A control method to improve the active power response speed of virtual synchronous machines in weak power grids

Abstract

This invention discloses a control method for improving the active power response speed of a virtual synchronous machine in a weak power grid. The method first uses a virtual negative impedance control loop to reduce the equivalent output impedance of the virtual synchronous machine and its dynamic response time of active power output. Then, it uses an active power feedforward control loop to enhance the transient damping of the virtual synchronous machine and its ability to suppress dynamic oscillations of active power output. This method can solve the problem of slow active power output dynamic response speed when a traditional virtual synchronous machine is connected to a weak power grid. It also has the advantages of accelerating the active power output response speed, avoiding power overshoot in the active power output, and reducing the output frequency overshoot amplitude. It is applicable to the field of virtual synchronous machine connection to weak power grid control in power electronics technology.

Description

Technical Field

[0001] This invention relates to the field of virtual synchronous generator control, and particularly to a control method for improving the active power response speed of a virtual synchronous generator under weak power grid conditions, applicable to the field of virtual synchronous generator integration into weak power grid control in power electronics technology. Background Technology

[0002] Traditional Virtual Synchronous Generators (VSGs) are well-suited for operation in weak grid environments, but their active power output inevitably slows down under step disturbances in the active power reference command. However, the current national standard GB / T38983.1-2020, "Virtual Synchronous Generators Part 1: General Rules," clearly specifies the active power frequency regulation start-up time, active power frequency regulation response time, and active power frequency regulation adjustment time for VSGs during grid-connected operation. This requires that the active power output of VSGs during grid-connected operation (including connection to weak grids) exhibit a fast dynamic response speed under disturbances such as active power reference commands and grid frequency.

[0003] To address this, various studies have been conducted, such as the article titled "Virtual Inertial Optimization Control Strategy Based on Frequency Stability Improvement," published in *Power System Protection and Control*, Vol. 50, No. 12, 2022, pp. 126-133. This article proposes adding a first-order differential feedforward compensation stage for active and frequency to the forward path of the active-frequency control loop of a traditional virtual synchronous generator (TVSG). This increases the transient damping of the TVSG grid-connected active power closed-loop system, suppressing dynamic oscillations and power overshoot in the TVSG grid-connected active power. However, it does not consider the adverse effects of high-frequency harmonics generated by differential operations on the TVSG grid-connected system, nor does it consider the optimization of the active power response speed when the TVSG is connected to a weak grid.

[0004] The article, titled "d-axis current differential feedforward control for optimizing the dynamic characteristics of energy storage VSG," published in *Power System Technology*, Vol. 46, No. 07, 2022, pp. 2510-2523, proposes a transient damping strategy that uses a first-order low-pass filter to filter the first-order differential feedforward term of the grid-connected active current of the virtual synchronous machine. This control strategy can, to some extent, eliminate high-frequency harmonics caused by differential operations and improve the loudness and speed of the grid-connected active current of the virtual synchronous machine. However, it upgrades the order of the grid-connected active current closed-loop system of the virtual synchronous machine to the third order, resulting in complex system parameter design and output frequency overshoot.

[0005] The article, titled "VSG Control Strategy Introducing Transient Electromagnetic Power Compensation," published in *Power System Technology*, Vol. 46, No. 04, 2022, pp. 1421-1429, describes a method to improve the transient equivalent damping of a TVSG grid-connected system by using a difference operation with a first-order electromagnetic power lag element, thus avoiding the differential operation element. However, it suffers from several drawbacks: the order of the active power closed-loop system connected to the TVSG remains third; the output frequency of the TVSG risks overshoot when responding to a step in the active power reference command; and the issue of not considering the improvement in active power response speed when the TVSG is connected to a weak grid.

[0006] The article, titled “A reference-feedforward-based damping method for virtual synchronous generator control”, by YUY, CHAUDHARY SK, TINAJERO G DA, et al., IEEE Transactions on Power Electronics, 2022, 37(7), 7566–7571 (“Virtual Synchronous Generator Damping Control Strategy Based on Active Reference Command Feedforward”, IEEE Journal of Power Electronics, 2022, Vol. 37, No. 7, pp. 7566–7571), proposes a transient damping strategy based on active reference command feedforward compensation. This strategy reduces the active power closed-loop system of the virtual synchronous generator to a typical second-order control system, which has the advantage of intuitive system parameter design. However, it does not consider the response performance of the virtual synchronous generator output frequency under active reference command disturbances, nor does it address the optimization of the active power response speed when the virtual synchronous generator is connected to a weak power grid.

[0007] As can be seen from the above, although the existing technology has solved the power overshoot problem of the grid-connected active power of the traditional virtual synchronous machine under the active power reference command disturbance condition, it still has disadvantages such as harmonic amplification caused by differential operation, risk of overshoot in output frequency, difficulty in designing control parameters due to the increase in system order, and failure to consider the optimization of active power response speed under weak grid conditions. Summary of the Invention

[0008] In order to overcome the limitations of various technical solutions given in the background art, this invention addresses the problem that the output active power of a traditional virtual synchronous machine slows down under a step disturbance of the active power reference command when it is connected to a weak power grid. It provides a control method to improve the active power response speed of the virtual synchronous machine under a weak power grid. This control method can not only improve the response speed of the output active power of the virtual synchronous machine, but also avoid power overshoot and reduce the output frequency overshoot amplitude.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A control method for improving the active power response speed of a virtual synchronous machine in a weak power grid includes the following steps:

[0011] Step 1, Primary voltage regulation control section, setting the q-axis voltage reference E of the virtual synchronizer. qref =0, setting the reactive power reference command Q of the virtual synchronous machine to 0. ref Subtract the reactive power Q output of the virtual synchronizer e Then multiply by the primary voltage regulation coefficient k Q The voltage deviation ΔE is obtained, and the grid rated voltage E0 is added to the voltage deviation ΔE to obtain the d-axis voltage reference E of the virtual synchronous machine. dref ;

[0012] Step 2, Virtual Negative Impedance Control Section: The d-axis and q-axis voltage references E obtained in Step 1 for the virtual synchronizer. dref E qref Add and subtract the q-axis and d-axis output currents i of the virtual synchronizer respectively. q i d Multiply by the output angular frequency ω of the virtual synchronizer and the virtual impedance L v After the proportional circuit, the d-axis and q-axis voltage commands E of the virtual synchronizer are obtained respectively. * d E * q ;

[0013] Step 3, the active power feedforward control section, transmits the active power reference command P from the virtual synchronous machine. ref Subtract the active power P output of the virtual synchronous machine e The power difference ΔP between the two is obtained, and the power difference ΔP is processed through a circuit containing the virtual inertia coefficient J, the grid rated angular frequency ω0, and the primary frequency regulation coefficient k. P , and feedforward coefficient k c The active power feedforward control quantity δ is obtained after the first-order low-pass filter stage. c ;

[0014] Step 4, the rotor motion equation part, the power difference ΔP obtained in step 3 is processed by including the virtual inertia coefficient J, the grid rated angular frequency ω0, and the primary frequency regulation coefficient k. P After the first-order low-pass filter stage, the angular frequency deviation Δω is obtained. The angular frequency deviation Δω is added to the grid rated angular frequency ω0 to obtain the output angular frequency ω of the virtual synchronous machine.

[0015] Step 5: Subtract the grid angular frequency ω from the output angular frequency ω of the virtual synchronizer obtained in Step 4. g The work angle δ is then obtained through integration. g , the work angle δ g Add the active power feedforward control quantity δ obtained in step 3 c Obtain the power factor angle δ of the virtual synchronizer;

[0016] Step 6: Multiply the power factor angle δ of the virtual synchronizer obtained in Step 5 by the synchronization voltage coefficient K to obtain the output active power P of the virtual synchronizer. e ;

[0017] Step 7: Integrate the output angular frequency ω of the virtual synchronizer obtained in Step 4 and add it to the active power feedforward control quantity δ obtained in Step 3. c The output phase θ of the virtual synchronizer is obtained, and the output phase θ is used as the phase for the d-q coordinate transformation. The voltage commands E of the d-axis and q-axis of the virtual synchronizer obtained in step 2 are then applied. * d E * q Performing a dq coordinate transformation yields the three-phase voltage modulation signal E in the abc coordinate system. * abc Then, the three-phase voltage modulation signal E * abc The drive signals for the inverter bridge switching transistors of the converter are generated through the SVPWM modulation stage.

[0018] Preferably, the d-axis voltage of the virtual synchronizer in step 1 is referenced to E. dref The calculation formula used is:

[0019] E dref =(Q ref -Q e )k Q +E0.

[0020] Preferably, the d-axis and q-axis voltage commands E of the virtual synchronizer in step 2 are... * d E * q The calculation formula used is:

[0021]

[0022] Preferably, the formula used to calculate the power difference ΔP in step 3 is:

[0023] ΔP=P ref -P e ,

[0024] Active feedforward control quantity δ c The calculation formula used is:

[0025]

[0026] In the formula, s is the Laplace operator.

[0027] Preferably, the formula used to calculate the angular frequency deviation Δω in step 4 is:

[0028]

[0029] The formula for calculating the output angular frequency ω of the virtual synchronizer is:

[0030] ω = Δω + ω0,

[0031] In the formula, s is the Laplace operator.

[0032] Preferably, the formula used to calculate the power factor angle δ of the virtual synchronizer in step 5 is:

[0033]

[0034] In the formula, s is the Laplace operator.

[0035] Preferably, the output of the virtual synchronizer in step 6 is active power P. e The calculation formula used is:

[0036]

[0037] In the formula, U g E is the voltage amplitude of the grid, E is the voltage amplitude of the virtual synchronous machine output, and X is the equivalent inductive reactance of the line.

[0038] Preferably, the formula used to calculate the output phase θ of the virtual synchronizer in step 7 is:

[0039]

[0040] In the formula, s is the Laplace operator.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention provides a control method for improving the active power response speed of a virtual synchronous machine in a weak power grid. This method first utilizes a virtual negative impedance control loop to reduce the equivalent output impedance of the virtual synchronous machine and its dynamic response time of active power output. Then, it utilizes an active power feedforward control loop to enhance the transient damping of the virtual synchronous machine and its ability to suppress dynamic oscillations of active power output. This method solves the problem of slowed active power response speed when a traditional virtual synchronous machine is connected to a weak power grid. It also has the advantages of accelerating the active power response speed, avoiding power overshoot, and reducing the amplitude of output frequency overshoot. It is applicable to the field of virtual synchronous machine integration into weak power grids in power electronics technology. Attached Figure Description

[0043] Figure 1 This is a diagram of the overall control structure of the virtual synchronous machine integrated into a weak power grid according to an embodiment of the present invention.

[0044] Figure 2 This is a schematic diagram of the primary voltage regulation of a virtual synchronous machine that includes virtual negative impedance.

[0045] Figure 3 This is a schematic diagram for calculating the active power feedforward control quantity.

[0046] Figure 4 This is a schematic diagram of coordinate transformation and modulation according to an embodiment of the present invention.

[0047] Figure 5 This is a comparison of the simulation waveforms of the virtual synchronizer before and after adopting this invention.

[0048] Figure 6 This is a comparison of experimental waveforms before and after the virtual synchronizer was implemented using this invention. Detailed Implementation

[0049] The following detailed embodiments will be further described in conjunction with the above-mentioned figures, as follows:

[0050] Please see Figure 1 The present invention proposes a control method for improving the active power response speed of a virtual synchronous machine under weak power grid conditions, comprising the following steps:

[0051] Step 1, primary voltage regulation control section, such as Figure 2 As shown, the q-axis voltage reference E of the virtual synchronizer is set. qref =0, setting the reactive power reference command Q of the virtual synchronous machine to 0. ref Subtract the reactive power Q output of the virtual synchronizer e Then multiply by the primary voltage regulation coefficient k Q The voltage deviation ΔE is obtained, and the grid rated voltage E0 is added to the voltage deviation ΔE to obtain the d-axis voltage reference E of the virtual synchronous machine. dref .

[0052] Among them, the d-axis voltage reference E of the virtual synchronous machine dref The calculation formula used is:

[0053] E dref =(Q ref -Q e )k Q +E0.

[0054] Step 2, Virtual Negative Impedance Control Section: The d-axis and q-axis voltage references E obtained in Step 1 for the virtual synchronizer. dref E qref Add and subtract the q-axis and d-axis output currents i of the virtual synchronizer respectively. q i d Multiply by the output angular frequency ω of the virtual synchronizer and the virtual impedance L v After the proportional circuit, the d-axis and q-axis voltage commands E of the virtual synchronizer are obtained respectively. * d E * q .

[0055] Among them, the d-axis and q-axis voltage commands E of the virtual synchronizer * d E * q The calculation formula used is:

[0056]

[0057] Step 3, active power feedforward control section, such as Figure 3 As shown, the active power reference command P of the virtual synchronizer is... ref Subtract the active power P output of the virtual synchronous machine e The power difference ΔP between the two is obtained, and the power difference ΔP is processed through a circuit containing the virtual inertia coefficient J, the grid rated angular frequency ω0, and the primary frequency regulation coefficient k. P , and feedforward coefficient k c The active power feedforward control quantity δ is obtained after the first-order low-pass filter stage. c .

[0058] The formula used to calculate the power difference ΔP is as follows:

[0059] ΔP=P ref -P e ,

[0060] Active feedforward control quantity δ c The calculation formula used is:

[0061]

[0062] In the formula, s is the Laplace operator.

[0063] Step 4, the rotor motion equation part, the power difference ΔP obtained in step 3 is processed by including the virtual inertia coefficient J, the grid rated angular frequency ω0, and the primary frequency regulation coefficient k. P After the first-order low-pass filter stage, the angular frequency deviation Δω is obtained. The angular frequency deviation Δω is added to the grid rated angular frequency ω0 to obtain the output angular frequency ω of the virtual synchronous machine.

[0064] The formula used to calculate the angular frequency deviation Δω is as follows:

[0065]

[0066] The formula for calculating the output angular frequency ω of the virtual synchronizer is:

[0067] ω = Δω + ω0,

[0068] In the formula, s is the Laplace operator.

[0069] Step 5: Subtract the grid angular frequency ω from the output angular frequency ω of the virtual synchronizer obtained in Step 4. g The work angle δ is then obtained through integration. g , the work angle δ g Add the active power feedforward control quantity δ obtained in step 3 c The power factor angle δ of the virtual synchronizer is obtained.

[0070] The formula for calculating the power factor angle δ of the virtual synchronizer is as follows:

[0071]

[0072] In the formula, s is the Laplace operator.

[0073] Step 6: Multiply the power factor angle δ of the virtual synchronizer obtained in Step 5 by the synchronization voltage coefficient K to obtain the output active power P of the virtual synchronizer. e .

[0074] Among them, the output of the virtual synchronous machine has active power P e The calculation formula used is:

[0075]

[0076] In the formula, U g E is the voltage amplitude of the grid, E is the voltage amplitude of the virtual synchronous machine output, and X is the equivalent inductive reactance of the line.

[0077] Step 7, as follows Figure 4 As shown, the output angular frequency ω of the virtual synchronizer obtained in step 4 is integrated and then added to the active power feedforward control quantity δ obtained in step 3. cThe output phase θ of the virtual synchronizer is obtained, and the output phase θ is used as the phase for the d-q coordinate transformation. The voltage commands E of the d-axis and q-axis of the virtual synchronizer obtained in step 2 are then applied. * d E * q Performing a dq coordinate transformation yields the three-phase voltage modulation signal E in the abc coordinate system. * abc Then, the three-phase voltage modulation signal E * abc The drive signals for the inverter bridge switching transistors of the converter are generated through the SVPWM modulation stage.

[0078] The formula for calculating the output phase θ of the virtual synchronizer is as follows:

[0079]

[0080] In the formula, s is the Laplace operator.

[0081] Example

[0082] To verify the control effect of the proposed method for improving the active power response speed of a virtual synchronous machine (APFC-VSG) in weak power grids, the APFC-VSG control method was compared with the existing traditional / typical virtual synchronous machine (TVSG) control method (described in the background section as "VSG control strategy with transient electromagnetic power compensation," published in *Power System Technology*, Vol. 46, No. 04, 2022, pp. 1421-1429) through simulation and experiments. The main comparison focused on the performance in responding to the active power reference command P. ref Output active power P under step disturbance conditions e Its dynamic response performance at the output frequency. Specifically:

[0083] First, the relevant parameters are set. In this embodiment, the relevant parameter settings in the APFC-VSG control method of the present invention are as follows:

[0084] The virtual synchronous machine has a rated capacity of 100kVA and an active power reference command P. ref The power supply is 20kW, the grid's rated angular frequency ω0 is 314.16 rad / s, and the virtual inertia coefficient J is 6 kg·m. 2 The primary frequency modulation coefficient k P It is 15915.5 J / rad, and the primary voltage regulation coefficient k Q 1.4×10 -4 Grid voltage amplitude U gThe voltage is 311V, the output voltage amplitude E of the virtual synchronizer is 311V, and the equivalent inductive reactance X of the line is 0.864Ω. Therefore, the corresponding short-circuit capacity ratio SCR = 1.67 (according to the definition in IEEE Standard 1204-1997, SCR < 2 indicates an extremely weak power grid). This is an extremely weak power grid scenario, and the synchronization voltage coefficient K = 1.5U. g The E / X ratio is 167918.4. In this embodiment, a virtual impedance L is set. V The value of L is a negative real number. V The value is set to -1.5mH, meaning that the equivalent inductive reactance X of the line corresponding to the APFC-VSG control method proposed in this invention is reduced from 0.864Ω to 0.393Ω, and the corresponding synchronization voltage coefficient K is increased from 167918.4 to 369164.1. Simultaneously, combined with... Figure 1 And through a complex formula derivation process, the feedforward coefficient k c The range of values ​​should be Here, k c Set it to 0.12.

[0085] Based on the above parameter settings, simulation and experimental comparison tests were conducted, as follows:

[0086] The simulation and experimental test conditions were set as follows: at the initial moment, the virtual synchronous machine stably outputs 20kW of grid-connected active power; at 3s, the active power reference command P... ref The power output jumped from 20kW to 60kW.

[0087] Based on the above working conditions, the following results were obtained: Figure 5 and Figure 6 The simulation and experimental test comparison chart shown below. Figure 5 , Figure 6 In this paper, APFC-VSG represents the control method proposed in this invention for improving the active power response speed of a virtual synchronous machine under weak power grid conditions, and TVSG represents an existing conventional virtual synchronous machine control method. That is, the curve pointed to by TVSG is the test waveform before the application of this invention, specifically the dynamic response test waveform of the existing conventional virtual synchronous machine control method. The curve pointed to by APFC-VSG is the test waveform after the application of this invention, specifically the dynamic response test waveform of the control method proposed in this invention for improving the active power response speed of a virtual synchronous machine under weak power grid conditions.

[0088] according to Figure 5 It can be seen that the APFC-VSG proposed in this invention, compared with the existing TVSG, has an active power output in the active power reference command P. refIn the process of stepping from 20kW to 60kW, it has smaller power overshoot, faster response speed and smaller output frequency overshoot amplitude. Specifically, on the one hand, the output active power regulation time corresponding to the APFC-VSG proposed in this invention is 0.3s, which is less than the 1.2s corresponding to the existing TVSG; on the other hand, the output frequency overshoot amplitude of the virtual synchronous machine corresponding to the APFC-VSG proposed in this invention is 0.14Hz, which is lower than the 0.27Hz corresponding to the existing TVSG.

[0089] And from Figure 6 It can be concluded that the APFC-VSG proposed in this invention, compared with the existing TVSG, has a higher output active power in the active power reference command P. ref Under step disturbances, it exhibits smaller power overshoot, faster response speed, and smaller output frequency overshoot amplitude. Specifically, on the one hand, the output active power regulation time corresponding to the APFC-VSG proposed in this invention is 0.25s, which is less than the 1s corresponding to the existing TVSG; on the other hand, the output frequency overshoot amplitude of the virtual synchronous machine corresponding to the APFC-VSG proposed in this invention is 0.12Hz, which is lower than the 0.24Hz corresponding to the existing TVSG.

[0090] Will Figure 6 and Figure 5 A comparison of the results clearly shows that this implementation method... Figure 6 The experimental test results can be compared with Figure 5 The simulation test results in both tests show a one-to-one correspondence, and both fully demonstrate that the APFC-VSG proposed in this invention is superior to the existing TVSG in terms of active power reference instruction P. ref Under step disturbances, it has the advantages of faster output active power response, smaller output active power overshoot and smaller output frequency overshoot.

[0091] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A control method for improving the active response speed of a virtual synchronous machine under a weak power grid, characterized in that, The method comprises the following steps: Step 1, primary voltage regulation control part, set the q-axis voltage reference E of the virtual synchronous machine qref = 0, the reactive power reference instruction Q of the virtual synchronous machine ref minus the output reactive power Q of the virtual synchronous machine e post-multiply by the primary voltage regulation coefficient k Q get the voltage deviation ΔE, add the voltage deviation ΔE to the grid rated voltage E0 to get the d-axis voltage reference E of the virtual synchronous machine dref ; Step 2, virtual negative impedance control part, the d-axis and q-axis voltage reference E of the virtual synchronous machine obtained in step 1 dref 、 qref The q-axis and d-axis output currents i of the virtual synchronous machine are added and subtracted respectively q 、 d After being multiplied by a proportional link containing the output angular frequency ω of the virtual synchronous machine and the virtual impedance L, the d-axis and q-axis voltage instructions E of the virtual synchronous machine are obtained respectively v * d 、 * q ;​ Step 3, active power feedforward control part, the active reference instruction P of the virtual synchronous machine ref Subtract the output active power P of the virtual synchronous machine e Get the power difference ΔP, and pass the power difference ΔP through a first-order low-pass filter link containing the virtual inertia coefficient J, the rated angular frequency ω0 of the power grid, the primary frequency modulation coefficient k P , and the feedforward coefficient k c to get the active power feedforward control amount δ c ; Step 4, rotor motion equation part, the power difference ΔP obtained in step 3 is passed through a first-order low-pass filter link containing a virtual inertia coefficient J, a power grid rated angular frequency ω0, and a primary frequency modulation coefficient k P to obtain an angular frequency deviation Δω, and the angular frequency deviation Δω is added to the power grid rated angular frequency ω0 to obtain an output angular frequency ω of the virtual synchronous machine; Step 5, subtract the grid angular frequency ω from the output angular frequency ω of the virtual synchronous machine obtained in step 4 g After the integral operation, the power angle δ is obtained g , the power angle δ is obtained g , the active power feedforward control amount δ obtained in step 3 is added c to obtain the power factor angle δ of the virtual synchronous machine; Step 6, multiply the power factor angle δ of the virtual synchronous machine obtained in step 5 by the synchronous voltage coefficient K to obtain the output active power P of the virtual synchronous machine e ; Step 7, the output angular frequency ω of the virtual synchronous machine obtained in step 4 is integrated and the active feedforward control amount δ obtained in step 3 is added c The output phase θ of the virtual synchronous machine is obtained, and the output phase θ is used as the phase for dq coordinate transformation, and the d-axis and q-axis voltage commands E of the virtual synchronous machine obtained in step 2 are subjected to dq coordinate transformation * d , E * q The dq coordinate transformation is performed to obtain three-phase voltage modulation signals E in the abc coordinate system * abc The three-phase voltage modulation signals E are subjected to SVPWM modulation to generate drive signals for the inverter bridge switches * abc ​ 2. The control method for improving the active response speed of a virtual synchronous machine under a weak power grid according to claim 1, characterized in that, The d-axis voltage reference E of the virtual synchronous machine in step 1 dref The used calculation formula is: E dref = (Q ref - Q e )k Q + E0.

3. The control method for improving the active response speed of a virtual synchronous machine under a weak power grid according to claim 1, characterized in that, The d-axis and q-axis voltage commands E of the virtual synchronous machine in step 2 * d , E * q The calculation formula used is:

4. The control method for improving the active response speed of a virtual synchronous machine under a weak power grid according to claim 1, characterized in that, The calculation formula of the power difference ΔP in step 3 is: ΔP = P ref - P e , Active feedforward control quantity δ c The calculation formula used is: In the formula, s is a Laplace operator.

5. The control method for improving the active response speed of a virtual synchronous machine under a weak power grid according to claim 1, characterized in that, The calculation formula of the angular frequency deviation Δω in step 4 is: The calculation formula of the output angular frequency ω of the virtual synchronous machine is: ω = Δω + ω0, In the formula, s is a Laplace operator.

6. The control method for improving the active response speed of a virtual synchronous machine under a weak power grid according to claim 1, characterized in that, The calculation formula of the power factor angle δ of the virtual synchronous machine in step 5 is: In the formula, s is a Laplace operator.

7. The control method for improving the active response speed of a virtual synchronous machine under a weak power grid according to claim 1, characterized in that, The output active power P of the virtual synchronous machine in step 6 e The calculation formula used is: In the formula, U g is the grid voltage amplitude, E is the virtual synchronous machine output voltage amplitude, and X is the line equivalent inductance.

8. The control method for improving the active response speed of a virtual synchronous machine under a weak power grid according to claim 1, characterized in that, The calculation formula of the output phase θ of the virtual synchronous machine in step 7 is: In the formula, s is a Laplace operator.

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