Method and system for determining short-circuit current of grid-forming power electronic device, and storage medium, electronic device, chip, program product and program

Abstract

Disclosed in the present invention are a method and system for determining a short-circuit current of a grid-forming power electronic device. The method comprises: establishing a short-circuit equivalent model for a grid-forming power electronic device, and initializing a dynamic compensation current value to 0; acquiring a node voltage prediction value and a fixed branch short-circuit current prediction value on the basis of the present dynamic compensation current value and the short-circuit equivalent model for the grid-forming power electronic device; determining a power electronic device short-circuit current prediction value on the basis of the present fixed branch short-circuit current prediction value and the present dynamic compensation current value; determining the maximum current limit value, an active current limit value and a reactive current limit value of the power electronic device under an actual short-circuit fault; performing three-level amplitude limiting, and determining an active current value and a reactive current value after amplitude limiting; calculating a compensation current dynamic correction amount; and if the present compensation current dynamic correction amount is less than or equal to a preset threshold, determining that the present power electronic device short-circuit current prediction value is the short-circuit current actual value of the grid-forming power electronic device.

Description

A method and system for determining short-circuit current of a grid-type power electronic device, a storage medium, an electronic device, a chip, a program product, and a program

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on the Chinese patent application with application number 202311559084.8, application date November 22, 2023, and invention name “A method and system for determining the short-circuit current of grid-type power electronic equipment”, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field

[0003] The present invention relates to the technical field of power system simulation, and more specifically, to a method and system for determining the short-circuit current of a grid-type power electronic device, a storage medium, an electronic device, a chip, a program product, and a program. Background Art

[0004] Power electronic devices, such as renewable energy generation units and energy storage devices, based on grid-connected converters present voltage source characteristics to the grid, closely mimicking the characteristics of conventional synchronous generators. They provide active frequency, voltage support, and damping for the grid, effectively alleviating transient overvoltage and insufficient frequency support capacity issues associated with high renewable energy and DC power grid integration, and thus have broad application prospects. Currently, there is considerable research on various control schemes for grid-connected power electronic devices, but this research primarily focuses on electromagnetic simulation platforms for microgrids or small-scale grids. Currently, there is a lack of research on the large-scale integration of grid-connected power electronic devices into the grid. Short-circuit current calculation for grid-connected power electronic devices connected to the grid, specifically for engineering calculations, would provide theoretical and practical support for device selection and switch breaking capacity verification. Currently, there are no relevant literature reports on short-circuit current calculation for grid-connected power electronic devices. Existing commercial short-circuit current calculation software also fails to consider grid-connected power electronic device models.

[0005] Conventional short-circuit current calculation methods represent various components in the power grid using circuit models, primarily impedance models, admittance models, voltage source models with internal impedance, and constant current source models. These circuit models and their topological connections are used to construct positive-sequence, negative-sequence, and zero-sequence networks, generating node voltage equations for each sequence. Boundary condition equations can be established for each fault point based on the fault type. By combining the node voltage equations and boundary condition equations, the voltage values ​​for each sequence at all nodes in the power grid and the short-circuit current at the short-circuit point can be calculated.

[0006] High-proportion power electronic power supply equipment, such as wind power and photovoltaic power generation, differs from traditional synchronous units in principle and structure, which means that their short-circuit current characteristics are fundamentally different from those of traditional generators. They cannot be simply ignored, nor can they be equated with a potential source after subtransient / transient reactance, as with traditional synchronous generators. In the early stages of renewable energy development, the scale was small, and the short-circuit current provided to the grid connection point was far less than the short-circuit level of the grid connection point itself, which had little impact on the accuracy of short-circuit current calculations. In recent years, the installed capacity of wind power and photovoltaic power generation has grown rapidly, and the short-circuit current they provide will become non-negligible. With the continuous expansion of the power grid and the widespread integration of power electronic power sources and grid equipment, the short-circuit current calculation theories and methods based on the principles of traditional synchronous motors are no longer able to meet the requirements of grid development in terms of completeness and accuracy.

[0007] Therefore, a method for determining the short-circuit current of grid-type power electronic equipment is needed.

[0008] Summary of the Invention

[0009] The present invention proposes a method and system for determining the short-circuit current of a grid-type power electronic device, a storage medium, an electronic device, a chip, a program product, and a program to solve the problem of how to efficiently and accurately determine the short-circuit current of a grid-type power electronic device.

[0010] In order to solve the above problem, according to one aspect of the present invention, a method for determining the short-circuit current of a grid-type power electronic device is provided, the method comprising:

[0011] Step 1: Establish a short-circuit equivalent model of a grid-type power electronic device and initialize the dynamic compensation current value to 0;

[0012] Step 2: obtaining a node voltage prediction value and a fixed branch short-circuit current prediction value of the grid-type power electronic device based on the current dynamic compensation current value and the short-circuit equivalent model of the grid-type power electronic device;

[0013] Step 3: determining a predicted short-circuit current value of the power electronic device based on the current predicted short-circuit current value of the fixed branch and the current dynamic compensation current value;

[0014] Step 4: Determine the maximum current limit, active current limit, and reactive current limit of the power electronic equipment under an actual short-circuit fault based on the current node voltage prediction value, the low voltage ride-through strategy, and the current limiting strategy of the grid-connected power electronic equipment;

[0015] Step 5: Based on the preset limiting strategy, three-level limiting is performed according to the current short-circuit current prediction value, maximum current limit, active current limit, and reactive current limit of the power electronic equipment, and the active current value and reactive current value after limiting are determined;

[0016] Step 6: Calculate the dynamic correction amount of the compensation current based on the current short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the current active current value, and the reactive current value;

[0017] Step 7: If the current dynamic correction amount of the compensation current is less than or equal to the preset threshold, determine the current short-circuit current prediction value of the power electronic device as the actual short-circuit current value of the grid-forming power electronic device.

[0018] In some embodiments, the short-circuit equivalent model of the grid-type power electronic device includes: a fixed branch and a dynamic current compensation branch connected in parallel; the fixed branch includes: an internal potential and a virtual impedance connected in series; the dynamic current compensation branch includes: a controlled current source, the size of which is dynamically adjusted according to the short-circuit current of the grid-type power electronic device.

[0019] In some embodiments, determining the short-circuit current prediction value of the power electronic device according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value includes:

[0020] in, is the predicted value of the short-circuit current of the power electronic equipment determined in the nth iteration calculation; is the predicted value of the fixed branch short-circuit current during the nth iteration calculation; is the dynamic compensation current value during the nth iteration calculation.

[0021] In some embodiments, the method of performing three-level limiting based on a preset limiting strategy according to the current short-circuit current prediction value, maximum current limit, active current limit, and reactive current limit of the power electronic device, and determining the active current value and reactive current value after limiting, includes:

[0022] When the preset limiting strategy is the reactive power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n) , I max(n)},

[0023] When the preset limiting strategy is the active power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n) , I max(n)},

[0024] When the preset limiting strategy is the equal-proportional priority strategy, the active current value and reactive current value after limiting are determined by the following method, including:

[0025] If k < 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{k*|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{k*|I q0 +I qs(n) |, I qmax(n)},

[0026] If k ≥ 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n)},

[0027] Among them, I qlim(n) and I dlim(n) are the reactive current value and active current value after limiting determined in the nth iteration calculation; I q0 and I d0 are the q-axis component and d-axis component of the initial current of the power flow, respectively; I qs(n) and I ds(n) are the q-axis component and d-axis component of the short-circuit current prediction value of the power electronic equipment determined in the nth iteration calculation; I qmax(n) , I dmax(n) and I max(n) are the reactive current limit, active current limit and maximum current limit during the nth iteration calculation respectively; k is the proportional adjustment coefficient.

[0028] In some embodiments, the step of calculating the dynamic correction amount of the compensation current based on the current short-circuit current prediction value of the power electronic device, the initial current of the power flow, the current active current value, and the current reactive current value includes:

[0029] in, The dynamic correction value of the compensation current determined during the nth iteration calculation; is the predicted value of the short-circuit current of the power electronic equipment during the nth iteration calculation; is the initial current of the power flow; I qlim(n)and I dlim(n) They are respectively the reactive current value and active current value after limiting determined in the nth iterative calculation.

[0030] In some embodiments, the method further comprises:

[0031] If the current dynamic correction amount of the compensation current is greater than the preset threshold, the dynamic compensation current value is adjusted according to the current dynamic correction amount of the compensation current, the dynamic compensation current value is re-determined, and the calculation is returned to step 2 to be recalculated until the current dynamic correction amount of the compensation current is less than or equal to the preset threshold. The current short-circuit current prediction value of the power electronic device is determined to be the actual short-circuit current value of the grid-type power electronic device.

[0032] In some embodiments, adjusting the dynamic compensation current value according to the current dynamic correction amount of the compensation current to re-determine the dynamic compensation current value includes:

[0033] in, is the dynamic compensation current value during the n+1th iteration calculation; is the dynamic compensation current value during the nth iteration calculation; It is the dynamic correction value of the compensation current determined during the nth iterative calculation.

[0034] According to another aspect of the present invention, a system for determining a short-circuit current of a grid-type power electronic device is provided, the system comprising:

[0035] A model building unit is used to build a short-circuit equivalent model of a grid-type power electronic device and initialize the dynamic compensation current value to 0;

[0036] A model calculation unit, configured to obtain a node voltage prediction value and a fixed branch short-circuit current prediction value of the grid-type power electronic device based on the current dynamic compensation current value and the short-circuit equivalent model of the grid-type power electronic device;

[0037] a short-circuit current prediction value determination unit, configured to determine a short-circuit current prediction value of a power electronic device based on a current fixed branch short-circuit current prediction value and a current dynamic compensation current value;

[0038] A current limit determination unit is used to determine the maximum current limit, active current limit, and reactive current limit of the power electronic equipment under an actual short-circuit fault based on the current node voltage prediction value, the low voltage ride-through strategy, and the current limiting strategy of the grid-type power electronic equipment;

[0039] A three-level amplitude limiting calculation unit is used to perform three-level amplitude limiting based on a preset amplitude limiting strategy and the current short-circuit current prediction value, maximum current limit, active current limit, and reactive current limit of the power electronic equipment, and determine the active current value and reactive current value after amplitude limiting;

[0040] A compensation current dynamic correction amount determination unit is used to calculate the compensation current dynamic correction amount based on the current short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the current active current value and the reactive current value;

[0041] The short-circuit current actual value determination unit is used to determine the current short-circuit current prediction value of the power electronic equipment as the actual short-circuit current value of the grid-type power electronic equipment if the current dynamic correction amount of the compensation current is less than or equal to a preset threshold.

[0042] In some embodiments, the short-circuit equivalent model of the grid-type power electronic device includes: a fixed branch and a dynamic current compensation branch connected in parallel; the fixed branch includes: an internal potential and a virtual impedance connected in series; the dynamic current compensation branch includes: a controlled current source, the size of which is dynamically adjusted according to the short-circuit current of the grid-type power electronic device.

[0043] In some embodiments, the short-circuit current prediction value determining unit determines the short-circuit current prediction value of the power electronic device according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value, including:

[0044] in, is the predicted value of the short-circuit current of the power electronic equipment determined in the nth iteration calculation; is the predicted value of the fixed branch short-circuit current during the nth iteration calculation; is the dynamic compensation current value during the nth iteration calculation.

[0045] In some embodiments, the three-level limiting calculation unit performs three-level limiting based on a preset limiting strategy and the current short-circuit current prediction value, maximum current limit, active current limit, and reactive current limit of the power electronic device, and determines the active current value and reactive current value after limiting, including:

[0046] When the preset limiting strategy is the reactive power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n) , I max(n)},

[0047] When the preset limiting strategy is the active power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n) , I max(n)},

[0048] When the preset limiting strategy is the equal-proportional priority strategy, the active current value and reactive current value after limiting are determined by the following method, including:

[0049] When the preset limiting strategy is the equal-proportional priority strategy, the active current value and reactive current value after limiting are determined by the following method, including:

[0050] If k < 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{k*|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{k*|I q0 +I qs(n) |, I qmax(n)},

[0051] If k ≥ 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n)},

[0052] Among them, I qlim(n) and I dlim(n) are the reactive current value and active current value after limiting determined in the nth iteration calculation; I q0 and I d0 are the q-axis component and d-axis component of the initial current of the power flow, respectively; I qs(n) and I ds(n) are the q-axis component and d-axis component of the short-circuit current prediction value of the power electronic equipment determined in the nth iteration calculation; I qmax(n) , I dmax(n) and I max(n) are the reactive current limit, active current limit and maximum current limit during the nth iteration calculation respectively; k is the proportional adjustment coefficient.

[0053] In some embodiments, the compensation current dynamic correction amount determination unit calculates the compensation current dynamic correction amount according to the current short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the current active current value, and the current reactive current value, including:

[0054] in, The dynamic correction value of the compensation current determined during the nth iteration calculation; is the predicted value of the short-circuit current of the power electronic equipment during the nth iteration calculation; is the initial current of the power flow; I qlim(n) and I dlim(n) They are respectively the reactive current value and active current value after limiting determined in the nth iterative calculation.

[0055] In some embodiments, the system further comprises:

[0056] The dynamic compensation current adjustment unit is used to adjust the dynamic compensation current value according to the current dynamic compensation current correction amount if the current dynamic correction amount of the compensation current is greater than the preset threshold value, redetermine the dynamic compensation current value, and enter the model calculation unit for recalculation until the current dynamic correction amount of the compensation current is less than or equal to the preset threshold value, and determine that the current short-circuit current prediction value of the power electronic device is the actual short-circuit current value of the grid-type power electronic device.

[0057] In some embodiments, the dynamic compensation current adjustment unit adjusts the dynamic compensation current value according to the current compensation current dynamic correction amount to re-determine the dynamic compensation current value, including:

[0058] in, is the dynamic compensation current value during the n+1th iteration calculation; is the dynamic compensation current value during the nth iteration calculation; It is the dynamic correction value of the compensation current determined during the nth iterative calculation.

[0059] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, any step of a method for determining a short-circuit current of a grid-type power electronic device is implemented.

[0060] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0061] The computer-readable storage medium described above; and

[0062] One or more processors are configured to execute the program in the computer-readable storage medium.

[0063] According to another aspect of the present invention, the present invention provides a chip, comprising:

[0064] Memory for storing computer programs;

[0065] The processor is connected to the memory and is used to call and run a computer program from the memory, so that the device equipped with the chip executes the above-mentioned method for determining the short-circuit current of the grid-type power electronic device.

[0066] According to another aspect of the present invention, the present invention provides a computer program product, comprising computer program instructions, which enable a computer to execute the above method for determining the short-circuit current of a grid-type power electronic device.

[0067] According to another aspect of the present invention, the present invention provides a computer program, which, when executed on a computer, enables the computer to execute the above-mentioned method for determining the short-circuit current of a grid-type power electronic device.

[0068] The present invention provides a method and system for determining the short-circuit current of a grid-type power electronic device, comprising: step 1, establishing a short-circuit equivalent model of the grid-type power electronic device, and initializing a dynamic compensation current value to 0; step 2, obtaining a node voltage prediction value and a fixed branch short-circuit current prediction value of the grid-type power electronic device based on the short-circuit equivalent model of the grid-type power electronic device according to the current dynamic compensation current value; step 3, determining the short-circuit current prediction value of the power electronic device according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value; step 4, determining the short-circuit current prediction value of the power electronic device according to the current node voltage prediction value, the low voltage ride-through strategy and the current limiting strategy of the grid-type power electronic device. The maximum current limit, active current limit and reactive current limit of the equipment under an actual short-circuit fault; Step 5, based on the preset limiting strategy, perform three-level limiting according to the current short-circuit current prediction value, maximum current limit, active current limit and reactive current limit of the power electronic equipment, and determine the active current value and reactive current value after limiting; Step 6, calculate the dynamic correction amount of the compensation current according to the current short-circuit current prediction value of the power electronic equipment, the initial current of the flow, the current active current value and the reactive current value; Step 7, if the current dynamic correction amount of the compensation current is less than or equal to the preset threshold, determine that the current short-circuit current prediction value of the power electronic equipment is the actual short-circuit current value of the grid-type power electronic equipment. The present invention can take into account the influence of the low voltage ride-through strategy and current limiting strategy on the short-circuit current during a short-circuit fault of a grid-type power electronic device, and realize accurate simulation of the short-circuit current characteristics of the grid-type power electronic device. Under the current limiting strategy of the grid-type power electronic device, both the internal potential and the virtual impedance are variable, which can effectively avoid the problem of greatly reduced computing efficiency caused by the re-modification and decomposition of the admittance array in the short-circuit current calculation, and can retain the short-circuit current characteristics brought by the control strategy without changing the internal potential and the virtual impedance, so that the short-circuit current characteristics can be accurately simulated without changing the virtual impedance. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0070] FIG1 is a flow chart of a method 100 for determining a short-circuit current of a grid-type power electronic device according to an embodiment of the present invention;

[0071] FIG2 is a schematic diagram of a short-circuit equivalent model of a grid-type power electronic device according to an embodiment of the present invention;

[0072] FIG3 is a schematic structural diagram of a system 300 for determining short-circuit current of a grid-type power electronic device according to an embodiment of the present invention;

[0073] FIG4 is a schematic structural diagram of a chip 400 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0074] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0075] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0076] FIG1 is a flow chart of a method 100 for determining the short-circuit current of a grid-type power electronic device according to an embodiment of the present invention. As shown in FIG1 , the method for determining the short-circuit current of a grid-type power electronic device provided by an embodiment of the present invention can take into account the impact of the low voltage ride-through strategy and current limiting strategy on the short-circuit current during a short-circuit fault of the grid-type power electronic device, and accurately simulate the short-circuit current characteristics of the grid-type power electronic device. Under the current limiting strategy of the grid-type power electronic device, both the internal potential and the virtual impedance are variable, which can effectively avoid the problem of significantly reduced computational efficiency caused by re-modification and decomposition of the admittance matrix in the short-circuit current calculation, and can retain the short-circuit current characteristics brought by the control strategy without changing the internal potential and virtual impedance, so that the short-circuit current characteristics can be accurately simulated without changing the virtual impedance. The method 100 for determining the short-circuit current of a grid-type power electronic device provided by an embodiment of the present invention starts from step 101. In step 101, a short-circuit equivalent model of the grid-type power electronic device is established, and the dynamic compensation current value is initialized to 0.

[0077] In some embodiments, the short-circuit equivalent model of the grid-type power electronic device includes: a fixed branch and a dynamic current compensation branch connected in parallel; the fixed branch includes: an internal potential and a virtual impedance connected in series; the dynamic current compensation branch includes: a controlled current source, the size of which is dynamically adjusted according to the short-circuit current of the grid-type power electronic device.

[0078] In the present invention, the calculation of the short-circuit current of the grid-type power electronic equipment is implemented based on the short-circuit equivalent model of the grid-type power electronic equipment, and the model is the basis of the calculation.

[0079] As shown in Figure 2, in terms of the model, according to the basic principles of grid-type power electronic equipment, the main circuit of the grid-type power electronic equipment can be expressed in the form of a controlled internal potential in series with a virtual impedance. Based on the above main circuit, an equivalent model for the short-circuit current calculation of the grid-type power electronic equipment is established. The short-circuit equivalent model of the grid-type power electronic equipment consists of two parts: one part is a fixed branch, which is composed of an internal potential in series with a virtual impedance; the other part is a dynamic current compensation branch, which is equivalent to a controlled current source, and the current can be dynamically adjusted according to the short-circuit current of the grid-type power electronic equipment. The size and direction of the controlled current source are not restricted. The two branches are connected in parallel to form a complete short-circuit equivalent model of the grid-type power electronic equipment. In Figure 2, E is the internal potential, Z is the internal potential, and Z is the dynamic current compensation branch. eq is the virtual impedance; is the dynamic compensation current value.

[0080] After the model is established, the grid-type power electronic equipment short-circuit equivalent model is connected to the grid to calculate the short-circuit current. When calculating the actual short-circuit current, the predicted current correction method is used. It is assumed that the initial current of the power flow is And set the initial dynamic compensation current value to 0.

[0081] In step 102 , according to the current dynamic compensation current value and based on the short-circuit equivalent model of the grid-type power electronic equipment, a node voltage prediction value and a fixed branch short-circuit current prediction value of the grid-type power electronic equipment are obtained.

[0082] In step 103 , a short-circuit current prediction value of the power electronic device is determined according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value.

[0083] In some embodiments, determining the short-circuit current prediction value of the power electronic device according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value includes:

[0084] in, is the predicted value of the short-circuit current of the power electronic equipment determined in the nth iteration calculation; is the predicted value of the fixed branch short-circuit current during the nth iteration calculation; is the dynamic compensation current value during the nth iteration calculation.

[0085] In step 104, the maximum current limit, active current limit, and reactive current limit of the power electronic equipment under an actual short-circuit fault are determined based on the current node voltage prediction value, the low voltage ride-through strategy, and the current limiting strategy of the grid-type power electronic equipment.

[0086] In the present invention, iterative calculation is required. In each calculation process, first, according to the current dynamic compensation current value, only the fixed branch is considered, the impedance of the grid-type power electronic equipment model is included in the grid admittance array, and a calculation equation is formed according to the grid structure, boundary conditions, virtual impedance parameters, etc. The equation is solved to obtain the node voltage prediction value of the grid-type power electronic equipment and the fixed branch short-circuit current prediction value. Then, according to the difference between the fixed branch short-circuit current prediction value and the current dynamic compensation current value, the predicted value of the node voltage of the grid-type power electronic equipment and the fixed branch short-circuit current prediction value are obtained. Determine the predicted short-circuit current value of power electronic equipment; where, is the predicted value of the short-circuit current of the power electronic equipment determined in the nth iteration calculation; is the predicted value of the fixed branch short-circuit current during the nth iteration calculation; is the dynamic compensation current value during the nth iteration. Then, based on the node voltage prediction value, the low voltage ride-through strategy and current limiting strategy of the grid-type power electronic equipment, the maximum current limit, active current limit and reactive current limit of the power electronic equipment under actual short-circuit fault are determined.

[0087] For example, set the iteration number to n. In the first calculation process (i.e. when n=1), the dynamic compensation current value Considering only fixed branches, the impedance of the grid-type power electronic equipment model is included in the grid admittance matrix. The calculation equation is formed according to the grid structure, boundary conditions, virtual impedance parameters, etc. The first predicted node voltage value of the grid-type power electronic equipment is obtained by solving the equation. and fixed branch predicted short-circuit current value Then, the predicted value of short-circuit current of power electronic equipment can be obtained during the first calculation process. The active current value is I ds(1) , the reactive current value is I qs(1) Then, according to the predicted node voltage, the low voltage ride-through strategy and current limiting strategy of the grid-type power electronic equipment, the maximum current limit I under the actual short-circuit fault in the first calculation process is obtained. max(1) , active current limit I dmax(1) and reactive current limit I qmax(1) .

[0088] In step 105, based on the preset limiting strategy, three-level limiting is performed according to the current short-circuit current prediction value, maximum current limit, active current limit and reactive current limit of the power electronic equipment to determine the active current value and reactive current value after limiting.

[0089] In some embodiments, the method of performing three-level limiting based on a preset limiting strategy according to the current short-circuit current prediction value, maximum current limit, active current limit, and reactive current limit of the power electronic device, and determining the active current value and reactive current value after limiting, includes:

[0090] When the preset limiting strategy is the reactive power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n) , I max(n)},

[0091] When the preset limiting strategy is the active power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n) , I max(n)},

[0092] When the preset limiting strategy is the equal-proportional priority strategy, the active current value and reactive current value after limiting are determined by the following method, including:

[0093] If k < 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{k*|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{k*|I q0 +I qs(n) |, I qmax(n)},

[0094] If k ≥ 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n)},

[0095] Among them, I qlim(n) and I dlim(n) are the reactive current value and active current value after limiting determined in the nth iteration calculation; I q0and I d0 are the q-axis component and d-axis component of the initial current of the power flow, respectively; I qs(n) and I ds(n) are the q-axis component and d-axis component of the short-circuit current prediction value of the power electronic equipment determined in the nth iteration calculation; I qmax(n) , I dmax(n) and I max(n) are the reactive current limit, active current limit and maximum current limit during the nth iteration calculation respectively; k is the proportional adjustment coefficient.

[0096] In the present invention, after determining the short-circuit current prediction value, maximum current limit, active current limit and reactive current limit of the power electronic equipment, it is necessary to adjust the short-circuit current prediction value of the power electronic equipment according to different limiting strategies such as reactive power priority, active power priority or proportional limiting. Perform three-level limiting to obtain the active current value I after limiting dlim(n) and reactive current value I qlim(n) .

[0097] The specific calculation process includes:

[0098] (1) If the reactive power priority strategy is adopted, the reactive current value after limiting is I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n) , I max(n)}, the active current value after limiting is

[0099] (2) If the active power priority strategy is adopted, the active current value after limiting is I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n) , I max(n)}, the reactive current value after limiting is

[0100] (3) If the equal proportion priority strategy is adopted, If k < 1, the active current value after limiting is I dlim(n) =min{k*|I d0 +I ds(n) |, I dmax(n)}, otherwise I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n)}; If k < 1, the reactive current value after limiting is I qlim(n) =min{k*|I q0 +I qs(n) |, Iqmax(n)}, otherwise I qlim(n) =min{|I q0 +I qs(n) |,I qmax(n)}.

[0101] Among them, I qlim(n) and I dlim(n) are the reactive current value and active current value after limiting determined in the nth iteration calculation; I q0 and I d0 are the q-axis component and d-axis component of the initial current of the power flow, respectively; I qs(n) and I ds(n) are the q-axis component and d-axis component of the short-circuit current prediction value of the power electronic equipment determined in the nth iteration calculation; I qmax(n) , I dmax(n) and I max(n) are the reactive current limit, active current limit and maximum current limit during the nth iteration calculation respectively; k is the proportional adjustment coefficient.

[0102] In step 106 , a dynamic correction amount of the compensation current is calculated based on the current short-circuit current prediction value of the power electronic device, the initial current of the power flow, the current active current value, and the current reactive current value.

[0103] In some embodiments, the step of calculating the dynamic correction amount of the compensation current based on the current predicted short-circuit current of the power electronic device, the initial current of the power flow, the current active current value, and the current reactive current value includes:

[0104] in, The dynamic correction value of the compensation current determined during the nth iteration calculation; is the predicted value of the short-circuit current of the power electronic equipment during the nth iteration calculation; is the initial current of the power flow; I qlim(n) and I dlim(n) They are respectively the reactive current value and active current value after limiting determined in the nth iterative calculation.

[0105] In step 107 , if the current dynamic correction amount of the compensation current is less than or equal to the preset threshold, the current predicted value of the short-circuit current of the power electronic device is determined to be the actual value of the short-circuit current of the grid-type power electronic device.

[0106] In the present invention, whether to end the iterative process is determined based on the dynamic correction amount of the compensation current. The dynamic correction amount of the compensation current is determined by the short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the active current and the reactive current after the limit, and its reference direction is the direction of the busbar outflow. The calculation formula is: when When the short-circuit current prediction value of the power electronic equipment is less than or equal to the preset threshold, the iterative calculation ends. is the actual value of the short-circuit current of the grid-type power electronic equipment.

[0107] In some embodiments, the method further comprises:

[0108] If the current dynamic correction amount of the compensation current is greater than the preset threshold, the dynamic compensation current value is adjusted according to the current dynamic correction amount of the compensation current, the dynamic compensation current value is re-determined, and the calculation is returned to step 102 to be recalculated until the current dynamic correction amount of the compensation current is less than or equal to the preset threshold, and the current short-circuit current prediction value of the power electronic device is determined to be the actual short-circuit current value of the grid-type power electronic device.

[0109] In some embodiments, adjusting the dynamic compensation current value according to the current dynamic correction amount of the compensation current to re-determine the dynamic compensation current value includes:

[0110] in, is the dynamic compensation current value during the n+1th iteration calculation; is the dynamic compensation current value during the nth iteration calculation; It is the dynamic correction value of the compensation current determined during the nth iterative calculation.

[0111] In the present invention, if is greater than the preset threshold, then according to the formula Update the dynamic compensation current value and return to step 102 to recalculate and solve the equation again until the dynamic correction amount of the compensation current is less than or equal to the preset threshold value, and determine the current short-circuit current prediction value of the power electronic equipment is the actual value of the short-circuit current of the grid-type power electronic equipment.

[0112] Figure 3 is a schematic diagram of the structure of a system 300 for determining the short-circuit current of a grid-type power electronic device according to an embodiment of the present invention. As shown in Figure 3, the system 300 for determining the short-circuit current of a grid-type power electronic device provided by an embodiment of the present invention includes: a model establishment unit 301, a model calculation unit 302, a short-circuit current prediction value determination unit 303, a current limit value determination unit 304, a three-level limit calculation unit 305, a compensation current dynamic correction amount determination unit 306, and a short-circuit current actual value determination unit 307.

[0113] In some embodiments, the model building unit 301 is used to build a short-circuit equivalent model of a grid-type power electronic device and initialize the dynamic compensation current value to 0.

[0114] In some embodiments, the short-circuit equivalent model of the grid-type power electronic device includes: a fixed branch and a dynamic current compensation branch connected in parallel; the fixed branch includes: an internal potential and a virtual impedance connected in series; the dynamic current compensation branch includes: a controlled current source, the size of which is dynamically adjusted according to the short-circuit current of the grid-type power electronic device.

[0115] In some embodiments, the model calculation unit 302 is used to obtain the node voltage prediction value and the fixed branch short-circuit current prediction value of the grid-type power electronic device based on the current dynamic compensation current value and the grid-type power electronic device short-circuit equivalent model.

[0116] In some embodiments, the short-circuit current prediction value determining unit 303 is configured to determine a short-circuit current prediction value of the power electronic device according to a current fixed branch short-circuit current prediction value and a current dynamic compensation current value.

[0117] In some embodiments, the short-circuit current prediction value determining unit 303 determines the short-circuit current prediction value of the power electronic device according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value, including:

[0118] in, is the predicted value of the short-circuit current of the power electronic equipment determined in the nth iteration calculation; is the predicted value of the fixed branch short-circuit current during the nth iteration calculation; is the dynamic compensation current value during the nth iteration calculation.

[0119] In some embodiments, the current limit determination unit 304 is used to determine the maximum current limit, active current limit and reactive current limit of the power electronic equipment under an actual short circuit fault based on the current node voltage prediction value, the low voltage ride-through strategy and current limiting strategy of the grid-type power electronic equipment.

[0120] In some embodiments, the three-level limiting calculation unit 305 is used to perform three-level limiting based on a preset limiting strategy, according to the current short-circuit current prediction value, maximum current limit, active current limit and reactive current limit of the power electronic equipment, and determine the active current value and reactive current value after limiting.

[0121] In some embodiments, the three-level limiting calculation unit 305 performs three-level limiting based on a preset limiting strategy and the current short-circuit current prediction value, maximum current limit, active current limit, and reactive current limit of the power electronic device, and determines the active current value and reactive current value after limiting, including:

[0122] When the preset limiting strategy is the reactive power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n) , I max(n)},

[0123] When the preset limiting strategy is the active power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n) , I max(n)},

[0124] When the preset limiting strategy is the equal-proportional priority strategy, the active current value and reactive current value after limiting are determined by the following method, including:

[0125] If k < 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{k*|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{k*|I q0 +I qs(n) |, I qmax(n)},

[0126] If k ≥ 1, the active current and reactive current values ​​after limiting are determined using the following method, including: I dlim(n) =min{|I d0 +I ds(n) |, I dmax(n)}, I qlim(n) =min{|I q0 +I qs(n) |, I qmax(n)},

[0127] Among them, I qlim(n) and I dlim(n) are the reactive current value and active current value after limiting determined in the nth iteration calculation; I q0 and I d0 are the q-axis component and d-axis component of the initial current of the power flow, respectively; I qs(n) and I ds(n) are the q-axis component and d-axis component of the short-circuit current prediction value of the power electronic equipment determined in the nth iteration calculation; I qmax(n), I dmax(n) and I max(n) are the reactive current limit, active current limit and maximum current limit during the nth iteration calculation respectively; k is the proportional adjustment coefficient.

[0128] In some embodiments, the compensation current dynamic correction amount determination unit 306 is configured to calculate the compensation current dynamic correction amount according to the current short-circuit current prediction value of the power electronic device, the initial current of the power flow, the current active current value, and the current reactive current value.

[0129] In some embodiments, the compensation current dynamic correction amount determining unit 306 calculates the compensation current dynamic correction amount according to the current short-circuit current prediction value of the power electronic device, the initial current of the power flow, the current active current value, and the current reactive current value, including:

[0130] in, The dynamic correction value of the compensation current determined during the nth iteration calculation; is the predicted value of the short-circuit current of the power electronic equipment during the nth iteration calculation; is the initial current of the power flow; I qlim(n) and I dlim(n) They are respectively the reactive current value and active current value after limiting determined in the nth iterative calculation.

[0131] In some embodiments, the short-circuit current actual value determination unit 307 is used to determine that the current short-circuit current prediction value of the power electronic device is the actual short-circuit current value of the grid-type power electronic device if the current dynamic correction amount of the compensation current is less than or equal to a preset threshold.

[0132] In some embodiments, the system further comprises:

[0133] The dynamic compensation current adjustment unit is used to adjust the dynamic compensation current value according to the current dynamic compensation current correction amount if the current dynamic correction amount of the compensation current is greater than the preset threshold value, redetermine the dynamic compensation current value, and enter the model calculation unit for recalculation until the current dynamic correction amount of the compensation current is less than or equal to the preset threshold value, and determine that the current short-circuit current prediction value of the power electronic device is the actual short-circuit current value of the grid-type power electronic device.

[0134] In some embodiments, the dynamic compensation current adjustment unit adjusts the dynamic compensation current value according to the current compensation current dynamic correction amount to re-determine the dynamic compensation current value, including:

[0135] in, is the dynamic compensation current value during the n+1th iteration calculation; is the dynamic compensation current value during the nth iteration calculation; It is the dynamic correction value of the compensation current determined during the nth iterative calculation.

[0136] The system 300 for determining the short-circuit current of a grid-type power electronic device according to the embodiment of the present invention corresponds to the method 100 for determining the short-circuit current of a grid-type power electronic device according to another embodiment of the present invention, and will not be described in detail herein.

[0137] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, any step of a method for determining a short-circuit current of a grid-type power electronic device is implemented.

[0138] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0139] The computer-readable storage medium described above; and

[0140] One or more processors are configured to execute the program in the computer-readable storage medium.

[0141] According to another aspect of the present invention, a chip is provided. FIG4 is a schematic structural diagram of a chip provided in an embodiment of the present invention. The chip 400 shown in FIG4 includes a processor 410, which can call and execute a computer program from a memory to implement the method in the embodiment of the present invention.

[0142] In some embodiments, as shown in FIG4 , the chip 400 may further include a memory 420 , wherein the processor 410 may call and execute a computer program from the memory 420 to implement the method in the embodiment of the present invention.

[0143] The memory 420 may be a separate device independent of the processor 410 , or may be integrated into the processor 410 .

[0144] In some embodiments, the chip 400 may further include an input interface 430. The processor 410 may control the input interface 430 to communicate with other devices or chips, and specifically, may obtain information or data sent by other devices or chips.

[0145] In some embodiments, the chip 400 may further include an output interface 440. The processor 410 may control the output interface 440 to communicate with other devices or chips, and specifically, may output information or data to other devices or chips.

[0146] In some embodiments, the chip can be applied to the electronic device in the embodiments of the present invention, and the chip can implement the corresponding processes implemented by the electronic device in the various methods of the embodiments of the present invention. For the sake of brevity, they will not be repeated here.

[0147] It should be understood that the chip mentioned in the embodiment of the present invention can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0148] An embodiment of the present invention further provides a computer program product, including computer program instructions.

[0149] Optionally, the computer program product can be applied to the electronic device in the embodiment of the present invention, and the computer program instructions enable the computer to execute the corresponding processes implemented by the electronic device in the various methods of the embodiment of the present invention. For the sake of brevity, they are not repeated here.

[0150] An embodiment of the present invention also provides a computer program.

[0151] Optionally, the computer program can be applied to the electronic device in the embodiment of the present invention. When the computer program runs on the computer, the computer executes the corresponding processes implemented by the electronic device in the various methods of the embodiment of the present invention. For the sake of brevity, they are not repeated here.

[0152] The present invention has been described with reference to a few embodiments. However, it is apparent to those skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the present invention.

[0153] Generally, all terms used in this disclosure are to be interpreted according to their ordinary meaning in the art, unless explicitly defined otherwise herein. All references to "a / the / the [device, component, etc.]" are to be interpreted openly as referring to at least one instance of the device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily need to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0154] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0155] The present application is described with reference to the flow chart and / or block diagram of the method, device (system), and computer program product according to the embodiment of the present application. It should be understood that each flow process and / or box in the flow chart and / or block diagram and the combination of the flow process and / or box in the flow chart and / or block diagram can be realized 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 processing machine or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for realizing the function specified in one flow chart flow or multiple flows and / or one box or multiple boxes of the block diagram.

[0156] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0157] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for determining the short-circuit current of a grid-type power electronic device, the method comprising: Establish a short-circuit equivalent model of grid-type power electronic equipment and initialize the dynamic compensation current value to 0; According to the current dynamic compensation current value, obtaining the node voltage prediction value and the fixed branch short-circuit current prediction value of the grid-type power electronic equipment based on the grid-type power electronic equipment short-circuit equivalent model; Determine the short-circuit current prediction value of the power electronic equipment according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value; According to the current node voltage prediction value, the low voltage ride-through strategy and current limiting strategy of the grid-type power electronic equipment, the maximum current limit, active current limit and reactive current limit of the power electronic equipment under the actual short-circuit fault are determined; Based on the preset limiting strategy, three-level limiting is performed according to the current short-circuit current prediction value, maximum current limit, active current limit and reactive current limit of the power electronic equipment, and the active current value and reactive current value after limiting are determined; Calculate the dynamic correction amount of the compensation current according to the current short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the current active current value and the reactive current value; If the current dynamic correction amount of the compensation current is less than or equal to the preset threshold, the current short-circuit current prediction value of the power electronic equipment is determined to be the actual short-circuit current value of the grid-forming power electronic equipment.

2. The method according to claim 1, wherein: The short-circuit equivalent model of the grid-type power electronic device includes: a fixed branch and a dynamic current compensation branch connected in parallel; the fixed branch includes: an internal potential and a virtual impedance connected in series; the dynamic current compensation branch includes: a controlled current source, the size of which is dynamically adjusted according to the short-circuit current of the grid-type power electronic device.

3. The method according to claim 1 or 2, wherein: The method of determining the short-circuit current prediction value of the power electronic device according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value includes: in, is the predicted value of short-circuit current of the power electronic equipment determined in the nth iteration calculation; is the predicted value of the short-circuit current of the fixed branch during the nth iteration calculation; It is the dynamic compensation current value during the nth iteration calculation.

4. The method according to any one of claims 1 to 3, wherein: The preset limiting strategy is based on the current short-circuit current prediction value, maximum current limit value, active current limit value and reactive current limit value of the power electronic equipment to perform three-level limiting, and determine the active current value and reactive current value after limiting, including: When the preset limiting strategy is the reactive power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: IN qlim(n) =min{|I q0 +I qs(n) |,I qmax(n) ,IN max(n) }, When the preset limiting strategy is the active power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: IN dlim(n) =min{|I d0 +I ds(n) |,I dmax(n) ,IN max(n) }, When the preset limiting strategy is the equal-proportional priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: If k < 1, the active current and reactive current values ​​after limiting are determined by the following method, including: IN dlim(n) =min{k*|I d0 +I ds(n) |,I dmax(n) }, IN qlim(n) =min{k*|I q0 +I qs(n) |,I qmax(n) }, If k ≥ 1, the active current and reactive current values ​​after limiting are determined by the following method, including: IN dlim(n) =min{|I d0 +I ds(n) |,I dmax(n) }, IN qlim(n) =min{|I q0 +I qs(n) |,I qmax(n) }, Among them, I qlim(n) and I dlim(n) are the reactive current value and active current value after limiting determined in the nth iteration calculation; I q0 and I d0 are the q-axis component and d-axis component of the initial current of the power flow, respectively; I qs(n) and I ds(n) are the q-axis component and d-axis component of the short-circuit current prediction value of the power electronic equipment determined in the nth iteration calculation; I qmax(n) ,I dmax(n) and I max(n) are the reactive current limit, active current limit and maximum current limit during the nth iteration calculation respectively; k is the proportional adjustment coefficient.

5. The method according to any one of claims 1 to 4, wherein: The method of calculating the dynamic correction amount of the compensation current according to the current short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the current active current value and the reactive current value comprises: in, The dynamic correction amount of the compensation current determined during the nth iteration calculation; is the predicted value of short-circuit current of power electronic equipment at the nth iteration calculation; is the initial current of the power flow; I qlim(n) and I dlim(n) They are respectively the reactive current value and active current value after limiting determined in the nth iterative calculation.

6. The method according to any one of claims 1 to 5, wherein: The method further comprises: If the current dynamic correction amount of the compensation current is greater than the preset threshold, the dynamic compensation current value is adjusted according to the current dynamic correction amount of the compensation current, the dynamic compensation current value is re-determined, and the node voltage prediction value and the fixed branch short-circuit current prediction value of the grid-type power electronic device are obtained based on the current dynamic compensation current value and the grid-type power electronic device short-circuit equivalent model, until the current dynamic correction amount of the compensation current is less than or equal to the preset threshold, and the current power electronic device short-circuit current prediction value is determined to be the actual value of the short-circuit current of the grid-type power electronic device.

7. The method according to claim 6, wherein: The step of adjusting the dynamic compensation current value according to the current dynamic correction amount of the compensation current to re-determine the dynamic compensation current value includes: in, is the dynamic compensation current value during the n+1th iteration calculation; is the dynamic compensation current value during the nth iteration calculation; It is the dynamic correction amount of the compensation current determined during the nth iteration calculation.

8. A system for determining short-circuit current of a grid-connected power electronic device, the system comprising: A model building unit is used to build a short-circuit equivalent model of a grid-type power electronic device and initialize a dynamic compensation current value to 0; A model calculation unit, used for obtaining a node voltage prediction value and a fixed branch short-circuit current prediction value of the grid-type power electronic device based on the short-circuit equivalent model of the grid-type power electronic device according to the current dynamic compensation current value; A short-circuit current prediction value determination unit, used to determine a short-circuit current prediction value of a power electronic device according to a current fixed branch short-circuit current prediction value and a current dynamic compensation current value; A current limit determination unit is used to determine the maximum current limit, active current limit and reactive current limit of the power electronic equipment under an actual short circuit fault according to the current node voltage prediction value, the low voltage ride-through strategy and current limiting strategy of the grid-forming power electronic equipment; The three-level limiting calculation unit is used to calculate the current short-circuit current of the power electronic equipment based on the preset limiting strategy. The predicted value, the maximum current limit, the active current limit and the reactive current limit are limited in three levels to determine the active current value and the reactive current value after the limit; A compensation current dynamic correction amount determination unit is used to calculate the compensation current dynamic correction amount according to the current short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the current active current value and the reactive current value; The short-circuit current actual value determination unit is used to determine the current short-circuit current prediction value of the power electronic equipment as the short-circuit current actual value of the grid-forming power electronic equipment if the current dynamic correction amount of the compensation current is less than or equal to a preset threshold.

9. The system according to claim 8, wherein: The short-circuit equivalent model of the grid-type power electronic device includes: a fixed branch and a dynamic current compensation branch connected in parallel; the fixed branch includes: an internal potential and a virtual impedance connected in series; the dynamic current compensation branch includes: a controlled current source, the size of which is dynamically adjusted according to the short-circuit current of the grid-type power electronic device.

10. The system according to claim 8 or 9, wherein: The short-circuit current prediction value determination unit determines the short-circuit current prediction value of the power electronic device according to the current fixed branch short-circuit current prediction value and the current dynamic compensation current value, including: in, is the predicted value of short-circuit current of the power electronic equipment determined in the nth iteration calculation; is the predicted value of the short-circuit current of the fixed branch during the nth iteration calculation; It is the dynamic compensation current value during the nth iteration calculation.

11. The system according to any one of claims 8 to 10, wherein: The three-level amplitude limiting calculation unit performs three-level amplitude limiting based on a preset amplitude limiting strategy, according to the current short-circuit current prediction value, maximum current limit value, active current limit value and reactive current limit value of the power electronic equipment, and determines the active current value and reactive current value after amplitude limiting, including: When the preset limiting strategy is the reactive power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: IN qlim(n) =min{|I q0 +I qs(n) |,I qmax(n) ,IN max(n) }, When the preset limiting strategy is the active power priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: IN dlim(n) =min{|I d0 +I ds(n) |,I dmax(n) ,IN max(n) }, When the preset limiting strategy is the equal-proportional priority strategy, the active current value and reactive current value after limiting are determined by the following method, including: If k < 1, the active current and reactive current values ​​after limiting are determined by the following method, including: IN dlim(n) =min{k*|I d0 +I ds(n) |,I dmax(n) }, IN qlim(n) =min{k*|I q0 +I qs(n) |,I qmax(n) }, If k ≥ 1, the active current and reactive current values ​​after limiting are determined by the following method, including: IN dlim(n) =min{|I d0 +I ds(n) |,I dmax(n) }, IN qlim(n) =min{|I q0 +I qs(n) |,I qmax(n) }, Among them, I qlim(n) and I dlim(n) are the reactive current value and active current value after limiting determined in the nth iteration calculation. Current value; I q0 and I d0 are the q-axis component and d-axis component of the initial current of the power flow, respectively; I qs(n) and I ds(n) are the q-axis component and d-axis component of the short-circuit current prediction value of the power electronic equipment determined in the nth iteration calculation; I qmax(n) ,I dmax(n) and I max(n) are the reactive current limit, active current limit and maximum current limit during the nth iteration calculation respectively; k is the proportional adjustment coefficient.

12. The system according to any one of claims 8 to 11, wherein: The compensation current dynamic correction amount determination unit calculates the compensation current dynamic correction amount according to the current short-circuit current prediction value of the power electronic equipment, the initial current of the power flow, the current active current value and the reactive current value, including: in, The dynamic correction amount of the compensation current determined during the nth iteration calculation; is the predicted value of short-circuit current of power electronic equipment at the nth iteration calculation; is the initial current of the power flow; I qlim(n) and I dlim(n) They are respectively the reactive current value and active current value after limiting determined in the nth iterative calculation.

13. The system according to any one of claims 8 to 12, wherein: The system further comprises: The dynamic compensation current adjustment unit is used to adjust the dynamic compensation current value according to the current dynamic compensation current correction amount if the current dynamic correction amount of the compensation current is greater than a preset threshold value, redetermine the dynamic compensation current value, and enter the model calculation unit for recalculation until the current dynamic correction amount of the compensation current is less than or equal to the preset threshold value, and determine that the current power electronic device short-circuit current prediction value is the actual short-circuit current value of the grid-type power electronic device.

14. The system according to claim 13, wherein: The dynamic compensation current adjustment unit adjusts the dynamic compensation current value according to the current compensation current dynamic correction amount to re-determine the dynamic compensation current value, including: in, is the dynamic compensation current value during the n+1th iteration calculation; is the dynamic compensation current value during the nth iteration calculation; It is the dynamic correction amount of the compensation current determined during the nth iteration calculation.

15. A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method according to any one of claims 1 to 7.

16. An electronic device, comprising: The computer readable storage medium as claimed in claim 15; as well as, One or more processors are used to execute the program in the computer-readable storage medium.

17. A chip, comprising: Memory for storing computer programs; A processor, connected to the memory, is used to call and run a computer program from the memory, so that a device equipped with the chip executes the method as claimed in any one of claims 1 to 7.

18. A computer program product, comprising a computer program or instructions, wherein when the computer program or instructions are executed by a processor, the method according to any one of claims 1 to 7 is implemented.

19. A computer program, the computer program causing a computer to execute the method according to any one of claims 1 to 7.

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