Calculation method and device for short-circuit current of power system, medium and terminal

Abstract

The invention discloses a method and a device for calculating short-circuit current of an electric power system, a medium and a terminal, relates to the technical field of short-circuit current calculation of the electric power system, and mainly aims to solve the problem that the short-circuit current of a multi-source heterogeneous electric power system cannot be accurately calculated in the prior art. Comprising the following steps: simulating a short-circuit fault in a simulation environment of a target power system, and constructing a non-fault node admittance matrix; calculating an initial current value of each power supply node to obtain an initial system-wide node injection current vector of the target power system, calculating a quotient between the initial system-wide node injection current vector and a non-fault node admittance matrix to obtain a first iteration system-wide node voltage vector of the target power system, and constructing an iteration solution equation; and performing iterative solution on the basis of the iterative solution equation until a preset convergence condition is met, obtaining a full-system node voltage vector after iteration is completed, and calculating the short-circuit current of the target power system according to the full-system node voltage vector after iteration is completed.

Description

Technical Field

[0001] This application relates to the field of power system short-circuit current calculation technology, and in particular to a method, device, medium, and terminal for calculating power system short-circuit current. Background Technology

[0002] To ensure the safe and stable operation of the power system in actual production, it is necessary to select appropriate circuit breaker models and correctly configure relay actions. This requires accurate knowledge of the power system's short-circuit current. Therefore, during the planning process before construction, it is necessary to simulate and calculate the power system's short-circuit current in advance.

[0003] Currently, the methods for calculating short-circuit current in power systems mainly focus on modeling methods for single power source types.

[0004] However, as the proportion of new energy sources and power electronic devices connected to the power system increases, the power system is being transformed from a traditional synchronous generator-dominated structure to a multi-source heterogeneous system. This makes modeling methods based on a single power source type unsuitable for the transformed power system. Because the current superposition effect of multiple heterogeneous power sources cannot be accurately quantified, the short-circuit current of the transformed power system cannot be accurately calculated. Summary of the Invention

[0005] In view of this, this application provides a method, apparatus, medium, and terminal for calculating short-circuit current in a power system, with the main purpose of improving the existing method for accurately calculating short-circuit current in multi-source heterogeneous power systems.

[0006] According to one aspect of this application, a method for calculating short-circuit current in a power system is provided, comprising: A short-circuit fault is simulated in the simulation environment of the target power system, and the corresponding non-fault node admittance matrix is ​​constructed. The non-fault node admittance moment is obtained by correcting the whole system node admittance matrix of the target power system based on the simulated short-circuit fault. The initial current values ​​of each power node in the target power system are calculated to obtain the initial total system node injection current vector of the target power system. The quotient between the initial total system node injection current vector and the non-fault node admittance matrix is ​​calculated to obtain the first iteration total system node voltage vector of the target power system. An iterative solution equation is constructed based on the initial total system node injection current vector, the non-fault node admittance matrix, and the first iteration total system node voltage vector. The power source types include infinite source power source type, motor type power source type, and inverter type power source type. The iterative solution is performed based on the given equation until the preset convergence condition is met, and the node voltage vector of the entire system after the iteration is completed is obtained. The short-circuit current of the target power system is then calculated based on the node voltage vector of the entire system after the iteration is completed.

[0007] Preferably, the step of simulating short-circuit faults in the simulation environment of the target power system and constructing the corresponding admittance matrix of non-faulty nodes includes: Obtain the design data of the target power system, and construct the total system node admittance matrix of the target power system based on the design data; Based on the design data, a simulation environment for the target power system is constructed, and a short-circuit fault is simulated in the simulation environment. The fault node of the simulated short-circuit fault is determined. In the whole system node admittance matrix, the entire row and the entire column corresponding to the fault node are deleted to correct the whole system node admittance matrix and obtain the non-fault node admittance matrix.

[0008] Preferably, the step of calculating the initial current values ​​of each power node in the target power system to obtain the initial total system node injection current vector of the target power system includes: Determine the power type of each power node in the target power system; For power nodes of the infinite source type, the equivalent impedance value between the power node and the fault node is calculated, and the quotient between the bus voltage amplitude before the short-circuit fault of the power node and the equivalent impedance value is determined as the initial current value of the power node, expressed as the following formula. , in, Power nodes representing infinite source power types The short-circuit current value contributed to the faulty node. Indicates power node The bus voltage amplitude before the short-circuit fault, This represents the equivalent impedance between a power node and a fault node in an infinite-source power supply type. For a power node of the motor-type power supply type, based on the generator terminal voltage amplitude, active power value, and reactive power value before the short-circuit fault, the pre-short-circuit transient potential of the power node is calculated, as well as the transfer impedance between the fault node and the power node. The quotient between the pre-short-circuit transient potential and the transfer impedance is determined as the initial current value of the power node, expressed as the following formula. , , , in, This indicates the generator current at the power node of the motor-type power supply. This indicates the active power value of the power node before a short-circuit fault in a motor-type power supply. This indicates the reactive power value of the power node before a short-circuit fault in a motor-type power supply. Indicates conjugate. Power nodes indicating motor type power supply The subtransient potential, This indicates the generator terminal voltage amplitude at the power node of the motor-type power supply before a short-circuit fault. The subtransient reactance of a power node representing a motor-type power supply is... Represents the imaginary part of a complex number. Indicates the distance from fault node k to power node The transfer impedance between them This represents the self-impedance of the faulty node k. This represents the short-circuit current value contributed by the power node of the motor-type power supply to the fault node k. For power nodes of inverter type, the initial current value of the power node is determined by the voltage amplitude before the short circuit fault and the active power value before the short circuit fault. By integrating the initial current values ​​of each power node, the initial total system node injection current vector of the target power system is obtained.

[0009] Preferably, determining the power type of each power node included in the target power system includes: The equivalent impedance between each power node and the fault node is calculated and expressed as the following formula; , in, This represents the equivalent impedance between the power supply node and the faulty node. Represents a node With nodes The equivalent impedance of all communication channels between them; If the equivalent impedance is less than a preset equivalent impedance threshold, then the power type of the power node corresponding to the equivalent impedance is determined to be an infinite source power type. If the equivalent impedance is greater than the preset equivalent impedance threshold, the power type of the power node is determined according to the grid connection mode of the power node corresponding to the equivalent impedance. Among them, the power node directly connected to the grid through a generator is a motor type power type, and the power node connected to the grid through a power electronic inverter is an inverter type power type.

[0010] Preferably, before calculating the initial current values ​​of each power node in the target power system to obtain the initial total system node injection current vector of the target power system, the method further includes: Based on the design data of the target power system, the pre-fault power flow calculation results of the target power system before the occurrence of a short-circuit fault are calculated, so as to obtain the bus voltage amplitude before the short-circuit fault of the power node of the infinite source power type, the generator terminal voltage amplitude before the short-circuit fault of the power node of the motor type power type, the active power value before the short-circuit fault and the reactive power value before the short-circuit fault of the power node of the inverter type power type.

[0011] Preferably, the iterative solution based on the iterative equation until a preset convergence condition is met, to obtain the node voltage vector of the entire system after the iteration, includes: Substituting the injected current vector of all system nodes in the previous iteration into the iterative solution equation, we obtain the voltage vector of all system nodes in the current iteration. Based on the current iteration of the full system node voltage vector, the previous iteration current value of each power node is updated to obtain the current injection vector of the full system node in the current iteration. Substitute the current vector injected into all system nodes in the current iteration into the iterative solution equation to obtain the voltage vector of all system nodes in the next iteration; If the residual between the full system node voltage vector of the next iteration and the full system node voltage vector of the current iteration is less than the preset convergence tolerance, then the full system node voltage vector of the next iteration is determined as the full system node voltage vector that has completed the iteration.

[0012] Preferably, the step of updating the previous iteration current value of each of the power supply nodes based on the current iteration-wide system node voltage vector to obtain the current iteration-wide system node injection current vector includes: For power nodes of the infinite source power type, the current value of the current iteration is determined to be the current value of the previous iteration; For a power node of motor type, the current iteration subtransient potential of the power node is calculated based on the current iteration generator terminal voltage amplitude, active power value before short circuit fault, and reactive power value before short circuit fault. The transfer impedance between the fault node and the power node is also calculated. The quotient between the current iteration subtransient potential and the transfer impedance is determined as the current iteration current value of the power node. For power nodes of inverter-type power supplies, a preset voltage sag threshold is obtained. The current iteration voltage amplitude of the power node is compared with the preset voltage sag threshold to obtain a comparison result. Based on the following formula, the current iteration current value of the power node is determined according to the comparison result. , in, This represents the current value of the power node in the current iteration for an inverter-type power supply. This represents the active power value of a power node in an inverter-type power supply before a short-circuit fault. This represents the current iteration voltage amplitude of a power node of the inverter power type; By integrating the current values ​​of each power node in the current iteration, the current vector of the entire system nodes in the current iteration of the target power system is obtained.

[0013] According to another aspect of this application, a device for calculating short-circuit current in a power system is provided, comprising: The non-fault node admittance matrix construction module is used to simulate short-circuit faults in the simulation environment of the target power system and construct the corresponding non-fault node admittance matrix. The non-fault node admittance matrix is ​​obtained by correcting the whole system node admittance matrix of the target power system based on the simulated short-circuit fault. The iterative equation construction module is used to calculate the initial current value of each power node in the target power system, obtain the initial total system node injection current vector of the target power system, calculate the quotient between the initial total system node injection current vector and the non-fault node admittance matrix, obtain the first iterative total system node voltage vector of the target power system, and construct iterative equations based on the initial total system node injection current vector, the non-fault node admittance matrix, and the first iterative total system node voltage vector. The power source types include infinite source power source type, motor type power source type, and inverter type power source type. The iterative solution module is used to iteratively solve the iterative solution equation until a preset convergence condition is met, obtain the full system node voltage vector after the iteration is completed, and calculate the short-circuit current of the target power system based on the full system node voltage vector after the iteration is completed.

[0014] Preferably, the non-fault node admittance matrix construction module is used for: Obtain the design data of the target power system, and construct the total system node admittance matrix of the target power system based on the design data; Based on the design data, a simulation environment for the target power system is constructed, and a short-circuit fault is simulated in the simulation environment. The fault node of the simulated short-circuit fault is determined. In the whole system node admittance matrix, the entire row and the entire column corresponding to the fault node are deleted to correct the whole system node admittance matrix and obtain the non-fault node admittance matrix.

[0015] Preferably, the iterative equation construction module includes: A power type determination unit is used to determine the power type of each power node included in the target power system; The initial current calculation unit is used to calculate the equivalent impedance value between the power node and the fault node for a power node of the infinite source power type, and to determine the initial current value of the power node as the quotient between the bus voltage amplitude before the short-circuit fault and the equivalent impedance value, expressed as the following formula. , in, Power nodes representing infinite source power types The short-circuit current value contributed to the faulty node. Indicates power node The bus voltage amplitude before the short-circuit fault, This represents the equivalent impedance between a power node and a fault node in an infinite-source power supply type. The initial current calculation unit is further configured to, for power nodes of the motor-type power supply type, calculate the pre-short-circuit transient potential of the power node based on the generator terminal voltage amplitude, active power value, and reactive power value before the short-circuit fault, and calculate the transfer impedance between the fault node and the power node. The quotient between the pre-short-circuit transient potential and the transfer impedance is determined as the initial current value of the power node, expressed as the following formula. , , , in, This indicates the generator current at the power node of the motor-type power supply. This indicates the active power value of the power node before a short-circuit fault in a motor-type power supply. This indicates the reactive power value of the power node before a short-circuit fault in a motor-type power supply. Indicates conjugate. Power nodes indicating motor type power supply The subtransient potential, This indicates the generator terminal voltage amplitude at the power node of the motor-type power supply before a short-circuit fault. The subtransient reactance of a power node representing a motor-type power supply is... Represents the imaginary part of a complex number. Indicates the distance from fault node k to power node The transfer impedance between them This represents the self-impedance of the faulty node k. This represents the short-circuit current value contributed by the power node of the motor-type power supply to the fault node k. The initial current value calculation unit is also used to determine the initial current value of the power node by taking the voltage amplitude before the short circuit fault and the active power value before the short circuit fault for the power node of the inverter power type. An integration unit is used to integrate the initial current values ​​of each of the power supply nodes to obtain the initial total system node injection current vector of the target power system.

[0016] Preferably, the power type determination unit is used for: The equivalent impedance between each power node and the fault node is calculated and expressed as the following formula; , in, This represents the equivalent impedance between the power supply node and the faulty node. Represents a node With nodes The equivalent impedance of all communication channels between them; If the equivalent impedance is less than a preset equivalent impedance threshold, then the power type of the power node corresponding to the equivalent impedance is determined to be an infinite source power type. If the equivalent impedance is greater than the preset equivalent impedance threshold, the power type of the power node is determined according to the grid connection mode of the power node corresponding to the equivalent impedance. Among them, the power node directly connected to the grid through a generator is a motor type power type, and the power node connected to the grid through a power electronic inverter is an inverter type power type.

[0017] Preferably, before the iterative equation construction module, the device further includes a pre-fault power flow calculation module, used for: Based on the design data of the target power system, the pre-fault power flow calculation results of the target power system before the occurrence of a short-circuit fault are calculated, so as to obtain the bus voltage amplitude before the short-circuit fault of the power node of the infinite source power type, the generator terminal voltage amplitude before the short-circuit fault of the power node of the motor type power type, the active power value before the short-circuit fault and the reactive power value before the short-circuit fault of the power node of the inverter type power type.

[0018] Preferably, the iterative solution module includes: The system node voltage vector update unit is used to substitute the system node injected current vector of the previous iteration into the iterative solution equation to obtain the system node voltage vector of the current iteration. The system-wide node injection current vector update unit is used to update the previous iteration current value of each power supply node based on the current iteration system-wide node voltage vector to obtain the current iteration system-wide node injection current vector. The system-wide node voltage vector update unit is also used to substitute the current injected current vector of the current iteration of the system-wide nodes into the iterative solution equation to obtain the system-wide node voltage vector of the next iteration. The convergence determination unit is used to determine the system node voltage vector of the next iteration as the system node voltage vector that has completed the iteration if the residual between the system node voltage vector of the next iteration and the system node voltage vector of the current iteration is less than a preset convergence tolerance.

[0019] Preferably, the system-wide node injection current vector update unit is used for: For power nodes of the infinite source power type, the current value of the current iteration is determined to be the current value of the previous iteration; For a power node of motor type, the current iteration subtransient potential of the power node is calculated based on the current iteration generator terminal voltage amplitude, active power value before short circuit fault, and reactive power value before short circuit fault. The transfer impedance between the fault node and the power node is also calculated. The quotient between the current iteration subtransient potential and the transfer impedance is determined as the current iteration current value of the power node. For power nodes of inverter-type power supplies, a preset voltage sag threshold is obtained. The current iteration voltage amplitude of the power node is compared with the preset voltage sag threshold to obtain a comparison result. Based on the following formula, the current iteration current value of the power node is determined according to the comparison result. , in, This represents the current value of the power node in the current iteration for an inverter-type power supply. This represents the active power value of a power node in an inverter-type power supply before a short-circuit fault. This represents the current iteration voltage amplitude of a power node of the inverter power type; By integrating the current values ​​of each power node in the current iteration, the current vector of the entire system nodes in the current iteration of the target power system is obtained.

[0020] According to another aspect of this application, a storage medium is provided that stores at least one executable instruction, which causes a processor to perform an operation corresponding to the above-described method for calculating the short-circuit current of a power system.

[0021] According to another aspect of this application, a terminal is provided, comprising: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other through the communication bus; The memory is used to store at least one executable instruction, which causes the processor to perform the operation corresponding to the above-described method for calculating the short-circuit current of the power system.

[0022] By employing the above technical solutions, the technical solutions provided in the embodiments of this application have at least the following advantages: This application provides a method, apparatus, medium, and terminal for calculating short-circuit current in a power system. First, a short-circuit fault is simulated in a simulation environment of the target power system, and a corresponding non-faulty node admittance matrix is ​​constructed. The non-faulty node admittance matrix is ​​obtained by correcting the total system node admittance matrix of the target power system based on the simulated short-circuit fault. Second, the initial current values ​​of each power source node in the target power system are calculated to obtain the initial total system node injected current vector. The quotient between the initial total system node injected current vector and the non-faulty node admittance matrix is ​​calculated to obtain the first iterative total system node voltage vector of the target power system. An iterative solution equation is constructed based on the initial total system node injected current vector, the non-faulty node admittance matrix, and the first iterative total system node voltage vector. The power source types include infinite source power sources, motor-type power sources, and inverter-type power sources. Finally, the iterative solution equation is iteratively solved until a preset convergence condition is met, resulting in a completed total system node voltage vector. The short-circuit current of the target power system is calculated based on the completed iterative total system node voltage vector. Compared with existing technologies, the embodiments of this application incorporate the impact of changes in pre-fault operating states on short-circuit current by constructing iterative solution equations. This reduces the deviation between the calculated short-circuit current of the target power system and the actual dynamic response, thereby improving the accuracy of short-circuit current calculation. Furthermore, when constructing iterative solution equations, multiple types of power sources are modeled, including infinite-source power sources, motor-type power sources, and inverter-type power sources. This makes the iterative solution equations more applicable to power systems after the transition. At the same time, due to the modeling of multiple power source types, the current superposition effect of each type of power source is quantified, further improving the accuracy of short-circuit current calculation.

[0023] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a method for calculating short-circuit current in a power system according to an embodiment of this application is shown. Figure 2 A flowchart illustrating another method for calculating short-circuit current in a power system provided in an embodiment of this application is shown. Figure 3 A block diagram of a power system short-circuit current calculation device provided in an embodiment of this application is shown; Figure 4 A schematic diagram of the structure of a terminal provided in an embodiment of this application is shown. Detailed Implementation

[0025] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0026] 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.

[0027] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0028] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0029] 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.

[0030] The embodiments of this application can be applied to computer systems / servers that can operate with a wide range of other general-purpose or special-purpose computing system environments or configurations. Examples of well-known computing systems, environments, and / or configurations suitable for use with computer systems / 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 that include any of the above systems, etc.

[0031] Computer systems / servers can be described in the general context of computer system executable instructions (such as program modules) executed by the 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 performed by remote processing devices linked through a communication network. In distributed cloud computing environments, program modules can reside on local or remote computing system storage media, including storage devices.

[0032] This application provides a method for calculating the short-circuit current in a power system, such as... Figure 1 As shown, the method includes: 101. Simulate short-circuit faults in the simulation environment of the target power system and construct the corresponding admittance matrix of non-faulty nodes.

[0033] The non-fault node admittance matrix is ​​obtained by correcting the total system node admittance matrix of the target power system based on a simulated short-circuit fault. The total system node admittance matrix includes the line admittances of each power source node in the target power system. The non-fault node admittance matrix is ​​obtained by deleting the entire row and column elements corresponding to the fault node from the total system node admittance matrix. In this embodiment, the current execution terminal can be the short-circuit current calculation unit of the power system planning module.

[0034] 102. Calculate the initial current value of each power node in the target power system to obtain the initial total system node injection current vector of the target power system. Calculate the quotient between the initial total system node injection current vector and the admittance matrix of the non-faulty node to obtain the first iteration total system node voltage vector of the target power system. Based on the initial total system node injection current vector, the admittance matrix of the non-faulty node and the first iteration total system node voltage vector, construct the iterative solution equation.

[0035] The power supply types include infinite source power supply, motor power supply, and inverter power supply; the initial current value of each power supply node is calculated based on the voltage amplitude before the short circuit fault of each power supply node; the node voltage vector of the entire system in the first iteration is the initial value of the iteration, not the voltage amplitude before the short circuit fault.

[0036] It should be noted that the iterative solution equation is based on multiple types of power sources, such as infinite source power sources, motor power sources, and inverter power sources, encompassing new energy sources and power electronic equipment. This makes the iterative solution equation more applicable to the power system after the transformation. At the same time, due to the modeling of multiple types of power sources, the current superposition effect of each type of power source is quantified, which improves the accuracy of short-circuit current calculation.

[0037] 103. Iteratively solve the equations until the preset convergence condition is met to obtain the node voltage vector of the entire system after the iteration is completed. Then, calculate the short-circuit current of the target power system based on the node voltage vector of the entire system after the iteration is completed.

[0038] The preset convergence condition can be that the residual between the injected current vectors of the whole system nodes in two iterations or the residual between the voltage vectors of the whole system nodes in two iterations is less than the preset residual threshold.

[0039] It should be noted that each iteration can reflect the actual level of the power node voltage, thus taking into account the impact of changes in the pre-fault operating state on the short-circuit current. This reduces the deviation between the calculated short-circuit current of the target power system and the actual dynamic response, thereby improving the accuracy of the short-circuit current calculation.

[0040] Compared with existing technologies, the embodiments of this application incorporate the impact of changes in pre-fault operating states on short-circuit current by constructing iterative solution equations. This reduces the deviation between the calculated short-circuit current of the target power system and the actual dynamic response, thereby improving the accuracy of short-circuit current calculation. Furthermore, when constructing iterative solution equations, multiple types of power sources are modeled, including infinite-source power sources, motor-type power sources, and inverter-type power sources. This makes the iterative solution equations more applicable to power systems after the transition. At the same time, due to the modeling of multiple power source types, the current superposition effect of each type of power source is quantified, further improving the accuracy of short-circuit current calculation.

[0041] This application provides another method for calculating the short-circuit current in a power system, such as... Figure 2 As shown, the method includes: 201. Simulate short-circuit faults in the simulation environment of the target power system and construct the corresponding admittance matrix of non-faulty nodes.

[0042] Accordingly, step 201 of the embodiment specifically includes: obtaining the design data of the target power system and constructing the whole system node admittance matrix of the target power system based on the design data; constructing a simulation environment of the target power system based on the design data and simulating a short-circuit fault in the simulation environment; determining the fault node of the simulated short-circuit fault, and deleting the entire row and column elements corresponding to the fault node in the whole system node admittance matrix to correct the whole system node admittance matrix and obtain the non-fault node admittance matrix.

[0043] The design data includes, but is not limited to, load data, power supply data, and transmission network data. Load data is used to characterize the load size of each node in the power system. Power supply data includes installed capacity of generating units, power supply classification parameters, etc. Transmission network data includes transmission network topology, line admittance, line capacity, etc.

[0044] 202. Based on the design data of the target power system, calculate the pre-fault power flow calculation results of the target power system before a short-circuit fault occurs.

[0045] The pre-fault power flow calculation results include: the bus voltage amplitude before the short-circuit fault of the power node of the infinite source power type, the generator terminal voltage amplitude before the short-circuit fault of the power node of the motor type power type, the active power value before the short-circuit fault and the reactive power value before the short-circuit fault, and the voltage amplitude before the short-circuit fault and the active power value before the short-circuit fault of the power node of the inverter type power type.

[0046] Understandably, this occurs before a short circuit fault, i.e. under normal operating conditions.

[0047] 203. Determine the power source type of each power source node in the target power system.

[0048] Accordingly, step 203 of the embodiment specifically includes: calculating the equivalent impedance between each power supply node and the fault node, expressed as the following formula; , in, This represents the equivalent impedance between the power supply node and the faulty node. Represents a node With nodes The equivalent impedance of all interconnecting channels is generally taken as its magnitude. As a quantitative indicator of electrical distance; If the equivalent impedance is less than the preset equivalent impedance threshold, then the power type of the power node corresponding to the equivalent impedance is determined to be an infinite source power type. If the equivalent impedance is greater than the preset equivalent impedance threshold, the power type of the power node is determined according to the grid connection method of the power node corresponding to the equivalent impedance. Among them, the power node directly connected to the grid through the generator is the motor type, and the power node connected to the grid through the power electronic inverter is the inverter type.

[0049] It should be noted that the smaller the equivalent impedance value, the stronger the voltage control capability of the power supply node over the fault node. The physical essence is that the superposition effect of the power supply's internal resistance and the network impedance approaches zero. When the equivalent impedance value approaches zero, the power supply exhibits infinite source characteristics: the bus voltage remains constant during a fault, the short-circuit current is determined only by the grid topology impedance, and there is no dynamic attenuation process. Therefore, it can be considered a power supply node of the infinite source type. Additionally, power supply nodes directly connected to the grid through generators, such as squirrel-cage induction generator wind power generation and doubly-fed induction generator wind power generation, and power supply nodes connected to the grid through power electronic inverters, such as photovoltaic power generation, direct-drive permanent magnet synchronous wind turbines, and DC systems, are also considered.

[0050] 204. Calculate the initial current value of each power source node in the target power system to obtain the initial total system node injection current vector of the target power system.

[0051] Accordingly, step 204 of the embodiment specifically includes: for a power node of the infinite source power type, calculating the equivalent impedance value between the power node and the fault node, and determining the quotient between the bus voltage amplitude before the short-circuit fault of the power node and the equivalent impedance value as the initial current value of the power node, expressed as the following formula. , in, Power nodes representing infinite source power types The short-circuit current value contributed to the faulty node. Indicates power node The bus voltage amplitude before the short-circuit fault, This represents the equivalent impedance between a power node and a fault node in an infinite-source power supply type. For power nodes of the motor-type power supply type, the pre-short-circuit transient potential of the power node is calculated based on the generator terminal voltage amplitude, active power value, and reactive power value before the short-circuit fault. The transfer impedance between the fault node and the power node is also calculated. The quotient between the pre-short-circuit transient potential and the transfer impedance is determined as the initial current value of the power node, expressed by the following formula. , , , in, This indicates the generator current at the power node of the motor-type power supply. This indicates the active power value of the power node before a short-circuit fault in a motor-type power supply. This indicates the reactive power value of the power node before a short-circuit fault in a motor-type power supply. Indicates conjugate. Power nodes indicating motor type power supply The subtransient potential, This indicates the generator terminal voltage amplitude at the power node of the motor-type power supply before a short-circuit fault. The subtransient reactance of a power node representing a motor-type power supply is... Represents the imaginary part of a complex number. Indicates the distance from fault node k to power node The transfer impedance between them This represents the self-impedance of the faulty node k. This represents the short-circuit current value contributed by the power node of the motor-type power supply to the fault node k. For power nodes of inverter type, the initial current value of the power node is determined by the voltage amplitude before the short circuit fault and the active power value before the short circuit fault. By integrating the initial current values ​​of each power node, the initial total system node injection current vector of the target power system is obtained.

[0052] 205. Calculate the quotient between the initial total system node injection current vector and the non-fault node admittance matrix to obtain the first iteration total system node voltage vector of the target power system, and construct the iterative solution equation.

[0053] In this embodiment, the quotient between the initial full-system node injection current vector in step 204 of the embodiment and the non-fault node admittance matrix in step 201 of the embodiment is first calculated to obtain the first iteration full-system node voltage vector.

[0054] Furthermore, in step 205 of the embodiment, the construction of the iterative solution equation specifically includes: based on the initial total system node injection current vector, the non-fault node admittance matrix, and the first iteration total system node voltage vector, constructing the iterative solution equation, expressed as the following formula. , in, Represents the node voltage vector of the entire system. This represents the admittance matrix of the non-faulty node. This represents the node injection current vector of the entire system.

[0055] 206. Iteratively solve the equations until the preset convergence condition is met, and obtain the node voltage vector of the entire system after the iteration is completed.

[0056] Accordingly, step 206 of the embodiment specifically includes: substituting the injected current vector of the entire system nodes in the previous iteration into the iterative solution equation to obtain the voltage vector of the entire system nodes in the current iteration; updating the current value of each power node in the previous iteration based on the voltage vector of the entire system nodes in the current iteration to obtain the injected current vector of the entire system nodes in the current iteration; substituting the injected current vector of the entire system nodes in the current iteration into the iterative solution equation to obtain the voltage vector of the entire system nodes in the next iteration; if the residual between the voltage vector of the entire system nodes in the next iteration and the voltage vector of the entire system nodes in the current iteration is less than the preset convergence tolerance, then the voltage vector of the entire system nodes in the next iteration is determined as the voltage vector of the entire system nodes after the iteration is completed.

[0057] Specifically, initially, the initial system-wide node injection current vector is substituted into the iterative solution equation to obtain the first iteration system-wide node voltage vector. Based on the first iteration system-wide node voltage vector, the initial current values ​​of each power supply node are updated to obtain the first iteration system-wide node injection current vector. Further, the first iteration system-wide node injection current vector is substituted into the iterative solution equation to obtain the second iteration system-wide node voltage vector. Further, based on the second iteration system-wide node voltage vector, the first iteration current values ​​of each power supply node are updated to obtain the second iteration system-wide node injection current vector. Further, the second iteration system-wide node injection current vector is substituted into the iterative solution equation to obtain the third iteration system-wide node voltage vector. Further, the residual between the third iteration system-wide node voltage vector and the second iteration system-wide node voltage vector is calculated. If the residual is less than a preset convergence tolerance, the third iteration system-wide node voltage vector is determined as the system-wide node voltage vector after completing the iteration. If the residual is greater than the preset convergence tolerance, the iterative solution continues until the residual is less than the preset convergence tolerance.

[0058] Furthermore, based on the current system-wide node voltage vector for the current iteration, the previous iteration current values ​​of each power node are updated to obtain the current injected current vector for the current system-wide node in the current iteration, including: For power nodes of the infinite source power type, the current value of the current iteration is determined to be the current value of the previous iteration.

[0059] It should be noted that, since the power nodes of the infinite source type have infinite source characteristics, the bus voltage is constant during the fault, the short-circuit current is determined only by the grid topology impedance, and there is no dynamic decay process. Therefore, the current value remains unchanged in each iteration.

[0060] For power nodes of the motor type, the current iteration subtransient potential of the power node is calculated based on the current iteration generator terminal voltage amplitude, active power value before the short circuit fault, and reactive power value before the short circuit fault. The transfer impedance between the fault node and the power node is also calculated. The quotient between the current iteration subtransient potential and the transfer impedance is determined as the current iteration current value of the power node. Specifically, it can be calculated based on the following formula in step 204 of the embodiment. , , , Understandably, during the iteration process, This represents the generator terminal voltage amplitude of the power node in the current iteration of the motor-type power supply.

[0061] For power nodes of inverter-type power supplies, a preset voltage sag threshold is obtained. The current iteration voltage amplitude of the power node is compared with the preset voltage sag threshold to obtain the comparison result. Based on the following formula, the current iteration current value of the power node is determined according to the comparison result. , in, This represents the current value of the power node in the current iteration for an inverter-type power supply. This represents the active power value of a power node in an inverter-type power supply before a short-circuit fault. This represents the current iteration voltage amplitude of a power node of the inverter power type.

[0062] It should be noted that inverter-type power nodes refer to new energy sources and DC systems connected to the grid via inverters. Inverter-type new energy sources are connected to the grid through power electronic converters, and the short-circuit current is limited by the converter control strategy, resulting in a smaller amplitude and rapid decay. Examples include photovoltaic power generation and direct-drive permanent magnet synchronous wind power generation that requires a full-power converter for grid connection. The impact of UHVDC grid connection on short-circuit current can be categorized into LCC-HVDC. We will discuss two types of power supply nodes: VSC and HVDC. LCC-HVDC grid connection can be seen as adding a constant current source at the grid connection point. VSC-HVDC grid connection is similar to inverter-type new energy cluster grid connection. Considering its low-voltage ride-through capability, it can be treated as a current source whose current varies with the port voltage. Based on this, the fault current characteristics of the power node of the inverter type depend on its control strategy. When a short-circuit fault occurs, due to the isolation effect of the DC side of the inverter power supply, considering the transient effect after the short-circuit fault, it can be approximately assumed that the power input to the DC side of the inverter remains constant. The DC side energy of the power node of the inverter type is set as a voltage-controlled current source with control circuit. After passing through the inverter bridge circuit, it becomes a three-phase AC power supply connected to the grid. Considering the current withstand capability of the switches in the inverter, the maximum allowable current of the power node of the inverter type is limited to 1.2~2pu, thereby limiting the priority of active current so as to leave room for reactive current during the fault.

[0063] Based on this, if the voltage amplitude of the current iteration is greater than or equal to the preset voltage drop threshold (e.g., 0.9 times the voltage amplitude before the short-circuit fault), then the current value of the power node of the inverter power type is determined to be [value missing]. If the voltage amplitude of the current iteration is less than the preset voltage drop threshold, and If the current is less than the maximum allowable current (e.g., twice the current before the short-circuit fault), then the current value of the power node for the inverter power supply type in the current iteration is determined. If the voltage amplitude of the current iteration is less than the preset voltage drop threshold, and If the current is greater than or equal to the maximum allowable current, then the current value of the power node for the inverter power type in the current iteration is 2.

[0064] Finally, by integrating the current values ​​of each power node in the current iteration, the current vector of the entire system nodes in the current iteration of the target power system is obtained.

[0065] 207. Calculate the short-circuit current of the target power system based on the node voltage vector of the entire system after the iteration is completed.

[0066] It is understood that the short-circuit current of the target power system is used to characterize the sum of all currents flowing into the fault node. Based on this, in the embodiments of this application, the voltage magnitude of each voltage node in the iterated whole system node voltage vector is multiplied by the admittance between the voltage node and the fault node, and then all products are summed to obtain the short-circuit current of the target power system.

[0067] This application provides a method for calculating the short-circuit current of a power system. First, a short-circuit fault is simulated in a simulation environment of the target power system, and a corresponding non-faulty node admittance matrix is ​​constructed. The non-faulty node admittance matrix is ​​obtained by correcting the total system node admittance matrix of the target power system based on the simulated short-circuit fault. Second, the initial current values ​​of each power source node in the target power system are calculated to obtain the initial total system node injected current vector. The quotient between the initial total system node injected current vector and the non-faulty node admittance matrix is ​​calculated to obtain the first iterative total system node voltage vector of the target power system. An iterative solution equation is constructed based on the initial total system node injected current vector, the non-faulty node admittance matrix, and the first iterative total system node voltage vector. The power source types include infinite source power sources, motor-type power sources, and inverter-type power sources. Finally, the iterative solution equation is iteratively solved until a preset convergence condition is met, resulting in a completed total system node voltage vector. The short-circuit current of the target power system is then calculated based on the completed iterative total system node voltage vector. Compared with existing technologies, the embodiments of this application incorporate the impact of changes in pre-fault operating states on short-circuit current by constructing iterative solution equations. This reduces the deviation between the calculated short-circuit current of the target power system and the actual dynamic response, thereby improving the accuracy of short-circuit current calculation. Furthermore, when constructing iterative solution equations, multiple types of power sources are modeled, including infinite-source power sources, motor-type power sources, and inverter-type power sources. This makes the iterative solution equations more applicable to power systems after the transition. At the same time, due to the modeling of multiple power source types, the current superposition effect of each type of power source is quantified, further improving the accuracy of short-circuit current calculation.

[0068] Furthermore, as a response to the above Figure 1 The implementation of the method shown in this application provides a device for calculating the short-circuit current of a power system, such as... Figure 3 As shown, the device includes: Non-fault node admittance matrix construction module 31, iterative equation construction module 32, iterative solution module 33; The non-fault node admittance matrix construction module 31 is used to simulate a short-circuit fault in the simulation environment of the target power system and construct the corresponding non-fault node admittance matrix. The non-fault node admittance matrix is ​​obtained by correcting the whole system node admittance matrix of the target power system based on the simulated short-circuit fault. The iterative equation construction module 32 is used to calculate the initial current value of each power node in the target power system, obtain the initial total system node injection current vector of the target power system, calculate the quotient between the initial total system node injection current vector and the non-fault node admittance matrix, obtain the first iterative total system node voltage vector of the target power system, and construct iterative equations based on the initial total system node injection current vector, the non-fault node admittance matrix and the first iterative total system node voltage vector. The power source type includes infinite source power source type, motor type power source type and inverter type power source type. The iterative solution module 33 is used to perform iterative solutions based on the iterative solution equations until a preset convergence condition is met, to obtain the full system node voltage vector after the iteration is completed, and to calculate the short-circuit current of the target power system based on the full system node voltage vector after the iteration is completed.

[0069] In specific application scenarios, the non-fault node admittance matrix construction module is used for: Obtain the design data of the target power system, and construct the total system node admittance matrix of the target power system based on the design data; Based on the design data, a simulation environment for the target power system is constructed, and a short-circuit fault is simulated in the simulation environment. The fault node of the simulated short-circuit fault is determined. In the whole system node admittance matrix, the entire row and the entire column corresponding to the fault node are deleted to correct the whole system node admittance matrix and obtain the non-fault node admittance matrix.

[0070] In specific application scenarios, the iterative equation-solving and construction module includes: A power type determination unit is used to determine the power type of each power node included in the target power system; The initial current calculation unit is used to calculate the equivalent impedance value between the power node and the fault node for a power node of the infinite source power type, and to determine the initial current value of the power node as the quotient between the bus voltage amplitude before the short-circuit fault and the equivalent impedance value, expressed as the following formula. , in, Power nodes representing infinite source power types The short-circuit current value contributed to the faulty node. Indicates power node The bus voltage amplitude before the short-circuit fault, This represents the equivalent impedance between a power node and a fault node in an infinite-source power supply type. The initial current calculation unit is further configured to, for power nodes of the motor-type power supply type, calculate the pre-short-circuit transient potential of the power node based on the generator terminal voltage amplitude, active power value, and reactive power value before the short-circuit fault, and calculate the transfer impedance between the fault node and the power node. The quotient between the pre-short-circuit transient potential and the transfer impedance is determined as the initial current value of the power node, expressed as the following formula. , , , in, This indicates the generator current at the power node of the motor-type power supply. This indicates the active power value of the power node before a short-circuit fault in a motor-type power supply. This indicates the reactive power value of the power node before a short-circuit fault in a motor-type power supply. Indicates conjugate. Power nodes indicating motor type power supply The subtransient potential, This indicates the generator terminal voltage amplitude at the power node of the motor-type power supply before a short-circuit fault. The subtransient reactance of a power node representing a motor-type power supply is... Represents the imaginary part of a complex number. Indicates the distance from fault node k to power node The transfer impedance between them This represents the self-impedance of the faulty node k. This represents the short-circuit current value contributed by the power node of the motor-type power supply to the fault node k. The initial current value calculation unit is also used to determine the initial current value of the power node by taking the voltage amplitude before the short circuit fault and the active power value before the short circuit fault for the power node of the inverter power type. An integration unit is used to integrate the initial current values ​​of each of the power supply nodes to obtain the initial total system node injection current vector of the target power system.

[0071] In specific application scenarios, the power type determination unit is used for: The equivalent impedance between each power node and the fault node is calculated and expressed as the following formula; , in, This represents the equivalent impedance between the power supply node and the faulty node. Represents a node With nodes The equivalent impedance of all communication channels between them; If the equivalent impedance is less than a preset equivalent impedance threshold, then the power type of the power node corresponding to the equivalent impedance is determined to be an infinite source power type. If the equivalent impedance is greater than the preset equivalent impedance threshold, the power type of the power node is determined according to the grid connection mode of the power node corresponding to the equivalent impedance. Among them, the power node directly connected to the grid through a generator is a motor type power type, and the power node connected to the grid through a power electronic inverter is an inverter type power type.

[0072] In specific application scenarios, before the iterative equation construction module, the device further includes a pre-fault power flow calculation module, used for: Based on the design data of the target power system, the pre-fault power flow calculation results of the target power system before the occurrence of a short-circuit fault are calculated, so as to obtain the bus voltage amplitude before the short-circuit fault of the power node of the infinite source power type, the generator terminal voltage amplitude before the short-circuit fault of the power node of the motor type power type, the active power value before the short-circuit fault and the reactive power value before the short-circuit fault of the power node of the inverter type power type.

[0073] In specific application scenarios, the iterative solution module includes: The system node voltage vector update unit is used to substitute the system node injected current vector of the previous iteration into the iterative solution equation to obtain the system node voltage vector of the current iteration. The system-wide node injection current vector update unit is used to update the previous iteration current value of each power supply node based on the current iteration system-wide node voltage vector to obtain the current iteration system-wide node injection current vector. The system-wide node voltage vector update unit is also used to substitute the current injected current vector of the current iteration of the system-wide nodes into the iterative solution equation to obtain the system-wide node voltage vector of the next iteration. The convergence determination unit is used to determine the system node voltage vector of the next iteration as the system node voltage vector that has completed the iteration if the residual between the system node voltage vector of the next iteration and the system node voltage vector of the current iteration is less than a preset convergence tolerance.

[0074] In specific application scenarios, the system-wide node injection current vector update unit is used for: For power nodes of the infinite source power type, the current value of the current iteration is determined to be the current value of the previous iteration; For a power node of motor type, the current iteration subtransient potential of the power node is calculated based on the current iteration generator terminal voltage amplitude, active power value before short circuit fault, and reactive power value before short circuit fault. The transfer impedance between the fault node and the power node is also calculated. The quotient between the current iteration subtransient potential and the transfer impedance is determined as the current iteration current value of the power node. For power nodes of inverter-type power supplies, a preset voltage sag threshold is obtained. The current iteration voltage amplitude of the power node is compared with the preset voltage sag threshold to obtain a comparison result. Based on the following formula, the current iteration current value of the power node is determined according to the comparison result. , in, This represents the current value of the power node in the current iteration for an inverter-type power supply. This represents the active power value of a power node in an inverter-type power supply before a short-circuit fault. This represents the current iteration voltage amplitude of a power node of the inverter power type; By integrating the current values ​​of each power node in the current iteration, the current vector of the entire system nodes in the current iteration of the target power system is obtained.

[0075] This application provides a device for calculating the short-circuit current of a power system. First, a short-circuit fault is simulated in a simulation environment of the target power system, and a corresponding non-faulty node admittance matrix is ​​constructed. The non-faulty node admittance matrix is ​​obtained by correcting the total system node admittance matrix of the target power system based on the simulated short-circuit fault. Second, the initial current values ​​of each power source node in the target power system are calculated to obtain the initial total system node injected current vector. The quotient between the initial total system node injected current vector and the non-faulty node admittance matrix is ​​calculated to obtain the first iterative total system node voltage vector of the target power system. An iterative solution equation is constructed based on the initial total system node injected current vector, the non-faulty node admittance matrix, and the first iterative total system node voltage vector. The power source types include infinite source power sources, motor-type power sources, and inverter-type power sources. Finally, the iterative solution equation is iteratively solved until a preset convergence condition is met, resulting in a completed total system node voltage vector. The short-circuit current of the target power system is calculated based on the completed iterative total system node voltage vector. Compared with existing technologies, the embodiments of this application incorporate the impact of changes in pre-fault operating states on short-circuit current by constructing iterative solution equations. This reduces the deviation between the calculated short-circuit current of the target power system and the actual dynamic response, thereby improving the accuracy of short-circuit current calculation. Furthermore, when constructing iterative solution equations, multiple types of power sources are modeled, including infinite-source power sources, motor-type power sources, and inverter-type power sources. This makes the iterative solution equations more applicable to power systems after the transition. At the same time, due to the modeling of multiple power source types, the current superposition effect of each type of power source is quantified, further improving the accuracy of short-circuit current calculation.

[0076] According to one embodiment of this application, a storage medium is provided, the storage medium storing at least one executable instruction, which can execute the method for calculating the short-circuit current of the power system in any of the above method embodiments.

[0077] Based on this understanding, the technical solution of this application can be embodied in the form of a software product. The software product can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, or portable hard drive), and includes several instructions to cause a computer device (such as a personal computer, server, or network device) to execute the methods described in the various implementation scenarios of this application.

[0078] Figure 4 The diagram shows a structural schematic of a terminal according to one embodiment of the present application. The specific embodiments of the present application do not limit the specific implementation of the terminal.

[0079] like Figure 4As shown, the terminal may include: a processor 402, a communications interface 404, a memory 406, and a communications bus 408.

[0080] The processor 402, communication interface 404, and memory 406 communicate with each other via communication bus 408.

[0081] Communication interface 404 is used to communicate with other network elements such as clients or other servers.

[0082] The processor 402 is used to execute program 410, specifically to execute the relevant steps in the above-described embodiment of the method for calculating the short-circuit current of the power system.

[0083] Specifically, program 410 may include program code that includes computer operation instructions.

[0084] Processor 402 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application. The computer device includes one or more processors, which may be processors of the same type, such as one or more CPUs; or they may be processors of different types, such as one or more CPUs and one or more ASICs.

[0085] Memory 406 is used to store program 410. Memory 406 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0086] Specifically, program 410 can be used to cause processor 402 to perform the following operations: A short-circuit fault is simulated in the simulation environment of the target power system, and the corresponding non-fault node admittance matrix is ​​constructed. The non-fault node admittance moment is obtained by correcting the whole system node admittance matrix of the target power system based on the simulated short-circuit fault. The initial current values ​​of each power node in the target power system are calculated to obtain the initial total system node injection current vector of the target power system. The quotient between the initial total system node injection current vector and the non-fault node admittance matrix is ​​calculated to obtain the first iteration total system node voltage vector of the target power system. An iterative solution equation is constructed based on the initial total system node injection current vector, the non-fault node admittance matrix, and the first iteration total system node voltage vector. The power source types include infinite source power source type, motor type power source type, and inverter type power source type. The iterative solution is performed based on the given equation until the preset convergence condition is met, and the node voltage vector of the entire system after the iteration is completed is obtained. The short-circuit current of the target power system is then calculated based on the node voltage vector of the entire system after the iteration is completed.

[0087] The storage medium may also include an operating system and a network communication module. The operating system is a program that manages the hardware and software resources of the physical device used to calculate the short-circuit current in the power system, supporting the operation of information processing programs and other software and / or programs. The network communication module is used to enable communication between the various components within the storage medium, as well as communication with other hardware and software in the information processing physical device.

[0088] 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.

[0089] The methods and systems of this application 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 this application are not limited to the order specifically described above, unless otherwise specifically stated. Furthermore, in some embodiments, this application may also be implemented as a program recorded on a recording medium, the program including machine-readable instructions for implementing the methods according to this application. Thus, this application also covers recording media storing programs for performing the methods according to this application.

[0090] Obviously, those skilled in the art should understand that the modules or steps of this application described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented here, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0091] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method of calculating short circuit current of a power system, characterized by, The method comprises the following steps: simulate a short-circuit fault in a simulation environment of a target power system, and build a corresponding non-fault node admittance matrix, wherein the non-fault node admittance matrix is obtained by modifying a full-system node admittance matrix of the target power system based on the simulated short-circuit fault; calculate initial current values of each power source node included in the target power system to obtain an initial full-system node injection current vector of the target power system, calculate a quotient between the initial full-system node injection current vector and the non-fault node admittance matrix to obtain a first iteration full-system node voltage vector of the target power system, and build an iterative solving equation based on the initial full-system node injection current vector, the non-fault node admittance matrix and the first iteration full-system node voltage vector, wherein the power source types include an infinite source power source type, a motor type power source type and an inverter type power source type; perform iterative solving based on the iterative solving equation until a preset convergence condition is met to obtain a full-system node voltage vector after iteration, and calculate a short-circuit current of the target power system according to the full-system node voltage vector after iteration.

2. The method of claim 1, wherein, The method of simulating a short-circuit fault in a simulation environment of a target power system and building a corresponding non-fault node admittance matrix comprises the following steps: obtain design data of the target power system, and build a full-system node admittance matrix of the target power system based on the design data; build a simulation environment of the target power system based on the design data, and simulate a short-circuit fault in the simulation environment; determine a fault node of the simulated short-circuit fault, delete whole row elements and whole column elements corresponding to the fault node in the full-system node admittance matrix to modify the full-system node admittance matrix and obtain a non-fault node admittance matrix.

3. The method of claim 1, wherein, The method of calculating initial current values of each power source node included in the target power system to obtain an initial full-system node injection current vector of the target power system comprises the following steps: determine power source types of each power source node included in the target power system; for a power source node of an infinite source power source type, calculate an equivalent impedance value between the power source node and a fault node, and determine a quotient between a bus voltage amplitude of the power source node before short-circuit fault and the equivalent impedance value as an initial current value of the power source node, which is expressed as the following formula, wherein, a power node representing an infinite source power type a short circuit current value contributed to the fault node, a power node representing an infinite source power type a short circuit pre-fault bus voltage magnitude, an equivalent impedance value between the power node representing an infinite source power type and the fault node; for a power source node of a motor type power source type, calculate a pre-fault transient potential of the power source node according to a generator end voltage amplitude of the power source node before short-circuit fault, an active power value before short-circuit fault and a reactive power value before short-circuit fault, calculate a transfer impedance between the fault node and the power source node, and determine a quotient between the pre-fault transient potential and the transfer impedance as the initial current value of the power source node, which is expressed as the following formula, ， ， ， wherein, generator current of a power supply node representing the power supply type of the motor type power supply, pre-fault active power value of a power supply node representing the power supply type of the motor type power supply, pre-fault reactive power value of a power supply node representing the power supply type of the motor type power supply, denotes conjugate, a power supply node representing the power supply type of the motor type power supply sub-transient potential, pre-fault generator terminal voltage magnitude of a power supply node representing the power supply type of the motor type power supply, sub-transient reactance of a power supply node representing the power supply type of the motor type power supply, denotes complex imaginary part, denotes transfer impedance between fault node k and a power supply node , denotes self-impedance of fault node k, short-circuit current value contributed by a power supply node representing the power supply type of the motor type power supply to fault node k; for a power source node of an inverter type power source type, determine a quotient between a voltage amplitude of the power source node before short-circuit fault and an active power value before short-circuit fault as the initial current value of the power source node. Integrate initial current values of each of the power supply nodes to obtain an initial full-system node injection current vector of the target power system.

4. The method of claim 3, wherein, The method further comprises, before the calculating the initial current values of each of the power supply nodes included in the target power system to obtain the initial full-system node injection current vector of the target power system: Calculate equivalent impedance between each of the power supply nodes and the fault node, respectively, and represent as the following formula: ， wherein, represents the equivalent impedance between the power node and the fault node, represents the equivalent impedance between the power node and the fault node, represents the equivalent impedance between the power node and the fault node, represents the equivalent impedance between the power node and the fault node, If the equivalent impedance is less than a preset equivalent impedance threshold, determine that the power supply type of the power supply node corresponding to the equivalent impedance is an infinite source power supply type; If the equivalent impedance is greater than the preset equivalent impedance threshold, determine the power supply type of the power supply node according to a grid-connected mode of the power supply node, wherein the power supply node directly connected to the grid through a generator is a motor type power supply type, and the power supply node connected to the grid through a power electronic inverter is an inverter type power supply type.

5. The method of claim 3, wherein, Before the calculating the initial current values of each of the power supply nodes included in the target power system to obtain the initial full-system node injection current vector of the target power system, the method further comprises: Based on the design data of the target power system, calculate a pre-fault flow calculation result of the target power system before a short-circuit fault occurs, to obtain, from the pre-fault flow calculation result, a short-circuit fault pre-bus voltage amplitude of the power supply node of the infinite source power supply type, a short-circuit fault pre-generator terminal voltage amplitude of the power supply node of the motor type power supply type, a short-circuit fault pre-active power value and a short-circuit fault pre-reactive power value, a short-circuit fault pre-voltage amplitude of the power supply node of the inverter type power supply type, and a short-circuit fault pre-active power value.

6. The method of claim 1, wherein, The iterative solving based on the iterative solving equation is performed until a preset convergence condition is met, to obtain a full-system node voltage vector after iteration is completed, comprising: Substitute the full-system node injection current vector after the previous iteration into the iterative solving equation to obtain a full-system node voltage vector after the current iteration; Update the current value of each of the power supply nodes based on the full-system node voltage vector after the current iteration to obtain a full-system node injection current vector after the current iteration; Substitute the full-system node injection current vector after the current iteration into the iterative solving equation to obtain a full-system node voltage vector after the next iteration; If a residual error between the full-system node voltage vector after the next iteration and the full-system node voltage vector after the current iteration is less than a preset convergence tolerance, determine the full-system node voltage vector after the next iteration as the full-system node voltage vector after iteration is completed.

7. The method of claim 6, wherein, The updating of the current value of each of the power supply nodes based on the full-system node voltage vector after the current iteration to obtain the full-system node injection current vector after the current iteration comprises: For the power supply node of the infinite source power supply type, determine the current iteration current value as the previous iteration current value; For the power supply node of the motor type power supply type, according to the current iteration generator end voltage amplitude, the short-circuit fault before the active power value and the short-circuit fault before the reactive power value of the power supply node, the current iteration transient potential of the power supply node is calculated, and the transfer impedance between the fault node and the power supply node is calculated, and the quotient between the current iteration transient potential and the transfer impedance is determined as the current iteration current value of the power supply node; For the power supply node of the inverter type power supply type, a preset voltage drop threshold is obtained, the current iteration voltage amplitude of the power supply node is compared with the preset voltage drop threshold to obtain a comparison result, and based on the following formula, the current iteration current value of the power supply node is determined according to the comparison result, ， wherein, represents the current sub-iteration current value of the power node of the inverter type power supply, represents the short-circuit fault pre-active power value of the power node of the inverter type power supply, represents the current sub-iteration voltage amplitude value of the power node of the inverter type power supply; The current iteration current values of the power supply nodes are integrated to obtain the current iteration full-system node injection current vector of the target power system.

8. An apparatus for calculating short circuit current of a power system, characterized by comprising: Comprise: The non-fault node admittance matrix construction module is used for simulating a short-circuit fault in a simulation environment of a target power system and constructing a corresponding non-fault node admittance matrix, wherein the non-fault node admittance matrix is obtained by correcting a full-system node admittance matrix of the target power system based on the simulated short-circuit fault; The iteration solving equation construction module is used for calculating initial current values of each power supply node included in the target power system to obtain an initial full-system node injection current vector of the target power system, calculating the quotient between the initial full-system node injection current vector and the non-fault node admittance matrix to obtain a first iteration full-system node voltage vector of the target power system, and constructing an iteration solving equation based on the initial full-system node injection current vector, the non-fault node admittance matrix and the first iteration full-system node voltage vector, wherein the power supply type includes an infinite source power supply type, a motor type power supply type and an inverter type power supply type; The iteration solving module is used for performing iteration solving based on the iteration solving equation until a preset convergence condition is met to obtain a full-system node voltage vector after iteration, and calculating a short-circuit current of the target power system according to the full-system node voltage vector after iteration.

9. A storage medium having stored therein at least one executable instruction, characterized in that, The executable instructions enable the processor to perform operations corresponding to the power system short-circuit current calculation method of any one of claims 1-7.

10. A terminal comprising: The processor, the memory, the communication interface and the communication bus complete communication among each other through the communication bus; The memory is used to store at least one executable instruction, and the executable instructions enable the processor to perform operations corresponding to the power system short-circuit current calculation method of any one of claims 1-7.

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