Method for calculating direct current component of short circuit current and device therefor

Abstract

The application relates to a short-circuit current direct-current component calculation method and a calculation device thereof. The method comprises the following steps: constructing a short-circuit equivalent model; obtaining a short-circuit capacity of a three-phase alternating-current system and a decay time constant of a direct-current component; determining equivalent resistance and equivalent inductance based on the short-circuit capacity and the decay time constant; constructing a three-dimensional finite element model of an arc to determine arc resistance and arc inductance; and determining the direct-current component of the short-circuit current based on the short-circuit equivalent model. In the construction of the short-circuit equivalent model, the arc resistance and the arc inductance of the short-circuit arc are considered, the equivalent resistance and the equivalent inductance in the short-circuit equivalent model are determined, and the arc resistance and the arc inductance in the equivalent model are determined, so that the finally determined short-circuit equivalent model is obtained, the direct-current component of the short-circuit current is determined, the more accurate calculation of the direct-current component is completed, and the risk that the circuit breaker cannot be opened due to the excessive short-circuit current direct-current component is more accurately evaluated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system fault analysis, in particular to a method for calculating a direct current component of short-circuit current and a device thereof. BACKGROUND

[0002] With the increase of the voltage level of the power grid in the power system, the continuous application of large-capacity generators and transformers, the ratio of the reactance to the resistance of the primary equipment increases, and the time constant of the direct current component of the short-circuit current gradually increases, so that the direct current component of the short-circuit current in the power system will exceed the short-circuit breaking capacity of the circuit breaker, thereby there is a risk that the direct current component of the short-circuit current exceeds the standard and causes the circuit breaker to be unable to break. In the related art, when calculating the direct current component of the short-circuit current, the arc resistance is not considered, which may cause deviation in the calculation of the direct current component, thereby exaggerating the risk that the circuit breaker is unable to break due to the direct current component of the short-circuit current exceeding the standard. SUMMARY

[0003] Therefore, it is necessary to provide a method, device, computer equipment, computer readable storage medium and computer program product for calculating the direct current component of the short-circuit current, which can more accurately calculate the direct current component of the short-circuit current.

[0004] In a first aspect, the present application provides a method for calculating a direct current component of short-circuit current. The method comprises: constructing a short-circuit equivalent model; wherein the short-circuit equivalent model comprises a short-circuit current equivalent circuit and an arc equivalent circuit, the short-circuit current equivalent circuit is connected to the arc equivalent circuit through a switch, the short-circuit current equivalent circuit comprises an equivalent resistance and an equivalent inductance connected in series, and the arc equivalent circuit comprises an arc resistance and an arc inductance connected in series; obtaining a short-circuit capacity and a decay time constant of a direct current component of a three-phase alternating current system; determining the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant; constructing a three-dimensional finite element model of the arc to determine the arc resistance and the arc inductance; and determining the direct current component of the short-circuit current based on the short-circuit equivalent model.

[0005] In one of the embodiments, the step of obtaining the short-circuit capacity and the decay time constant of the direct current component of the three-phase alternating current system comprises: calculating the short-circuit capacity based on an equivalent voltage source method; and calculating the decay time constant based on an equivalent frequency method.

[0006] In one of the embodiments, the step of determining the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant comprises: determining the equivalent inductance based on the short-circuit capacity and an alternating current component; and determining the equivalent resistance based on the equivalent inductance and the decay time constant.

[0007] In one of the embodiments, the step of determining the equivalent inductance based on the short-circuit capacity and the AC component includes: taking the square of the AC component and the quotient of a first product as the equivalent inductance; wherein the first product is the product of an angular velocity and the short-circuit capacity.

[0008] In one of the embodiments, the step of determining the equivalent resistance based on the equivalent inductance and the decay time constant includes: taking the quotient of the equivalent inductance and the decay time constant as the equivalent resistance.

[0009] In one of the embodiments, the method further includes: obtaining a current short-circuit current passing through the switch; determining a current arc resistance based on a preset correspondence relationship and the current short-circuit current; wherein the preset correspondence relationship is a correspondence relationship between short-circuit currents and arc resistances determined by the short-circuit equivalent model; and determining a DC component of the current short-circuit current according to the current arc resistance.

[0010] In a second aspect, the present application further provides a method for calculating a DC component of a short-circuit current. The method includes: constructing a short-circuit equivalent model; wherein the short-circuit equivalent model includes a short-circuit current equivalent circuit and an arc equivalent circuit, the short-circuit current equivalent circuit is connected to the arc equivalent circuit through a switch, the short-circuit current equivalent circuit includes an equivalent resistance and an equivalent inductance connected in series, and the arc equivalent circuit includes an arc resistance and an arc inductance connected in series; obtaining a short-circuit capacity and a decay time constant of a DC component of a three-phase AC system; determining the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant; constructing a three-dimensional finite element model of the arc to determine the arc resistance and the arc inductance; and determining a DC component of a short-circuit current based on the short-circuit equivalent model.

[0011] In a third aspect, the present application further provides a computer device. The computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0012] In a fourth aspect, the present application further provides a computer readable storage medium. The computer readable storage medium stores a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0013] In a fifth aspect, the present application further provides a computer program product. The computer program product includes a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0014] The method, device, computer device, computer readable storage medium and computer program product for calculating the direct current component of the short-circuit current consider the arc resistance and arc inductance of the short-circuit arc when the short-circuit equivalent model is constructed, determine the equivalent resistance and equivalent inductance in the short-circuit equivalent model through the short-circuit capacity and decay time constant, and determine the arc resistance and arc inductance in the equivalent model through the construction of the three-dimensional finite element model of the arc, so that the finally determined short-circuit equivalent model is obtained, and the direct current component of the short-circuit current is determined, the more accurate calculation of the direct current component is completed, and the risk that the circuit breaker cannot be broken due to the excessive direct current component of the short-circuit current is more accurately evaluated. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0016] Figure 1 A flowchart of a method for calculating the direct current component of the short-circuit current in an embodiment;

[0017] Figure 2 An equivalent circuit diagram of a short-circuit equivalent model in an embodiment;

[0018] Figure 3 A flowchart of determining the short-circuit capacity and decay time constant in an embodiment;

[0019] Figure 4 A flowchart of determining the equivalent resistance and equivalent inductance in an embodiment;

[0020] Figure 5 A flowchart of determining the arc resistance according to the three-dimensional finite element model in an embodiment;

[0021] Figure 6 A flowchart of a method for calculating the direct current component of the short-circuit current in another embodiment;

[0022] Figure 7 A module diagram of a device for calculating the direct current component of the short-circuit current in an embodiment;

[0023] Figure 8 An internal structure diagram of a computer device in an embodiment. DETAILED DESCRIPTION

[0024] For the purpose of promoting an understanding of the application, the application will now be described in greater detail with reference to the figures. The embodiments shown in the figures are intended to explain the present application and are not meant to limit the present application. Rather, the present application can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0026] It should be understood that the terms "first", "second", etc. used herein can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element.

[0027] As described in the background, in the prior art, when calculating the direct current component of short-circuit current, the arc resistance of the circuit breaker is not considered, which may cause the calculation of the direct current component to be too large, resulting in an overestimation of the risk of the circuit breaker when evaluating the risk of the circuit breaker being unable to break due to the over-standard direct current component of short-circuit current, and further resulting in the replacement of a switchgear that does not exist a risk, thereby increasing the cost of modification.

[0028] Based on the above reasons, the present application provides a method and device for calculating the direct current component of short-circuit current, computer equipment, computer readable storage medium and computer program product, which can more accurately calculate the direct current component of short-circuit current and more accurately evaluate the risk of the circuit breaker.

[0029] In one embodiment, as shown in Figure 1 A method for calculating the direct current component of short-circuit current is provided, which is described by taking the computer equipment as an example, and includes the following steps:

[0030] Step S110, constructing a short-circuit equivalent model.

[0031] Specifically, when calculating the direct current component of short-circuit current, the present application first constructs a short-circuit equivalent model including a short-circuit arc. As shown in Figure 2As shown, the short-circuit equivalent model includes: a short-circuit current equivalent circuit and an arc equivalent circuit. The short-circuit current equivalent circuit is an equivalent circuit in traditional short-circuit current calculation, which can be equivalent to an RLC circuit. The short-circuit current equivalent circuit includes an equivalent resistance and an equivalent inductance in series, that is, R1 and L1 in the figure. The arc equivalent circuit is an equivalent circuit considering the impedance and inductance of the short-circuit arc, which can also be equivalent to an RLC circuit. The arc equivalent circuit includes an arc resistance and an arc inductance in series, that is, R2 and L2 in the figure. The short-circuit current equivalent circuit is connected to the arc equivalent circuit through a switch CB, thereby forming a complete short-circuit equivalent model. The breaking process of the switch can simulate whether the three-phase alternating current system is short-circuited, and the parameters of the arc generated in the short-circuit process can be simulated by the arc equivalent circuit.

[0032] In step S120, the short-circuit capacity of the three-phase alternating current system and the decay time constant of the direct current component are obtained.

[0033] Specifically, after the short-circuit equivalent model is constructed, the parameters of each element in the short-circuit equivalent model need to be calculated. First, the short-circuit capacity of the current three-phase alternating current system and the decay time constant of the direct current component are calculated by a traditional short-circuit current calculation method. The short-circuit capacity is the maximum short-circuit current when a node in the three-phase alternating current system is short-circuited. The direct current component of the short-circuit current is mainly generated by the inductance (such as the inductance of a transformer, a motor, and other devices) in the circuit at the moment of short-circuit. When the circuit is short-circuited, the current in the inductance cannot change abruptly, so it will maintain the current value at the moment before the short-circuit occurs and gradually decay. This maintained and decaying current is the direct current component, and the time from the start of the decay to the end of the decay is the decay time constant.

[0034] In step S130, the equivalent resistance and the equivalent inductance are determined based on the short-circuit capacity and the decay time constant.

[0035] Specifically, after the short-circuit capacity of the current three-phase alternating current system and the decay time constant of the direct current component are obtained, the size of the equivalent resistance and the equivalent inductance in the short-circuit current equivalent circuit can be determined based on the short-circuit capacity and the decay time constant.

[0036] In step S140, a three-dimensional finite element model of the arc is constructed to determine the arc resistance and the arc inductance.

[0037] Specifically, when calculating the arc resistance and arc inductance in the arc equivalent circuit, a three-dimensional finite element model of the arc needs to be constructed. The three-dimensional finite element model of the arc is an arc plasma finite element model built based on magnetohydrodynamics, and the model involves multiple field couplings such as momentum, energy, electromagnetic field, and radiation field. By solving the model using a finite element simulation software, the arc resistance and arc inductance of the arc in the whole process from generation to disappearance can be obtained. It can be understood that the arc resistance presents a nonlinear change with the short-circuit current, and the arc resistance at different times when the arc is generated spans multiple orders of magnitude. Therefore, the arc resistance calculated by the three-dimensional finite element model is nonlinearly changed with time.

[0038] In step S150, the direct current component of the short-circuit current is determined based on the short-circuit equivalent model.

[0039] Specifically, after the equivalent resistance, equivalent inductance, arc resistance, and arc inductance are calculated through the above steps, the change of the direct current component of the short-circuit current when the arc resistance exists can be determined by combining the connection relationship in the short-circuit equivalent model, so as to complete the fine calculation of the direct current component.

[0040] The above method for calculating the direct current component of the short-circuit current considers the arc resistance and arc inductance of the short-circuit arc when constructing the short-circuit equivalent model, and determines the equivalent resistance and equivalent inductance in the short-circuit equivalent model through the short-circuit capacity and the decay time constant, and determines the arc resistance and arc inductance in the equivalent model by constructing a three-dimensional finite element model of the arc, so as to obtain the finally determined short-circuit equivalent model, and determine the direct current component of the short-circuit current, complete more accurate calculation of the direct current component, and more accurately assess the risk of the circuit breaker being unable to break due to the direct current component of the short-circuit current exceeding the standard.

[0041] In one embodiment, as shown in FIG. 1, Figure 3 The step of obtaining the short-circuit capacity and the decay time constant of the direct current component of the three-phase alternating current system in step S120 includes:

[0042] In step S121, the short-circuit capacity is calculated based on the equivalent voltage source method.

[0043] Specifically, in the calculation of the short-circuit capacity, i.e., the maximum short-circuit current, the equivalent voltage source method is used for calculation. The equivalent voltage source method is proposed by IEC60909 standard, and is widely used. The IEEE / ANSI related standards also recommend using the equivalent voltage source method. Existing short-circuit current calculation programs such as DSP, BPA, PSASP, PSS\E all support this method, and the short-circuit capacity can be quickly calculated by using the equivalent voltage source method.

[0044] In step S121, the decay time constant is calculated based on the equivalent frequency method.

[0045] Specifically, the embodiment calculates the decay time constant by the equivalent frequency method. The equivalent frequency method adopted by the national standard "Three-phase AC system short-circuit current calculation standard" is the most widely used method for calculating the peak value of the short-circuit current DC component and the decay time constant. The decay time constant of the short-circuit current DC component can be quickly calculated by the equivalent frequency method.

[0046] In one embodiment, as shown in FIG. 1, in step S130, the step of determining the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant comprises: Figure 4

[0047] In step S131, the equivalent inductance is determined based on the short-circuit capacity and the AC component.

[0048] Specifically, in the embodiment, after obtaining the short-circuit capacity and the decay time constant of the DC component of the three-phase AC system, the equivalent inductance is first determined according to the short-circuit capacity and in combination with the AC component. In some embodiments, the step of determining the equivalent inductance based on the short-circuit capacity and the AC component comprises: taking the quotient of the square of the AC component and the first product as the equivalent inductance; wherein the first product is the product of the angular velocity and the short-circuit capacity. That is, the equivalent inductance L1 is determined by the following formula:

[0049]

[0050] wherein U is the voltage value of the short-circuit current AC component, is the angular velocity of the three-phase AC system, S k is the short-circuit capacity.

[0051] In step S132, the equivalent resistance is determined based on the equivalent inductance and the decay time constant.

[0052] Specifically, after the equivalent inductance is determined, the equivalent resistance is determined by combining the equivalent inductance and the decay time constant. In some embodiments, the step of determining the equivalent resistance based on the equivalent inductance and the decay time constant comprises: taking the quotient of the equivalent inductance and the decay time constant as the equivalent resistance. That is, the equivalent resistance R1 is determined by the following formula:

[0053]

[0054] wherein L1 is the equivalent inductance, is the decay time constant of the DC component.

[0055] In one embodiment, as shown in FIG. 1, in step S130, the step of determining the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant comprises: Figure 5 ​As shown, the process of constructing a three-dimensional finite element model of the arc in an embodiment to determine the arc resistance. The three-dimensional finite element model of the arc includes a power system simulation part and an arc simulation part. The power system simulation part can use power system simulation software (such as PSCAD) to construct the corresponding simulation circuit according to the short circuit equivalent model. The arc simulation part can use simulation software (such as fluent) to construct the corresponding finite element model of the arc plasma. After the power system simulation starts running, the software starts the simulation calculation of the circuit, and when a certain simulation condition or time is reached, a trigger signal is given to control the switch CB to open, and the trigger signal is also used to control the arc simulation part to start simulation. The power system simulation part is ready to send data to the arc simulation part through the communication pipe, and opens the server to wait for connection. After the communication pipe of the power system simulation part and the arc simulation part is successfully connected, the power system simulation part starts to send the arc-related data (such as arc resistance, arc current, etc.) to the arc simulation part. The power system simulation part continues to perform iterative calculation of the circuit and updates the related parameters of the arc. After starting to run, the arc simulation part first performs the necessary initialization setting, and is ready to receive the data of the power system simulation part. The arc simulation part opens the client of the communication pipe for receiving the data sent by the power system simulation part. After the communication pipe of the arc simulation part and the power system simulation part is successfully connected, the arc simulation part receives the arc data (such as arc resistance, arc current, etc.) sent by the power system simulation part, and the arc simulation part updates the resistance and current of the arc according to the received data, and performs iterative calculation of the arc using the updated arc parameters. The power system simulation part and the arc simulation part will stop simulation after a predetermined simulation time.

[0056] In one embodiment, as shown in Figure 6 The method for calculating the direct current component of the short circuit current further includes:

[0057] In step S210, the current short circuit current passing through the switch is obtained.

[0058] Specifically, in actual use, the method for calculating the direct current component of the short circuit current in the embodiment first obtains the current short circuit current passing through the switch through the current transformer.

[0059] In step S220, the current arc resistance is determined based on a preset corresponding relationship and the current short circuit current.

[0060] Specifically, after the current short-circuit current is obtained, the current short-circuit current is matched in the preset correspondence relationship to determine the current arc resistance corresponding to the current short-circuit current. The preset correspondence relationship is the correspondence relationship between the short-circuit current and the arc resistance determined by the short-circuit equivalent model. The preset correspondence relationship is the correspondence relationship between the short-circuit current and the arc resistance in the current three-phase alternating current system pre-stored in the process of simulation based on the short-circuit equivalent model, and one short-circuit current corresponds to one arc resistance. Through the steps of pre-storing and directly matching, it is not necessary to simulate the three-phase alternating current system in real time, the calculation amount in use is reduced, and the efficiency of determining the current arc resistance is improved.

[0061] In step S230, the direct current component of the current short-circuit current is determined according to the current arc resistance.

[0062] Specifically, after the current arc resistance is determined, the equivalent resistance, the equivalent inductance and the arc inductance are pre-stored, and the change of the direct current component of the short-circuit current when the arc resistance exists is determined by combining the connection relationship in the short-circuit equivalent model, so that the fine calculation of the direct current component is quickly completed.

[0063] It should be understood that, although each step in the flowchart involved in each of the above-described embodiments is displayed in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, at least part of the steps in the flowchart involved in each of the above-described embodiments can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least part of other steps or steps or stages in other steps.

[0064] Based on the same inventive concept, the present application also provides a short-circuit current direct current component calculation device for implementing the above-mentioned short-circuit current direct current component calculation method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme described in the above method, so the specific limitations in one or more short-circuit current direct current component calculation device embodiments provided below can refer to the limitations of the short-circuit current direct current component calculation method in the above text, which will not be repeated here.

[0065] In one embodiment, as shown in Figure 7 A short-circuit current direct current component calculation device is provided, which includes a first model construction module 310, a parameter acquisition module 320, a parameter determination module 330, a second model construction module 340 and a direct current component determination module 350, wherein:

[0066] The first model construction module 310 is configured to construct a short-circuit equivalent model; wherein the short-circuit equivalent model comprises a short-circuit current equivalent circuit and an arc equivalent circuit, the short-circuit current equivalent circuit is connected to the arc equivalent circuit through a switch, the short-circuit current equivalent circuit comprises an equivalent resistance and an equivalent inductance connected in series, and the arc equivalent circuit comprises an arc resistance and an arc inductance connected in series;

[0067] The parameter acquisition module 320 is configured to acquire a short-circuit capacity of a three-phase alternating current system and a decay time constant of a direct current component;

[0068] The parameter determination module 330 is configured to determine the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant;

[0069] The second model construction module 340 is configured to construct a three-dimensional finite element model of the arc to determine the arc resistance and the arc inductance;

[0070] The direct current component determination module 350 is configured to determine a direct current component of a short-circuit current based on the short-circuit equivalent model.

[0071] In one embodiment, the parameter acquisition module 320 is further configured to calculate the short-circuit capacity based on an equivalent voltage source method and calculate the decay time constant based on an equivalent frequency method.

[0072] In one embodiment, the parameter determination module 330 is further configured to determine the equivalent inductance based on the short-circuit capacity and an alternating current component and determine the equivalent resistance based on the equivalent inductance and the decay time constant.

[0073] In one embodiment, the parameter determination module 330 is further configured to take a quotient value of the square of the alternating current component and a first product as the equivalent inductance; wherein the first product is a product of an angular velocity and the short-circuit capacity.

[0074] In one embodiment, the parameter determination module 330 is further configured to take a quotient value of the equivalent inductance and the decay time constant as the equivalent resistance.

[0075] In one embodiment, the short-circuit current direct current component calculation device further comprises:

[0076] The current detection module is configured to acquire a current short-circuit current passing through the switch;

[0077] The data matching module is configured to determine a current arc resistance based on a preset corresponding relationship and the current short-circuit current; wherein the preset corresponding relationship is a corresponding relationship between the short-circuit current and the arc resistance determined by the short-circuit equivalent model;

[0078] The current determination module is configured to determine a direct current component of the current short-circuit current according to the current arc resistance.

[0079] The modules in the short-circuit current DC component calculation device can be implemented by software, hardware, or a combination thereof. The modules can be embedded in a processor in a computer device or independent of the processor, or stored in a memory in the computer device to be invoked by the processor to perform the operations of the modules.

[0080] In one embodiment, a computer device is provided, which can be a terminal, and an internal structure diagram of the computer device can be as shown in FIG. 1. Figure 8 The computer device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. The processor, the memory, and the input / output interface are connected through a system bus, and the communication interface, the display unit, and the input device are connected to the system bus through the input / output interface. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for running the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is configured to exchange information between the processor and external devices. The communication interface of the computer device is configured to perform wired or wireless communication with external terminals. The wireless communication can be achieved by WIFI, mobile cellular network, NFC (near field communication), or other technologies. The computer program is executed by the processor to implement a short-circuit current DC component calculation method. The display unit of the computer device is configured to form a visually visible picture, which can be a display screen, a projection device, or a virtual reality imaging device. The display screen can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, a trackball, or a touchpad arranged on the shell of the computer device, or an external keyboard, a touchpad, a mouse, or the like.

[0081] Those skilled in the art can understand that Figure 8 The structure shown in FIG. 1 is only a block diagram of part of the structure related to the scheme of the present application, and does not limit the computer device to which the scheme of the present application is applied. Specifically, the computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0082] In one embodiment, a computer device is provided, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0083] In an embodiment, a computer readable storage medium is provided, having stored thereon a computer program, which, when executed by a processor, implements the steps of any of the above method embodiments.

[0084] In an embodiment, a computer program product is provided, comprising a computer program which, when executed by a processor, implements the steps of any of the above method embodiments.

[0085] A person of ordinary skill in the art can understand that all or part of the processes in the above method embodiments can be completed by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above method embodiments. Any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of a non-volatile and volatile memory. The non-volatile memory can include a read-only memory (ROM), a magnetic tape, a floppy disk, a flash memory, an optical storage, a high-density embedded non-volatile memory, a resistive memory (ReRAM), a magnetoresistive random access memory (MRAM), a ferroelectric memory (FRAM), a phase change memory (PCM), a graphene memory, etc. The volatile memory can include a random access memory (RAM) or an external cache memory, etc. As an illustration but not limitation, the RAM can be in various forms, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a blockchain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0086] Any combination of the technical features of the above embodiments can be made, and to make the description concise, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist, it should be considered as the scope of the present application.

[0087] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific manner, but should not be construed as limiting the scope of the patent of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for calculating the DC component of a short-circuit current, characterized in that, The method includes: Construct a short-circuit equivalent model; wherein, the short-circuit equivalent model includes: a short-circuit current equivalent circuit and an arc equivalent circuit, the short-circuit current equivalent circuit is connected to the arc equivalent circuit through a switch, the short-circuit current equivalent circuit includes an equivalent resistance and an equivalent inductance connected in series, and the arc equivalent circuit includes an arc resistance and an arc inductance connected in series. Obtain the short-circuit capacity and DC component decay time constant of the three-phase AC system; The equivalent resistance and the equivalent inductance are determined based on the short-circuit capacity and the decay time constant; A three-dimensional finite element model of the electric arc is constructed to determine the arc resistance and the arc inductance; The DC component of the short-circuit current is determined based on the short-circuit equivalent model.

2. The method for calculating the DC component of short-circuit current according to claim 1, characterized in that, The steps for obtaining the short-circuit capacity and DC component decay time constant of the three-phase AC system include: The short-circuit capacity is calculated based on the equivalent voltage source method; The decay time constant is calculated based on the equivalent frequency method.

3. The method for calculating the DC component of short-circuit current according to claim 1, characterized in that, The step of determining the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant includes: The equivalent inductance is determined based on the short-circuit capacity and the AC component. The equivalent resistance is determined based on the equivalent inductance and the decay time constant.

4. The method for calculating the DC component of short-circuit current according to claim 3, characterized in that, The step of determining the equivalent inductance based on the short-circuit capacity and the AC component includes: The quotient of the square of the AC component and the first product is taken as the equivalent inductance; wherein the first product is the product of the angular velocity and the short-circuit capacity.

5. The method for calculating the DC component of short-circuit current according to claim 3, characterized in that, The step of determining the equivalent resistance based on the equivalent inductance and the decay time constant includes: The quotient of the equivalent inductance and the decay time constant is taken as the equivalent resistance.

6. The method for calculating the DC component of short-circuit current according to any one of claims 1 to 5, characterized in that, The method further includes: Obtain the current short-circuit current through the switch; The current arc resistance is determined based on a preset correspondence and the current short-circuit current; wherein the preset correspondence is the correspondence between the short-circuit current and the arc resistance determined by the short-circuit equivalent model. The DC component of the current short-circuit current is determined based on the current arc resistance.

7. A device for calculating the DC component of short-circuit current, characterized in that, The device includes: The first model construction module is used to construct a short-circuit equivalent model; wherein, the short-circuit equivalent model includes: a short-circuit current equivalent circuit and an arc equivalent circuit, the short-circuit current equivalent circuit is connected to the arc equivalent circuit through a switch, the short-circuit current equivalent circuit includes an equivalent resistance and an equivalent inductance connected in series, and the arc equivalent circuit includes an arc resistance and an arc inductance connected in series. The parameter acquisition module is used to obtain the short-circuit capacity and the decay time constant of the DC component of the three-phase AC system. The parameter determination module is used to determine the equivalent resistance and the equivalent inductance based on the short-circuit capacity and the decay time constant; The second model building module is used to build a three-dimensional finite element model of the electric arc to determine the arc resistance and the arc inductance. A DC component determination module is used to determine the DC component of the short-circuit current based on the short-circuit equivalent model.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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