive power; the reactive power is obtained according to the reactive power and the reference reactive power, and the active power includes a second coupling disturbance amount about the active power, including:

[0081] According to the active power, the reference active power and the estimated value of the active power, the active power includes a first coupling disturbance amount about the reactive power; according to the reactive power, the reference reactive power and the estimated value of the reactive power, the reactive power includes a second coupling disturbance amount about the active power.

[0082] In the embodiment of the present application, a first coupled disturbance amount about reactive power in active power is obtained by a first extended state observer, and a second coupled disturbance amount about active power in reactive power is obtained by a second extended state observer; and active power and reactive power are decoupled according to the first coupled disturbance amount and the second coupled disturbance amount. The method is simple and can improve the robustness of power decoupling.

[0083] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The method embodiment described above is merely schematic, in which the units described as separate components may or may not be physically separated, and the components indicated as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0084] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A grid-connected converter based on virtual synchronous generator technology, characterized in that: include: A power conversion circuit, a filter circuit, a first extended state observer, a second extended state observer and a controller; The DC side of the power conversion circuit is used to connect to a DC source, the AC side of the power conversion circuit is connected to a first end of the filter circuit, and the second end of the filter circuit is used to connect to a power grid; The first extended state observer is used to obtain a first coupled disturbance amount of active power with respect to reactive power; The second extended state observer is used to obtain a second coupled disturbance amount with respect to the active power in the reactive power; The controller is used to decouple the active power and the reactive power according to the first coupling disturbance amount and the second coupling disturbance amount.

2. The grid-connected converter according to claim 1, characterized in that: The controller is also used to obtain the active power and reactive power of the grid-connected converter according to the output voltage and output current of the power conversion circuit.

3. The grid-connected converter according to claim 2, characterized in that: The controller is specifically used to use the active power as feedback active power; obtain a small signal component Δω about angular frequency by using a first transfer function to obtain a difference between the reference active power, the feedback active power and the first coupling disturbance; and obtain a small signal component Δδ about phase by using a second transfer function to obtain Δω; The Δδ is passed through the first power small signal transfer function H Pδ The first active power component is obtained, and the Δδ is converted into the first active power component by the third power small signal transfer function H Qδ The second reactive power component is obtained; the reactive power is used as the feedback reactive power, and the difference between the reference reactive power, the feedback reactive power and the first coupling disturbance is obtained through the third transfer function to obtain the small signal component ΔE about the effective value of the electromotive force; the ΔE is obtained through the second power small signal transfer function H PE The second component of the active power is obtained, and the ΔE is calculated by the fourth power small signal transfer function H QE A first reactive power component is obtained; wherein the active power includes the first active power component and the second active power component, and the reactive power includes the first reactive power component and the second reactive power component.

4. The grid-connected inverter according to claim 2 or 3, characterized in that: The first extended state observer is specifically used to obtain, based on the active power, the reference active power and the estimated value of the active power, the active power includes a first coupled disturbance amount regarding the reactive power; the second extended state observer is specifically used to obtain, based on the reactive power, the reference reactive power and the estimated value of the reactive power, the active power includes a second coupled disturbance amount regarding the active power.

5. The grid-connected inverter according to claim 4, characterized in that: The first extended state observer is further used for using the active power estimate as the feedback active power estimate, obtaining the first coupling disturbance amount by using the difference between the active power and the estimated value of the feedback active power through a fourth transfer function and a fifth transfer function, obtaining the first parameter by using a sixth transfer function, and obtaining the second parameter by using a seventh transfer function; obtaining the active power estimate according to the reference active power, the active power, the first coupling disturbance amount, the first parameter, and the second parameter; The second extended state observer is also used for the reactive power estimate as the feedback reactive power estimate, and the difference between the reactive power and the estimated value of the feedback reactive power is used to obtain the second coupling disturbance through the eighth transfer function and the ninth transfer function, and the third parameter is obtained through the tenth transfer function; the reactive power estimate is obtained according to the reference reactive power, the reactive power, the second coupling disturbance and the third parameter.

6. The grid-connected inverter according to claim 2, characterized in that: The controller is specifically used to perform Clarke transformation on the output voltage of the power conversion circuit to obtain a first output voltage eα and a second output voltage eβ, and to perform Clarke transformation on the output current of the power conversion circuit to obtain a first output current Iα and a second output current Iβ; the product of the first output voltage eα and the first output current Iα plus the product of the second output voltage eβ and the second output current Iβ obtains the active power; the product of the second output voltage eβ and the first output current Iα plus the product of the first output voltage eα and the second output current Iβ obtains the reactive power.

7. A control method for a grid-connected inverter based on virtual synchronous generator technology, characterized in that: The grid-connected converter comprises a power conversion circuit and a filter circuit; wherein the DC side of the power conversion circuit is used to connect to a DC source, the AC side of the power conversion circuit is connected to a first end of the filter circuit, and the second end of the filter circuit is used to connect to a power grid; The method comprises: Acquire a first coupled disturbance amount of active power with respect to reactive power, and a second coupled disturbance amount of reactive power with respect to active power; The active power and the reactive power are decoupled according to the first coupling disturbance amount and the second coupling disturbance amount.

8. The method according to claim 7, characterized in that The method further comprises: The active power and reactive power of the grid-connected converter are obtained according to the output voltage and output current of the power conversion circuit.

9. The method according to claim 8, characterized in that The decoupling of the active power and the reactive power according to the first coupling disturbance amount and the second coupling disturbance amount includes: The active power is used as the feedback active power; the difference between the reference active power, the feedback active power and the first coupling disturbance is obtained through a first transfer function to obtain a small signal component Δω about the angular frequency; the Δω is used to obtain a small signal component Δδ about the phase through a second transfer function; the Δδ is obtained through a first power small signal transfer function H Pδ The first active power component is obtained, and the Δδ is converted into the first active power component by the third power small signal transfer function H Qδ Obtaining a second reactive power component; The reactive power is used as the feedback reactive power, and the difference between the reference reactive power, the feedback reactive power and the first coupling disturbance is obtained through the third transfer function to obtain a small signal component ΔE about the effective value of the electromotive force; the ΔE is obtained through the second power small signal transfer function H PE The second component of the active power is obtained, and the ΔE is calculated by the fourth power small signal transfer function H QE A first reactive power component is obtained; wherein the active power includes the first active power component and the second active power component, and the reactive power includes the first reactive power component and the second reactive power component.

10. The method according to claim 8, characterized in that The step of obtaining a first coupled disturbance amount in active power with respect to reactive power and a second coupled disturbance amount in reactive power with respect to active power comprises: According to the active power, the reference active power and the estimated value of the active power, a first coupling disturbance amount about the reactive power included in the active power is obtained; according to the reactive power, the reference reactive power and the estimated value of the reactive power, a second coupling disturbance amount about the active power included in the reactive power is obtained.

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