Alternating current and direct current component calculation method and system for short-circuit current

Abstract

The invention belongs to the field of short-circuit current detection, and provides an AC / DC component calculation method and system for short-circuit current, and the method comprises the steps: determining three maximum values based on an oscillogram of the short-circuit current, fitting the relation among the amplitude of a voltage source, the line impedance and the amplitude of a transient component through the three maximum values, and calculating the amplitude of the transient component. Determining the ratio of the equivalent resistance to the equivalent inductance; the equivalent resistance and the equivalent inductance are determined according to the relation between the line impedance and the equivalent resistance and the equivalent inductance and the ratio of the equivalent resistance to the equivalent inductance; determining an impedance angle based on the relationship between the equivalent resistance and the equivalent inductance and the impedance angle; determining a phase angle according to the initial condition of the short-circuit current, and determining a closing phase angle according to the relation among the phase angle, the impedance angle and the transient component amplitude; and determining an alternating-current component of the short-circuit current and a direct-current component at any moment based on a short-circuit current analytic expression by using the equivalent resistance, the equivalent inductance, the impedance angle and the closing phase angle.

Description

Technical Field

[0001] This invention belongs to the field of short-circuit current detection technology, specifically relating to a method and system for calculating the AC and DC components of short-circuit current. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] High-voltage AC circuit breakers are core protection devices in power systems, and their making capacity directly affects the safety and stability of the power grid. International and national standards have established stringent assessment criteria for type testing of circuit breakers. Specifically, GB / T1984-2024 "High-voltage AC Circuit Breakers" clarifies the requirements and parameter definitions for short-circuit making tests in several key clauses: As specified in clause 7.105.2.1 of the standard, the circuit breaker must be able to close the pre-breakdown arc current. The test must consider two extreme conditions: closing at the peak voltage (within ±15°) to generate a symmetrical short-circuit current and the longest pre-breakdown time; and closing at the zero point of the voltage waveform to generate a completely asymmetrical short-circuit current. This requires precise determination of the closing phase angle in the test waveform.

[0004] According to Clause 7.103.2.1, the power factor of the test circuit must be strictly controlled, and its average value should not exceed 0.15.

[0005] Clause 5.103 states that the peak value of the rated short-circuit making current is obtained by multiplying the effective value of the AC component of the rated short-circuit breaking current by a specific peak factor.

[0006] In addition, Clause 5.101.1 stipulates that the rated short-circuit current must be characterized by its effective value of AC component and the percentage of DC component (or DC time constant), and clarifies the boundary for determining symmetry.

[0007] Therefore, the accurate extraction of parameters such as closing phase angle, power factor, RMS value of AC component, percentage of DC component, and peak factor is a core technical step in objectively evaluating whether a circuit breaker meets standard requirements and completes performance certification. Currently, this field typically relies on digital signal processing algorithms to analyze the acquired voltage and current waveforms to calculate these parameters.

[0008] However, the inventors discovered that traditional parameter extraction and calculation methods have inherent flaws in real-world experimental environments, resulting in severely insufficient accuracy. The main reasons are as follows: First, complex electromagnetic interference leads to waveform distortion. Short-circuit tests are accompanied by intense transient electromagnetic processes, creating an extremely complex electromagnetic environment. The current waveform output by the data acquisition equipment will be superimposed with a large amount of high-frequency noise interference. These non-periodic high-frequency signals severely interfere with traditional algorithms based on power frequency models (such as zero-crossing detection and Fourier transform), causing significant errors in the identification and calculation of key parameters such as the closing phase angle and the effective value of the AC component.

[0009] Second, the transient response of the measurement system introduces inaccurate signals. The test process involves a sharp transition from steady state to transient state. As part of the system, the measurement system (including sensors, transmission links, and data acquisition cards) also exhibits a transient response. This response introduces high-frequency oscillation components generated by the measurement system itself into the current waveform. These components do not originate from the actual current of the circuit breaker under test, but are included in the traditional algorithm, resulting in severe distortion of the extracted DC component, peak factor, and other parameters, failing to accurately reflect the actual breaking performance of the circuit breaker.

[0010] In summary, existing parameter extraction methods are limited by field interference and the characteristics of the measurement system itself, making it difficult to meet the high-precision requirements for test evaluation proposed by the GB / T 1984-2024 standard. They cannot effectively suppress high-frequency noise, identify and eliminate transient responses of the measurement system, thus making it difficult to achieve high-precision extraction of key parameters in complex test environments and failing to guarantee the accuracy and authority of circuit breaker test results. Summary of the Invention

[0011] To address the aforementioned problems, this invention proposes a method and system for calculating parameters such as the closing phase angle, power factor, AC component, DC component, and peak value of short-circuit current. This invention fits the relationship between the voltage source amplitude, line impedance, and transient component amplitude by applying multiple maxima of the short-circuit current. Then, based on the parameters in the analytical formula for the short-circuit current, it determines the voltage source closing phase angle, voltage source power factor, AC component of the short-circuit current, DC component of the short-circuit current, and peak value, thereby improving the accuracy and precision of the calculation of these parameters.

[0012] According to some embodiments, the first aspect of the present invention provides a method for calculating the voltage source closing phase angle, voltage source power factor, AC component of short-circuit current, DC component of short-circuit current, and peak factor for short-circuit current, employing the following technical solution: A method for calculating the voltage source closing phase angle, voltage source power factor, AC component of short-circuit current, DC component of short-circuit current, and peak factor for short-circuit current includes: Based on the waveform of the short-circuit current, three maxima are determined. The relationship between the voltage source amplitude, line impedance, and transient component amplitude is fitted using the three maxima to determine the ratio of equivalent resistance to equivalent inductance. The equivalent resistance and equivalent inductance are determined based on the relationship between line impedance and equivalent resistance and equivalent inductance, as well as the ratio of equivalent resistance to equivalent inductance. The impedance angle is determined based on the relationship between equivalent resistance, equivalent inductance and impedance angle; The phase angle is determined by the initial conditions of the short-circuit current, and the closing phase angle is determined by the relationship between the phase angle, the impedance angle, and the amplitude of the transient component. By utilizing equivalent resistance, equivalent inductance, impedance angle, and closing phase angle, the AC component and DC component of the short-circuit current at any given time are determined based on the analytical formula of the short-circuit current.

[0013] Furthermore, the method of using three maxima to fit the relationship between the voltage source amplitude, line impedance, and transient component amplitude to determine the ratio of equivalent resistance to equivalent inductance is as follows: By using the three maxima and their corresponding time points, the relationship between the voltage source amplitude, line impedance, and transient component amplitude is fitted to obtain the current expressions for the three maxima; By converting the current expressions for the three maxima, the ratio of equivalent resistance to equivalent inductance is determined.

[0014] Furthermore, the expression for the maximum current is:

[0015] in, It is the maximum value of the current. It is the amplitude of the transient component. It is the line impedance. It is the voltage source amplitude. It is the equivalent inductance. It is the equivalent resistance. This is the moment when the AC component of the short-circuit current reaches its maximum value.

[0016] Furthermore, the determination of the impedance angle based on the relationship between equivalent resistance, equivalent inductance, and impedance angle specifically involves:

[0017] in, It is the impedance angle. It is the equivalent inductance. It is the equivalent resistance. It is angular frequency.

[0018] Furthermore, the determination of the closing phase angle using the relationship between the phase angle, impedance angle, and transient component amplitude is specifically as follows:

[0019] in, It is the closing phase angle of the voltage source. It is the impedance angle. It is the phase angle. It is the amplitude of the transient component. It is the line impedance. It is the amplitude of the voltage source.

[0020] Furthermore, the analytical expression for the short-circuit current is specifically as follows:

[0021] in, It is the closing phase angle of the voltage source. It is the impedance angle. It is the amplitude of the transient component. It is the line impedance. It is the voltage source amplitude. It is angular frequency. It is the equivalent inductance. It is the equivalent resistance. It's the moment of short circuit.

[0022] According to some embodiments, a second aspect of the present invention provides a system for calculating the AC and DC components of short-circuit current, employing the following technical solution: A system for calculating the AC / DC components of short-circuit current, comprising: The resistance-to-inductance ratio calculation module is configured to determine three maxima based on the waveform of the short-circuit current, and then use these three maxima to fit the relationship between the voltage source amplitude, line impedance, and transient component amplitude to determine the ratio of equivalent resistance to equivalent inductance. The resistance and inductance determination module is configured to determine the equivalent resistance and equivalent inductance based on the relationship between the line impedance and the equivalent resistance and equivalent inductance, as well as the ratio of the equivalent resistance to the equivalent inductance. The impedance angle calculation module is configured to determine the impedance angle based on the relationship between equivalent resistance and equivalent inductance and the impedance angle. The voltage source closing phase angle calculation module is configured to determine the phase angle based on the initial conditions of the short-circuit current, and to determine the voltage source closing phase angle by utilizing the relationship between the phase angle, impedance angle, and transient component amplitude. The AC / DC component calculation module is configured to use equivalent resistance, equivalent inductance, impedance angle, and voltage source closing phase angle to determine the AC component and DC component of the short-circuit current at any time based on the short-circuit current analytical formula.

[0023] According to some embodiments, a third aspect of the present invention provides a computer-readable storage medium.

[0024] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in a method for calculating the AC / DC components of short-circuit current as described in the first embodiment above.

[0025] According to some embodiments, a fourth aspect of the present invention provides a computer device.

[0026] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the AC / DC component calculation method for short-circuit current as described in the first embodiment above.

[0027] According to some embodiments, a fifth aspect of the present invention provides a computer program product or computer program.

[0028] A computer program product or computer program includes computer instructions stored in a computer-readable storage medium, wherein a processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the steps in a method for calculating the AC / DC components of short-circuit current as described in the first embodiment above.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention fits multiple maxima points of the short-circuit current waveform, a method inherently possessing resistance to high-frequency interference. While high-frequency noise may superimpose on the waveform, its energy is relatively small, limiting its impact on the overall shape of the current envelope (the line connecting the maxima points). By using the constraint that the time interval between maxima is one period, high-frequency maxima are filtered out, allowing for the selection of true maxima for fitting. The fitting algorithm effectively avoids clutter interference, ensuring the accuracy and precision of the calculated parameters. It effectively smooths random noise and reconstructs the dominant trend of transient current changes. Parameters such as the voltage source closing phase angle, line impedance, and AC and DC components of the short-circuit current obtained based on this fitting relationship are no longer calculated based on a single susceptible zero-crossing or peak point, but rather on the statistically optimal solution of multiple data points, significantly improving the accuracy, precision, and robustness of the calculation results. This fundamentally overcomes the impact of high-frequency interference on parameter extraction accuracy, achieving high-precision calculation of key parameters.

[0030] The core innovation of this invention lies in the fact that its mathematical model directly includes analytical terms characterizing the transient process. By fitting multiple maxima points, the algorithm can simultaneously calculate parameters representing the real physical system (voltage source, line impedance) and parameters representing the transient process. This allows the invention to effectively distinguish and separate the real short-circuit current component generated by the actual opening of the circuit breaker from the spurious oscillation component generated by the measurement system response from the mixed measurement signals. Therefore, the final determined DC component percentage and peak value more realistically reflect the actual operating conditions of the circuit breaker, avoiding performance misjudgments caused by measurement system distortion; it accurately removes the non-real components introduced by the transient response of the measurement system, ensuring the authenticity and reliability of the parameters.

[0031] The method of this invention is based on a physical analytical model of short-circuit current and performs parameter inversion through a data-driven approach, making it an adaptive analysis process. It does not rely on prior assumptions about the frequency or amplitude of interference, and can adapt to the varying electromagnetic environments and different measurement system configurations at different test sites. It effectively reduces subjective errors and uncertainties introduced by human intervention, ensuring the objectivity and reproducibility of the analysis results. It has a solid physical foundation, strong adaptability, and reduces reliance on prior knowledge and human experience. Attached Figure Description

[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0033] Figure 1 This is a flowchart of a method for calculating the AC / DC components of short-circuit current in an embodiment of the present invention; Figure 2 This is a schematic diagram of the high-capacity short-circuit test in an embodiment of the present invention; Figure 3 This is the short-circuit current in the embodiments of the present invention. Waveform diagram; Figure 4 This is a comparison waveform diagram of the predicted and actual short-circuit current generated in the embodiments of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, 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 invention pertains.

[0036] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0037] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0038] Example 1 like Figure 1 As shown, this embodiment provides a method for calculating the AC and DC components of short-circuit current. This embodiment uses the application of this method to a server as an example for illustration. It is understood that this method can also be applied to terminals, and can also be applied to systems including terminals, servers, and other components, and can be implemented through interaction between the terminal and the server. The server can be an independent physical server, a server cluster composed of multiple physical servers, or a distributed system. It can also be a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network servers, cloud communication, middleware services, domain name services, CDN security services, and big data and artificial intelligence platforms. The terminal can be a smartphone, tablet, laptop, desktop computer, smart speaker, smartwatch, etc., but is not limited to these. The terminal and server can be directly or indirectly connected via wired or wireless communication, which is not limited herein. In this embodiment, the method includes the following steps: Step S1: Based on the waveform of the short-circuit current, determine the three maxima, and use the three maxima to fit the relationship between the voltage source amplitude, line impedance and transient component amplitude to determine the ratio of equivalent resistance to equivalent inductance. Step S2: Determine the equivalent resistance and equivalent inductance based on the relationship between line impedance and equivalent resistance and equivalent inductance, and the ratio of equivalent resistance to equivalent inductance. Step S3: Determine the impedance angle based on the relationship between equivalent resistance, equivalent inductance and impedance angle; Step S4: Determine the phase angle based on the initial conditions of the short-circuit current, and determine the voltage source closing phase angle by utilizing the relationship between the phase angle, impedance angle, and transient component amplitude. Step S5: Using the equivalent resistance, equivalent inductance, impedance angle, and voltage source closing phase angle, determine the AC component and DC component of the short-circuit current at any time based on the short-circuit current analytical formula.

[0039] Specifically, the schematic diagram of the high-capacity short-circuit test is as follows: Figure 2 As shown, in When the test sample TO is closed, the short-circuit current equation is: (1); in: —Line impedance; — angular frequency; —Impedance angle; —Voltage phase angle at the moment of closing; — Transient component amplitude (determined by initial conditions); Because the maximum current occurs When the steady-state component reaches its peak, the expression for the maximum time is: (2); in, 0,1,2,3…….

[0040] Therefore, the current at the maximum value can be expressed as: (3); That is, the sum of the steady-state component amplitude and the transient component amplitude.

[0041] In step S1, such as Figure 3 The figure shows the current. The waveform diagram, assuming three maxima are measured. , , and the corresponding time , , And the voltage source amplitude It is known that they satisfy the following relationship: (4); (5); (6); Then, calculate The process is as follows: Eliminate by the ratio of two adjacent maxima and The formula is as follows: (7); (8); because (Because the interval between adjacent maxima of alternating current is one cycle), therefore: (9); set up ,but: (10); Solving this equation will yield the answer. : (11); After expansion, we get: (12); use Take the logarithm: (13); In step S2, the transient component amplitude is calculated. Using any maximum point, such as ( , ): (14); Sure and Given: (15); and The answer has already been found, therefore: (16); The equivalent resistance can be obtained by solving equations (13), (15), and (16) simultaneously. and equivalent inductance Specifically: (17); (18).

[0042] In step S3, because ,and and The answer has already been found, therefore It can also be solved.

[0043] In step S4, the closing phase angle is determined. Phase angle in the short-circuit current analytical formula This can be determined through the initial current conditions. According to the switching rule, the inductor current cannot change abruptly; therefore, hour ,but: (19); Solving for: (20); in, , , All have been calculated.

[0044] In step S5, the AC and DC components are determined, and the required parameters are... , , , Substituting into the short-circuit current analytical formula (1), the AC component (steady-state component) and the DC component (transient component) at any time can be calculated, as follows: AC component expression: (twenty one); DC component expression: (twenty two); It can not only obtain the AC component and the DC component at the moment of contact separation, but also calculate the voltage source power factor. And the peak value coefficient, and then determine whether it meets the standard requirements, as follows: Voltage source power factor: (twenty three); Peak factor: (twenty four); The parameters directly output by the calculation in this embodiment, such as the closing phase angle (used to determine whether it meets the extreme operating conditions of 7.105.2.1), power factor (used to verify whether it meets the requirements of 7.103.2.1), the effective value of AC component and the percentage of DC component (used to characterize current symmetry according to 5.101.1), and the peak factor (used to correlate with the closing current of 5.103), correspond one-to-one with the provisions of GB / T 1984-2024 standard.

[0045] Experimental process The first step is to determine the total current based on the test waveform. Extract the first three maxima and their times. The data is as follows: =52.17818kA; =43.92479kA; =38.59598kA; =9.60192ms=0.00960192s; The second step is to obtain the result according to equation (12). =28.8864777754; The third step, according to Seeking, ; Fourth step, according to equation (13), ; Fourth step, according to equation (14), ; Fifth step, according to equation (17), =0.0240463661Ω; Fifth step, according to equation (18), =0.0010992723H; Step 6, according to Seeking, 1.5012788657 rad ; Transform into an angle: °; Step 7: Obtain the result according to equation (20). ; Right now 0.0327290022 rad ; Transform into an angle: 1.8752336959°; Step 7: Substitute the corresponding parameter values ​​according to equation (21) to obtain the expression for the AC component: ; Right now ; Step 7: Substitute the corresponding parameter values ​​according to equation (22) to obtain the expression for the AC component: ; Step 8: Calculate the power factor according to equation (23): 0.0694614820; Step 9: According to equation (24), the peak coefficient is obtained: =2.5505709293; like Figure 4As shown, the comparison between the predicted and actual results of the short-circuit current demonstrates that, due to the fundamental guarantee of extraction accuracy and authenticity, the test results generated by this invention can provide scientific, objective, and indisputable data evidence for whether a circuit breaker can pass stringent tests such as T100s, greatly enhancing the authority of the type test results, strictly meeting standard requirements, and providing authoritative and reliable data support for circuit breaker performance certification.

[0046] Example 2 This embodiment provides a system for calculating the AC and DC components of short-circuit current, including: The resistance-to-inductance ratio calculation module is configured to determine three maxima based on the waveform of the short-circuit current, and then use these three maxima to fit the relationship between the voltage source amplitude, line impedance, and transient component amplitude to determine the ratio of equivalent resistance to equivalent inductance. The resistance and inductance determination module is configured to determine the equivalent resistance and equivalent inductance based on the relationship between the line impedance and the equivalent resistance and equivalent inductance, as well as the ratio of the equivalent resistance to the equivalent inductance. The impedance angle calculation module is configured to determine the impedance angle based on the relationship between equivalent resistance and equivalent inductance and the impedance angle. The closing phase angle calculation module is configured to determine the phase angle based on the initial conditions of the short-circuit current, and to determine the closing phase angle by utilizing the relationship between the phase angle, impedance angle, and transient component amplitude. The AC / DC component calculation module is configured to use equivalent resistance, equivalent inductance, impedance angle, and closing phase angle to determine the AC component of the short-circuit current and the DC component at any time based on the short-circuit current analytical formula.

[0047] The examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in Embodiment 1 above. It should be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0048] The descriptions of each embodiment in the above embodiments have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0049] The proposed system can be implemented in other ways. For example, the system embodiments described above are merely illustrative, and the division of modules described above is only a logical functional division. In actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed.

[0050] Example 3 This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the AC / DC component calculation method for short-circuit current as described in Embodiment 1 above.

[0051] Example 4 This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the AC / DC component calculation method for short-circuit current as described in Embodiment 1 above.

[0052] Example 5 This embodiment provides a computer program product or computer program, including computer instructions stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the steps in the AC / DC component calculation method for short-circuit current described in Embodiment 1 above.

[0053] Those skilled in the art will understand that embodiments of the present invention can provide methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0054] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0055] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0056] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0057] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0058] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for calculating the AC and DC components of short-circuit current, characterized in that, include: Based on the waveform of the short-circuit current, three maxima are determined. The relationship between the voltage source amplitude, line impedance, and transient component amplitude is fitted using the three maxima to determine the ratio of equivalent resistance to equivalent inductance. The equivalent resistance and equivalent inductance are determined based on the relationship between line impedance and equivalent resistance and equivalent inductance, as well as the ratio of equivalent resistance to equivalent inductance. The impedance angle is determined based on the relationship between equivalent resistance, equivalent inductance and impedance angle; The phase angle is determined by the initial conditions of the short-circuit current, and the closing phase angle is determined by the relationship between the phase angle, the impedance angle, and the amplitude of the transient component. By utilizing equivalent resistance, equivalent inductance, impedance angle, and closing phase angle, the AC component and DC component of the short-circuit current at any given time are determined based on the analytical formula of the short-circuit current.

2. The method for calculating the AC / DC components of short-circuit current as described in claim 1, characterized in that, The method of using three maxima to fit the relationship between the voltage source amplitude, line impedance, and transient component amplitude to determine the ratio of equivalent resistance to equivalent inductance is as follows: By using the three maxima and their corresponding time points, the relationship between the voltage source amplitude, line impedance, and transient component amplitude is fitted to obtain the current expressions for the three maxima; By converting the current expressions for the three maxima, the ratio of equivalent resistance to equivalent inductance is determined.

3. The method for calculating the AC / DC components of short-circuit current as described in claim 2, characterized in that, The expression for the maximum current is: in, It is the maximum value of the current. It is the amplitude of the transient component. It is the line impedance. It is the voltage source amplitude. It is the equivalent inductance. It is the equivalent resistance. This is the moment when the AC component of the short-circuit current reaches its maximum value.

4. The method for calculating the AC / DC components of short-circuit current as described in claim 1, characterized in that, The impedance angle is determined based on the relationship between equivalent resistance, equivalent inductance, and impedance angle, specifically as follows: in, It is the impedance angle. It is the equivalent inductance. It is the equivalent resistance. It is angular frequency.

5. The method for calculating the AC / DC components of short-circuit current as described in claim 1, characterized in that, The method of determining the closing phase angle by utilizing the relationship between the phase angle, impedance angle, and transient component amplitude is as follows: in, It is the closing phase angle. It is the impedance angle. It is the phase angle. It is the amplitude of the transient component. It is the line impedance. It is the amplitude of the voltage source.

6. The method for calculating the AC / DC components of short-circuit current as described in claim 1, characterized in that, The analytical expression for the short-circuit current is as follows: in, It is the closing phase angle. It is the impedance angle. It is the amplitude of the transient component. It is the line impedance. It is the voltage source amplitude. It is angular frequency. It is the equivalent inductance. It is the equivalent resistance. It's the moment of short circuit.

7. A system for calculating the AC / DC components of short-circuit current, characterized in that, include: The resistance-to-inductance ratio calculation module is configured to determine three maxima based on the waveform of the short-circuit current, and then use these three maxima to fit the relationship between the voltage source amplitude, line impedance, and transient component amplitude to determine the ratio of equivalent resistance to equivalent inductance. The resistance and inductance determination module is configured to determine the equivalent resistance and equivalent inductance based on the relationship between the line impedance and the equivalent resistance and equivalent inductance, as well as the ratio of the equivalent resistance to the equivalent inductance. The impedance angle calculation module is configured to determine the impedance angle based on the relationship between equivalent resistance and equivalent inductance and the impedance angle. The closing phase angle calculation module is configured to determine the phase angle based on the initial conditions of the short-circuit current, and to determine the closing phase angle by utilizing the relationship between the phase angle, impedance angle, and transient component amplitude. The AC / DC component calculation module is configured to use equivalent resistance, equivalent inductance, impedance angle, and closing phase angle to determine the AC component and DC component of the short-circuit current at any time based on the short-circuit current analytical formula.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the method for calculating the AC and DC components of short-circuit current as described in any one of claims 1-6.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the AC / DC component calculation method for short-circuit current as described in any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the steps in the method for calculating the AC / DC components of short-circuit current as described in any one of claims 1-6.

Images