Grid-forming Inverter Regulation Method, Device, Equipment and Medium under Distribution Network Fault

Abstract

The present invention discloses a method, device, equipment and medium for regulating a network-forming converter under a distribution network fault, which are used to solve the technical problem that the virtual impedance control of the network-forming converter is difficult to adjust in real time, affecting the stability of the power grid. The method includes: equivalently representing the network-forming converter as an internal electromotive force and a virtual impedance and incorporating them into the power grid, and correcting the grid connection point voltage and the phase angle of the grid connection point voltage of the network-forming converter to obtain a corrected grid connection point voltage and a corrected grid connection point voltage phase angle; obtaining the AC current of the network-forming converter under the corrected grid connection point voltage; when the AC current is less than a preset current threshold, triggering a steady-state control mode, and determining the virtual impedance gain through a closed-loop feedback mechanism with the minimum power coupling coefficient as the target to regulate the network-forming converter; when the AC current is greater than the preset current threshold and less than the maximum allowable current, triggering a fault control mode, and determining the optimal virtual impedance gain according to the magnitude of the fault current and a preset hierarchical threshold; and regulating the network-forming converter by using the optimal virtual impedance gain.

Description

Technical Field

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

[0002] With the transformation of the global energy structure, the proportion of renewable energy sources 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 ability of the distribution network has been significantly reduced, thereby affecting the stability of the power grid. Especially in the context of large-scale renewable energy access, the power grid's ability to respond to sudden faults faces a severe test. The protection systems of traditional distribution networks usually rely on the fault currents provided by synchronous machines and generator sets to achieve protection functions. However, with the grid connection of renewable energy sources, the fault current tolerance of these systems has gradually weakened, resulting in the difficulty for the distribution network to quickly recover during a fault, and even possibly causing equipment damage or system collapse.

[0003] In order to improve the fault response ability of the distribution network, a grid-forming converter can maintain the frequency and voltage stability of the power grid by controlling its own output power in the absence of a synchronous machine. It not only has the ability to regulate frequency and voltage, but also can quickly respond and provide necessary support when a fault occurs in the power grid. However, the fault current tolerance of the grid-forming converter is limited and it cannot withstand large-scale short-circuit currents like traditional synchronous machines. Therefore, in order to ensure its reliable operation under grid faults, 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 the fault current by simulating the equivalent impedance of the line in the power grid, preventing the system from overloading. The core idea of this strategy is to adjust the relationship between the output current of the converter and the system load, thereby limiting the excessive peak value of the fault current. 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 in the case of multiple distributed power sources being grid-connected, the functional fluctuations of different power sources are intertwined, making the power decoupling of the power grid more difficult, and the traditional virtual impedance control is difficult to cope with the challenges brought about by power fluctuations. Currently, the traditional virtual impedance control has deficiencies in power decoupling and cannot accurately distinguish the impact of fluctuations of different power sources on the system, resulting in unsatisfactory control effects.

[0005] In addition, with the complexity of the power grid scale and topology, the adaptability of traditional strategies is poor, and it is difficult to quickly address the non-linear problems brought about by load and generation changes in the power grid. The dynamic changes and non-linear characteristics of the power grid make it difficult to adjust virtual impedance control in real time. Especially in the case of high load or extreme fluctuations, the real-time performance and computing power of control strategies 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 regulating a network-forming converter under a distribution network fault, aiming to solve the technical problem that the existing virtual impedance control of the network-forming converter is difficult to adjust in real time and affects the stability of the power grid.

[0007] The present invention provides a method for regulating a network-forming converter under a distribution network fault, including:

[0008] Equivalent the network-forming converter to an internal electromotive force and a virtual impedance and incorporate it into the power grid, and correct the connection point voltage and the connection point voltage phase angle of the network-forming converter to obtain a corrected connection point voltage and a corrected connection point voltage phase angle;

[0009] Obtain the alternating current of the network-forming converter under the corrected connection point voltage;

[0010] When the alternating current is less than a preset current threshold, trigger a steady-state control mode, aiming at the minimum power coupling coefficient, determine the virtual impedance gain through a closed-loop feedback mechanism, and use the virtual impedance gain to regulate the network-forming converter;

[0011] When the alternating current is greater than the preset current threshold and less than the maximum allowable current, trigger a fault control mode, and determine the optimal virtual impedance gain according to the magnitude of the fault current and a preset grading threshold;

[0012] Use the optimal virtual impedance gain to regulate the network-forming converter.

[0013] Optionally, the step of correcting the connection point voltage and the connection point voltage phase angle of the network-forming converter to obtain a corrected connection point voltage and a corrected connection point voltage phase angle includes:

[0014] Obtain the power grid impedance, the magnitude of the fault current, the voltage phase angle before correction, and the output current of the network-forming converter;

[0015] Calculate the initial value of the virtual impedance according to the power grid impedance and the magnitude of the fault current;

[0016] Calculate the initial connection point voltage according to the initial value of the virtual impedance, the internal electromotive force, and the output current;

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

[0018] Calculate the initial corrected grid connection point voltage phase angle based on the voltage phase angle before correction and the virtual impedance angle;

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

[0020] Determine 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 desired phase angle is less than a preset phase angle error tolerance;

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

[0022] If so, use the initial grid connection point voltage as the corrected grid connection point voltage, and determine the initial corrected grid connection point voltage phase angle as the corrected grid connection point voltage phase angle.

[0023] Optionally, the step of triggering the steady-state control mode when the AC current is less than a preset current threshold, aiming at the minimum power coupling coefficient, determining the virtual impedance gain through a closed-loop feedback mechanism, and adjusting the grid-forming converter with the virtual impedance gain includes:

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

[0025] Construct a coupling coefficient analytical expression according to the first grid connection point power expression;

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

[0027] Aim at the minimum power coupling coefficient, determine the virtual impedance gain through a closed-loop feedback mechanism, and adjust the grid-forming converter with the virtual impedance gain.

[0028] Optionally, the construction steps of the small-signal model include:

[0029] Obtain the first active power and the first reactive power output by the internal electromotive force of the grid-forming converter;

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

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

[0032] Generate a small-signal model of power control coupling 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; the step of triggering a fault control mode and determining the virtual impedance optimal gain according to the magnitude of the fault current and a preset grading threshold when the alternating current is greater than the preset current threshold and less than the maximum allowable current includes:

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

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

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

[0038] The present invention also provides a grid-forming converter adjustment device under a distribution network fault, including:

[0039] A correction module for equivalent the grid-forming converter to an internal electromotive force and a virtual impedance and incorporating them into the power grid, and correcting the grid connection point voltage and the grid connection point voltage phase angle of the grid-forming converter to obtain a corrected grid connection point voltage and a corrected grid connection point voltage phase angle;

[0040] An alternating current acquisition module for acquiring the alternating current of the grid-forming converter under the corrected grid connection point voltage;

[0041] A first adjustment module for triggering a steady-state control mode when the alternating current is less than the preset current threshold, determining the virtual impedance gain with the minimum power coupling coefficient as the target through a closed-loop feedback mechanism, and adjusting the grid-forming converter using the virtual impedance gain;

[0042] A virtual impedance optimal gain determination module for triggering a fault control mode when the alternating current is greater than the preset current threshold and less than the maximum allowable current, and determining the virtual impedance optimal gain according to the magnitude of the fault current and a preset grading threshold;

[0043] A second adjustment module for adjusting the grid-forming converter using the virtual impedance optimal gain.

[0044] Optionally, the correction module includes:

[0045] A parameter acquisition sub-module, configured to acquire the grid impedance, the fault current amplitude, the voltage phase angle before correction, and the output current of the grid-forming converter;

[0046] A virtual impedance initial value calculation sub-module, configured to calculate an initial value of the virtual impedance according to the grid impedance and the fault current amplitude;

[0047] An initial connection point voltage calculation sub-module, configured to calculate an initial connection point voltage according to the initial value of the virtual impedance, the internal electromotive force, and the output current;

[0048] A virtual impedance angle calculation sub-module, configured to calculate a virtual impedance angle according to the initial value of the virtual impedance;

[0049] An initial corrected connection point voltage phase angle calculation sub-module, configured to calculate an initial corrected connection point voltage phase angle according to the voltage phase angle before correction and the virtual impedance angle;

[0050] A reference voltage and desired phase angle acquisition sub-module, configured to acquire the reference voltage and the desired phase angle of the connection point;

[0051] A judgment sub-module, configured to judge whether the absolute value of the difference between the initial 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 connection point voltage phase angle and the desired phase angle is less than a preset phase angle error tolerance;

[0052] A return sub-module, configured to, if not, return to the step of acquiring the grid impedance, the fault current amplitude, the voltage phase angle before correction, and the output current of the grid-forming converter;

[0053] A corrected connection point voltage and corrected connection point voltage phase angle determination sub-module, configured to, if so, use the initial connection point voltage as the corrected connection point voltage, and determine the initial corrected connection point voltage phase angle as the corrected connection point voltage phase angle.

[0054] Optionally, the first adjustment module includes:

[0055] A first connection point power expression construction sub-module, configured to trigger a steady-state control mode when the AC current is less than a preset current threshold, and construct a first connection point power expression through a preset small-signal model;

[0056] A coupling coefficient analysis expression construction sub-module, configured to construct a coupling coefficient analysis expression according to the first connection point power expression;

[0057] A power coupling coefficient generation sub-module, configured to generate a power coupling coefficient according to the coupling coefficient analysis expression;

[0058] The first regulator module is used to determine the virtual impedance gain through a closed-loop feedback mechanism with the minimum power coupling coefficient as the target, and adjust the network-forming converter using the virtual impedance gain.

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

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

[0061] The processor is used to execute the method for adjusting the network-forming converter under the distribution network fault described in any one of the above according to the instructions in the program codes.

[0062] The present invention also provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the method for adjusting the network-forming converter under the distribution network fault described in any one of the above.

[0063] As can be seen from the above technical solutions, the present invention has the following advantages: The present invention discloses a method for adjusting a network-forming converter under a distribution network fault, and specifically discloses: equivalent the network-forming converter to an internal electromotive force and a virtual impedance and incorporate them into the power grid, and correct the grid connection point voltage and the grid connection point voltage phase angle of the network-forming converter to obtain the corrected grid connection point voltage and the corrected grid connection point voltage phase angle; obtain the alternating current of the network-forming converter under the corrected grid connection point voltage; when the alternating current is less than a preset current threshold, trigger the steady-state control mode, determine the virtual impedance gain through a closed-loop feedback mechanism with the minimum power coupling coefficient as the target, and adjust the network-forming converter using the virtual impedance gain; when the alternating current is greater than the preset current threshold and less than the maximum allowable current, trigger the fault control mode, and determine the optimal virtual impedance gain according to the magnitude of the fault current and the preset grading threshold; adjust the network-forming converter using the optimal virtual impedance gain. The present invention realizes the dynamic adjustment of parameters by finely adjusting the virtual negative resistance and virtual impedance parameters, ensuring the efficient operation and reliability of the system. Description of the Drawings

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

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

[0066] Figure 2 The topology decoupling and control system of the network-forming converter provided by the embodiment of the present invention;

[0067] Figure 3 The grid-connected equivalent circuit of the centralized network-forming converter provided by the embodiment of the present invention;

[0068] Figure 4 The equivalent circuit after the virtual impedance control is applied;

[0069] Figure 5 The schematic diagram of the small-signal model of the network-forming converter;

[0070] Figure 6 The schematic diagram of the principle in the fault current limiting stage in the embodiment of the present invention;

[0071] Figure 7 The structural block diagram of a network-forming converter regulating device under the fault of the distribution network provided by the embodiment of the present invention. Specific embodiments

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

[0073] To make the invention purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0074] Please refer to Figure 1 , Figure 1 The step flowchart of a method for regulating a network-forming converter under the fault of a distribution network provided by the embodiment of the present invention.

[0075] A method for regulating a network-forming converter under the fault of a distribution network provided by the present invention is applied to the topology decoupling and control system of the network-forming converter. The method may specifically include the following steps:

[0076] Step 101, equivalent the network-forming converter to an internal electromotive force and a virtual impedance and incorporate them into the power grid, and correct the grid connection point voltage and the grid connection point voltage phase angle of the network-forming converter to obtain the corrected grid connection point voltage and the corrected grid connection point voltage phase angle;

[0077] The network-forming converter is a new type of converter that can actively construct voltage and frequency in the power system. When the network-forming converter is connected to the power grid, it can regulate the power grid during grid faults, enabling the power grid to return to a relatively stable state.

[0078] As Figure 2 and Figure 3 shown Figure 2 is the topology decoupling and control system of the network-forming converter provided by the embodiment of the present invention; Figure 3 is the grid-connected equivalent circuit of the centralized network-forming converter provided by the embodiment of the present invention. The topology decoupling and control system of the embodiment of the present invention adopts the virtual synchronous machine control of network-forming. The virtual synchronous machine control is mainly divided into three parts: power synchronization loop control, virtual impedance control, and double closed-loop control. Among them, the active power control loop of the power synchronization link can simulate the inertia and damping characteristics of the synchronous machine, and at the same time add active power droop control to respond to the grid frequency change, and finally generate the phase of the grid-connected point voltage. The reactive power control loop contains reactive power droop control, and generates the amplitude of the grid-connected point voltage by simulating the excitation characteristics of the synchronous machine. To achieve power decoupling and fault current limiting, the amplitude and phase angle of the grid-connected point voltage generated by the power synchronization link need to be corrected by virtual impedance control and then enter the voltage-current double closed-loop control. Among them, the voltage-current double 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, obtain the grid impedance, fault current amplitude, voltage phase angle before correction, and output current of the network-forming converter;

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

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

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

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

[0085] S16, obtain the reference voltage and desired phase angle of the grid-connected point;

[0086] S17, determine whether the absolute value of the difference between the initial grid-connected point voltage and the reference voltage is less than the preset voltage error tolerance, and whether the absolute value of the difference between the initial corrected grid-connected point voltage phase angle and the desired phase angle is less than the 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-forming converter;

[0088] S19. If so, use the initial connection point voltage as the corrected connection point voltage, and determine the initial corrected connection point voltage phase angle as the corrected connection point voltage phase angle.

[0089] During the correction process, the grid-forming converter is equivalent to an internal electromotive force E and a virtual impedance connected in series to the grid. According to the grid impedance and the fault current amplitude I fault , dynamically calculate the initial value of the virtual impedance:

[0090]

[0091] where 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 the virtual impedance, is the initial value of the virtual resistance, is the initial value of the virtual reactance, j is the imaginary unit, is the grid impedance, is the grid resistance, is the grid reactance.

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

[0093]

[0094] where E is the amplitude of the internal electromotive force of the grid-forming converter, I is the output current, is the initial value of the virtual impedance.

[0095] To ensure voltage stability, the correction target is:

[0096] ,

[0097] where is the reference voltage set by the system, which changes dynamically with the changes of U g , the virtual impedance, and the grid impedance angle.

[0098] By adjusting the gains of the virtual resistance R v and the virtual reactance X v , make:

[0099]

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

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

[0102]

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

[0104] The correction target is:

[0105]

[0106] wherein, is the expected phase angle of the grid connection point to achieve power decoupling.

[0107] By dynamically adjusting the virtual impedance gain, such that:

[0108]

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

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

[0111]

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

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

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

[0115]

[0116] wherein, i is the output current of the grid-forming converter, U is the amplitude of the output voltage of the grid-forming converter, U g is the amplitude of the grid voltage, δ is the phase angle difference between the internal electromotive force of the grid-forming converter and the grid voltage, θ is the grid impedance angle, defined as , wherein R g is the resistance component of the grid impedance, X g is the reactance component of the grid impedance, and Z is the equivalent impedance, including the grid impedance and the virtual impedance .

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

[0118]

[0119] Among them, 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 grid-forming converter can be respectively expressed as:

[0121]

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

[0123]

[0124] When the grid characteristics are not purely resistive or purely inductive, the partial derivatives of the active power and reactive power output by the grid-forming converter with respect to δ and U exist, and there is coupling between δ and U . Therefore, it is impossible to achieve independent control of the active power δ or U by separately controlling P or the reactive power Q .

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

[0126] Step 102: Obtain the AC current of the grid-forming converter under the corrected grid connection point voltage;

[0127] Step 103: When the AC current is less than the preset current threshold, trigger the steady-state control mode, target the minimum power coupling coefficient, determine the virtual impedance gain through a closed-loop feedback mechanism, and adjust the grid-forming converter using the virtual impedance gain;

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

[0129] When the AC current of the network-forming converter is less than the preset current threshold, it enters the steady-state control mode. According to the grid impedance characteristics, the virtual resistance is dynamically adjusted. With the goal of minimizing the power coupling coefficient, the virtual negative resistance gain is calibrated in real time through a closed-loop feedback mechanism to achieve the 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 the preset current threshold, trigger the steady-state control mode, and construct the first connection point power expression through a preset small-signal model;

[0132] S22, construct the coupling coefficient analysis expression according to the first connection point power expression;

[0133] S23, generate the power coupling coefficient according to the coupling coefficient analysis expression;

[0134] S24, with the goal of minimizing the power coupling coefficient, determine the virtual impedance gain through a closed-loop feedback mechanism, and use the virtual impedance gain to adjust the network-forming converter.

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

[0136]

[0137] where E is the internal electromotive force of the network-forming converter, U is the connection point voltage, , is the phase angle difference between the internal electromotive force and the connection point voltage.

[0138] Introduce a small-signal model, and through linearization under small perturbations, construct the coupling coefficient analysis expression:

[0139]

[0140] Based on the closed-loop feedback mechanism, the virtual resistance gain k R and the virtual reactance gain k X are calibrated in real time, with the goal of minimizing the power coupling coefficient:

[0141]

[0142] When the power decoupling is completed.

[0143] Among them, the construction steps of the small-signal model include:

[0144] S31, obtain the first active power and the first reactive power output by the internal electromotive force of the network-forming converter;

[0145] S32. Generate a second grid connection point power expression based on the first active power, the first reactive power, the internal electromotive force, and the virtual impedance;

[0146] S33. Generate a small-signal analytical expression based on the second grid connection point power expression;

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

[0148] In specific implementation, as Figure 4 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 inductance, 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 the decoupling control is to achieve the power decoupling at point B. The power characteristics at point A are:

[0149]

[0150] where P1 and Q1 are the first active power and the first reactive power output at point A respectively, X and R are the line inductive reactance and the line resistance respectively, and are defined as X = ωL1 + ωL v , R = R v + R1, E is the internal electromotive force of the grid-forming converter, U g is the grid connection point voltage, and δ0 and δ are the steady-state phase angle of the internal electromotive force and the grid connection point voltage phase angle respectively.

[0151] Further represent the grid connection point voltage through the electromotive force and the virtual impedance, and list the analytical expressions of the second grid connection point power (including active power and reactive power):

[0152]

[0153] When the virtual negative resistance R v = -R l is added, the active power and reactive power at point B can be simplified to:

[0154]

[0155] Based on the above power equations, further derive the small-signal analytical expressions of the active control link and the reactive control link of the grid-forming converter:

[0156]

[0157] And when the internal electromotive force power angle δ0 is relatively small, the above formula is further simplified:

[0158]

[0159] Furthermore, a small-signal control model for power control coupling is obtained (as Figure 5 shown):

[0160]

[0161] where P and Q are the active power and reactive power output by the converter, E is the internal electromotive force of the network-forming converter, U g is the grid-connected point voltage, is the phase angle between the internal electromotive force of the network-forming converter and the grid-connected point voltage, X and R are the grid reactance and resistance, X v , R v are the virtual reactance and virtual resistance, △E, △ are small-signal perturbation variables (small perturbations of the internal electromotive force and phase angle).

[0162] Power coupling coefficient:

[0163]

[0164] In the small-signal model, the power coupling coefficients G Pδ and G QE exhibit the same power coupling characteristics: when G Pδ is significantly greater than G PE , the active power is mainly controlled by the phase angle; when G QE is significantly greater than G Qδ , the reactive power is mainly controlled by the voltage amplitude. By adjusting the virtual impedance parameters R v , X v , the power control decoupling effect of the small-signal model can be optimized.

[0165] Step 104: When the AC current is greater than the preset current threshold and less than the maximum allowable current, trigger the fault control mode, and determine the optimal gain of the virtual impedance according to the magnitude of the fault current and the preset grading threshold;

[0166] Step 105: Adjust the network-forming converter using the optimal gain of the virtual impedance.

[0167] As Figure 6 shown, i 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, enter the steady-state control mode.

[0168] In the embodiment of the present invention, when the AC current is greater than the preset current threshold and less than the maximum allowable current, trigger the fault control mode, and determine the optimal gain of the virtual impedance according to the magnitude of the fault current and the preset grading threshold.

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

[0170] S41. When the alternating current is greater than the preset current threshold and less than the maximum allowable current, trigger the fault control mode;

[0171] S42. When the fault current is greater than the preset first-level threshold and less than the preset second-level threshold, calculate the optimal virtual resistance gain according to the fault current, the preset first threshold, and the first preset resistance adjustment coefficient, and calculate the optimal virtual reactance gain 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 second-level threshold and less than the preset third-level threshold, calculate the optimal virtual resistance gain according to the fault current, the preset second threshold, and the second preset resistance adjustment coefficient, and calculate the optimal virtual reactance gain 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, use the preset maximum resistance gain as the optimal virtual resistance gain and the preset maximum reactance gain as the optimal virtual reactance gain.

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

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

[0176] (2) The second-level threshold (I th2 = 1.5I n ): The fault current increases significantly, and start to adjust the linear-exponential hybrid gain curve;

[0177] (3) The third-level threshold (I th3 = 2.0I n ): The fault current is close to the equipment limit, and adopt the fast saturation gain mode.

[0178] Among them, I n is the rated current of the grid-forming converter, and I th1 , I th2 , I th3 are the first-level, second-level, and third-level current thresholds respectively, and are proportionally adjusted according to the rated current according to 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 calculation formula for the optimal virtual resistance gain is:

[0180]

[0181] The formula for calculating the optimal gain of virtual reactance is as follows:

[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 formula for calculating the optimal gain of virtual resistance is:

[0185]

[0186] The formula for calculating the optimal gain of 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 optimal gain of virtual resistance, and the preset maximum reactance gain is used as the optimal gain of 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 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, ensuring 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 fault and the current change rate dI / dt, and use the real-time collected data as the input of the fuzzy controller for fuzzy inference.

[0196] (2) Fuzzification processing. Divide the fault current amplitude and change rate into different levels, construct a fuzzy membership function, and calculate the membership degrees of the current amplitude and change rate.

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

[0198] If the current amplitude is small and the change rate is slow, maintain the current impedance parameters; if the current amplitude is large and the change rate is fast, significantly increase the virtual resistance and decrease the virtual reactance; if the current amplitude is moderate and the change rate is medium, adjust the impedance according to a linear law.

[0199] (4) Defuzzification. Defuzzify the fuzzy output through weighted average or centroid method to obtain specific virtual impedance parameters:

[0200]

[0201] where Z new is the adjusted virtual impedance, Z1, Z2, Z3 are the impedance values corresponding to the fuzzy rule output, and μ1, μ2, μ3 are the membership degrees.

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

[0203]

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

[0205] Please refer to Figure 7 , Figure 7 which is the structural block diagram of a grid-forming converter regulation device under a distribution network fault provided by an embodiment of the present invention.

[0206] An embodiment of the present invention provides a grid-forming converter regulation device under a distribution network fault, including:

[0207] A correction module 701, configured to equivalent the grid-forming converter to an internal electromotive force and a virtual impedance and incorporate them into the power grid, and correct the grid connection point voltage and the grid connection point voltage phase angle of the grid-forming converter to obtain a corrected grid connection point voltage and a corrected grid connection point voltage phase angle;

[0208] An AC current acquisition module 702, configured to acquire the AC current of the grid-forming converter under the corrected grid connection point voltage;

[0209] A first regulation module 703, configured to trigger a steady-state control mode when the AC current is less than a preset current threshold, determine the virtual impedance gain with the minimum power coupling coefficient as the target through a closed-loop feedback mechanism, and regulate the grid-forming converter by using the virtual impedance gain;

[0210] The virtual impedance optimal gain determination module 704 is configured to trigger a fault control mode when the alternating current is greater than a preset current threshold and less than the maximum allowable current, and determine the virtual impedance optimal gain according to the magnitude of the fault current and the preset grading threshold;

[0211] The second adjustment module 705 is configured to adjust the grid-forming converter by using the virtual impedance optimal gain.

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

[0213] A parameter acquisition sub-module, configured to acquire 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 sub-module, configured to calculate the virtual impedance initial value according to the grid impedance and the fault current amplitude;

[0215] An initial connection point voltage calculation sub-module, configured to calculate the initial connection point voltage according to the virtual impedance initial value, the internal electromotive force, and the output current;

[0216] A virtual impedance angle calculation sub-module, configured to calculate the virtual impedance angle according to the virtual impedance initial value;

[0217] An initial corrected connection point voltage phase angle calculation sub-module, configured to calculate the initial corrected connection point voltage phase angle according to the voltage phase angle before correction and the virtual impedance angle;

[0218] A reference voltage and desired phase angle acquisition sub-module, configured to acquire the reference voltage and the desired phase angle of the connection point;

[0219] A judgment sub-module, configured to judge whether the absolute value of the difference between the initial 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 connection point voltage phase angle and the desired phase angle is less than a preset phase angle error tolerance;

[0220] A return sub-module, configured to, if not, return to the step of acquiring the grid impedance, the fault current amplitude, the voltage phase angle before correction, and the output current of the grid-forming converter;

[0221] A corrected connection point voltage and corrected connection point voltage phase angle determination sub-module, configured to, if so, use the initial connection point voltage as the corrected connection point voltage and determine the initial corrected connection point voltage phase angle as the corrected connection point voltage phase angle.

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

[0223] A first connection point power expression construction sub-module, configured to trigger a steady-state control mode when the alternating current is less than a preset current threshold, and construct a first connection point power expression through a preset small-signal model;

[0224] A coupling coefficient analytical expression construction sub-module, configured to construct a coupling coefficient analytical expression according to the first grid connection point power expression;

[0225] A power coupling coefficient generation sub-module, configured to generate a power coupling coefficient according to the coupling coefficient analytical expression;

[0226] A first regulation sub-module, aiming at minimizing the power coupling coefficient, determining the virtual impedance gain through a closed-loop feedback mechanism, and regulating the network-forming converter by using the virtual impedance gain.

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

[0228] A first active power and first reactive power acquisition module, configured to acquire the first active power and the first reactive power output by the internal potential of the network-forming converter;

[0229] A second grid connection point power expression generation module, configured to generate a second grid connection 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, configured to generate a small-signal analytical expression based on the second grid connection point power expression;

[0231] A small-signal model generation module, configured to generate a small-signal model of power control coupling according to the small-signal analytical expression.

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

[0233] A fault control mode trigger sub-module, configured to trigger a fault control mode when the AC current is greater than a preset current threshold and less than the maximum allowable current;

[0234] A first optimal virtual impedance gain calculation sub-module, configured to calculate the optimal virtual resistance gain according to the fault current, a preset first threshold, and a first preset resistance adjustment coefficient, and calculate the optimal virtual reactance gain according to the fault current, the preset first threshold, and a first preset reactance adjustment coefficient when the fault current is greater than a preset first-level threshold and less than a preset second-level threshold;

[0235] A second optimal virtual impedance gain calculation sub-module, configured to calculate the optimal virtual resistance gain according to the fault current, a preset second threshold, and a second preset resistance adjustment coefficient, and calculate the optimal virtual reactance gain according to the fault current, the preset second threshold, and a second preset reactance adjustment coefficient when the fault current is greater than the preset second-level threshold and less than a preset third-level threshold;

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

[0237] An embodiment of the present invention also provides an electronic device, which includes a processor and a memory:

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

[0239] The processor is used to execute the grid-forming converter regulation method under the distribution network fault in the embodiment of the present invention according to the instructions in the program codes.

[0240] An embodiment of the present invention also provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the grid-forming converter regulation method under the distribution network fault in the embodiment of the present invention.

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

[0242] Each embodiment in this specification is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0243] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a device, or a computer program product. Therefore, the embodiments of the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, 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 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 flowcharts and / or block diagrams, and the combination of processes and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal devices generate for realizing in the process Figure 1 one process or multiple processes and / or blocksFigure 1 means for the functions specified in one or more boxes.

[0245] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction means that implements in the process Figure 1 one process or multiple processes and / or boxes Figure 1 the functions specified in one or more boxes.

[0246] These computer program instructions may also be loaded onto a computer or other programmable data processing terminal device, such that a series of operation steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable terminal device provide for implementing in the process Figure 1 one process or multiple processes and / or boxes Figure 1 the steps of the functions specified in one or more boxes.

[0247] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling 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 for analysis, stored data, displayed data, etc.) involved in this application are all information and data that have been authorized by the user or fully authorized by all parties. And the collection, use and processing of relevant data need to comply with the relevant laws, regulations and standards of relevant countries and regions, and corresponding operation entrances are provided for users to choose to authorize or refuse.

[0249] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or terminal device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the said element.

[0250] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate 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, and a virtual impedance gain is determined through a closed-loop feedback mechanism with the goal of minimizing the power coupling coefficient, and the virtual impedance gain is used to adjust the grid-connected converter, including: 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; Taking the power coupling coefficient as the minimum as the goal, determining the virtual impedance gain through a closed-loop feedback mechanism, and using the virtual impedance gain to adjust the grid-connected converter; 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 a virtual impedance optimal gain is determined according to the fault current size and a preset classification threshold, wherein the virtual impedance optimal gain includes a virtual resistance optimal gain and a virtual reactance optimal gain, including: 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; The virtual impedance optimal gain is used to adjust the grid-connected converter.

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; Calculating an 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 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.

4. A grid-connected converter adjustment device under distribution network fault, used to execute the method according to any one of claims 1 to 3, 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.

5. The device according to claim 4, 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-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; 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.

6. The device according to claim 4, 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.

7. An electronic device, characterized in that: The device comprises a processor and a memory: The memory is used to store program code and transmit the program code 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 1-3.

8. 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 faults as described in any one of claims 1-3.

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