A direct current transmission line protection method, system, medium, and device

Abstract

A direct current transmission line protection method, system, medium and device are disclosed, the method comprising: obtaining a calculated voltage and a measured voltage at a first measurement point and a second measurement point of a direct current transmission line; determining a first similarity corresponding to the first measurement point and a second similarity corresponding to the second measurement point according to the calculated voltage and the measured voltage; determining a first fault direction corresponding to the first measurement point and a second fault direction corresponding to the second measurement point according to the first similarity and the second similarity respectively; determining a fault type based on the first fault direction and the second fault direction. The application determines the fault direction of the line fault based on the similarity between the calculated voltage and the measured voltage, and determines whether the line has an internal fault based on the fault direction, which can be used as a backup protection for the direct current transmission line in different structures of the direct current power grid, and has good rapidity and sensitivity.

Description

Technical Field

[0001] This invention relates to the field of relay protection technology, and more specifically, to a method, system, medium, and device for protecting DC transmission lines. Background Technology

[0002] The safe and stable operation of a complex DC power grid requires a reliable DC power grid protection system. The main requirements for DC power grid protection are: (1) Sensitivity: the protection system must be able to detect faults; (2) Selectivity: the protection system must be able to identify and isolate faulty areas, and ensure normal operation of non-faulty areas; (3) Speed: the protection system must be able to operate and quickly isolate faults by transmitting power to switching equipment; (4) Reliability: after the main protection fails, backup protection must ensure that the fault can be cleared. Currently, the protection configurations for different DC power grid structures adopt the ultra-high voltage / extra-high voltage dual-terminal DC transmission system protection configuration scheme. There is a lack of coordination and cooperation between the protection systems of different parts of the DC power grid. The main protection is equipped with traveling wave protection and differential undervoltage protection, while the backup protection is equipped with longitudinal current differential protection, etc. The fault identification capability of the main protection is constrained by factors such as transition resistance, mutual inductance, and lightning strikes, and the backup protection has a long operating delay (on the order of seconds).

[0003] Therefore, a new method for protecting DC transmission lines is needed. Summary of the Invention

[0004] This invention proposes a method, system, medium, and equipment for the protection of DC transmission lines, in order to solve the problem of how to efficiently and accurately determine faults inside and outside the DC transmission line.

[0005] To address the above problems, according to one aspect of the present invention, a method for protecting DC transmission lines is provided, the method comprising:

[0006] Obtain the calculated voltage and measured voltage at the first and second measurement points of the DC transmission line;

[0007] The first similarity corresponding to the first measurement point and the second similarity corresponding to the second measurement point are determined based on the calculated voltage and the measured voltage.

[0008] The first fault direction corresponding to the first measurement point and the second fault direction corresponding to the second measurement point are determined based on the first similarity and the second similarity, respectively.

[0009] The fault type is determined based on the first fault direction and the second fault direction.

[0010] Preferably, the method obtains the calculated voltage using the following method:

[0011]

[0012] Among them, u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; i x (k+1) and i x (k) represents the current at measurement point x at time k+1 and time k, respectively; ΔT is the sampling time interval; n is the number of sampling times; C0, L0, L line1 and R arm These are the submodule capacitor, bridge arm inductor, DC line-side inductor, and DC-side stray resistance, respectively.

[0013] Preferably, the method determines the first similarity and the second similarity using the following methods:

[0014]

[0015] Where, r x The similarity score corresponds to measurement point x on a DC transmission line, where measurement point x is located at the installation location of the DC transmission line's measurement and protection system; u x (k) represents the measured voltage at measurement point x on the DC transmission line at time k; u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; n represents the number of sampling times.

[0016] Preferably, the method determines the fault direction by:

[0017] If the similarity is greater than or equal to the first preset similarity threshold, the fault direction is determined to be positive.

[0018] If the similarity is less than the second preset similarity threshold, the fault direction is determined to be reversed.

[0019] Preferably, determining the fault type based on the first fault direction and the second fault direction includes:

[0020] When both the first fault direction and the second fault direction are positive, the fault type is determined to be an intra-zone fault; otherwise, the fault type is determined to be an extra-zone fault.

[0021] According to another aspect of the present invention, a DC transmission line protection system is provided, the system comprising:

[0022] The data acquisition unit is used to acquire the calculated voltage and measured voltage at the first and second measurement points of the DC transmission line;

[0023] A similarity determination unit is used to determine a first similarity corresponding to a first measurement point and a second similarity corresponding to a second measurement point based on the calculated voltage and the measured voltage.

[0024] The fault direction determination unit is used to determine the first fault direction corresponding to the first measurement point and the second fault direction corresponding to the second measurement point based on the first similarity and the second similarity, respectively.

[0025] The fault type determination unit is used to determine the fault type based on the first fault direction and the second fault direction.

[0026] Preferably, the data acquisition unit acquires the calculated voltage using the following method:

[0027]

[0028] Among them, u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; i x (k+1) and i x (k) represents the current at measurement point x at time k+1 and time k, respectively; ΔT is the sampling time interval; n is the number of sampling times; C0, L0, L line1 and R arm These are the submodule capacitor, bridge arm inductor, DC line-side inductor, and DC-side stray resistance, respectively.

[0029] Preferably, the similarity determination unit determines the first similarity and the second similarity using the following method:

[0030]

[0031] Where, r x The similarity score corresponds to measurement point x on a DC transmission line, where measurement point x is located at the installation location of the DC transmission line's measurement and protection system; u x (k) represents the measured voltage at measurement point x on the DC transmission line at time k; u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; n represents the number of sampling times.

[0032] Preferably, the fault direction determining unit determines the fault direction using the following method:

[0033] If the similarity is greater than or equal to the first preset similarity threshold, the fault direction is determined to be positive.

[0034] If the similarity is less than the second preset similarity threshold, the fault direction is determined to be reversed.

[0035] Preferably, the fault type determination unit determines the fault type based on the first fault direction and the second fault direction, including:

[0036] When both the first fault direction and the second fault direction are positive, the fault type is determined to be an intra-zone fault; otherwise, the fault type is determined to be an extra-zone fault.

[0037] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods for protecting a DC transmission line.

[0038] According to another aspect of the present invention, the present invention provides an electronic device, comprising:

[0039] The aforementioned computer-readable storage medium; and

[0040] One or more processors for executing a program in the computer-readable storage medium.

[0041] This invention provides a method, system, medium, and device for protecting DC transmission lines. The method includes: acquiring calculated voltage and measured voltage at a first measurement point and a second measurement point on the DC transmission line; determining a first similarity corresponding to the first measurement point and a second similarity corresponding to the second measurement point based on the calculated voltage and the measured voltage; determining a first fault direction corresponding to the first measurement point and a second fault direction corresponding to the second measurement point based on the first similarity and the second similarity, respectively; and determining the fault type based on the first fault direction and the second fault direction. This invention determines the fault direction of a line fault based on the similarity between the calculated voltage and the measured voltage, and determines whether an intra-regional fault has occurred based on the fault direction. It can serve as backup protection for DC transmission lines in DC power grids of different structures, exhibiting good speed and sensitivity. Attached Figure Description

[0042] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0043] Figure 1 This is a flowchart of a DC transmission line protection method 100 according to an embodiment of the present invention;

[0044] Figure 2 The diagram shows a hybrid three-terminal DC transmission system according to an embodiment of the present invention.

[0045] Figure 3 (a), (b) and (c) are schematic diagrams of protection characteristic quantities during intra-area faults according to embodiments of the present invention;

[0046] Figure 4 (a), (b) and (c) are schematic diagrams of protection characteristic quantities during external faults according to embodiments of the present invention;

[0047] Figure 5This is a schematic diagram of the structure of a DC transmission line protection system 500 according to an embodiment of the present invention. Detailed Implementation

[0048] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0049] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0050] Figure 1 This is a flowchart of a DC transmission line protection method 100 according to an embodiment of the present invention. Figure 1 As shown, the DC transmission line protection method provided by this embodiment of the invention determines the fault direction of the line fault based on the similarity between the calculated voltage and the measured voltage, and determines whether an intra-area fault has occurred based on the fault direction. It can serve as backup protection for DC transmission lines in DC power grids of different structures, exhibiting good speed and sensitivity. The DC transmission line protection method 100 provided by this embodiment of the invention begins at step 101, in which the calculated voltage and measured voltage at the first and second measurement points of the DC transmission line are obtained.

[0051] Preferably, the method obtains the calculated voltage using the following method:

[0052]

[0053] Among them, u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; i x (k+1) and i x (k) represents the current at measurement point x at time k+1 and time k, respectively; ΔT is the sampling time interval; n is the number of sampling times; C0, L0, L line1 and R arm These are the submodule capacitor, bridge arm inductor, DC line-side inductor, and DC-side stray resistance, respectively.

[0054] In this invention, the influence of electromagnetic coupling between the positive and negative poles of the line is considered, and the fault information of the positive and negative poles is decoupled to obtain the line mode component and the ground mode component. Compared with the line mode component, the ground mode component is unstable and suffers severe attenuation and dispersion over long-distance lines. Therefore, this invention selects the line mode component for calculation, and the data window length is selected as 2ms.

[0055] In this invention, the voltage u is calculated at the DC line measuring point. xj (k) The calculation method is as follows: Substitute the extracted current fault component into the calculation equation to obtain the discrete voltage fault component. Specifically, it is calculated using the following formula:

[0056]

[0057] Among them, u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; i x (k+1) and i x (k) represents the current at measurement point x at time k+1 and time k, respectively; ΔT is the sampling time interval; n is the number of sampling times; C0, L0, L line1 and R arm These are the submodule capacitor, bridge arm inductor, DC line-side inductor, and DC-side stray resistance, respectively.

[0058] Among them, x can be selected as the protection installation point M or N on both sides of the line.

[0059] In step 102, the first similarity corresponding to the first measurement point and the second similarity corresponding to the second measurement point are determined based on the calculated voltage and the measured voltage.

[0060] Preferably, the method determines the first similarity and the second similarity using the following methods:

[0061]

[0062] Where, r x The similarity score corresponds to measurement point x on a DC transmission line, where measurement point x is located at the installation location of the DC transmission line's measurement and protection system; u x (k) represents the measured voltage at measurement point x on the DC transmission line at time k; u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; n represents the number of sampling times.

[0063] In step 103, the first fault direction corresponding to the first measurement point and the second fault direction corresponding to the second measurement point are determined based on the first similarity and the second similarity, respectively.

[0064] Preferably, the method determines the fault direction by:

[0065] If the similarity is greater than or equal to the first preset similarity threshold, the fault direction is determined to be positive.

[0066] If the similarity is less than the second preset similarity threshold, the fault direction is determined to be reversed.

[0067] This invention utilizes cosine similarity to describe the waveform similarity between the calculated voltage fault component and the measured voltage fault component at the protection measurement point. Cosine similarity measures the similarity between two vectors by measuring the cosine of the angle between their inner product space. When applied to two spatial vectors with independent variation patterns, its calculation formula is as follows:

[0068]

[0069] Where, r x The similarity score corresponds to measurement point x on a DC transmission line, where measurement point x is located at the installation location of the DC transmission line's measurement and protection system; u x (k) represents the measured voltage at measurement point x on the DC transmission line at time k; u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; n represents the number of sampling times. x represents protection measurement points M or N on both sides of the DC transmission line.

[0070] For any measurement point, when the changing trends of two vectors are exactly the same, the two vectors are 100% positively correlated, and the cosine similarity is 1; when the changing trends of two vectors are completely opposite, the two vectors are 100% negatively correlated, and the cosine similarity is -1; when the changing trends of two variables are significantly different and completely independent, the cosine similarity is 0. When protecting against a positive fault, the calculated voltage and measured voltage waveforms at the measurement point have a high degree of overlap, and they are positively correlated, with a cosine similarity close to 1; when protecting against a reverse fault, the calculated voltage and measured voltage waveforms differ significantly, and the cosine similarity is low and negative, indicating a negative correlation. Therefore, for any measurement point, if the similarity is greater than or equal to the first preset similarity threshold, the fault direction is determined to be positive; if the similarity is less than the second preset similarity threshold, the fault direction is determined to be reverse. The first similarity threshold can be 0.9, and the second similarity threshold can be 0.

[0071] In step 104, the fault type is determined based on the first fault direction and the second fault direction.

[0072] Preferably, determining the fault type based on the first fault direction and the second fault direction includes:

[0073] When both the first fault direction and the second fault direction are positive, the fault type is determined to be an intra-zone fault; otherwise, the fault type is determined to be an extra-zone fault.

[0074] In this invention, if the fault direction of both measurement points is positive, the fault type can be determined to be an intra-zone fault; conversely, if the fault direction of one measurement point is negative, the fault type can be determined to be an extra-zone fault.

[0075] The following specific examples illustrate the embodiments of the present invention.

[0076] (1) Faults within the DC transmission line area

[0077] In such Figure 2 In the three-terminal operation mode of the DC system shown, a bipolar short circuit occurs on DC line l1. The distance from the fault point to the rectifier side outlet is 10% of the total line length. The protection characteristic quantities are as follows: Figure 3 As shown. By Figure 3 (a) It can be seen that after the fault, the fault voltage amplitude at the rectifier end increases rapidly, and the protection element is activated. Within 2-3 ms after the fault occurs in the zone, the calculated fault voltage at protection point M and the measured fault voltage fluctuate in roughly the same direction, and their waveforms have a large overlap. Calculation shows that the cosine similarity of the voltage waveform at the rectifier end measurement point is 0.9105, which is greater than the threshold value of 0.15, indicating a positive fault. Figure 3 (b) and Figure 3 (c) It can be seen that the fault voltage amplitude at the inverter end increases rapidly after the fault, and the protection components are activated. Within 2-3 ms after the fault occurs within the zone, the calculated and measured fault voltages at protection points N1 and N2 fluctuate in roughly the same direction. Calculations show that the cosine similarity of the voltage waveform at measurement point N1 is 0.9986; the cosine similarity at measurement point N2 is 0.9977, both exceeding the threshold value of 0.15, indicating a forward fault. Based on the judgment results at the rectifier and inverter ends, a forward fault within the DC line can be confirmed.

[0078] (2) Faults outside the DC transmission line area

[0079] Combination Figure 2 As shown, a metallic bipolar fault occurred at f4, outside the current-limiting reactor of MMC1 in the inverter station. The voltage fault component waveform at the three-terminal measuring points of the system is as follows. Figure 4 As shown, Figure 4 In the diagram, (a) and (c) represent the voltage fault components at points M and N2, respectively. The calculated similarity of the voltage waveform at N2 is 0.9918, and the similarity at M is 0.7629. The calculated and measured voltage waveforms show an overall positive correlation, indicating a forward fault. Figure 4 (b) It can be seen that the cosine similarity of the voltage waveform at N1 is -0.3996, which is judged as a reverse fault. Based on the judgment results of the rectifier end and the inverter end, it can be determined that an external fault of the DC line has occurred.

[0080] Figure 5This is a schematic diagram of the structure of a DC transmission line protection system 500 according to an embodiment of the present invention. Figure 5 As shown, the DC transmission line protection system 500 provided in this embodiment of the invention includes: a data acquisition unit 501, a similarity determination unit 502, a fault direction determination unit 503, and a fault type determination unit 504.

[0081] Preferably, the data acquisition unit 501 is used to acquire the calculated voltage and measured voltage at the first measurement point and the second measurement point of the DC transmission line.

[0082] Preferably, the data acquisition unit 501 acquires the calculated voltage using the following method:

[0083]

[0084] Among them, u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; i x (k+1) and i x (k) represents the current at measurement point x at time k+1 and time k, respectively; ΔT is the sampling time interval; n is the number of sampling times; C0, L0, L line1 and R arm These are the submodule capacitor, bridge arm inductor, DC line-side inductor, and DC-side stray resistance, respectively.

[0085] Preferably, the similarity determination unit 502 is used to determine the first similarity corresponding to the first measurement point and the second similarity corresponding to the second measurement point based on the calculated voltage and the measured voltage.

[0086] Preferably, the similarity determination unit 502 determines the first similarity and the second similarity in the following manner:

[0087]

[0088] Where, r x The similarity score corresponds to measurement point x on a DC transmission line, where measurement point x is located at the installation location of the DC transmission line's measurement and protection system; u x (k) represents the measured voltage at measurement point x on the DC transmission line at time k; u xj (k) represents the calculated voltage at measurement point x on the DC transmission line at time k; n represents the number of sampling times.

[0089] Preferably, the fault direction determination unit 503 is used to determine the first fault direction corresponding to the first measurement point and the second fault direction corresponding to the second measurement point based on the first similarity and the second similarity, respectively.

[0090] Preferably, the fault direction determination unit 503 determines the fault direction using the following method:

[0091] If the similarity is greater than or equal to the first preset similarity threshold, the fault direction is determined to be positive.

[0092] If the similarity is less than the second preset similarity threshold, the fault direction is determined to be reversed.

[0093] Preferably, the fault type determination unit 504 is used to determine the fault type based on the first fault direction and the second fault direction.

[0094] Preferably, the fault type determination unit 504 determines the fault type based on the first fault direction and the second fault direction, including:

[0095] When both the first fault direction and the second fault direction are positive, the fault type is determined to be an intra-zone fault; otherwise, the fault type is determined to be an extra-zone fault.

[0096] The DC transmission line protection system 500 of this invention corresponds to the DC transmission line protection method 100 of another embodiment of this invention, and will not be described again here.

[0097] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods for protecting a DC transmission line.

[0098] According to another aspect of the present invention, the present invention provides an electronic device, comprising:

[0099] The aforementioned computer-readable storage medium; and

[0100] One or more processors for executing a program in the computer-readable storage medium.

[0101] The invention has been described with reference to a few embodiments. However, as will be known to those skilled in the art, and as defined in the appended claims, other embodiments besides those disclosed above fall equivalently within the scope of the invention.

[0102] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to “a / the / the [device, component, etc.]” ​​are openly interpreted as at least one instance of said device, component, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed unless explicitly stated otherwise.

[0103] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment 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, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0104] 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, and 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 illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0105] 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 1 The function specified in one or more boxes.

[0106] 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.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for protecting DC transmission lines, characterized in that, The method includes: Obtain the calculated voltage and measured voltage at the first and second measurement points of the DC transmission line; The first similarity corresponding to the first measurement point and the second similarity corresponding to the second measurement point are determined based on the calculated voltage and the measured voltage. The first fault direction corresponding to the first measurement point and the second fault direction corresponding to the second measurement point are determined based on the first similarity and the second similarity, respectively. The fault type is determined based on the first fault direction and the second fault direction. The method obtains the calculated voltage using the following approach: , in, The calculated voltage at measurement point x on the DC transmission line at time k; and These are the currents at measurement point x at time k+1 and time k, respectively; The sampling time interval is n; the number of sampling times is n0, L0, L... line1 and R arm These are the submodule capacitor, bridge arm inductor, DC line-side inductor, and DC-side stray resistance, respectively. The method determines the first similarity and the second similarity in the following ways: ， in, The similarity score corresponds to measurement point x on the DC transmission line, where measurement point x is located at the installation location of the DC transmission line measurement and protection system. The measured voltage at measurement point x on the DC transmission line at time k; The voltage at measurement point x on the DC transmission line at time k is the calculated voltage; n is the number of sampling times.

2. The method according to claim 1, characterized in that, The method determines the direction of the fault using the following methods: If the similarity is greater than or equal to the first preset similarity threshold, the fault direction is determined to be positive. If the similarity is less than the second preset similarity threshold, the fault direction is determined to be reversed.

3. The method according to claim 1, characterized in that, Determining the fault type based on the first fault direction and the second fault direction includes: When both the first fault direction and the second fault direction are positive, the fault type is determined to be an intra-zone fault; otherwise, the fault type is determined to be an extra-zone fault.

4. A DC transmission line protection system, characterized in that, The system includes: The data acquisition unit is used to acquire the calculated voltage and measured voltage at the first and second measurement points of the DC transmission line; A similarity determination unit is used to determine a first similarity corresponding to a first measurement point and a second similarity corresponding to a second measurement point based on the calculated voltage and the measured voltage. The fault direction determination unit is used to determine the first fault direction corresponding to the first measurement point and the second fault direction corresponding to the second measurement point based on the first similarity and the second similarity, respectively. A fault type determination unit is used to determine the fault type based on the first fault direction and the second fault direction. The data acquisition unit acquires the calculated voltage using the following method: , in, The calculated voltage at measurement point x on the DC transmission line at time k; and These are the currents at measurement point x at time k+1 and time k, respectively; The sampling time interval is n; the number of sampling times is n0, L0, L... line1 and R arm These are the submodule capacitor, bridge arm inductor, DC line-side inductor, and DC-side stray resistance, respectively. The similarity determination unit determines the first similarity and the second similarity using the following methods: ， in, The similarity score corresponds to measurement point x on the DC transmission line, where measurement point x is located at the installation location of the DC transmission line measurement and protection system. The measured voltage at measurement point x on the DC transmission line at time k; The voltage at measurement point x on the DC transmission line at time k is the calculated voltage; n is the number of sampling times.

5. The system according to claim 4, characterized in that, The fault direction determination unit determines the fault direction using the following methods: If the similarity is greater than or equal to the first preset similarity threshold, the fault direction is determined to be positive. If the similarity is less than the second preset similarity threshold, the fault direction is determined to be reversed.

6. The system according to claim 4, characterized in that, The fault type determination unit determines the fault type based on the first fault direction and the second fault direction, including: When both the first fault direction and the second fault direction are positive, the fault type is determined to be an intra-zone fault; otherwise, the fault type is determined to be an extra-zone fault.

7. 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 of the method as described in any one of claims 1-3.

8. An electronic device, characterized in that, include: The computer-readable storage medium as described in claim 7; as well as One or more processors for executing a program in the computer-readable storage medium.

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