Method, device and equipment for adjusting network construction converter under power distribution network fault and medium

Abstract

The invention discloses a method, a device and equipment for adjusting a network construction converter under a power distribution network fault and a medium, which are used for solving the technical problems that virtual impedance control of the network construction converter is difficult to adjust in real time and the stability of a power grid is influenced. Comprising the following steps: enabling a network construction converter to be equivalent to internal potential and virtual impedance to be merged into a power grid, and correcting a grid-connected point voltage and a grid-connected point voltage phase angle of the network construction converter to obtain a corrected grid-connected point voltage and a corrected grid-connected point voltage phase angle; obtaining the alternating current of the grid-forming converter under the corrected grid-connected point voltage; when the alternating current is smaller than a preset current threshold value, a steady-state control mode is triggered, and a virtual impedance gain is determined through a closed-loop feedback mechanism by taking the minimum power coupling coefficient as a target so as to adjust the network construction converter; when the alternating current is larger than a preset current threshold value and smaller than the maximum allowable current, a fault control mode is triggered, and the optimal gain of virtual impedance is determined according to the magnitude of the fault current and a preset grading threshold value; and the virtual impedance optimal gain is adopted to adjust the network construction converter.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-connected converter regulation, and in particular to a grid-connected converter regulation method, device, equipment and medium under distribution network fault. Background Art

[0002] With the transformation of the global energy structure, the proportion of renewable energy such as distributed photovoltaic, wind power, and energy storage in the distribution network has gradually increased. Due to the low inertia characteristics of these power electronic devices, the frequency response capability of the distribution network has been significantly reduced, which in turn affects the stability of the power grid. Especially in the context of large-scale renewable energy access, the grid's ability to respond to sudden faults faces severe tests. The protection system of traditional distribution networks usually relies on the fault current provided by synchronous machines and generators to achieve protection functions, but with the grid connection of renewable energy, the fault current tolerance of these systems has gradually weakened, making it difficult for the distribution network to recover quickly when a fault occurs, and may even cause equipment damage or system collapse.

[0003] In order to improve the fault response capability of the distribution network, the grid-type converter can maintain the frequency and voltage stability of the grid by controlling its own output power in the absence of synchronous machines. It not only has the ability to regulate frequency and voltage, but also can respond quickly and provide necessary support when a grid fault occurs. However, the fault current tolerance of the grid-type converter is limited and it cannot withstand large-scale short-circuit currents like traditional synchronous machines. Therefore, in order to ensure its reliable operation in the event of a grid fault, an effective fault current suppression strategy must be introduced.

[0004] As a relatively mature current limiting strategy, virtual impedance control can limit the amplitude of fault current and prevent system overload by simulating the equivalent impedance of the line in the power grid. The core idea of ​​this strategy is to limit the excessive peak value of fault current by adjusting the relationship between the output current of the converter and the system load. However, the traditional method of virtual impedance control does not fully consider the complex power decoupling requirements brought about by diversified power sources and load fluctuations in the distribution network. In the distribution network, especially when multiple distributed power sources are connected to the grid, the functional fluctuations of different power sources are intertwined, making the power decoupling of the power grid more difficult, and traditional virtual impedance control is difficult to cope with the challenges brought about by power fluctuations. At present, traditional virtual impedance control has shortcomings in power decoupling and cannot accurately distinguish the impact of fluctuations of different power sources on the system. This leads to unsatisfactory control effect.

[0005] In addition, as the scale and topology of the power grid become more complex, the adaptability of traditional strategies is poor, and it is difficult to quickly respond to nonlinear problems caused by changes in load and power generation in the power grid. The dynamic changes and nonlinear characteristics of the power grid make it difficult to adjust virtual impedance control in real time, especially under high load or extreme fluctuations. The real-time performance and computing power of the control strategy are insufficient, affecting the stability of the power grid. Summary of the invention

[0006] The present invention provides a method, device, equipment and medium for adjusting a grid-connected converter under a distribution network fault, which is used to solve the technical problem that the existing grid-connected converter virtual impedance control is difficult to adjust in real time, affecting the stability of the power grid.

[0007] The present invention provides a method for adjusting a grid-connected converter under a distribution network fault, comprising:

[0008] The grid-connecting converter is equivalent to an internal potential and a virtual impedance and connected to the power grid, and the grid-connecting point voltage and the grid-connecting point voltage phase angle of the grid-connecting converter are corrected to obtain a corrected grid-connecting point voltage and a corrected grid-connecting point voltage phase angle;

[0009] Obtaining the alternating current of the grid-connected converter under the corrected grid-connected point voltage;

[0010] When the AC current is less than a preset current threshold, a steady-state control mode is triggered, with the goal of minimizing the power coupling coefficient, a virtual impedance gain is determined through a closed-loop feedback mechanism, and the grid-connected converter is adjusted using the virtual impedance gain;

[0011] When the AC current is greater than the preset current threshold and less than the maximum allowable current, a fault control mode is triggered, and an optimal gain of the virtual impedance is determined according to the fault current magnitude and the preset classification threshold;

[0012] The optimal gain of the virtual impedance is used to adjust the grid-connected converter.

[0013] Optionally, the step of correcting the grid connection point voltage and the grid connection point voltage phase angle of the grid-connected converter to obtain the corrected grid connection point voltage and the corrected grid connection point voltage phase angle comprises:

[0014] Obtaining grid impedance, fault current amplitude, voltage phase angle before correction and output current of the grid-connected converter;

[0015] Calculating an initial value of a virtual impedance according to the grid impedance and the fault current amplitude;

[0016] Calculating an initial grid connection point voltage according to the initial value of the virtual impedance, the internal potential and the output current;

[0017] Calculating a virtual impedance angle according to the initial value of the virtual impedance;

[0018] Calculate the initial corrected grid connection point voltage phase angle according to the pre-corrected voltage phase angle and the virtual impedance angle;

[0019] Obtain the reference voltage and expected phase angle of the grid connection point;

[0020] Determine whether the absolute value of the difference between the initial grid-connected point voltage and the reference voltage is less than a preset voltage error tolerance, and whether the absolute value of the difference between the initial corrected grid-connected point voltage phase angle and the expected phase angle is less than a preset phase angle error tolerance;

[0021] If not, return to the step of obtaining the grid impedance, the fault current amplitude, the voltage phase angle before correction, and the output current of the grid-connected converter;

[0022] If yes, the initial grid-connected point voltage is used as the modified grid-connected point voltage, and the initial modified grid-connected point voltage phase angle is determined as the modified grid-connected point voltage phase angle.

[0023] Optionally, when the AC current is less than a preset current threshold, a steady-state control mode is triggered, a virtual impedance gain is determined through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and the step of using the virtual impedance gain to adjust the grid-connected converter includes:

[0024] When the AC current is less than a preset current threshold, a steady-state control mode is triggered, and a first grid-connected point power expression is constructed through a preset small signal model;

[0025] Constructing an analytical expression for the coupling coefficient according to the first grid connection point power expression;

[0026] Generate a power coupling coefficient according to the coupling coefficient analytical expression;

[0027] With the goal of minimizing the power coupling coefficient, a virtual impedance gain is determined through a closed-loop feedback mechanism, and the virtual impedance gain is used to adjust the grid-connected converter.

[0028] Optionally, the step of constructing the small signal model includes:

[0029] Obtaining a first active power and a first reactive power outputted by the internal potential of the grid-connecting converter;

[0030] generating a second grid connection point power expression according to the first active power, the first reactive power, the internal potential and the virtual impedance;

[0031] Generate a small signal analytical expression based on the second grid connection point power expression;

[0032] A small signal model of power control coupling is generated according to the small signal analytical expression.

[0033] Optionally, the virtual impedance optimal gain includes a virtual resistance optimal gain and a virtual reactance optimal gain; when the AC current is greater than the preset current threshold and less than the maximum allowable current, the fault control mode is triggered, and the step of determining the virtual impedance optimal gain according to the fault current size and the preset classification threshold includes:

[0034] When the AC current is greater than the preset current threshold and less than the maximum allowable current, a fault control mode is triggered;

[0035] When the fault current is greater than the preset first-level threshold and less than the preset second-level threshold, the optimal gain of the virtual resistor is calculated according to the fault current, the preset first threshold and the first preset resistance adjustment coefficient, and the optimal gain of the virtual reactance is calculated according to the fault current, the preset first threshold and the first preset reactance adjustment coefficient;

[0036] When the fault current is greater than the preset secondary threshold and less than the preset tertiary threshold, the optimal gain of the virtual resistor is calculated according to the fault current, the preset second threshold and the second preset resistance adjustment coefficient, and the optimal gain of the virtual reactance is calculated according to the fault current, the preset second threshold and the second preset reactance adjustment coefficient;

[0037] When the fault current reaches the preset third-level threshold, the preset maximum resistance gain is used as the optimal virtual resistance gain, and the preset maximum reactance gain is used as the optimal virtual reactance gain.

[0038] The present invention also provides a network converter adjustment device under a distribution network fault, comprising:

[0039] A correction module is used to connect the grid-connected converter to the grid equivalent to internal potential and virtual impedance, and to correct the grid-connected point voltage and grid-connected point voltage phase angle of the grid-connected converter to obtain a corrected grid-connected point voltage and a corrected grid-connected point voltage phase angle;

[0040] An AC current acquisition module, used to acquire the AC current of the grid-connected converter under the corrected grid-connected point voltage;

[0041] A first regulating module is used for triggering a steady-state control mode when the AC current is less than a preset current threshold, determining a virtual impedance gain through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and regulating the grid-connected converter using the virtual impedance gain;

[0042] A virtual impedance optimal gain determination module, used to trigger a fault control mode when the AC current is greater than the preset current threshold and less than the maximum allowable current, and determine the virtual impedance optimal gain according to the fault current size and the preset classification threshold;

[0043] The second regulating module is used to regulate the grid-connected converter by using the optimal gain of the virtual impedance.

[0044] Optionally, the correction module includes:

[0045] A parameter acquisition submodule, used to obtain the grid impedance, the fault current amplitude, the voltage phase angle before correction and the output current of the grid-connected converter;

[0046] A virtual impedance initial value calculation submodule, used to calculate the virtual impedance initial value according to the grid impedance and the fault current amplitude;

[0047] An initial grid-connected point voltage calculation submodule, used to calculate the initial grid-connected point voltage according to the initial value of the virtual impedance, the internal potential and the output current;

[0048] A virtual impedance angle calculation submodule, used for calculating the virtual impedance angle according to the virtual impedance initial value;

[0049] An initial correction grid connection point voltage phase angle calculation submodule, used to calculate an initial correction grid connection point voltage phase angle according to the pre-correction voltage phase angle and the virtual impedance angle;

[0050] A reference voltage and expected phase angle acquisition submodule, used to acquire a reference voltage and an expected phase angle of a grid-connected point;

[0051] A judgment submodule, used to judge whether the absolute value of the difference between the initial grid-connected point voltage and the reference voltage is less than a preset voltage error tolerance, and whether the absolute value of the difference between the initial corrected grid-connected point voltage phase angle and the expected phase angle is less than a preset phase angle error tolerance;

[0052] A return submodule, for returning to the step of obtaining the grid impedance, the fault current amplitude, the voltage phase angle before correction and the output current of the grid-connected converter if no;

[0053] The modified grid connection point voltage and modified grid connection point voltage phase angle determination submodule is used to use the initial grid connection point voltage as the modified grid connection point voltage and determine the initial modified grid connection point voltage phase angle as the modified grid connection point voltage phase angle.

[0054] Optionally, the first adjustment module includes:

[0055] A first grid-connected point power expression constructing submodule, used for triggering a steady-state control mode when the AC current is less than a preset current threshold, and constructing a first grid-connected point power expression through a preset small signal model;

[0056] A coupling coefficient analytical expression constructing submodule, used to construct a coupling coefficient analytical expression according to the first grid connection point power expression;

[0057] A power coupling coefficient generating submodule, used for generating a power coupling coefficient according to the coupling coefficient analytical expression;

[0058] The first regulating submodule is used to determine the virtual impedance gain through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and use the virtual impedance gain to regulate the grid-connected converter.

[0059] The present invention also provides an electronic device, the device comprising a processor and a memory:

[0060] The memory is used to store program code and transmit the program code to the processor;

[0061] The processor is used to execute the grid-connected converter adjustment method under distribution network fault as described in any one of the above items according to the instructions in the program code.

[0062] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program code, and the program code is used to execute the grid-connected converter adjustment method under distribution network fault as described in any one of the above items.

[0063] It can be seen from the above technical scheme that the present invention has the following advantages: the present invention discloses a method for adjusting a grid-forming converter under a distribution network fault, and specifically discloses: the grid-forming converter is equivalent to an internal potential and a virtual impedance and is connected to the grid, and the grid-forming converter's grid-forming point voltage and grid-forming point voltage phase angle are corrected to obtain the corrected grid-forming point voltage and the corrected grid-forming point voltage phase angle; the AC current of the grid-forming converter under the corrected grid-forming point voltage is obtained; when the AC current is less than a preset current threshold, the steady-state control mode is triggered, and the virtual impedance gain is determined through a closed-loop feedback mechanism with the power coupling coefficient as the minimum target, and the grid-forming converter is adjusted by the virtual impedance gain; when the AC current is greater than the preset current threshold and less than the maximum allowable current, the fault control mode is triggered, and the optimal virtual impedance gain is determined according to the fault current size and the preset classification threshold; the optimal virtual impedance gain is used to adjust the grid-forming converter. The present invention realizes dynamic parameter adjustment by finely adjusting the virtual negative resistance and virtual impedance parameters, thereby ensuring the efficient operation and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0065] Figure 1 A flowchart of the steps of a method for adjusting a grid-connected converter under a distribution network fault provided by an embodiment of the present invention;

[0066] Figure 2 A topological decoupling and control system for a grid-connected converter provided in an embodiment of the present invention;

[0067] Figure 3 A grid-connected equivalent circuit of a centralized grid-connected converter provided by an embodiment of the present invention;

[0068] Figure 4 is the equivalent circuit after virtual impedance control is put into operation;

[0069] Figure 5 It is a schematic diagram of the small signal model of the grid-connected converter;

[0070] Figure 6 This is a schematic diagram of the fault current limiting stage in an embodiment of the present invention;

[0071] Figure 7 A structural block diagram of a grid-connected converter regulating device under distribution network fault provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0072] The embodiments of the present invention provide a method, device, equipment and medium for adjusting a grid-connected converter under a distribution network fault, which are used to solve the technical problem that the existing grid-connected converter virtual impedance control is difficult to adjust in real time, affecting the stability of the power grid.

[0073] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0074] See also Figure 1 , Figure 1 A flowchart of the steps of a method for adjusting a grid-connected converter under a distribution network fault is provided in an embodiment of the present invention.

[0075] The present invention provides a method for adjusting a grid-connected converter under a distribution network fault, which is applied to a topological decoupling and control system of a grid-connected converter. The method may specifically include the following steps:

[0076] Step 101, the grid-connected converter is equivalent to the internal potential and virtual impedance and connected to the grid, and the grid-connected point voltage and grid-connected point voltage phase angle of the grid-connected converter are corrected to obtain the corrected grid-connected point voltage and the corrected grid-connected point voltage phase angle;

[0077] The grid-building converter is a new type of converter that can actively build voltage and frequency in the power system. When the grid-building converter is put into the power grid, it can adjust the power grid when a fault occurs, so that the power grid can be restored to a more stable state.

[0078] like Figure 2 and Figure 3 As shown, Figure 2 A topological decoupling and control system for a grid-connected converter provided in an embodiment of the present invention; Figure 3 The grid-connected equivalent circuit of the centralized grid-connected converter provided in the embodiment of the present invention. The topological decoupling and control system of the embodiment of the present invention adopts the virtual synchronous machine control of the grid. The virtual synchronous machine control is mainly divided into three parts: power synchronization loop control, virtual impedance control, and dual closed-loop control. Among them, the active control loop of the power synchronization link can simulate the inertia and damping characteristics of the synchronous machine, and at the same time, the active droop control is added to respond to the change of the grid frequency, and finally the phase of the grid connection point voltage is generated. The reactive control loop contains reactive power droop control, and generates the amplitude of the grid connection point voltage by simulating the excitation characteristics of the synchronous machine. In order to realize power decoupling and fault current limiting, the grid connection point voltage amplitude and grid connection point voltage phase angle generated by the power synchronization link need to be corrected by virtual impedance control and then enter the voltage and current dual closed-loop control. Among them, the voltage and current dual closed-loop control includes a steady-state control mode and a fault control mode.

[0079] In one example, step 101 may include the following sub-steps:

[0080] S11, obtaining the grid impedance, the fault current amplitude, the voltage phase angle before correction and the output current of the grid-connected converter;

[0081] S12, calculating the initial value of the virtual impedance according to the grid impedance and the fault current amplitude;

[0082] S13, calculating the initial grid connection point voltage according to the initial value of the virtual impedance, the internal potential and the output current;

[0083] S14, calculating the virtual impedance angle according to the initial value of the virtual impedance;

[0084] S15, calculating the initial corrected grid connection point voltage phase angle according to the voltage phase angle before correction and the virtual impedance angle;

[0085] S16, obtaining a reference voltage and a desired phase angle of the grid connection point;

[0086] S17, determining whether the absolute value of the difference between the initial grid connection point voltage and the reference voltage is less than a preset voltage error tolerance, and whether the absolute value of the difference between the initial corrected grid connection point voltage phase angle and the expected phase angle is less than a preset phase angle error tolerance;

[0087] S18, if not, return to the step of obtaining the grid impedance, the fault current amplitude, the voltage phase angle before correction, and the output current of the grid-connected converter;

[0088] S19: If yes, the initial grid connection point voltage is used as the modified grid connection point voltage, and the initial modified grid connection point voltage phase angle is determined as the modified grid connection point voltage phase angle.

[0089] In the correction process, the grid-connected converter is equivalent to the internal potential E and the virtual impedance Connected to the grid in series, according to the grid impedance and the fault current amplitude I fault , dynamically calculate the initial value of virtual impedance:

[0090]

[0091] Among them, α and β are adjustment coefficients, which are dynamically adjusted according to the fault current amplitude. When the fault current increases, α decreases and β increases to enhance the current limiting effect, and vice versa. is the initial value of virtual impedance, is the initial value of the virtual resistance, is the initial value of virtual reactance, j is an imaginary unit, is the grid impedance, is the grid resistance, is the grid reactance.

[0092] After adding virtual impedance control, the initial grid connection point voltage U' is:

[0093]

[0094] Where E is the potential amplitude in the grid converter, I is the output current, is the initial value of virtual impedance.

[0095] To ensure voltage stability, the correction targets are:

[0096] ,

[0097] in, The reference voltage set for the system, with U g , virtual impedance, and grid impedance angle change dynamically.

[0098] By adjusting the virtual resistor R v and virtual reactance X v Gain, so that:

[0099]

[0100] in, is the voltage error tolerance (generally within 1%).

[0101] After adding virtual impedance, the initial correction of the grid connection point voltage phase angle is for:

[0102]

[0103] in, is the voltage phase angle before correction, θ v =arctan(X v / R v ) is the virtual impedance angle.

[0104] The revised goals are:

[0105]

[0106] in, is the desired phase angle at the grid connection point to achieve power decoupling.

[0107] By dynamically adjusting the virtual impedance gain, we can achieve:

[0108]

[0109] in, is the phase angle error tolerance (generally within 1°).

[0110] The correction process is considered complete when the following conditions are met:

[0111]

[0112] After the above conditions are met, the correction is completed and the voltage and current dual closed-loop control is entered.

[0113] The grid-connected equivalent circuit of the grid-connected converter is as follows:

[0114] The grid-connected converter can be equivalent to a voltage source to form a power transmission model. At this time, the output current of the grid-connected converter is:

[0115]

[0116] Where i is the output current of the grid-connected converter, U is the output voltage amplitude of the grid-connected converter, and U g is the grid voltage amplitude, δ is the phase angle difference between the potential inside the grid converter and the grid voltage, and θ is the grid impedance angle, which is defined as , where R g is the resistance component of the grid impedance, X g is the reactance component of the grid impedance, Z is the equivalent impedance, including the grid impedance and virtual impedance .

[0117] The apparent power output of the converter is:

[0118]

[0119] Where P is the active power, Q is the reactive power, I* is the complex conjugate of the current, and j is the imaginary unit.

[0120] Further applying Euler's formula, the active power and reactive power output by the converter can be expressed as:

[0121]

[0122] Taking partial derivatives of P and Q with respect to δ and U respectively, we can get:

[0123]

[0124] When the grid characteristics are not purely resistive or purely inductive, the active power and reactive power output by the grid-connected converter are δ and U The partial derivative exists δ and U coupling, so it is impossible to control δ or U Realize active power P or reactive power Q Independent control.

[0125] In addition, the grid characteristics are enhanced as the impedance angle θ increases, that is, the impedance ratio of the grid R g / X g The larger the value, the stronger the coupling between active power and reactive power. To achieve power decoupling control, the virtual resistance R needs to be adjusted dynamically. v and virtual reactance X v , making the equivalent grid impedance tend to be purely inductive, thereby ensuring the decoupling effect.

[0126] Step 102, obtaining the AC current of the grid-connected converter under the corrected grid-connected point voltage;

[0127] Step 103, when the AC current is less than the preset current threshold, the steady-state control mode is triggered, with the power coupling coefficient minimized as the goal, the virtual impedance gain is determined through a closed-loop feedback mechanism, and the virtual impedance gain is used to adjust the grid-connected converter;

[0128] like Figure 6 As shown, th is a preset current threshold. When the AC current is less than the preset current threshold, the steady-state control mode is entered.

[0129] When the AC current of the grid-connected converter is less than the preset current threshold, it enters the steady-state control mode and dynamically adjusts the virtual resistance according to the grid impedance characteristics, with the goal of minimizing the power coupling coefficient. Through the closed-loop feedback mechanism, the virtual negative resistance gain is calibrated in real time to achieve decoupling of active and reactive power.

[0130] In one example, step 103 may include the following sub-steps:

[0131] S21, when the AC current is less than a preset current threshold, a steady-state control mode is triggered, and a first grid-connected point power expression is constructed through a preset small signal model;

[0132] S22, constructing an analytical expression for the coupling coefficient according to the first grid connection point power expression;

[0133] S23, generating a power coupling coefficient according to an analytical expression of the coupling coefficient;

[0134] S24, with the goal of minimizing the power coupling coefficient, determines the virtual impedance gain through a closed-loop feedback mechanism, and uses the virtual impedance gain to adjust the grid-connected converter.

[0135] In a specific implementation, when the AC current of the grid-connected converter is less than the preset current threshold, the steady-state control mode can be triggered, and the power expression of the first grid-connected point can be constructed through the preset small signal model:

[0136]

[0137] Where E is the potential inside the grid converter, U is the grid connection point voltage, , is the phase angle difference between the internal potential and the grid connection point voltage.

[0138] The small signal model is introduced, and the analytical expression of the coupling coefficient is constructed through linear processing under small disturbances:

[0139]

[0140] Based on the closed-loop feedback mechanism, the virtual resistor gain k is calibrated in real time R and virtual reactance gain k X , the goal is to minimize the power coupling coefficient:

[0141]

[0142] when When , power decoupling is completed.

[0143] The steps for building the small signal model include:

[0144] S31, obtaining a first active power and a first reactive power outputted by the internal potential of the grid-connected converter;

[0145] S32, generating a second grid connection point power expression according to the first active power, the first reactive power, the internal potential and the virtual impedance;

[0146] S33, generating a small signal analytical expression based on the second grid connection point power expression;

[0147] S34, generating a small signal model of power control coupling according to the small signal analytical expression.

[0148] In the specific implementation, Figure 4 As shown, Figure 4 is the equivalent circuit after virtual impedance control is applied. Let the virtual resistance be -R l , at this time, the line impedance of the system can be equivalent to inductive, and the active power and reactive power output at point A are decoupled. Although the power at point A is decoupled, the real goal of decoupling control is to achieve power decoupling at point B. The power characteristics of point A are:

[0149]

[0150] Among them, P 1 With Q 1 They are the first active power and the first reactive power output at point A, respectively. X and R are the line inductance and line resistance, respectively. They are defined as X=ωL 1 +ωL v , R = R v +R 1 , E is the potential inside the grid converter, U g is the grid connection point voltage δ 0 and δ are the steady-state phase angle of the internal potential and the grid-connected point voltage phase angle, respectively.

[0151] Further, the grid connection point voltage is represented by potential and virtual impedance, and the analytical formula of the second grid connection point power (including active power and reactive power) is written out:

[0152]

[0153] When adding a virtual negative resistor R v =-R l , the active power and reactive power at point B can be simplified as:

[0154]

[0155] Based on the above power equation, the small signal analytical expressions of the active control link and reactive control link of the grid-connected converter are further derived:

[0156]

[0157] And the internal potential angle δ 0When is small, the above formula can be further simplified:

[0158]

[0159] Then the small signal control model of power control coupling is obtained (such as Figure 5 shown):

[0160]

[0161] Among them, P and Q are the active power and reactive power output by the converter, E is the internal potential of the grid converter, and U g is the grid voltage, is the phase angle between the internal potential of the grid converter and the grid connection point voltage, X and R are the grid reactance and resistance, X v , R v are virtual reactance and virtual resistance, △E, △ are small signal disturbance variables (small disturbances in the internal potential and phase angle).

[0162] Power coupling coefficient:

[0163]

[0164] In the small signal model, the power coupling coefficient G Pδ and G QE The same power coupling characteristics are shown: when G Pδ Significantly greater than G PE When G QE Significantly greater than G Qδ When the reactive power is mainly controlled by the voltage amplitude, the virtual impedance parameter R v , X v , which can optimize the power control decoupling effect of the small signal model.

[0165] Step 104, when the AC current is greater than a preset current threshold and less than a maximum allowable current, a fault control mode is triggered, and an optimal gain of the virtual impedance is determined according to the fault current and a preset classification threshold;

[0166] Step 105, using virtual impedance optimal gain to adjust the grid-connected converter.

[0167] like Figure 6 As shown, th is the preset current threshold, |i gac |When the AC current is greater than the preset current threshold and less than the maximum allowable current, it enters the steady-state control mode.

[0168] In the embodiment of the present invention, when the AC current is greater than a preset current threshold and less than a maximum allowable current, the fault control mode is triggered, and the optimal gain of the virtual impedance is determined according to the fault current size and the preset classification threshold.

[0169] In one example, the virtual impedance optimal gain may include a virtual resistance optimal gain and a virtual reactance optimal gain, and step 104 may include the following sub-steps:

[0170] S41, when the AC current is greater than a preset current threshold and less than a maximum allowable current, a fault control mode is triggered;

[0171] S42, when the fault current is greater than the preset first-level threshold and less than the preset second-level threshold, the optimal gain of the virtual resistor is calculated according to the fault current, the preset first threshold and the first preset resistance adjustment coefficient, and the optimal gain of the virtual reactance is calculated according to the fault current, the preset first threshold and the first preset reactance adjustment coefficient;

[0172] S43, when the fault current is greater than the preset secondary threshold and less than the preset tertiary threshold, the optimal gain of the virtual resistor is calculated according to the fault current, the preset second threshold and the second preset resistance adjustment coefficient, and the optimal gain of the virtual reactance is calculated according to the fault current, the preset second threshold and the second preset reactance adjustment coefficient;

[0173] S44, when the fault current reaches the preset third-level threshold, the preset maximum resistance gain is used as the optimal virtual resistance gain, and the preset maximum reactance gain is used as the optimal virtual reactance gain.

[0174] In the specific implementation, the classification threshold is designed as follows:

[0175] (1) Level 1 threshold (I th1 =1.1I n ): The fault current slightly exceeds the standard, and the control target is mainly to maintain power decoupling;

[0176] (2) Secondary threshold (I th2 =1.5I n ): The fault current increases significantly, and the linear-exponential mixed gain curve adjustment is started;

[0177] (3) Level 3 threshold (I th3 =2.0I n ): The fault current is close to the device limit and the fast saturation gain mode is used.

[0178] Among them, I n is the rated current of the grid converter, I th1 ,I th2 ,I th3 There are first, second and third level current thresholds respectively, which are adjusted in proportion to the rated current according to the different threshold levels.

[0179] When the fault current is greater than the preset first-level threshold and less than the preset second-level threshold, the best gain calculation formula for the virtual resistance is:

[0180]

[0181] The best gain calculation formula for the virtual reactance is:

[0182]

[0183] Wherein, and are adjustment coefficients to control the linear change rate. When the current slightly exceeds the first-level threshold, the suppression strength is small; as the current increases, the suppression strength gradually increases.

[0184] When the fault current is greater than the preset second-level threshold and less than the preset third-level threshold, the best gain calculation formula for the virtual resistance is:

[0185]

[0186] The best gain calculation formula for the virtual reactance is:

[0187]

[0188] Wherein, and are exponential growth adjustment coefficients to control the non-linear change of the gain curve.

[0189] When the fault current reaches the preset third-level threshold, the preset maximum resistance gain is used as the best gain of the virtual resistance, and the preset maximum reactance gain is used as the best gain of the virtual reactance. The formulas are as follows:

[0190]

[0191]

[0192] The present invention realizes the dynamic adjustment of parameters by finely adjusting the virtual negative resistance and virtual impedance parameters, ensuring the efficient operation of the system.

[0193] Furthermore, after completing the adjustment of the virtual impedance, the fuzzy control algorithm can be used to dynamically adjust each preset threshold according to the amplitude and change rate of the fault current to ensure the best effect of power decoupling and fault current suppression.

[0194] The specific steps of the adaptive threshold and fuzzy rules are as follows:

[0195] (1) Real-time monitor the current amplitude and change rate. Collect the fault current I faultThe real-time collected data is used as the input of the fuzzy controller to perform fuzzy reasoning.

[0196] (2) Fuzzy processing: The fault current amplitude and change rate are divided into different levels, a fuzzy membership function is constructed, and the membership of the current current amplitude and change rate is calculated.

[0197] (3) Fuzzy reasoning rules. According to the fuzzy rule table, determine the control measures required under the current state:

[0198] If the current amplitude is small and the rate of change is slow, the current impedance parameters are maintained; if the current amplitude is large and the rate of change is fast, the virtual resistance is significantly increased and the virtual reactance is reduced; if the current amplitude is moderate and the rate of change is medium, the impedance is adjusted according to the linear law.

[0199] (4) Defuzzification. The fuzzy output is defuzzified by weighted average or centroid method to obtain specific virtual impedance parameters:

[0200]

[0201] Where Z new is the adjusted virtual impedance, Z 1 , Z 2 , Z 3 is the impedance value corresponding to the fuzzy rule output, μ 1 , μ 2 , μ 3 is the degree of membership.

[0202] (5) Dynamically adjust the threshold and fuzzy rules. Adaptively adjust the threshold according to the grid operation status:

[0203]

[0204] Among them I th0 is the initial threshold, k is the adjustment coefficient, ΔI is the change in fault current amplitude, and the fuzzy rules are updated in real time to ensure that the optimal control effect can be maintained under different fault conditions.

[0205] See also Figure 7 , Figure 7 A structural block diagram of a grid-connected converter regulating device under distribution network fault provided by an embodiment of the present invention.

[0206] An embodiment of the present invention provides a network converter adjustment device under a distribution network fault, comprising:

[0207] The correction module 701 is used to connect the grid-connected converter to the grid equivalent to the internal potential and virtual impedance, and to correct the grid-connected point voltage and grid-connected point voltage phase angle of the grid-connected converter to obtain the corrected grid-connected point voltage and the corrected grid-connected point voltage phase angle;

[0208] The AC current acquisition module 702 is used to acquire the AC current of the grid-connected converter under the corrected grid connection point voltage;

[0209] The first regulating module 703 is used to trigger the steady-state control mode when the AC current is less than a preset current threshold, determine the virtual impedance gain through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and use the virtual impedance gain to regulate the grid-connected converter;

[0210] A virtual impedance optimal gain determination module 704 is used to trigger a fault control mode when the AC current is greater than a preset current threshold and less than a maximum allowable current, and to determine the virtual impedance optimal gain according to the fault current size and a preset classification threshold;

[0211] The second regulating module 705 is used to regulate the grid-connected converter by using the optimal gain of the virtual impedance.

[0212] In the embodiment of the present invention, the correction module 701 includes:

[0213] The parameter acquisition submodule is used to obtain the grid impedance, the fault current amplitude, the voltage phase angle before correction and the output current of the grid-forming converter;

[0214] A virtual impedance initial value calculation submodule is used to calculate the virtual impedance initial value according to the grid impedance and the fault current amplitude;

[0215] The initial grid connection point voltage calculation submodule is used to calculate the initial grid connection point voltage according to the initial value of the virtual impedance, the internal potential and the output current;

[0216] A virtual impedance angle calculation submodule is used to calculate the virtual impedance angle according to the initial value of the virtual impedance;

[0217] An initial correction grid connection point voltage phase angle calculation submodule is used to calculate the initial correction grid connection point voltage phase angle according to the voltage phase angle before correction and the virtual impedance angle;

[0218] A reference voltage and expected phase angle acquisition submodule, used to acquire a reference voltage and an expected phase angle of a grid-connected point;

[0219] A judgment submodule, used to judge whether the absolute value of the difference between the initial grid connection point voltage and the reference voltage is less than a preset voltage error tolerance, and whether the absolute value of the difference between the initial corrected grid connection point voltage phase angle and the expected phase angle is less than a preset phase angle error tolerance;

[0220] A return submodule is used for returning to the step of obtaining the grid impedance, the fault current amplitude, the voltage phase angle before correction and the output current of the grid-forming converter if no;

[0221] The modified grid connection point voltage and modified grid connection point voltage phase angle determination submodule is used to use the initial grid connection point voltage as the modified grid connection point voltage and determine the initial modified grid connection point voltage phase angle as the modified grid connection point voltage phase angle.

[0222] In the embodiment of the present invention, the first adjustment module 703 includes:

[0223] A first grid-connected point power expression constructing submodule, for triggering a steady-state control mode when the AC current is less than a preset current threshold, and constructing a first grid-connected point power expression through a preset small signal model;

[0224] A coupling coefficient analytical expression constructing submodule, used to construct a coupling coefficient analytical expression according to the first grid connection point power expression;

[0225] A power coupling coefficient generation submodule is used to generate a power coupling coefficient according to an analytical expression of the coupling coefficient;

[0226] The first regulating submodule is used to determine the virtual impedance gain through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and to use the virtual impedance gain to regulate the grid-forming converter.

[0227] In an embodiment of the present invention, the construction of a small signal model includes:

[0228] A first active power and a first reactive power acquisition module, used to acquire a first active power and a first reactive power outputted by the internal potential of the grid-connecting converter;

[0229] A second grid-connected point power expression generation module, used to generate a second grid-connected point power expression according to the first active power, the first reactive power, the internal potential and the virtual impedance;

[0230] A small signal analytical expression generation module, used to generate a small signal analytical expression based on the second grid connection point power expression;

[0231] The small signal model generation module is used to generate a small signal model of power control coupling according to a small signal analytical expression.

[0232] In the embodiment of the present invention, the virtual impedance optimal gain includes the virtual resistance optimal gain and the virtual reactance optimal gain; the virtual impedance optimal gain determination module 704 includes:

[0233] A fault control mode triggering submodule, used to trigger a fault control mode when the AC current is greater than a preset current threshold and less than a maximum allowable current;

[0234] A first virtual impedance optimal gain calculation submodule, used to calculate the optimal gain of the virtual resistor according to the fault current, the preset first threshold and the first preset resistance adjustment coefficient when the fault current is greater than the preset first threshold and less than the preset second threshold, and to calculate the optimal gain of the virtual reactance according to the fault current, the preset first threshold and the first preset reactance adjustment coefficient;

[0235] A second virtual impedance optimal gain calculation submodule, used to calculate the virtual resistance optimal gain according to the fault current, the preset second threshold and the second preset resistance adjustment coefficient, and calculate the virtual reactance optimal gain according to the fault current, the preset second threshold and the second preset reactance adjustment coefficient when the fault current is greater than the preset secondary threshold and less than the preset tertiary threshold;

[0236] The third virtual impedance optimal gain calculation submodule is used to use the preset maximum resistance gain as the virtual resistance optimal gain and the preset maximum reactance gain as the virtual reactance optimal gain when the fault current reaches the preset third-level threshold.

[0237] An embodiment of the present invention further provides an electronic device, the device comprising a processor and a memory:

[0238] The memory is used to store the program code and transmit the program code to the processor;

[0239] The processor is used to execute the grid-connecting converter adjustment method under distribution network fault according to the instructions in the program code.

[0240] The embodiment of the present invention further provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the grid-connected converter adjustment method under distribution network fault of the embodiment of the present invention.

[0241] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0242] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0243] It will be appreciated by those skilled in the art that the embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0244] The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0245] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0246] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0247] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0248] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0249] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0250] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for adjusting a grid-connected converter under a distribution network fault, characterized in that: include: The grid-connecting converter is equivalent to an internal potential and a virtual impedance and connected to the power grid, and the grid-connecting point voltage and the grid-connecting point voltage phase angle of the grid-connecting converter are corrected to obtain a corrected grid-connecting point voltage and a corrected grid-connecting point voltage phase angle; Obtaining the alternating current of the grid-connected converter under the corrected grid-connected point voltage; When the AC current is less than a preset current threshold, a steady-state control mode is triggered, with the goal of minimizing the power coupling coefficient, a virtual impedance gain is determined through a closed-loop feedback mechanism, and the grid-connected converter is adjusted using the virtual impedance gain; When the AC current is greater than the preset current threshold and less than the maximum allowable current, the fault control mode is triggered, the optimal virtual impedance gain is determined according to the fault current size and the preset classification threshold, and the grid-connected converter is adjusted using the optimal virtual impedance gain.

2. The method according to claim 1, characterized in that The step of correcting the grid connection point voltage and the grid connection point voltage phase angle of the grid-connected converter to obtain the corrected grid connection point voltage and the corrected grid connection point voltage phase angle comprises: Obtaining grid impedance, fault current amplitude, voltage phase angle before correction and output current of the grid-connected converter; Calculating an initial value of a virtual impedance according to the grid impedance and the fault current amplitude; Calculating an initial grid connection point voltage according to the initial value of the virtual impedance, the internal potential and the output current; Calculating a virtual impedance angle according to the initial value of the virtual impedance; Calculate the initial corrected grid connection point voltage phase angle according to the pre-corrected voltage phase angle and the virtual impedance angle; Obtain reference voltage and expected phase angle of the grid connection point; Determine whether the absolute value of the difference between the initial grid-connected point voltage and the reference voltage is less than a preset voltage error tolerance, and whether the absolute value of the difference between the initial corrected grid-connected point voltage phase angle and the expected phase angle is less than a preset phase angle error tolerance; If not, return to the step of obtaining the grid impedance, the fault current amplitude, the voltage phase angle before correction, and the output current of the grid-connected converter; If yes, the initial grid-connected point voltage is used as the modified grid-connected point voltage, and the initial modified grid-connected point voltage phase angle is determined as the modified grid-connected point voltage phase angle.

3. The method according to claim 1, characterized in that When the AC current is less than a preset current threshold, a steady-state control mode is triggered, a virtual impedance gain is determined through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and the step of using the virtual impedance gain to adjust the grid-connected converter includes: When the AC current is less than a preset current threshold, a steady-state control mode is triggered, and a first grid-connected point power expression is constructed through a preset small signal model; Constructing an analytical expression for the coupling coefficient according to the first grid connection point power expression; Generate a power coupling coefficient according to the coupling coefficient analytical expression; With the goal of minimizing the power coupling coefficient, a virtual impedance gain is determined through a closed-loop feedback mechanism, and the virtual impedance gain is used to adjust the grid-connected converter.

4. The method according to claim 3, characterized in that: The steps of constructing the small signal model include: Obtaining a first active power and a first reactive power outputted by the internal potential of the grid-connecting converter; generating a second grid connection point power expression according to the first active power, the first reactive power, the internal potential and the virtual impedance; Generate a small signal analytical expression based on the second grid connection point power expression; A small signal model of power control coupling is generated according to the small signal analytical expression.

5. The method according to claim 1, characterized in that The virtual impedance optimal gain includes a virtual resistance optimal gain and a virtual reactance optimal gain; when the AC current is greater than the preset current threshold and less than the maximum allowable current, the fault control mode is triggered, and the step of determining the virtual impedance optimal gain according to the fault current size and the preset classification threshold comprises: When the AC current is greater than the preset current threshold and less than the maximum allowable current, a fault control mode is triggered; When the fault current is greater than the preset first-level threshold and less than the preset second-level threshold, the optimal gain of the virtual resistor is calculated according to the fault current, the preset first threshold and the first preset resistance adjustment coefficient, and the optimal gain of the virtual reactance is calculated according to the fault current, the preset first threshold and the first preset reactance adjustment coefficient; When the fault current is greater than the preset secondary threshold and less than the preset tertiary threshold, the optimal gain of the virtual resistor is calculated according to the fault current, the preset second threshold and the second preset resistance adjustment coefficient, and the optimal gain of the virtual reactance is calculated according to the fault current, the preset second threshold and the second preset reactance adjustment coefficient; When the fault current reaches the preset third-level threshold, the preset maximum resistance gain is used as the optimal virtual resistance gain, and the preset maximum reactance gain is used as the optimal virtual reactance gain.

6. A grid-connected converter adjustment device under distribution network fault, characterized in that: include: A correction module is used to connect the grid-connected converter to the grid equivalent to internal potential and virtual impedance, and to correct the grid-connected point voltage and grid-connected point voltage phase angle of the grid-connected converter to obtain a corrected grid-connected point voltage and a corrected grid-connected point voltage phase angle; An AC current acquisition module, used to acquire the AC current of the grid-connected converter under the corrected grid-connected point voltage; A first regulating module is used for triggering a steady-state control mode when the AC current is less than a preset current threshold, determining a virtual impedance gain through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and regulating the grid-connected converter using the virtual impedance gain; A virtual impedance optimal gain determination module, used to trigger a fault control mode when the AC current is greater than the preset current threshold and less than the maximum allowable current, and determine the virtual impedance optimal gain according to the fault current size and the preset classification threshold; The second regulating module is used to regulate the grid-connected converter by using the optimal gain of the virtual impedance.

7. The device according to claim 6, characterized in that The correction module comprises: A parameter acquisition submodule, used to obtain the grid impedance, the fault current amplitude, the voltage phase angle before correction and the output current of the grid-connected converter; A virtual impedance initial value calculation submodule, used to calculate the virtual impedance initial value according to the grid impedance and the fault current amplitude; An initial grid connection point voltage calculation submodule, used to calculate the initial grid connection point voltage according to the initial value of the virtual impedance, the internal potential and the output current; A virtual impedance angle calculation submodule, used for calculating the virtual impedance angle according to the virtual impedance initial value; An initial correction grid connection point voltage phase angle calculation submodule, used to calculate an initial correction grid connection point voltage phase angle according to the pre-correction voltage phase angle and the virtual impedance angle; A reference voltage and expected phase angle acquisition submodule, used to acquire a reference voltage and an expected phase angle of a grid-connected point; A judgment submodule, used to judge whether the absolute value of the difference between the initial grid-connected point voltage and the reference voltage is less than a preset voltage error tolerance, and whether the absolute value of the difference between the initial corrected grid-connected point voltage phase angle and the expected phase angle is less than a preset phase angle error tolerance; A return submodule, for returning to the step of obtaining the grid impedance, the fault current amplitude, the voltage phase angle before correction and the output current of the grid-connected converter if no; The modified grid connection point voltage and modified grid connection point voltage phase angle determination submodule is used to use the initial grid connection point voltage as the modified grid connection point voltage and determine the initial modified grid connection point voltage phase angle as the modified grid connection point voltage phase angle.

8. The device according to claim 6, characterized in that The first adjustment module includes: A first grid-connected point power expression constructing submodule, used for triggering a steady-state control mode when the AC current is less than a preset current threshold, and constructing a first grid-connected point power expression through a preset small signal model; A coupling coefficient analytical expression constructing submodule, used to construct a coupling coefficient analytical expression according to the first grid connection point power expression; A power coupling coefficient generating submodule, used for generating a power coupling coefficient according to the coupling coefficient analytical expression; The first regulating submodule is used to determine the virtual impedance gain through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and use the virtual impedance gain to regulate the grid-connected converter.

9. An electronic device, characterized in that: The device comprises a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the grid-connected converter adjustment method under distribution network fault according to the instructions in the program code as described in any one of claims 1-5.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the grid-connected converter adjustment method under distribution network fault according to any one of claims 1 to 5.

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