A grid-connected inverter adaptive virtual impedance stabilization control method and system

Abstract

The application provides a grid-connected inverter adaptive virtual impedance stabilizing control method and system, obtains a grid-connected point voltage amplitude, an inverter side current amplitude and a power angle, calculates a grid impedance amplitude according to the grid-connected point voltage amplitude, the inverter side current amplitude and the power angle, records a calculated value as a grid impedance initial amplitude and saves the grid impedance initial amplitude when the calculated grid impedance amplitude reaches stability for the first time, obtains a difference value of the impedance amplitude by subtracting the grid impedance initial amplitude from the calculated grid impedance amplitude, judges whether the impedance amplitude difference satisfies a limited condition, outputs the impedance amplitude difference if the condition is satisfied, and otherwise outputs a set value; and sets control parameters of a virtual impedance link in front of a voltage and current double closed loop control according to the output, so that the application adjusts the virtual impedance in real time, reduces overshoot in a transient process of SCR switching, and suppresses power oscillation of the system.

Description

Technical Field

[0001] This invention belongs to the field of new energy grid-connected power generation technology, specifically relating to an adaptive virtual impedance stabilization control method and system for grid-connected inverters. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the widespread application of new energy power generation, its randomness and volatility have brought challenges to the stable operation of the power grid. Virtual Synchronous Generator (VSG) technology provides a new approach to solving this problem by simulating the operating characteristics of synchronous generators. It can effectively improve the grid's ability to accept new energy sources, thereby ensuring the stable operation of the system and facilitating the large-scale grid connection of new energy sources. Therefore, VSG technology has received more attention.

[0004] When an inverter using VSG control is connected to the grid, line switching and other processes may occur, which will cause changes in grid strength (SCR, Short Circuit Ratio). This will cause large fluctuations in the inverter's output power and current during the switching transient process, resulting in system oscillation and endangering the safe and stable operation of the system.

[0005] Currently, most research focuses on the stability of inverters under a wide range of SCRs. For VSG-controlled new energy systems, the focus is particularly on their ability to operate stably under weak grid conditions but their susceptibility to instability under strong grid conditions. However, there is relatively little research on the system stability during the transient process of SCR switching.

[0006] Therefore, in the context of changes in SCR, VSG should have strong anti-interference capabilities to ensure that the system has sufficient robustness to suppress system oscillations during transient processes of changes in grid strength and improve system stability. Summary of the Invention

[0007] To address the aforementioned problems, this invention proposes an adaptive virtual impedance stabilization control method and system for grid-connected inverters. Based on online calculation of the grid impedance amplitude, the virtual impedance value of the control loop is adaptively adjusted to suppress power and current oscillations during transient processes when the SCR changes. This simultaneously accelerates the response speed, shortens the transient time, improves equipment safety performance, and enables stable operation of the system under a wide range of SCR conditions.

[0008] According to some embodiments, the present invention adopts the following technical solution:

[0009] An adaptive virtual impedance stabilization control method for grid-connected inverters includes the following steps:

[0010] Obtain the voltage amplitude at the grid connection point, the current amplitude on the inverter side, and the power angle, and calculate the grid impedance amplitude based on them;

[0011] When the calculated grid impedance amplitude reaches stability for the first time, the calculated value is recorded as the initial amplitude of the grid impedance and saved. Once the initial amplitude of the grid impedance is calculated, the above stability determination process will no longer be performed. Before the initial amplitude of the grid impedance is calculated, the output remains at zero.

[0012] The difference in impedance amplitude is obtained by subtracting the initial amplitude of the grid impedance from the calculated amplitude of the grid impedance.

[0013] Determine whether the impedance amplitude difference meets the limiting conditions. If the conditions are met, output the impedance amplitude difference; otherwise, output the set value.

[0014] Based on the output, set the control parameters for the virtual impedance stage of the voltage and current dual closed-loop control.

[0015] As an alternative implementation, the process of obtaining the grid connection point voltage amplitude, inverter side current amplitude, and power angle includes obtaining the angular frequency difference between the grid connection point voltage, inverter side current, and active power control loop output, and obtaining the dq axis components of the grid connection point voltage and inverter side current through dq transformation.

[0016] The active power, reactive power, voltage amplitude, and current amplitude of the grid-connected inverter are calculated based on the dq-axis components of the grid-connected voltage and inverter-side current. The power angle is obtained by integrating the angular frequency difference.

[0017] As a further step, the active power P output by the grid-connected inverter is calculated. e and reactive power Q e The process includes:

[0018]

[0019] Calculate the voltage amplitude U of the power grid m and inverter-side current amplitude i m for:

[0020]

[0021] Among them, V Cd and V Cq Represent the d-axis and q-axis components of the grid connection point voltage, respectively. sd and i sq These represent the d-axis and q-axis components of the inverter-side current, respectively.

[0022] The calculation method for the work angle δ is as follows:

[0023] δ=∫(ω m -ω n )

[0024] ω m -ω n This is the angular frequency difference of the active control loop output.

[0025] As an alternative implementation method, the process of calculating the grid impedance magnitude includes:

[0026] After simplified calculation, the line impedance amplitude Z is:

[0027]

[0028] Where δ is the power angle, U m For the voltage amplitude at the grid connection point and i m This represents the inverter-side current amplitude.

[0029] As an alternative implementation, the process of recording and storing the calculated value as the initial amplitude of the power grid impedance includes determining whether the line impedance amplitude Z can stabilize at a predetermined value within a set time period of ±ΔZ. * Within the range, if the above conditions are met, the corresponding Z is recorded as the line impedance amplitude Z0 under the initial operating conditions. After recording the line impedance amplitude Z0, the process of determining whether Z is stable is terminated.

[0030] As an alternative implementation, determining whether the impedance amplitude difference meets a defined condition, and outputting the impedance amplitude difference if the condition is met, or setting the output to a set value otherwise, includes: setting an impedance threshold Z. th The absolute value of the difference in the magnitude of the grid impedance ΔZ, |ΔZ| and Z, are obtained through calculation. th The comparison is performed, and once the condition |ΔZ|>Z is met, the comparison is performed. th Then the output ΔZ will be started, and the process of |ΔZ|>Z will not be repeated thereafter. th Compare, otherwise set the output to zero.

[0031] As an alternative implementation, the process of setting the control parameters of the virtual impedance link of the voltage and current dual closed-loop control stage according to the output includes: multiplying the output by the corresponding feedback coefficient, and then adding it to the initial virtual resistance and virtual reactance of the control loop, and using the result as the control parameters of the virtual impedance link of the voltage and current dual closed-loop control stage.

[0032] As an alternative implementation, when the system's line impedance reaches a stable state again, the system operates the above steps under the new steady-state conditions.

[0033] An adaptive virtual impedance stabilization control system for a grid-connected inverter, comprising:

[0034] The grid impedance amplitude calculation module is configured to obtain the grid connection point voltage amplitude, inverter side current amplitude, and power angle, and calculate the grid impedance amplitude based on these values.

[0035] The stability judgment module is configured to record the calculated value as the initial amplitude of the grid impedance and save it when the calculated grid impedance amplitude first reaches stability. Once the initial amplitude of the grid impedance is calculated, the above stability judgment process will no longer be performed, and the output will remain at zero before the initial amplitude of the grid impedance is calculated.

[0036] The difference calculation module is configured to calculate the difference in impedance amplitude by subtracting the initial amplitude of the grid impedance from the calculated amplitude of the grid impedance.

[0037] The adaptive virtual impedance module is configured to determine whether the impedance amplitude difference meets the limiting conditions. If the conditions are met, the difference in impedance amplitude is output; otherwise, the output is set to the set value. Based on the output, the control parameters of the virtual impedance stage before the voltage and current dual closed-loop control are set.

[0038] An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the steps in the method described above.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] This invention innovatively proposes an adaptive virtual impedance stabilization control method for grid-connected inverters under varying grid strength. When SCR fluctuations occur, the virtual impedance is adjusted in real time based on the online calculated grid impedance amplitude, reducing overshoot during SCR switching transients, suppressing system power oscillations, and ensuring inverter stability. The main circuit data required for grid impedance amplitude calculation is also the data sampled by VSG control, eliminating the need for additional sampling equipment and effectively reducing costs. Furthermore, the proposed control method accelerates system response, enabling the system to quickly reach a stable state.

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0042] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0043] Figure 1This is the main circuit diagram of the grid-connected system in this embodiment;

[0044] Figure 2 This is a block diagram of the virtual synchronous generator control in this embodiment;

[0045] Figure 3 This is a block diagram of the adaptive virtual impedance control introduced in this embodiment;

[0046] Figure 4 This is the equivalent circuit diagram of the inverter stage of the grid-connected system in this embodiment;

[0047] Figure 5 The flowchart for the adaptive virtual impedance control introduced in this embodiment;

[0048] Figure 6 The waveforms of active power, voltage, and current output of the corresponding inverter are shown in the traditional virtual synchronous generator control method under the condition of changes in grid strength.

[0049] Figure 7 The improved virtual synchronous generator control in this embodiment is used to control the corresponding inverter output active power, voltage, and current waveforms under the condition of changes in grid strength. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0051] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0052] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0053] Where there is no conflict, the embodiments and features described in this application may be combined with each other.

[0054] Example 1

[0055] by Figure 1 Taking a three-phase grid-connected inverter as an example, from left to right, it includes the DC power supply V... dc A three-phase full-bridge inverter circuit composed of six IGBT switching transistors, and a filter inductor L. sand resistance R s Filter capacitor C f Grid-side inductance L g and resistance R g and AC power grid V gabc The output angular velocity of the VSG is denoted as ω. m The rated angular velocity of the power grid is denoted as ω. n Generally, the grid resistance is much smaller than the grid reactance, so the grid resistance can be ignored in the analysis.

[0056] Figure 2 This is a block diagram of a virtual synchronous generator control system. It mainly includes main circuit sampling, power loop, voltage and current dual closed loops, and an SVPWM module.

[0057] The power loop consists of two parts: an active power loop and a reactive power loop. The voltage amplitude reference signal E output by the reactive power loop is... dref and inverter-side output current i sabc Capacitor voltage V cabc i obtained after performing the Park transformation sdq V cdq Together, they serve as the input signals for the virtual impedance loop and the voltage-current dual closed-loop control loop, obtaining the reference signal for the inverter's dq-axis voltage. After passing through the Park inverse transform and the SVPWM loop, the three-phase modulated wave is finally obtained.

[0058] In the diagram, the control equation for the VSG is:

[0059]

[0060] Among them, P ref This represents the active power reference value, ω. m and ω n These represent the actual angular frequency and the rated angular frequency, respectively; J represents the moment of inertia; and D represents the moment of inertia. p Q represents the damping coefficient, θ represents the reference phase, and Q represents the damping coefficient. ref This represents the reactive power reference value, K represents the reactive power loop inertia coefficient, and D... q E represents the reactive power loop voltage droop factor. dref This represents the internal electromotive force of the virtual synchronous generator.

[0061] like Figure 5 As shown, the adaptive virtual impedance control method provided in this implementation case includes the following steps:

[0062] S1: Collect grid connection point voltage, inverter side current, and angular frequency difference ω of the active power control loop output. m -ω n The dq-axis components of the grid connection point voltage and the inverter side current are obtained through dq transformation;

[0063] S2: Calculate the active power P output by the grid-connected inverter based on the dq-axis components of the grid connection point voltage and the inverter-side current. e Reactive power Q e and the voltage amplitude U at the grid connection point m Current amplitude i m The power angle δ is obtained by integrating the angular frequency difference.

[0064] S3: Based on the voltage amplitude U at the grid connection point m Inverter-side current amplitude i m The power angle δ, obtained by integrating the output angular frequency difference of the active loop, is used to calculate the grid impedance amplitude Z in real time.

[0065] S4: When the calculated grid impedance amplitude reaches stability for the first time, the calculated value is recorded as Z0, i.e., the initial amplitude of the grid impedance, and saved. Once Z0 is calculated, the above stability judgment process will no longer be performed. Before Z0 is calculated, the output remains at zero.

[0066] S5: The difference between Z0 and the real-time calculated power grid impedance amplitude Z is used to obtain the impedance amplitude difference ΔZ = Z0 - Z;

[0067] S6: As Figure 3 As shown, it is determined whether the impedance magnitude difference meets the limiting conditions. If the conditions are met, the adaptive virtual impedance control module outputs ΔZ; otherwise, the output is set to 0, and the above judgment process will not be performed after startup.

[0068] S7: Based on the output of the adaptive virtual impedance control module, multiply by the feedback coefficient and then sum to the initial virtual resistance R of the control loop. v0 Virtual Reactance X v0 The sum is used as the control parameter for the virtual impedance element in the front stage of the voltage-current dual closed-loop control.

[0069] As described below, the online calculation of grid impedance has been simplified in actual control, reducing the amount of calculation, but it will introduce certain errors. Therefore, a feedback coefficient is added in S7 to correct these errors and improve the control effect of the system.

[0070] When the system's line impedance reaches a stable state again, the system operates under the new steady-state conditions.

[0071] Specifically, S2 includes the following steps:

[0072] The active power P output by the grid-connected inverter is calculated using the following formula. e and reactive power Q e :

[0073]

[0074] The grid voltage amplitude U is calculated using the following formula. m and inverter-side current amplitude i m :

[0075]

[0076] Among them, V Cd and V Cq Represent the d-axis and q-axis components of the grid connection point voltage, respectively. sd and i sq These represent the d-axis and q-axis components of the inverter-side current, respectively.

[0077] The calculation method for the work angle δ is as follows:

[0078] δ=∫(ω m -ω n (4)

[0079] The grid connection point voltage reference signal is obtained using the following formula:

[0080]

[0081] R v and X v R and Rconductivity represent virtual resistance and virtual reactance, respectively, obtained by the adaptive virtual impedance control loop. Under initial conditions, Rconductivity V and X v The values ​​are R respectively v0 X v0 V Cdref and V Cqref These represent the d-axis and q-axis reference signals for the grid connection point voltage, respectively.

[0082] The inverter's voltage command is obtained using the following formula:

[0083]

[0084] Among them, i sdref and i sqref These represent the given values ​​of the inverter-side current on the d-axis and q-axis, respectively. dref and e qref These represent the d-axis and q-axis components of the inverter voltage command, respectively, k pu and k iu k represents the proportional and integral coefficients of the voltage loop, respectively. pi and k ii L represents the proportional and integral coefficients of the current loop, respectively. s Indicates the inverter-side inductance, C f This represents the filter capacitor.

[0085] The calculation method for the magnitude of the power grid impedance in S3 is as follows:

[0086] Since the VSG operates under grid-connected conditions, the grid voltage can be assumed to remain constant, with an amplitude of U. gm =311V. In reality, there is a slight difference between the inverter-side current and the output current at the PCC point. To simplify calculations and reduce unnecessary sampling equipment, this paper uses the power angle δ calculated in S2 as the phase angle difference between the PCC point voltage and the three-phase grid voltage. m This is used as the amplitude of the output current at the PCC point. Simultaneously, based on the obtained grid connection point voltage amplitude U... m The line impedance amplitude is calculated online, and the specific calculation method is as follows:

[0087] like Figure 4 As shown, the line impedance amplitude can be calculated using the following formula:

[0088]

[0089] Where θ1 is the phase angle of the inverter output current (with the grid voltage phase as a reference).

[0090] Because the work angle δ is very small and U m ≈U gm Therefore, the formula for calculating the line impedance amplitude can be simplified as follows:

[0091]

[0092] In S4, Z0 is solved as follows:

[0093] Set the time value Δt and the impedance value ΔZ. * Based on the impedance amplitude Z calculated in S3, determine whether Z can stabilize at a specific value ±ΔZ within a time interval Δt. * Within the range, if the above conditions are met, the corresponding Z is recorded as the line impedance amplitude Z0 under the initial operating conditions. After recording the line impedance amplitude Z0, the procedure for determining whether Z is stable is terminated.

[0094] S6 specifically includes the following steps:

[0095] The impedance threshold Z is given according to the actual situation. th The absolute value of the difference in grid impedance magnitude ΔZ, |ΔZ| and Z, calculated in S5. th The comparison is performed, and once the condition |ΔZ|>Z is met, the comparison is performed. th Then the output ΔZ will be started, and the process of |ΔZ|>Z will not be repeated thereafter. th Compare, otherwise set the output to zero.

[0096] In S7, after obtaining the output ΔZ of the adaptive virtual impedance control loop according to the above steps, the virtual resistance and virtual reactance values ​​of the virtual impedance unit in the control loop are calculated according to the following formula:

[0097]

[0098] K1 and K2 are the feedback coefficients of the adaptive virtual impedance control module corresponding to the virtual resistance and virtual reactance.

[0099] Specifically, the formula for calculating the grid strength SCR is as follows:

[0100]

[0101] Among them, S ac It is the system short-circuit capacity, U n It is the rated AC voltage, P n This is the rated power; under rated conditions, the system's rated capacity S n =P n Z is the line impedance. Since the line resistance is much smaller than the line reactance, Z can be considered equal to the line reactance in the analysis.

[0102] Simulations were performed on the grid-connected operation of a three-phase grid-connected inverter using the control method described in this embodiment. Generally, an SCR of 6-10 or lower is considered a weak grid, while 20-25 or higher is considered a strong grid. Since VSG-controlled inverters often operate under weak grid conditions, the single-phase grid inductance L under the initial operating conditions of a single grid-connected inverter using VSG control was set. g The value is 20mH. According to formula (10), the corresponding grid strength SCR is 2.3.

[0103] The grid inductance was switched to 15mH, 10mH, 5mH, 2mH, 7.5mH, 15mH, and 20mH at 1s, 2s, 3s, 4s, 5s, 6s, and 7s, respectively, and the corresponding grid strength SCR became 3.1, 4.6, 9.2, 23, 6.1, 3.1, and 2.3, respectively, to simulate the switching process of grid strength under different conditions.

[0104] By comparing the traditional virtual synchronous generator control method (such as...) Figure 6 (as shown) and the virtual synchronous generator control of the present invention (such as Figure 7As shown in the figure, the control effect after the two control methods can be seen that the system can maintain stable operation after a certain adjustment after the SCR switching. However, the implementation method can reduce the oscillation of active power and current during the transient process of sudden changes in grid strength, reduce overshoot, accelerate the transient process, help the system adjust quickly, and after adjustment, the system can track the given value and maintain stable operation, thus improving the robustness and safety of the system.

[0105] Example 2

[0106] An adaptive virtual impedance stabilization control system for a grid-connected inverter, comprising:

[0107] The grid impedance amplitude calculation module is configured to obtain the grid connection point voltage amplitude, inverter side current amplitude, and power angle, and calculate the grid impedance amplitude based on these values.

[0108] The stability judgment module is configured to record the calculated value as the initial amplitude of the grid impedance and save it when the calculated grid impedance amplitude first reaches stability. Once the initial amplitude of the grid impedance is calculated, the above stability judgment process will no longer be performed, and the output will remain at zero before the initial amplitude of the grid impedance is calculated.

[0109] The difference calculation module is configured to calculate the difference in impedance amplitude by subtracting the initial amplitude of the grid impedance from the calculated amplitude of the grid impedance.

[0110] The adaptive virtual impedance module is configured to determine whether the impedance amplitude difference meets the limiting conditions. If the conditions are met, the difference in impedance amplitude is output; otherwise, the output is set to the set value. Based on the output, the control parameters of the virtual impedance stage before the voltage and current dual closed-loop control are set.

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art without creative effort within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adaptive virtual impedance stabilization control method for grid-connected inverters, characterized in that, Includes the following steps: Obtain the voltage amplitude at the grid connection point, the current amplitude on the inverter side, and the power angle, and calculate the grid impedance amplitude based on them; When the calculated grid impedance amplitude first reaches a stable value, the calculated value is recorded as the initial grid impedance amplitude and saved, including determining the line impedance amplitude. Z Can it remain stable at a predetermined value within a set time period? Within the specified range, if the above conditions are met, record the corresponding information. Z This refers to the line impedance amplitude under initial operating conditions. Z 0, when recording the line impedance amplitude Z After 0, terminate. Z The process of determining whether something is stable; Once the initial amplitude of the grid impedance is calculated, the above stability determination process will no longer be performed, and the output will remain at zero until the initial amplitude of the grid impedance is calculated. The difference in impedance amplitude is obtained by subtracting the initial amplitude of the grid impedance from the calculated amplitude of the grid impedance. Determine whether the impedance amplitude difference meets the specified conditions. If the conditions are met, output the impedance amplitude difference; otherwise, set the output to a set value, including: setting an impedance threshold. Z th The difference in the magnitude of the grid impedance obtained through calculation absolute value and Z th Compare them, and once a condition is met... Then start output And will not be carried out again afterwards. Compare, otherwise set the output to zero; Based on the output, set the control parameters for the virtual impedance stage of the voltage and current dual closed-loop control.

2. The adaptive virtual impedance stabilization control method for grid-connected inverters as described in claim 1, characterized in that, The process of obtaining the grid connection point voltage amplitude, inverter side current amplitude, and power angle includes obtaining the angular frequency difference between the grid connection point voltage, inverter side current, and active power control loop output, and obtaining the dq axis components of the grid connection point voltage and inverter side current through dq transformation. The active power, reactive power, voltage amplitude, and current amplitude of the grid-connected inverter are calculated based on the dq-axis components of the grid-connected voltage and inverter-side current. The power angle is obtained by integrating the angular frequency difference.

3. The adaptive virtual impedance stabilization control method for grid-connected inverters as described in claim 2, characterized in that, Calculate the active power output of the grid-connected inverter. P e and reactive power Q e The process includes: Calculate the voltage amplitude of the power grid U m and inverter-side current amplitude i m for: in, V Cd and V Cq These represent the d-axis and q-axis components of the grid connection point voltage, respectively. i sd and i sq These represent the d-axis and q-axis components of the inverter-side current, respectively. Gongjiao δ The calculation method is as follows: ω m -ω n The angular frequency difference of the active power control loop output. ω m To output angular velocity, ω n This is the rated angular velocity.

4. The adaptive virtual impedance stabilization control method for grid-connected inverters as described in claim 1, characterized in that, The process of calculating the magnitude of the power grid impedance includes: After simplified calculation, the line impedance amplitude Z is: in, δ For the angle 、U m For the voltage amplitude at the grid connection point and i m This represents the inverter-side current amplitude.

5. The adaptive virtual impedance stabilization control method for grid-connected inverters as described in claim 1, characterized in that, Based on the output, the process of setting the control parameters of the virtual impedance element in the front stage of the voltage-current dual closed-loop control includes: Based on the output of the adaptive virtual impedance control circuit The virtual resistance and virtual reactance values ​​of the virtual impedance unit in the control loop are calculated using the following formulas: in K 1. K 2 represents the feedback coefficients of the adaptive virtual impedance control module corresponding to the virtual resistance and virtual reactance; For the initial virtual resistance, This is the initial virtual reactance; The results are used as control parameters for the virtual impedance element in the front stage of the voltage-current dual closed-loop control.

6. The adaptive virtual impedance stabilization control method for grid-connected inverters as described in claim 1, characterized in that, When the system's line impedance reaches a stable state again, the system will run the above steps under the new steady-state conditions.

7. An adaptive virtual impedance stabilization control system for a grid-connected inverter, characterized in that, include: The grid impedance amplitude calculation module is configured to obtain the grid connection point voltage amplitude, inverter side current amplitude, and power angle, and calculate the grid impedance amplitude based on these values. The stability assessment module is configured to record and save the calculated grid impedance magnitude as the initial grid impedance magnitude when the calculated grid impedance magnitude first reaches a stable value. This includes determining the line impedance magnitude. Z Can it remain stable at a predetermined value within a set time period? Within the specified range, if the above conditions are met, record the corresponding information. Z This refers to the line impedance amplitude under initial operating conditions. Z 0, when recording the line impedance amplitude Z After 0, terminate. Z The process of determining whether something is stable; Once the initial amplitude of the grid impedance is calculated, the above stability determination process will no longer be performed, and the output will remain at zero until the initial amplitude of the grid impedance is calculated. The difference calculation module is configured to calculate the difference in impedance amplitude by subtracting the initial amplitude of the grid impedance from the calculated amplitude of the grid impedance. The adaptive virtual impedance module is configured to determine whether the impedance magnitude difference meets a defined condition. If the condition is met, it outputs the impedance magnitude difference; otherwise, the output is set to a preset value, including setting an impedance threshold. Z th The difference in the magnitude of the grid impedance obtained through calculation absolute value and Z th Compare them, and once a condition is met... Then start output And will not be carried out again afterwards. Compare, otherwise set the output to zero; Based on the output, set the control parameters for the virtual impedance stage of the voltage and current dual closed-loop control.

8. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the steps of the method according to any one of claims 1-6.

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