A method and system for calculating ac and dc components of short circuit current

Abstract

The application belongs to the field of short-circuit current detection, and provides a method and system for calculating AC and DC components of short-circuit current, which comprises determining three maximum values based on a waveform diagram of short-circuit current, fitting the relationship among voltage source amplitude, line impedance and transient component amplitude by using the three maximum values, determining the ratio of equivalent resistance and equivalent inductance, determining equivalent resistance and equivalent inductance according to the relationship between line impedance and equivalent resistance and equivalent inductance and the ratio of equivalent resistance and equivalent inductance, determining impedance angle based on the relationship between equivalent resistance and equivalent inductance and impedance angle, determining phase angle by initial conditions of short-circuit current, determining closing phase angle by using the relationship among phase angle, impedance angle and transient component amplitude, and determining AC component of short-circuit current and DC component at any moment based on short-circuit current analytical expression by using equivalent resistance, equivalent inductance, impedance angle and closing phase angle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of short-circuit current detection, and particularly relates to a method and system for calculating AC and DC components of short-circuit current. BACKGROUND

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

[0003] High-voltage AC circuit breakers are the core protection equipment of power systems, and their closing ability is directly related to the safety and stability of the power grid. International and national standards establish strict examination basis for type tests of circuit breakers. Specifically, GB / T 1984-2024 "High-voltage AC circuit breakers" clearly defines the requirements and parameter definitions of short-circuit closing tests in multiple key clauses:

[0004] As specified in standard clause 7.105.2.1, the circuit breaker must be able to close the pre-arcing current. The test needs to consider two extreme conditions: closing at the voltage peak value (within ±15° range) to produce a symmetrical short-circuit current and the longest pre-arcing time; closing at the voltage zero point to produce a completely asymmetric short-circuit current. This requires accurate determination of the closing phase angle in the test waveform.

[0005] According to clause 7.103.2.1, the power factor of the test circuit needs to be strictly controlled, and its average value should not exceed 0.15.

[0006] Clause 5.103 states that the peak value of the rated short-circuit closing current is obtained by multiplying the AC component effective value of the rated short-circuit breaking current by a specific peak factor.

[0007] In addition, clause 5.101.1 specifies that the rated short-circuit current is represented by its AC component effective value and DC component percentage (or DC time constant), and clearly defines the symmetry determination boundary.

[0008] As can be seen, the accurate extraction of parameters such as closing phase angle, power factor, AC component effective value, DC component percentage, and peak factor is a core technical link for objectively evaluating whether the circuit breaker meets the standard requirements and completes performance certification. Currently, the field usually relies on digital signal processing algorithms to analyze the collected voltage and current waveforms to calculate the above parameters.

[0009] However, the inventors have found that the traditional parameter extraction and calculation method has inherent defects in the real test site environment, resulting in a serious lack of result accuracy, and the main reasons are as follows:

[0010] First, complex electromagnetic interference leads to waveform distortion. The short-circuit test site is accompanied by strong transient electromagnetic processes, and the electromagnetic environment is extremely complex. The current waveform output by the data acquisition equipment will superimpose a large amount of high-frequency noise interference. These non-periodic high-frequency signals seriously interfere with the traditional algorithm based on the power frequency model (such as zero-crossing detection, Fourier transform, etc.), causing significant errors in the starting point identification and calculation of key parameters such as closing phase angle, alternating current component effective value, etc.

[0011] Second, the transient response of the measurement system introduces non-real signals. The test process is a dramatic change from steady state to transient state. The measurement system (including sensors, transmission links, and acquisition cards) is part of the system, and its own transient response process also exists. This response will introduce high-frequency oscillation components in the current waveform, which are not from the real current of the measured circuit breaker, but are included in the traditional algorithm, resulting in serious distortion of the extracted direct current component, peak coefficient, and other parameters, which cannot truly reflect the actual breaking performance of the circuit breaker.

[0012] In summary, the existing parameter extraction method is limited by the field interference and the characteristics of the measurement system itself, and it is difficult to meet the high-precision requirements of the test evaluation in GB / T 1984-2024 standard. It cannot effectively suppress high-frequency noise, identify and remove the transient response of the measurement system, so as to realize the high-precision extraction of key parameters in complex test environment, and cannot guarantee the accuracy and authority of the circuit breaker test results. SUMMARY

[0013] To solve the above problems, the present application provides a method and system for calculating the closing phase angle, power factor, alternating current component, direct current component, and peak coefficient of short-circuit current. The present application fits the relationship between the voltage source amplitude, line impedance, and transient component amplitude by multiple maximum values of short-circuit current, and determines the voltage source closing phase angle, voltage source power factor, short-circuit current alternating current component, short-circuit current direct current component, and peak coefficient based on the parameters in the short-circuit current analytical expression, thereby improving the calculation precision and accuracy of the above parameters.

[0014] According to some embodiments, the first aspect of the present application provides a method for calculating the voltage source closing phase angle, voltage source power factor, short-circuit current alternating current component, short-circuit current direct current component, and peak coefficient of short-circuit current. The following technical solutions are adopted:

[0015] A method for calculating the voltage source closing phase angle, voltage source power factor, short-circuit current alternating current component, short-circuit current direct current component, and peak coefficient of short-circuit current, comprising:

[0016] Three maximum values are determined based on a waveform diagram of the short-circuit current, a relationship among the voltage source amplitude, the line impedance and the transient component amplitude is fitted by using the three maximum values, and the ratio of the equivalent resistance and the equivalent inductance is determined;

[0017] The equivalent resistance and the equivalent inductance are determined according to the relationship between the line impedance and the equivalent resistance and the equivalent inductance and the ratio of the equivalent resistance and the equivalent inductance;

[0018] The impedance angle is determined based on the relationship between the equivalent resistance and the equivalent inductance and the impedance angle;

[0019] The phase angle is determined through the initial condition of the short-circuit current, and the closing phase angle is determined by using the relationship among the phase angle, the impedance angle and the transient component amplitude;

[0020] The alternating component of the short-circuit current and the direct component at any moment are determined based on the short-circuit current analytical expression by using the equivalent resistance, the equivalent inductance, the impedance angle and the closing phase angle.

[0021] Further, the ratio of the equivalent resistance and the equivalent inductance is determined by using the relationship among the voltage source amplitude, the line impedance and the transient component amplitude through the three maximum values, and specifically,

[0022] The relationship among the voltage source amplitude, the line impedance and the transient component amplitude is fitted by using the three maximum values and the time points corresponding to the three maximum values, and current expressions of the three maximum values are obtained;

[0023] The ratio of the equivalent resistance and the equivalent inductance is determined through conversion of the current expressions of the three maximum values.

[0024] Further, the current expression of the maximum value is:

[0025]

[0026] wherein, is the maximum value of the current, is the transient component amplitude, is the line impedance, is the voltage source amplitude, is the equivalent inductance, is the equivalent resistance, is the time when the alternating component of the short-circuit current reaches the maximum value.

[0027] Further, the impedance angle is determined based on the relationship between the equivalent resistance and the equivalent inductance and the impedance angle, and specifically,

[0028]

[0029] wherein, is the impedance angle, is the equivalent inductance, is the equivalent resistance, is the angular frequency.

[0030] Further, the closing phase angle is determined by using the relationship among the phase angle, the impedance angle and the transient component amplitude, and specifically:

[0031]

[0032] wherein, is the voltage source closing phase angle, is the impedance angle, is the phase angle, is the transient component amplitude, is the line impedance, is the voltage source amplitude.

[0033] Further, the short-circuit current analytical expression is specifically:

[0034]

[0035] wherein, is the voltage source closing phase angle, is the impedance angle, is the transient component amplitude, is the line impedance, is the voltage source amplitude, is the angular frequency, is the equivalent inductance, is the equivalent resistance, is the time of short-circuit.

[0036] According to some embodiments, a second aspect of the present application provides an alternating and direct current component calculation system for short-circuit current, which adopts the following technical solution:

[0037] An alternating and direct current component calculation system for short-circuit current, comprising:

[0038] A resistance-inductance ratio calculation module configured to determine three maximum values based on a waveform diagram of the short-circuit current, to determine the ratio of the equivalent resistance and the equivalent inductance by fitting the relationship among the voltage source amplitude, the line impedance and the transient component amplitude using the three maximum values;

[0039] A resistance-inductance determination module configured to determine the equivalent resistance and the equivalent inductance according to the relationship between the line impedance and the equivalent resistance and the equivalent inductance and the ratio of the equivalent resistance and the equivalent inductance;

[0040] An impedance angle calculation module configured to determine the impedance angle based on the relationship between the equivalent resistance and the equivalent inductance and the impedance angle;

[0041] The voltage source closing phase angle calculation module is configured to determine the phase angle through initial conditions of the short-circuit current, and determine the voltage source closing phase angle by using the relationship among the phase angle, the impedance angle and the transient component amplitude.

[0042] The AC and DC components calculation module is configured to determine the AC component and the DC component at any moment of the short-circuit current based on the short-circuit current analytical expression by using the equivalent resistance, the equivalent inductance, the impedance angle and the voltage source closing phase angle.

[0043] According to some embodiments, a third aspect of the present application provides a computer readable storage medium.

[0044] A computer readable storage medium, having stored thereon a computer program, which, when executed by a processor, implements the steps of the method for calculating AC and DC components of short-circuit current according to the first aspect.

[0045] According to some embodiments, a fourth aspect of the present application provides a computer device.

[0046] A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for calculating AC and DC components of short-circuit current according to the first aspect when executing the program.

[0047] According to some embodiments, a fifth aspect of the present application provides a computer program product or a computer program.

[0048] A computer program product or a computer program, comprising 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 the processor executes the computer instructions to make the computer device perform the steps of the method for calculating AC and DC components of short-circuit current according to the first aspect.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] The application extracts multiple maximum value points of the short-circuit current waveform for fitting, and this method itself has natural anti-high-frequency interference advantage. Because high-frequency noise is superimposed on the waveform, but the energy is relatively small, and the influence on the overall shape of the current envelope (i.e. the connecting line of the maximum value points) is limited. The high-frequency maximum value is filtered out by the constraint condition that the time interval between the maximum values is one period, so that the real maximum value fitting is selected, the noise interference is effectively avoided through the fitting algorithm, and the accuracy and accuracy of the calculated parameters are guaranteed; random noise can be effectively smoothed, and the dominant trend of the transient current is restored. The voltage source closing phase angle, line impedance, short-circuit current AC and DC components and other parameters obtained based on the fitting relationship are no longer calculated based on a single zero-crossing point or peak point which is easy to be disturbed, but are based on the statistical optimal solution of multiple data points, thereby significantly improving the accuracy, accuracy and robustness of the calculation result. The influence of high-frequency interference on the accuracy of parameter extraction is fundamentally overcome, and high-precision calculation of key parameters is realized.

[0051] The core innovation of the application is that the analytical term representing the transient process is directly included in the mathematical model. Through fitting of multiple maximum value points, the algorithm can simultaneously calculate the parameters representing the real physical system (voltage source, line impedance) and the parameters representing the transient process. This enables the application to effectively distinguish and separate the real short-circuit current component generated by the actual breaking of the circuit breaker from the false oscillation component generated by the measurement system response from the mixed measurement signal. Therefore, the final determined DC component percentage and peak coefficient more truly reflect the actual working condition of the circuit breaker, avoiding performance misjudgment caused by measurement system distortion; the non-real component introduced by the transient response of the measurement system is accurately stripped, ensuring the authenticity and reliability of the parameters.

[0052] The method of the application is based on the physical analytical model of short-circuit current, and performs parameter inversion in a data-driven manner, which is an adaptive analysis process. It does not depend on prior assumptions about the interference frequency or amplitude, and can adapt to different electromagnetic environments and different measurement system configurations in different test sites, effectively reducing the subjective errors and uncertainties introduced by manual intervention, ensuring the objectivity and reproducibility of the analysis results, having a solid physical basis, strong adaptability, and reducing the dependence on prior knowledge and manual experience. BRIEF DESCRIPTION OF DRAWINGS

[0053] The drawings accompanying the specification of the application form part of the application and serve to provide further understanding of the application. The schematic embodiments of the application and their descriptions serve to explain the application and do not constitute an improper limitation on the application.

[0054] Figure 1 is a flow chart of a short-circuit current AC and DC component calculation method in an embodiment of the application;

[0055] Figure 2 is a schematic diagram of a large-capacity short-circuit test principle in an embodiment of the present application;

[0056] Figure 3 is a waveform diagram of a short-circuit current in an embodiment of the present application;

[0057] Figure 4 is a waveform diagram of a comparison between a predicted short-circuit current and an actual short-circuit current generated by a test in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0059] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as would be understood by one of ordinary skill in the art to which the present application pertains.

[0060] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of a feature, step, operation, device, component, and / or combination thereof.

[0061] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0062] Embodiment One

[0063] As shown in Figure 1 , the present embodiment provides a method for calculating AC and DC components of a short-circuit current. The present embodiment is exemplified by the method being applied to a server. It should be understood that the method can also be applied to a terminal, and can also be applied to a system including a terminal and a server and implemented through interaction of the terminal and the server. The server can be a standalone physical server, a server cluster or a distributed system composed of multiple physical servers, a cloud server providing cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network servers, cloud communications, middleware services, domain name services, security services CDNs, and basic cloud computing services such as big data and artificial intelligence platforms. The terminal can be a smart phone, a tablet computer, a notebook computer, a desktop computer, a smart speaker, a smart watch, etc., but is not limited thereto. The terminal and the server can be directly or indirectly connected through wired or wireless communication, which is not limited in the present application. In the present embodiment, the method includes the following steps:

[0064] ​Step S1: three maximum values are determined based on the waveform of short-circuit current, the relationship among voltage source amplitude, line impedance and transient component amplitude is fitted by using the three maximum values, the ratio of equivalent resistance and equivalent inductance is determined;

[0065] Step S2: the equivalent resistance and equivalent inductance are determined according to the relationship between line impedance and equivalent resistance and equivalent inductance, and the ratio of equivalent resistance and equivalent inductance;

[0066] Step S3: the impedance angle is determined based on the relationship between equivalent resistance and equivalent inductance and impedance angle;

[0067] Step S4: the phase angle is determined by the initial condition of short-circuit current, and the relationship among phase angle, impedance angle and transient component amplitude is used to determine the voltage source closing phase angle;

[0068] Step S5: the alternating component of short-circuit current and direct current component at any time are determined based on the short-circuit current analytical expression by using equivalent resistance, equivalent inductance, impedance angle and voltage source closing phase angle.

[0069] Specifically, the principle diagram of large-capacity short-circuit test is shown in Figure 2 , the test sample TO is closed at , and then the short-circuit current analytical expression is:

[0070] (1);

[0071] Wherein:

[0072] Line impedance;

[0073] Angular frequency;

[0074] Impedance angle;

[0075] Voltage phase angle at closing time;

[0076] Transient component amplitude (determined by initial condition);

[0077] Since the current maximum value appears at , i.e. the steady-state component reaches the peak value, and thus the maximum time expression is:

[0078] (2);

[0079] Wherein, 0, 1, 2, 3…….

[0080] Therefore, the current at the maximum value can be expressed as:

[0081] (3);

[0082] i.e. the sum of the steady component amplitude and the transient component.

[0083] In step S1, as shown in the following figure, the current waveform is measured, and three maximum values Figure 3 are obtained, and the corresponding time points are also obtained. The amplitude of the voltage source is known, and they satisfy the following relationships:

[0084] (4);

[0085] (5);

[0086] (6);

[0087] Then, calculate , the process is as follows:

[0088] Take the ratio of the adjacent two maximum values to eliminate and , the formula is as follows:

[0089] (7);

[0090] (8);

[0091] Since (because the adjacent maximum values of alternating current are separated by one period), we have:

[0092] (9);

[0093] Let , then:

[0094] (10);

[0095] Solving this equation can obtain :

[0096] (11);

[0097] After expansion, we get:

[0098] (12);

[0099] Using​​​​​​​ , take logarithm:

[0100] (13);

[0101] In step S2, the amplitude of the transient component is calculated using any one of the maximum points, such as , ):

[0102] (14);

[0103] Determine and , given:

[0104] (15);

[0105] And has been solved, so:

[0106] (16);

[0107] Equations (13), (15) and (16) can be solved simultaneously to solve the equivalent resistance and the equivalent inductance , specifically:

[0108] (17);

[0109] (18).

[0110] In step S3, because , and and have been solved, so can also be solved.

[0111] In step S4, determine the closing phase angle , the phase angle in the short-circuit current analytical expression can be determined by the initial condition of the current. According to the switching rule: the inductance current cannot be suddenly changed, so when , then:

[0112] (19);

[0113] Solve:

[0114] (20);

[0115] Where, , , have been solved.

[0116] In step S5, the AC component and the DC component are determined, and the parameters are calculated , , , Substitute the short-circuit current analytical expression (1), the AC component (steady component) and the DC component (transient component) at any time can be calculated, as follows:

[0117] AC component expression:

[0118] (21);

[0119] DC component expression:

[0120] (22);

[0121] Not only the AC component and the DC component at the contact separation time can be obtained, but also the voltage source power factor and the peak coefficient can be calculated, and then it is determined whether it meets the standard requirements, as follows:

[0122] Voltage source power factor:

[0123] (23);

[0124] Peak coefficient:

[0125] (24);

[0126] The directly output parameters calculated in this embodiment, such as the closing phase angle (used to determine whether it meets the extreme working condition of 7.105.2.1), the power factor (used to verify whether it meets the requirements of 7.103.2.1), the AC component effective value and the DC component percentage (used to represent the current symmetry according to 5.101.1), and the peak coefficient (used to associate the closing current of 5.103), are completely corresponding to the provisions of GB / T 1984-2024 standard.

[0127] Test process

[0128] First, according to the test waveform total current , the first three maximum value points and time are extracted , and the data are as follows:

[0129] = 52.17818 kA; = 43.92479 kA; = 38.59598 kA;

[0130] = 9.60192 ms = 0.00960192 s;

[0131] Second step, according to formula (12) to obtain,

[0132] = 28.8864777754;

[0133] Third step, according to = 0.0010992723 H;

[0134] ;

[0135] Fourth step, according to formula (13) to obtain,

[0136] ;

[0137] Fourth step, according to formula (14) to obtain,

[0138] ;

[0139] Fifth step, according to formula (17) to obtain,

[0140] = 0.0240463661 Ω;

[0141] Fifth step, according to formula (18) to obtain,

[0142] = 0.0010992723 H;

[0143] Sixth step, according to = 0.0010992723 H;

[0144] 1.5012788657 rad ;

[0145] Convert to angle:

[0146] °;

[0147] Seventh step, according to formula (20) to obtain,

[0148] ;

[0149] That is 0.0327290022 rad ;

[0150] Convert to angle:

[0151] 1.8752336959°;

[0152] In the seventh step, according to formula (21), the AC component expression is obtained by substituting the corresponding parameter values:

[0153] ;

[0154] That is ;

[0155] In the seventh step, according to formula (22), the AC component expression is obtained by substituting the corresponding parameter values:

[0156] ;

[0157] In the eighth step, according to formula (23), the power factor is obtained:

[0158] 0.0694614820;

[0159] In the ninth step, according to formula (24), the peak coefficient is obtained:

[0160] =2.5505709293;

[0161] As shown in Figure 4 , the comparison between the predicted results and the actual results of the short-circuit current shows that, since the extraction accuracy and authenticity are fundamentally guaranteed, the test results generated by the application can provide scientific, objective and indisputable data evidence for whether the circuit breaker can pass the T100s and other harsh tests, greatly improving the authority of the type test results, strictly meeting the standard requirements, and providing authoritative and reliable data support for the performance certification of the circuit breaker.

[0162] Embodiment Two

[0163] The embodiment provides a system for calculating AC and DC components of a short-circuit current, comprising:

[0164] The resistance-inductance ratio calculation module is configured to determine three maximum values based on a waveform diagram of the short-circuit current, fit the relationship among a voltage source amplitude, a line impedance and a transient component amplitude by using the three maximum values, and determine the ratio of the equivalent resistance and the equivalent inductance;

[0165] The resistance-inductance determination module is configured to determine the equivalent resistance and the equivalent inductance according to the relationship between the line impedance and the equivalent resistance and the equivalent inductance and the ratio of the equivalent resistance and the equivalent inductance;

[0166] The impedance angle calculation module is configured to determine the impedance angle based on the relationship between the equivalent resistance and the equivalent inductance and the impedance angle;

[0167] The closing phase angle calculation module is configured to determine the phase angle through initial conditions of the short-circuit current, and determine the closing phase angle by using a relationship among the phase angle, the impedance angle, and the transient component amplitude.

[0168] The AC and DC component calculation module is configured to determine the AC component of the short-circuit current and the DC component at any moment based on a short-circuit current analytical expression by using the equivalent resistance, the equivalent inductance, the impedance angle, and the closing phase angle.

[0169] The above modules and the examples and application scenarios realized by the corresponding steps are the same, but are not limited to the content disclosed in Embodiment One. 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.

[0170] The description of each of the above embodiments has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0171] The proposed system can be implemented in other ways. For example, the system embodiments described above are only illustrative, for example, the division of the above modules is only a logical function division, and in actual implementation, there can be another division manner, for example, multiple modules can be combined or integrated into another system, or some features can be ignored or not executed.

[0172] Embodiment Three

[0173] The embodiment provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the steps in the AC and DC component calculation method for short-circuit current according to Embodiment One.

[0174] Embodiment Four

[0175] The embodiment provides a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor realizes the steps in the AC and DC component calculation method for short-circuit current according to Embodiment One when executing the program.

[0176] Embodiment Five

[0177] The embodiment provides a computer program product or a computer program, which includes computer instructions stored in a computer readable storage medium, and a processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions to enable the computer device to execute the steps in the AC and DC component calculation method for short-circuit current according to Embodiment One.

[0178] Those skilled in the art will appreciate that embodiments of the application can be readily used as a method, a system or a computer program product. Accordingly, the application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the application can take the form of a computer program product on one or more computer-readable storage media (including, but not limited to, magnetic disks or optical disks) embodying computer program code, for example, computer program code that can be executed by a computer or processor.

[0179] The present application is described in reference to the flowchart and / or block diagrams of the method, apparatus (system) and computer program product according to embodiments of the application. It should be understood that each flow and / or block in the flowchart and / or block diagrams and combinations of flows and / or blocks in the flowchart 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 device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, create means for implementing the functions specified in the flowchart and / or block diagrams block or blocks. Figure 1 one or more flows and / or blocks Figure 1 means for carrying out the function specified by the flow or flows and / or block or blocks.

[0180] These computer program instructions can also be stored in a computer-readable memory 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 memory produce an article of manufacture including instructions means which implement the function specified in the flowchart and / or block diagrams flow or flows and / or block or blocks. Figure 1 one or more flows and / or blocks Figure 1 means for carrying out the function specified by the flow or flows and / or block or blocks.

[0181] These computer program instructions can also be loaded onto a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer implemented process such that the instructions that execute on the computer or other programmable device provide steps for implementing the functions specified in the flowchart and / or block diagrams flow or flows and / or block or blocks. Figure 1 one or more flows and / or blocks Figure 1 means for carrying out the function specified by the flow or flows and / or block or blocks.

[0182] Those skilled in the art will appreciate that implementing all or part of the above-mentioned method embodiments can be achieved by computer program instructions instructing relevant hardware, and the program can be stored in a computer-readable storage medium, and when executed, can include the flow of each method embodiment described above. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0183] The above describes the specific embodiments of the present application in conjunction with the drawings, but is not a limitation on the scope of protection of the present application. Those skilled in the art should understand that various modifications or variations made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the scope of protection of the present application.

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 amplitude of the voltage source. 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 amplitude of the voltage source. 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.

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