A method and apparatus for calculating the strength limit criterion of a weak voltage support system

Abstract

This invention discloses a method and apparatus for calculating the strength limit criterion of a weak voltage support system. The method includes: constructing a Thevenin equivalent model of the weak voltage support system considering a power source connected to the grid via a converter; establishing a voltage-reactive power sensitivity analysis model based on the system Thevenin equivalent model, and determining a system voltage characteristic analysis model based on the voltage-reactive power sensitivity analysis model; performing monotonicity analysis on the system voltage characteristic analysis model, and determining the node critical voltage based on the voltage change caused by the grid connection of power electronic equipment at system nodes under voltage critical stability and the relationship between the node operating voltage; and calculating the strength limit criterion of the weak voltage support system based on the node critical voltage and system node parameters, wherein the strength limit criterion is used to evaluate the support strength of the weak voltage support system.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and more specifically, to a method and apparatus for calculating the strength limit criterion of a weak voltage support system. Background Technology

[0002] The short-circuit ratio is a common quantitative assessment indicator of voltage support strength in engineering, and can be used to establish a preliminary understanding of the strength of systems with a very high proportion of renewable energy. However, for extremely weak systems, the short-circuit ratio alone is insufficient to accurately characterize system stability, and its practicality is greatly reduced in extremely weak systems. Therefore, for power electronic power systems with extremely weak voltage support strength, it is necessary to further propose corresponding strength limit criteria to accurately determine the system's stability. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method and apparatus for calculating the strength limit criterion of a weak voltage support system.

[0004] According to one aspect of the present invention, a method for calculating the strength limit criterion of a weak voltage support system is provided, comprising:

[0005] Construct a Thevenin equivalent model of the system considering the weak voltage support system provided by the power source connected to the grid via the converter;

[0006] Based on the Thevenin equivalent model of the system, a voltage-reactive power sensitivity analysis model is established, and the system voltage characteristic analysis model is determined based on the voltage-reactive power sensitivity analysis model.

[0007] Monotonicity analysis was performed on the system voltage characteristic analysis model. Based on the relationship between the voltage change caused by the grid connection of power electronic equipment at system nodes when the system is in a voltage critical stability state and the node operating voltage, the node critical voltage was determined.

[0008] Based on the node critical voltage and system node parameters, the strength limit criterion of the weak voltage support system is calculated, whereby the strength limit criterion is used to evaluate the support strength of the weak voltage support system.

[0009] Optionally, the Thevenin equivalent model of the system is:

[0010]

[0011] In the formula, Let be the system potential at node i; Inject current into the power supply of the synchronous machine at node s; Inject current into the power supply of the node k-type grid-controlled converter; Inject current into the power supply of the grid-connected and grid-controlled converter at node j; Let be the mutual impedance between node i and nodes k, j, and s.

[0012] Optionally, the voltage-reactive power sensitivity analysis model is:

[0013]

[0014] In the formula, E i U i They represent The modulus of R ii X is the system equivalent resistance at node i; ii P is the system equivalent reactance at node i; i Q represents the active power output of the power source connected to the grid at node i; i The reactive power output of the power supply connected to the grid at node i; Let be the system potential at node i; Let be the operating voltage of node i;

[0015] The system voltage characteristic analysis model is as follows:

[0016]

[0017]

[0018] In the formula, Let ΔU be the voltage change caused by the grid connection of power electronic equipment at node i. i for The modulus.

[0019] Optionally, the node critical voltage is:

[0020]

[0021] In the formula, Let be the node critical voltage of node i; Let ΔU be the voltage change caused by the grid connection of power electronic equipment at node i. i for The modulus of P; i E represents the active power output of the power source connected to the grid at node i. i U i They represent The modulus, Let be the system potential at node i; R is the operating voltage of node i; ii Q is the system equivalent resistance at node i; i X represents the reactive power output of the power source connected to the grid at node i; ii Let be the system equivalent reactance at node i.

[0022] Optionally, the formula for calculating the ultimate strength criterion is:

[0023]

[0024] In the formula, CRSCR i U is the strength limit criterion for node i; N The nominal voltage of node i; Let be the system potential at node i. Let be the critical voltage of node i.

[0025] According to another aspect of the present invention, a calculation device for the strength limit criterion of a weak voltage support system is provided, comprising:

[0026] The module is used to build a Thevenin equivalent model of a system considering a weak voltage support system provided by a power source connected to the grid via a converter;

[0027] A module is established to build a voltage-reactive power sensitivity analysis model based on the Thevenin equivalent model of the system, and to determine the system voltage characteristic analysis model based on the voltage-reactive power sensitivity analysis model.

[0028] The analysis module is used to perform monotonicity analysis on the system voltage characteristic analysis model. Based on the voltage change caused by the grid connection of power electronic equipment at system nodes when the system is in a voltage critical stability state and the relationship between the node operating voltage, the critical voltage of the node is determined.

[0029] The calculation module is used to calculate the strength limit criterion of the weak voltage support system based on the node critical voltage and system node parameters. The strength limit criterion is used to evaluate the support strength of the weak voltage support system.

[0030] According to another aspect of the present invention, a computer-readable storage medium is provided, the storage medium storing a computer program for performing the methods described in any of the above aspects of the present invention.

[0031] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the method described in any of the preceding aspects of the present invention.

[0032] Therefore, this application proposes a method for calculating the short-circuit ratio index for real-time monitoring after considering the voltage support capability provided by power sources such as new energy sources connected to the grid via converters. This enables real-time and accurate judgment and analysis of the strength of weak voltage support systems, thereby reducing the risk of system instability. Attached Figure Description

[0033] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0034] Figure 1 This is a flowchart illustrating the calculation method for the strength limit criterion of a weak voltage support system provided in an exemplary embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the structure of a strength limit criterion calculation device for a weak voltage support system provided in an exemplary embodiment of the present invention;

[0036] Figure 3 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. Detailed Implementation

[0037] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0038] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0039] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0040] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0041] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0042] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0043] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0044] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0045] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0046] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0047] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0048] The embodiments of this invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate together with a wide range of other general-purpose or special-purpose computing system environments or configurations. Well-known examples of terminal devices, computing systems, environments, and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, and servers include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments including any of the above systems, etc.

[0049] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in distributed cloud computing environments, where tasks are executed by remote processing devices linked through communication networks. In distributed cloud computing environments, program modules can reside on local or remote computing system storage media, including storage devices.

[0050] Exemplary methods

[0051] Figure 1 This is a flowchart illustrating a method for calculating the strength limit criterion of a weak voltage support system according to an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as... Figure 1 As shown, the calculation method 100 for the strength limit criterion of a weak voltage support system includes the following steps:

[0052] Step 101: Construct a Thevenin equivalent model of the system considering the weak voltage support system provided by the power source connected to the grid via the converter;

[0053] Step 102: Based on the Thevenin equivalent model of the system, establish a voltage-reactive power sensitivity analysis model, and determine the system voltage characteristic analysis model based on the voltage-reactive power sensitivity analysis model.

[0054] Step 103: Perform monotonicity analysis on the system voltage characteristic analysis model. Based on the voltage change caused by the grid connection of power electronic devices at system nodes when the system is in a voltage critical stability state and the relationship between the node operating voltage, determine the node critical voltage.

[0055] Step 104: Calculate the strength limit criterion of the weak voltage support system based on the node critical voltage and system node parameters. The strength limit criterion is used to evaluate the support strength of the weak voltage support system.

[0056] Specifically, this application provides a method for calculating the strength limit criterion of a weak voltage support system, including:

[0057] Construct a system equivalent model that takes into account the impact of voltage support capability provided by power sources such as new energy sources connected to the grid via converters;

[0058] Based on the equivalent model, a system voltage characteristic analysis model and a voltage-reactive power sensitivity analysis model are established to analyze the system voltage characteristics.

[0059] A strength limit criterion calculation equation is constructed that takes into account the influence of the voltage support capability provided by power sources such as new energy sources connected to the grid via converters.

[0060] Optionally, a system equivalent model considering the impact of voltage support capability provided by power sources such as new energy sources connected to the grid via converters may be proposed, including:

[0061] Taking into account the voltage support provided by various power electronic devices, a Thevenin equivalent model of the system from the perspective of nodes is established, where the voltage at node i is:

[0062]

[0063] In the formula, ;; Let be the self-impedance of node i; Injection current provided for the power supply of node i converter; Inject current into the power supply of the synchronous machine at node s; Inject current into the power supply of the node k-type grid-controlled converter; Inject current into the power supply of the grid-connected and grid-controlled converter at node j; Let be the mutual impedance between node i and nodes k, j, and s.

[0064] The injection current provided by the new energy source at node i is:

[0065]

[0066]

[0067]

[0068] In the formula, The injection current provided for the new energy source at node i. The output power provided to node i's new energy source.

[0069] The system potential seen from node i is:

[0070]

[0071] In the formula, Let be the system potential at node i.

[0072] The Thevenin equivalent impedance of the system as seen from node i is the self-impedance of node i.

[0073]

[0074] In the formula, R ii X is the system equivalent resistance at node i; ii Let be the system equivalent reactance at node i.

[0075] Optionally, a system voltage characteristic analysis model can be established based on the equivalent model, including:

[0076] Based on the equivalent model, establish the voltage at node i. A quadratic equation in one variable with its square:

[0077]

[0078] In the formula, E i U i S i They represent The modulus.

[0079] Based on equation (7), the voltage-reactive power sensitivity analysis model is derived as follows:

[0080]

[0081] According to the equivalent model, x-axis and The relationship between them can be written as:

[0082]

[0083] Substituting equation (9) into the denominator of equation (8) and rearranging, we obtain the voltage characteristic analysis model:

[0084]

[0085]

[0086] In the formula, Let ΔU be the voltage change caused by the grid connection of power electronic equipment at node i. i for The modulus.

[0087] A monotonicity analysis is performed on equation (10). The system voltage has a physical meaning, therefore the initial state is U. i >ΔU i ,f(U i If )>0, it indicates that the system can operate stably; when U i =ΔU i At that time, f(U) i When ) = 0, the voltage-reactive power sensitivity is infinite, indicating that the system is in a critical voltage stability state. At this time, the node voltage change and the node voltage are both equal to the node critical voltage.

[0088]

[0089] In the formula, Let be the node critical voltage of node i.

[0090] Optionally, a strength limit criterion calculation method is proposed that takes into account the influence of the voltage support capability provided by power sources such as new energy sources connected to the grid via converters.

[0091] By analyzing U i With ΔU i The monotonic relationship between them allows for the construction of a critical real-time short circuit ratio (CRSCR) criterion:

[0092]

[0093] In the formula, CRSCR i Let i be the strength limit criterion for node i.

[0094] This application obtains the strength limit criterion calculation results of the weak voltage support system, compares them with the real-time short-circuit ratio calculation results based on local measurement information, and determines that the system is in a voltage critical state when the two results are the same. The real-time short-circuit ratio calculation equation based on local measurement information is as follows:

[0095]

[0096] In the formula, RSCR i Let i be the real-time short-circuit ratio of node i; The output power of node i; Let be the self-impedance of node i; U is the open-circuit voltage of the power electronic equipment at node i before grid connection; N Let i be the nominal voltage of node i.

[0097] Therefore, this application proposes a method for calculating the short-circuit ratio index for real-time monitoring after considering the voltage support capability provided by power sources such as new energy sources connected to the grid via converters. This enables real-time and accurate judgment and analysis of the strength of weak voltage support systems, thereby reducing the risk of system instability.

[0098] Exemplary device

[0099] Figure 2 This is a schematic diagram of the structure of a strength limit criterion calculation device for a weak voltage support system provided in an exemplary embodiment of the present invention. Figure 2 As shown, the device 200 includes:

[0100] Module 210 is used to construct a Thevenin equivalent model of a system considering a weak voltage support system provided by a power source connected to the grid via a converter;

[0101] Module 220 is established to build a voltage-reactive power sensitivity analysis model based on the Thevenin equivalent model of the system, and to determine the system voltage characteristic analysis model based on the voltage-reactive power sensitivity analysis model.

[0102] Analysis module 230 is used to perform monotonicity analysis on the system voltage characteristic analysis model. Based on the voltage change caused by the grid connection of power electronic equipment at system nodes when the system is in a voltage critical stability state and the relationship between the node operating voltage, the critical voltage of the node is determined.

[0103] The calculation module 240 is used to calculate the strength limit criterion of the weak voltage support system based on the node critical voltage and system node parameters. The strength limit criterion is used to evaluate the support strength of the weak voltage support system.

[0104] Optionally, the Thevenin equivalent model of the system is:

[0105]

[0106] In the formula, Let be the system potential at node i; Inject current into the power supply of the synchronous machine at node s; Inject current into the power supply of the node k-type grid-controlled converter; Inject current into the power supply of the grid-connected and grid-controlled converter at node j; Let be the mutual impedance between node i and nodes k, j, and s.

[0107] Optionally, the voltage-reactive power sensitivity analysis model is:

[0108]

[0109] In the formula, E i U i They represent The modulus of R ii X is the system equivalent resistance at node i; ii P is the system equivalent reactance at node i; i Q represents the active power output of the power source connected to the grid at node i; i The reactive power output of the power supply connected to the grid at node i; Let be the system potential at node i; Let be the operating voltage of node i;

[0110] The system voltage characteristic analysis model is as follows:

[0111]

[0112]

[0113] In the formula, Let ΔU be the voltage change caused by the grid connection of power electronic equipment at node i. i for The modulus.

[0114] Optionally, the node critical voltage is:

[0115]

[0116] In the formula, Let be the node critical voltage of node i; Let ΔU be the voltage change caused by the grid connection of power electronic equipment at node i. i for The modulus of P; i E represents the active power output of the power source connected to the grid at node i. i U i They represent The modulus, Let be the system potential at node i; R is the operating voltage of node i; ii Q is the system equivalent resistance at node i; i X represents the reactive power output of the power source connected to the grid at node i; ii Let be the system equivalent reactance at node i.

[0117] Optionally, the formula for calculating the ultimate strength criterion is:

[0118]

[0119] In the formula, CRSCR i U is the strength limit criterion for node i; N The nominal voltage of node i; Let be the system potential at node i. Let be the critical voltage of node i.

[0120] Exemplary electronic devices

[0121] Figure 3 This is the structure of an electronic device provided in an exemplary embodiment of the present invention. For example... Figure 3 As shown, the electronic device 30 includes one or more processors 31 and memory 32.

[0122] The processor 31 may be a central processing unit (CPU) or other form of processing unit with data processing and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0123] The memory 32 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 31 may execute the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above, and / or other desired functions. In one example, the electronic device may also include an input device 33 and an output device 34, these components being interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0124] In addition, the input device 33 may also include, for example, a keyboard, a mouse, etc.

[0125] The output device 34 can output various information to the outside. The output device 34 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0126] Of course, for the sake of simplicity, Figure 3 Only some of the components of this electronic device relevant to the present invention are shown, omitting components such as buses, input / output interfaces, etc. In addition, the electronic device may include any other suitable components depending on the specific application.

[0127] Exemplary computer program products and computer-readable storage media

[0128] In addition to the methods and apparatus described above, embodiments of the present invention may also be computer program products, which include computer program instructions that, when executed by a processor, cause the processor to perform the steps in the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0129] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of the present invention. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0130] Furthermore, embodiments of the present invention may also be computer-readable storage media storing computer program instructions thereon, which, when executed by a processor, cause the processor to perform the steps of the methods according to various embodiments of the present invention described in the "Exemplary Methods" section above.

[0131] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0132] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0133] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0134] The block diagrams of devices, systems, devices, and systems involved in this invention are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, systems, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0135] The methods and systems of the present invention may be implemented in many ways. For example, they may be implemented by software, hardware, firmware, or any combination of software, hardware, and firmware. The above-described order of steps for the methods is for illustrative purposes only, and the steps of the methods of the present invention are not limited to the order specifically described above unless otherwise specifically stated. Furthermore, in some embodiments, the present invention may also be implemented as a program recorded on a recording medium, the program comprising machine-readable instructions for implementing the methods according to the present invention. Thus, the present invention also covers recording media storing programs for performing the methods according to the present invention.

[0136] It should also be noted that in the systems, apparatus, and methods of the present invention, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered equivalents of the present invention. The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the invention. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the invention. Therefore, the invention is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0137] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A method for calculating the strength limit criterion of a weak voltage support system, characterized in that, include: Construct a Thevenin equivalent model of the system considering the weak voltage support system provided by the power source connected to the grid via the converter; Based on the Thevenin equivalent model of the system, a voltage-reactive power sensitivity analysis model is established, and based on the voltage-reactive power sensitivity analysis model, a system voltage characteristic analysis model is determined. Monotonicity analysis was performed on the system voltage characteristic analysis model. Based on the relationship between the voltage change caused by the grid connection of power electronic devices at system nodes when the system is in a voltage critical stability state and the node operating voltage, the node critical voltage was determined. Based on the node critical voltage and system node parameters, the strength limit criterion of the weak voltage support system is calculated, wherein the strength limit criterion is used to evaluate the support strength of the weak voltage support system; The voltage-reactive power sensitivity analysis model is as follows: In the formula, E i , U i They represent Ê i , Û i The modulus, R ii For nodes i The system equivalent resistance; X ii For nodes i The system equivalent reactance; P i For nodes i The active power output of a grid-connected power source; Q i For nodes i The reactive power output of a grid-connected power source; Ê i For nodes i The system potential at the location; Û i For nodes i Operating voltage; The system voltage characteristic analysis model is as follows: In the formula, Δ Û i For nodes i The voltage change caused by the grid connection of power electronic equipment, Δ U i For Δ Û i The modulus; The formula for calculating the strength limit criterion is as follows: In the formula, CRSCR i For nodes i The strength limit criterion; U N For nodes i Nominal voltage; Ê i For nodes i The system potential at that point, Û i,cri For nodes i The critical voltage.

2. The method according to claim 1, characterized in that, The Thevenin equivalent model of the system is: In the formula, Ê i For nodes i The system potential at the location; Î s For nodes s Synchronous machine power supply injection current; Î k For nodes k Power injection current of grid-type control converter; Î j For nodes j Grid-connected and grid-type control converter power injection current; Ẑ ik , Ẑ ij , Ẑ is For nodes i With nodes k , j , s The mutual impedance between them.

3. The method according to claim 1, characterized in that, The node critical voltage is: In the formula, Û i,cri For nodes i The node critical voltage; Δ Û i For nodes i The voltage change caused by the grid connection of power electronic equipment, Δ U i For Δ Û i The modulus; P i For nodes i The active power output of a grid-connected power source; E i , U i They represent Ê i , Û i The modulus, Ê i For nodes i The system potential at the location; Û i For nodes i Operating voltage; R ii For nodes i The system equivalent resistance; Q i For nodes i The reactive power output of a grid-connected power source; X ii For nodes i The system equivalent reactance.

4. A calculation device for the strength limit criterion of a weak voltage support system, used to implement the method of claim 1, characterized in that, include: The module is used to build a Thevenin equivalent model of a system considering a weak voltage support system provided by a power source connected to the grid via a converter; A module is established to build a voltage-reactive power sensitivity analysis model based on the Thevenin equivalent model of the system, and to determine the system voltage characteristic analysis model based on the voltage-reactive power sensitivity analysis model. The analysis module is used to perform monotonicity analysis on the system voltage characteristic analysis model, and to determine the critical voltage of the node based on the voltage change caused by the grid connection of the power electronic equipment of the system node when the system is in a voltage critical stability state and the relationship between the node operating voltage. The calculation module is used to calculate the strength limit criterion of the weak voltage support system based on the node critical voltage and system node parameters, wherein the strength limit criterion is used to evaluate the support strength of the weak voltage support system.

5. The apparatus according to claim 4, characterized in that, The node critical voltage is: In the formula, Û i,cri For nodes i The node critical voltage; Δ Û i For nodes i The voltage change caused by the grid connection of power electronic equipment, Δ U i For Δ Û i The modulus; P i For nodes i The active power output of a grid-connected power source; E i , U i They represent Ê i , Û i The modulus, Ê i For nodes i The system potential at the location; Û i For nodes i Operating voltage; R ii For nodes i The system equivalent resistance; Q i For nodes i The reactive power output of a grid-connected power source; X ii For nodes i The system equivalent reactance.

6. A computer-readable storage medium, characterized in that, The storage medium stores a computer program for performing the method described in any one of claims 1-3.

7. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1-3.

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