A short-circuit ratio adaptive test method and system for a network-configuration type power electronic converter based on secondary side cascading

Abstract

This invention discloses a method and system for testing the short-circuit ratio adaptability of a grid-connected power electronic converter based on secondary-side cascaded circuitry, belonging to the field of power testing technology. The method includes: performing an equivalent circuit for short-circuit ratio adaptability testing of a grid-connected power electronic converter based on the Thevenin / Norton equivalent circuit, and obtaining the equivalent results; based on the equivalent results, structurally adjusting the typical short-circuit ratio adaptability testing circuit to construct a secondary-side cascaded short-circuit ratio adaptability testing circuit for the grid-connected power electronic converter; and performing an adaptability test on the short-circuit ratio of the grid-connected power electronic converter based on the secondary-side cascaded short-circuit ratio adaptability testing circuit. This invention can evaluate the control strategy, dynamic performance, and grid-connected stability of grid-connected converters, providing key testing basis and verification means for their deployment, parameter tuning, and operating range delineation in real power grids.

Description

Technical Field

[0001] This invention relates to the field of power testing technology, and more specifically, to a method and system for testing the short-circuit ratio adaptability of a grid-type power electronic converter based on secondary-side cascading. Background Technology

[0002] Currently, testing of grid-connected power electronic converters mainly focuses on short-circuit ratio adaptability, generally using three methods: field testing, hardware-in-the-loop testing, and encapsulated digital models. The first method ensures complete consistency of control characteristics between new energy units, but it is more difficult and costly. Furthermore, the test system is often isolated from the grid, failing to reflect actual grid strength, and the response characteristics may differ from actual faults. The second method ensures consistent control characteristics of converters in new energy units, but it does not fully consider other auxiliary equipment such as pitch systems, and it also fails to reflect actual grid strength, resulting in some differences between response characteristics and actual faults. The third method, due to issues with simulation platforms and the sophistication of encapsulated models, also results in some differences between response characteristics and actual faults. Summary of the Invention

[0003] To address the above problems, this invention proposes a short-circuit ratio adaptability test method for grid-type power electronic converters based on secondary-side cascading, comprising: Based on the Thevenin / Norton equivalent circuit, the typical circuit for short-circuit ratio adaptability testing of grid-type power electronic converters is equivalently evaluated, and the equivalent results are obtained. Based on the equivalent results, the typical short-circuit ratio adaptability test circuit is structurally adjusted to construct a secondary-side cascaded short-circuit ratio adaptability test circuit for grid-type power electronic converters. Based on the aforementioned secondary-side cascaded short-circuit ratio adaptability test circuit, the short-circuit ratio adaptability test of the grid-type power electronic converter is performed. The structural adjustment of the typical short-circuit ratio adaptability test circuit includes: setting the typical short-circuit ratio adaptability test circuit to have no actual series admittance switching; adding a short-circuit ratio coefficient in the measurement stage so that the product of the actual current at the generator terminal and the short-circuit ratio coefficient is sent to the grid-type power electronic converter for control.

[0004] Optionally, the product of the actual terminal current and the short-circuit ratio coefficient is directly fed to the grid-type power electronic converter without transformation.

[0005] Optionally, the current supplied by the infinite current source in the secondary-side cascaded short-circuit ratio adaptability test circuit: in, It is an infinite current source.

[0006] Optionally, the current caused by the fault current of the grid-type power electronic converter in the secondary-side cascaded short-circuit ratio adaptability test circuit: in, As a voltage source, This is the equivalent admittance of the system.

[0007] Optional, the current collected by the grid-type power electronic converter: in, As a voltage source, For the system's equivalent admittance, This is the short-circuit ratio coefficient. It is an infinite current source. To superimpose current; in: in, It is a series admittance.

[0008] Furthermore, this invention also proposes a short-circuit ratio adaptability test system for a grid-type power electronic converter based on secondary-side cascading, comprising: The equivalent unit is used to perform equivalent testing of a typical circuit for short-circuit ratio adaptability testing of grid-type power electronic converters based on the Thevenin / Norton equivalent circuit, and obtain the equivalent results. An optimization unit is used to perform structural adjustments on the typical short-circuit ratio adaptability test circuit based on the equivalent results, and to construct a secondary-side cascaded short-circuit ratio adaptability test circuit for grid-type power electronic converters. The test unit is used to perform an adaptive test on the short-circuit ratio of the grid-type power electronic converter based on the secondary-side cascaded short-circuit ratio adaptive test circuit. The structural adjustment of the typical short-circuit ratio adaptability test circuit includes: setting the typical short-circuit ratio adaptability test circuit to have no actual series admittance switching; adding a short-circuit ratio coefficient in the measurement stage so that the product of the actual current at the generator terminal and the short-circuit ratio coefficient is sent to the grid-type power electronic converter for control.

[0009] Optionally, the product of the actual terminal current and the short-circuit ratio coefficient is directly fed to the grid-type power electronic converter without transformation.

[0010] Optionally, the current supplied by the infinite current source in the secondary-side cascaded short-circuit ratio adaptability test circuit: in, It is an infinite current source.

[0011] Optionally, the current caused by the fault current of the grid-type power electronic converter in the secondary-side cascaded short-circuit ratio adaptability test circuit: in, As a voltage source, This is the equivalent admittance of the system.

[0012] Optional, the current collected by the grid-type power electronic converter: in, As a voltage source, For the system's equivalent admittance, This is the short-circuit ratio coefficient. It is an infinite current source. To superimpose current; in: in, It is a series admittance.

[0013] In another aspect, the present invention also provides a computing device, comprising: one or more processors; A processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the method described above is implemented.

[0014] In another aspect, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the method described above.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for testing the short-circuit ratio adaptability of a grid-connected power electronic converter based on secondary-side cascaded circuitry. The method includes: performing an equivalent circuit for short-circuit ratio adaptability testing of a grid-connected power electronic converter using the Thevenin / Norton equivalent circuit to obtain the equivalent results; structurally adjusting the typical short-circuit ratio adaptability testing circuit based on the equivalent results to construct a secondary-side cascaded short-circuit ratio adaptability testing circuit for the grid-connected power electronic converter; and performing an adaptability test on the short-circuit ratio of the grid-connected power electronic converter based on the secondary-side cascaded short-circuit ratio adaptability testing circuit. The structural adjustment of the typical short-circuit ratio adaptability testing circuit includes: setting the typical short-circuit ratio adaptability testing circuit to have no actual series admittance switching; and adding a short-circuit ratio coefficient in the measurement stage so that the product of the actual terminal current and the short-circuit ratio coefficient is sent to the grid-connected power electronic converter for control. This invention uses a cascaded structure to flexibly and economically simulate continuous changes from a strong power grid to a weak power grid, thereby systematically evaluating the control strategy, dynamic performance, and grid-connected stability of grid-connected converters. It provides key test basis and verification methods for their deployment, parameter tuning, and operating range delineation in real power grids. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of a typical circuit for short-circuit ratio adaptability testing of a grid-type power electronic converter, as described in an embodiment of the present invention. Figure 3 This is a schematic diagram of the equivalent circuit for short-circuit ratio adaptability testing of a grid-type power electronic converter, as described in an embodiment of the method of the present invention. Figure 4 This is a schematic diagram of the independent operation of an infinite power supply in a typical circuit for short-circuit ratio adaptability testing of a grid-type power electronic converter, as described in an embodiment of the present invention. Figure 5 This is a schematic diagram of the standalone operation of a grid-type power electronic converter, representing a typical circuit for short-circuit ratio adaptability testing of a grid-type power electronic converter according to an embodiment of the method of the present invention. Figure 6 This is a circuit diagram for testing the cascaded short-circuit ratio adaptability of a grid-type power electronic converter secondary side according to an embodiment of the method of the present invention. Figure 7 This is a schematic diagram of the independent operation of an infinite power supply in the secondary side cascaded short-circuit ratio adaptability test circuit of a grid-type power electronic converter, as described in an embodiment of the present invention. Figure 8 This is a schematic diagram of the stand-alone operation of the grid-type power electronic converter, which is part of the secondary side cascaded short-circuit ratio adaptability test circuit of the grid-type power electronic converter in an embodiment of the present invention. Figure 9 This is a schematic diagram of a single-machine infinite bus system according to an embodiment of the method of the present invention; Figure 10 This is a schematic diagram of the terminal voltage of the secondary side cascaded short-circuit ratio adaptive simulation results after 2 seconds when the circuit returns to the original state according to the method embodiment of the present invention. Figure 11 This is a schematic diagram of the reactive power of the simulation results of the adaptive short-circuit ratio of the secondary side after restoring to the original circuit state 2s in the embodiment of the method of the present invention. Figure 12 This is a schematic diagram of the terminal voltage of the actual circuit short-circuit ratio adaptive simulation results after 2 seconds of restoring to the original circuit state in the embodiment of the method of the present invention. Figure 13 This is a schematic diagram of reactive power from the actual circuit short-circuit ratio adaptive simulation results after 2 seconds of restoring the circuit to its original state according to the method embodiment of the present invention. Figure 14 This is a schematic diagram of the terminal voltage of the secondary side cascaded short-circuit ratio adaptive response in an embodiment of the method of the present invention when the short-circuit ratio is reduced to 0.5 times the original value; Figure 15 This is a schematic diagram of reactive power in the case where the short-circuit ratio is reduced to 0.5 times the original value in an embodiment of the method of the present invention, showing the adaptive response of the secondary side cascaded short-circuit ratio. Figure 16 This is a schematic diagram of the terminal voltage when the short-circuit ratio is increased to 2.5 times the original value in an embodiment of the method of the present invention, showing the adaptive response of the cascaded short-circuit ratio on the secondary side. Figure 17 This is a schematic diagram of reactive power in the case where the short-circuit ratio is increased to 2.5 times the original value in an embodiment of the method of the present invention, showing the adaptive response of the secondary side cascaded short-circuit ratio. Figure 18 This is a structural diagram of the system of the present invention. Detailed Implementation

[0017] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0018] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0019] Example 1: This invention proposes a short-circuit ratio adaptability test method S100 for grid-type power electronic converters based on secondary-side cascade, such as... Figure 1 As shown, it includes: S101, Based on the Thevenin / Norton equivalent circuit, perform an equivalent test on a typical circuit for short-circuit ratio adaptability testing of grid-type power electronic converters and obtain the equivalent results; S102, Based on the equivalent results, the typical short-circuit ratio adaptability test circuit is structurally adjusted to construct a secondary-side cascaded short-circuit ratio adaptability test circuit for grid-type power electronic converters; S103, Based on the secondary-side cascaded short-circuit ratio adaptability test circuit, the short-circuit ratio of the grid-type power electronic converter is tested for adaptability. The structural adjustment of the typical short-circuit ratio adaptability test circuit includes: setting the typical short-circuit ratio adaptability test circuit to have no actual series admittance switching; adding a short-circuit ratio coefficient in the measurement stage so that the product of the actual current at the generator terminal and the short-circuit ratio coefficient is sent to the grid-type power electronic converter for control.

[0020] In this case, the product of the actual current at the generator terminal and the short-circuit ratio coefficient is directly fed to the grid-type power electronic converter without any transformation.

[0021] The current supplied by the infinite current source in the secondary-side cascaded short-circuit ratio adaptive test circuit is as follows: in, It is an infinite current source.

[0022] Among them, the current caused by the fault current of the grid-type power electronic converter in the secondary-side cascaded short-circuit ratio adaptability test circuit is: in, As a voltage source, This is the equivalent admittance of the system.

[0023] The current collected by the grid-type power electronic converter is as follows: in, As a voltage source, For the system's equivalent admittance, This is the short-circuit ratio coefficient. It is an infinite current source. To superimpose current; in: in, It is a series admittance.

[0024] The invention will be further illustrated below with specific examples: The specific implementation process includes: According to the Thevenin / Norton equivalent circuit, an infinite voltage source in series with an impedance can be equivalent to a current source and admittance in parallel. A typical circuit for testing the short-circuit ratio adaptability of a grid-type power electronic converter is shown below. Figure 2 As shown, where, I s Gs is the system equivalent admittance, and GF is the series admittance. The short-circuit ratio at the generator terminals of the power electronic converter can be changed by changing the value of GF.

[0025] For grid-type power electronic converters, stable operation with a low short-circuit ratio is an advantage over grid-connected converters. The short-circuit ratio is calculated as follows: By changing GF, the short-circuit ratio can be altered, and the network structure can be viewed as a voltage source. Its equivalent circuit is as follows: Figure 3 As shown; Similar to the equivalent circuit of a grid-connected power electronic converter, according to the superposition theorem, the terminal current of a grid-connected power electronic converter can be decomposed into two parts, one of which is an infinite power source. I S The provided current I 11 ,like Figure 4 As shown, the other part is the current provided by the grid-type converter. I 12 ,like Figure 5 As shown.

[0026] according to Figure 4 Therefore, the current supplied by the infinite power source is: (1) according to Figure 5 Therefore, the current supplied by the grid-type power electronic converter is: (2) According to the superposition theorem: (3) Cascaded short-circuit ratio adaptability test circuit on the secondary side of a grid-type power electronic converter, such as Figure 6 As shown. Compared with the conventional short-circuit ratio adaptability test circuit, there are two changes: first, there is no actual series admittance switching, so the power grid structure is not changed and the impact on the power grid is smaller; second, a short-circuit ratio coefficient n is added to the measurement stage, and the actual terminal current is... I 1 Product with short-circuit ratio coefficient n Ic The voltage at the generator terminal is sent directly to the converter for control without any transformation.

[0027] According to the superposition law, during a fault, the terminal of the power electronic converter consists of two parts: one part is the current supplied by the infinite power source. I 11 like Figure 7 As shown, the other part is the current generated by the power electronic converter. I 12 ,like Figure 8 As shown.

[0028] The voltage provided by the infinite power source is: (4) The voltage caused by the fault current in the power electronic converter is: (5) According to the superposition theorem: (6) The current collected by the converter is: (7) Let it be: (8) Formula (7) can be transformed into: (9) A comparison reveals that formula (9) is completely consistent with formula (3). By adjusting the short-circuit ratio coefficient n, the equivalent short-circuit ratio at the generator terminal can be increased / decreased to n times the original value without changing the power grid structure and retaining the power grid information.

[0029] The present invention will be illustrated below using a simulation analysis of a single-machine infinite bus system as an example: Build as Figure 9 The single-unit infinite bus system shown, the grid-type power electronic converter passes through T 1 , T 2 The two-stage boost converter to 220kV infinite voltage system has a rated voltage of 0.4kV and a rated capacity of 1MW. The parameters of each component are shown in Table 1, and the line parameters are shown in Table 2. Table 1

[0030] Table 2

[0031] Short-circuit ratio coefficients n=0.25, 0.5, 0.75 and n=1.5, 2.0, 2.5 were set to simulate the decrease and increase of the short-circuit ratio at the generator terminals of a grid-type power electronic converter, with a duration of 2 seconds. After 2 seconds, the circuit returned to its original state. The simulation results of the short-circuit ratio adaptability of the secondary side cascade and the actual circuit are as follows. Figure 10-13 As shown: The simulation results show that, under both the case of increased and decreased short-circuit ratio, the adaptive response characteristics of the secondary side cascaded short-circuit ratio are basically consistent with the actual response characteristics of the change in the short-circuit ratio at the machine terminal, thus verifying the accuracy of the adaptive response of the secondary side cascaded short-circuit ratio.

[0032] The following explanation uses a large-scale network system simulation analysis as an example: The same simulation example as 3.1.2 is used, with the same unit capacity and connection point, but the control strategy is different, and the initial short-circuit ratio at the generator terminal is scr=3.03. Figure 14-17 The adaptability of the secondary cascaded short-circuit ratio and the response to changes in the actual short-circuit ratio are presented when the short-circuit ratio is reduced to half of its original value and increased to 2.5 times its original value, respectively.

[0033] Simulation results show that the cascaded short-circuit ratio adaptability of the secondary side is almost identical to the response to changes in the actual short-circuit ratio, with virtually no error during the transient period. Unlike high- and low-voltage ride-through faults, the short-circuit ratio adaptability test is equivalent to a vertical fault in the network topology, only changing the topological parameters of a single component without altering the overall network structure, resulting in less disturbance. However, high- and low-voltage ride-through is equivalent to a horizontal fault, adding a faulty branch in parallel to the original network topology, thus changing the network topology and causing greater disturbance. Therefore, it exhibits different characteristics during the transient period.

[0034] Example 2: Furthermore, this invention also proposes a short-circuit ratio adaptability test system 200 for a grid-type power electronic converter based on secondary-side cascading, such as... Figure 18 As shown, it includes: Equivalent unit 201 is used to perform equivalent testing on a typical circuit for short-circuit ratio adaptability testing of grid-type power electronic converters based on the Thevenin / Norton equivalent circuit, and obtain the equivalent results. The optimization unit 202 is used to perform structural adjustments on the typical short-circuit ratio adaptability test circuit based on the equivalent results, and to construct a secondary-side cascaded short-circuit ratio adaptability test circuit for grid-type power electronic converters. Test unit 203 is used to perform short-circuit ratio adaptability test on the grid-type power electronic converter based on the secondary side cascaded short-circuit ratio adaptability test circuit; The structural adjustment of the typical short-circuit ratio adaptability test circuit includes: setting the typical short-circuit ratio adaptability test circuit to have no actual series admittance switching; adding a short-circuit ratio coefficient in the measurement stage so that the product of the actual current at the generator terminal and the short-circuit ratio coefficient is sent to the grid-type power electronic converter for control.

[0035] In this case, the product of the actual current at the generator terminal and the short-circuit ratio coefficient is directly fed to the grid-type power electronic converter without any transformation.

[0036] The current supplied by the infinite current source in the secondary-side cascaded short-circuit ratio adaptive test circuit is as follows: in, It is an infinite current source.

[0037] Among them, the current caused by the fault current of the grid-type power electronic converter in the secondary-side cascaded short-circuit ratio adaptability test circuit is: in, As a voltage source, This is the equivalent admittance of the system.

[0038] The current collected by the grid-type power electronic converter is as follows: in, As a voltage source, For the system's equivalent admittance, This is the short-circuit ratio coefficient. It is an infinite current source. To superimpose current; in: in, It is a series admittance.

[0039] This invention uses a cascaded structure to flexibly and economically simulate continuous changes from a strong power grid to a weak power grid, thereby systematically evaluating the control strategy, dynamic performance, and grid-connected stability of grid-connected converters. It provides key test basis and verification methods for their deployment, parameter tuning, and operating range delineation in real power grids.

[0040] Example 3: Based on the same inventive concept, this invention also provides a computer device, which includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement corresponding method flows or corresponding functions, thereby implementing the steps of the methods in the above embodiments.

[0041] Example 4: Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiments.

[0042] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, 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 storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0043] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0044] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0045] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0046] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0047] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for testing the short-circuit ratio adaptability of a grid-type power electronic converter based on secondary-side cascading, characterized in that, include: Based on the Thevenin / Norton equivalent circuit, the typical circuit for short-circuit ratio adaptability testing of grid-type power electronic converters is equivalently evaluated, and the equivalent results are obtained. Based on the equivalent results, the typical short-circuit ratio adaptability test circuit is structurally adjusted to construct a secondary-side cascaded short-circuit ratio adaptability test circuit for grid-type power electronic converters. Based on the aforementioned secondary-side cascaded short-circuit ratio adaptability test circuit, the short-circuit ratio adaptability test of the grid-type power electronic converter is performed. The structural adjustment of the typical short-circuit ratio adaptability test circuit includes: setting the typical short-circuit ratio adaptability test circuit to have no actual series admittance switching; adding a short-circuit ratio coefficient in the measurement stage so that the product of the actual current at the generator terminal and the short-circuit ratio coefficient is sent to the grid-type power electronic converter for control.

2. The short-circuit ratio adaptability test method for grid-type power electronic converters according to claim 1, characterized in that, The product of the actual current at the generator terminal and the short-circuit ratio coefficient is directly fed to the grid-type power electronic converter without any transformation.

3. The short-circuit ratio adaptability test method for grid-type power electronic converters according to claim 1, characterized in that, The current provided by the infinite current source in the secondary-side cascaded short-circuit ratio adaptive test circuit: in, It is an infinite current source.

4. The short-circuit ratio adaptability test method for grid-type power electronic converters according to claim 1, characterized in that, The current caused by the fault current of the grid-type power electronic converter in the secondary-side cascaded short-circuit ratio adaptive test circuit: in, As a voltage source, This is the equivalent admittance of the system.

5. The short-circuit ratio adaptability test method for grid-type power electronic converters according to claim 1, characterized in that, The current collected by the grid-type power electronic converter: in, As a voltage source, For the system's equivalent admittance, This is the short-circuit ratio coefficient. It is an infinite current source. To superimpose current; in: in, It is a series admittance.

6. A short-circuit ratio adaptability test system for a grid-type power electronic converter based on secondary-side cascading, characterized in that, include: The equivalent unit is used to perform equivalent testing of a typical circuit for short-circuit ratio adaptability testing of grid-type power electronic converters based on the Thevenin / Norton equivalent circuit, and obtain the equivalent results. An optimization unit is used to perform structural adjustments on the typical short-circuit ratio adaptability test circuit based on the equivalent results, and to construct a secondary-side cascaded short-circuit ratio adaptability test circuit for grid-type power electronic converters. The test unit is used to perform an adaptive test on the short-circuit ratio of the grid-type power electronic converter based on the secondary-side cascaded short-circuit ratio adaptive test circuit. The structural adjustment of the typical short-circuit ratio adaptability test circuit includes: setting the typical short-circuit ratio adaptability test circuit to have no actual series admittance switching; adding a short-circuit ratio coefficient in the measurement stage so that the product of the actual current at the generator terminal and the short-circuit ratio coefficient is sent to the grid-type power electronic converter for control.

7. The short-circuit ratio adaptability test system for grid-type power electronic converters according to claim 6, characterized in that, The product of the actual current at the generator terminal and the short-circuit ratio coefficient is directly fed to the grid-type power electronic converter without any transformation.

8. The short-circuit ratio adaptability test system for grid-type power electronic converters according to claim 6, characterized in that, The current provided by the infinite current source in the secondary-side cascaded short-circuit ratio adaptive test circuit: in, It is an infinite current source.

9. The short-circuit ratio adaptability test system for grid-type power electronic converters according to claim 6, characterized in that, The current caused by the fault current of the grid-type power electronic converter in the secondary-side cascaded short-circuit ratio adaptive test circuit: in, As a voltage source, This is the equivalent admittance of the system.

10. The short-circuit ratio adaptability test system for grid-type power electronic converters according to claim 6, characterized in that, The current collected by the grid-type power electronic converter: in, As a voltage source, For the system's equivalent admittance, This is the short-circuit ratio coefficient. It is an infinite current source. To superimpose current; in: in, It is a series admittance.

11. A computer device, characterized in that, include: One or more processors; A processor is used to execute one or more programs; When the one or more programs are executed by the one or more processors, the method described in any one of claims 1-5 is implemented.

12. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the method as described in any one of claims 1-5.

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