Extra-high voltage alternating current transmission line permanent fault identification method and system

Abstract

The invention discloses an extra-high voltage alternating current transmission line permanent fault identification method and system, and the method comprises the steps: obtaining the fault recording data of a three-phase voltage instantaneous value after the fault of an extra-high voltage transmission line with a shunt reactor, and determining two fault phases with an inter-phase fault based on the fault recording data; calculating an inter-phase differential mode voltage of the two fault phases based on the fault recording data; performing sliding window integration on the phase-to-phase differential mode voltage according to a preset time window by taking a breaker tripping off fault point arc quenching after the fault as a starting moment to obtain a phase-to-phase differential mode voltage integral value; and in a preset time window, if the inter-phase differential mode voltage integral value is continuously smaller than a preset integral threshold value, or the inter-phase differential mode voltage integral value is larger than the preset integral threshold value and the number of continuous sampling points is smaller than a preset number, it is determined that a permanent fault occurs. The method can be applied to fault type analysis of the ultra-high voltage transmission line and provides scheduling operation decisions for operation and maintenance personnel.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-high voltage alternating current transmission line fault identification, and more specifically, to an ultra-high voltage alternating current transmission line permanent fault identification method and system. Background Art

[0002] In modern society, electricity is indispensable. UHV AC transmission projects continue to advance with their advantages of large transmission capacity, long transmission distance and wide coverage. However, due to the combined influence of factors such as global warming, the normalization of extreme disasters has become more and more obvious, and the safe operation of the power grid faces severe challenges. At the same time, the geographical environment along the UHV transmission lines is complex, including areas prone to ice and snow disasters and areas prone to wildfire disasters. How to quickly identify and eliminate safety hazards of transmission lines in complex environments and ensure the safe and stable operation of transmission lines is an important problem faced by the operation and inspection management of transmission lines.

[0003] Based on the experience of power system operation and dispatching, line faults can usually be divided into instantaneous faults and permanent faults. Limited by the action strategy of the relay protection device of the UHV transmission line, the protection device will issue an automatic reclosing command only when a single-phase fault occurs on the line. If it is a transient fault, the line will resume operation after the circuit breaker recloses, which can greatly reduce the economic losses caused by the power outage due to the fault; if it is a single-phase permanent fault, the circuit breaker recloses on the permanent fault, causing the circuit breaker to trip again and the line to stop operating; if the line has a two-phase phase-to-phase, two-phase grounding, or three-phase grounding transient / permanent fault, the circuit breaker will trip permanently and the line will stop operating. However, in the face of line faults caused by severe weather conditions such as icing, rain and snow, it is difficult to conduct fault line inspections in a timely and rapid manner due to weather conditions, and thus it is impossible to quickly analyze the cause of the fault, which seriously affects the efficiency of fault troubleshooting and power supply restoration, and has a serious adverse impact on the reliability and resilience of the power supply of the power grid.

[0004] Although reclosing can eliminate line faults and quickly restore power supply for single-phase instantaneous faults, other types of faults require manual analysis combined with fault line inspection to determine the fault type. However, due to the accuracy of manual analysis and the progress of fault line inspection, power supply cannot usually be restored quickly, resulting in large economic losses. Therefore, there is an urgent need to form a method for identifying instantaneous and permanent fault types of UHV transmission lines that can be applied to different types of faults. Summary of the invention

[0005] The present invention provides a method and system for identifying permanent faults of an ultra-high voltage alternating current transmission line, so as to solve the problem of how to efficiently and quickly identify permanent faults of the line.

[0006] In order to solve the above problem, according to one aspect of the present invention, a method for identifying permanent faults in an ultra-high voltage AC transmission line is provided, the method comprising:

[0007] Obtaining fault recording data of instantaneous values ​​of three-phase voltages after a fault of an ultra-high voltage transmission line with a shunt reactor, and determining two fault phases where interphase faults occur based on the fault recording data;

[0008] Calculate the interphase differential mode voltage of the two fault phases based on the fault recording data;

[0009] Taking the arc extinguishing of the fault point after the circuit breaker trips after the fault as the starting time, performing sliding window integration on the phase-to-phase differential mode voltage according to a preset time window to obtain an integral value of the phase-to-phase differential mode voltage;

[0010] Within a preset time window, if the inter-phase differential mode voltage integral value is continuously less than the preset integral threshold value, or if the inter-phase differential mode voltage integral value is greater than the preset integral threshold value but the continuous number of sampling points is less than the preset number, it is determined that a permanent fault has occurred.

[0011] Preferably, the length of the preset time window T1=2T0, where T0 is the differential mode voltage resonance period.

[0012] Preferably, the preset integral threshold value K=M*T1, wherein M is a preset coefficient; and T1 is the length of a preset time window.

[0013] Preferably, the method further comprises:

[0014] If there are a continuous preset number of inter-phase differential mode voltage integral values ​​greater than or equal to a preset integral threshold value within a preset time window, it is determined that a transient fault occurs.

[0015] According to another aspect of the present invention, a permanent fault identification system for an ultra-high voltage AC transmission line is provided, the system comprising:

[0016] A fault phase determination unit is used to obtain fault recording data of instantaneous values ​​of three-phase voltage after a UHV transmission line with a shunt reactor fails, and determine two fault phases where interphase faults occur based on the fault recording data;

[0017] A phase-to-phase differential mode voltage calculation unit, used for calculating the phase-to-phase differential mode voltage of the two fault phases based on the fault recording data;

[0018] An integral value calculation unit is used to perform sliding window integration on the phase-to-phase differential mode voltage according to a preset time window, taking the arc extinguishing at the fault point when the circuit breaker trips after the fault as the starting time, to obtain an integral value of the phase-to-phase differential mode voltage;

[0019] The fault identification unit is used to determine that a permanent fault has occurred if, within a preset time window, the inter-phase differential mode voltage integral value is continuously less than a preset integral threshold value, or if the inter-phase differential mode voltage integral value is greater than the preset integral threshold value but the number of continuous sampling points is less than a preset number.

[0020] Preferably, the length of the preset time window T1=2T0, where T0 is the differential mode voltage resonance period.

[0021] Preferably, the preset integral threshold value K=M*T1, wherein M is a preset coefficient; and T1 is the length of a preset time window.

[0022] Preferably, the fault identification voltage is also used for:

[0023] If there are a continuous preset number of inter-phase differential mode voltage integral values ​​greater than or equal to a preset integral threshold value within a preset time window, it is determined that a transient fault occurs.

[0024] Based on 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 any step of a method for identifying permanent faults in an ultra-high voltage AC transmission line.

[0025] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0026] The computer-readable storage medium described above; and

[0027] One or more processors are used to execute the program in the computer-readable storage medium.

[0028] The present invention provides a method and system for identifying permanent faults in ultra-high voltage AC transmission lines, including: obtaining fault recording data of instantaneous values ​​of three-phase voltages after a fault in an ultra-high voltage transmission line with a shunt reactor, and determining two fault phases where a phase-to-phase fault occurs based on the fault recording data; calculating the phase-to-phase differential mode voltages of the two fault phases based on the fault recording data; taking the arc extinguishing of the fault point after the circuit breaker trips as the starting time, performing sliding window integration on the phase-to-phase differential mode voltage according to a preset time window to obtain the phase-to-phase differential mode voltage integral value; within a preset time window, if there is a phase-to-phase differential mode voltage integral value that is continuously less than a preset integral threshold value, or at the same time, there is a phase-to-phase differential mode voltage integral value that is greater than the preset integral threshold value but the number of continuous sampling points is less than a preset number, then it is determined that a permanent fault occurs. The method of the present invention is based on the differential mode voltage characteristics of the line after the fault, and realizes the instantaneous and permanent fault type identification of ultra-high voltage transmission lines with shunt reactors through an integral method, which can be applied to the fault type analysis of ultra-high voltage transmission lines and provide scheduling and operation decisions for operation and maintenance personnel, and has broad promotion prospects and application scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0030] Figure 1 is a flow chart of a method 100 for identifying permanent faults in an ultra-high voltage AC transmission line according to an embodiment of the present invention;

[0031] Figure 2 An equivalent circuit diagram of an ultra-high voltage transmission line with shunt reactors at both ends according to an embodiment of the present invention;

[0032] Figure 3 A simplified equivalent circuit diagram of a transient fault of a UHV transmission line according to an embodiment of the present invention;

[0033] Figure 4 is a schematic diagram of a fault phase differential mode voltage under a transient fault according to an embodiment of the present invention;

[0034] Figure 5 A simplified equivalent circuit diagram of a permanent fault of an ultra-high voltage transmission line according to an embodiment of the present invention;

[0035] Figure 6 is a schematic diagram of a fault phase differential mode voltage under a permanent fault according to an embodiment of the present invention;

[0036] Figure 7 A schematic diagram of a three-phase differential mode voltage calculated based on actual fault recording data of a BC two-phase permanent fault occurring in a certain line according to an embodiment of the present invention;

[0037] Figure 8 It is a schematic diagram of the three-phase differential mode voltage integral value calculated from the actual fault recording data of a BC two-phase permanent fault occurring in a certain line according to an embodiment of the present invention;

[0038] Fig. 9 Schematic diagram of the structure of a permanent fault identification system 900 for an ultra-high voltage AC transmission line according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0040] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0041] In order to solve the problem that it is difficult to quickly determine the fault type and make operation and dispatch decisions for UHV transmission line faults caused by extreme weather disasters such as freezing rain and snow, the present invention proposes a method for identifying transient and permanent faults of transmission lines based on the fault differential mode voltage integral value. It does not require the installation of additional data acquisition modules and analysis modules. Combined with line fault recording data, it can quickly and accurately identify transient and permanent faults. The present invention does not need to rely on line patrol results. Based on the fault cause identification results of the present invention, it makes dispatch and operation decisions, strongly supports line reclosing or trial transmission, ensures that the line is quickly and safely restored to operation, and reduces economic losses caused by power outages.

[0042] Figure 1 FIG. 1 is a flow chart of a method 100 for identifying permanent faults in a UHV AC transmission line according to an embodiment of the present invention. Figure 1 As shown, the method for identifying permanent faults of ultra-high voltage AC transmission lines provided by the embodiment of the present invention is based on the differential mode voltage characteristics of the line after the fault, and realizes the instantaneous and permanent fault type identification of ultra-high voltage transmission lines with shunt reactors through the integration method. It can be applied to the fault type analysis of ultra-high voltage transmission lines and provide scheduling and operation decisions for operation and maintenance personnel, and has broad promotion prospects and application scale. The method for identifying permanent faults of ultra-high voltage AC transmission lines 100 provided by the embodiment of the present invention starts from step 101. At 101, the fault recording data of the instantaneous value of the three-phase voltage after the ultra-high voltage transmission line with shunt reactors is obtained, and the two fault phases where the phase-to-phase fault occurs are determined based on the fault recording data.

[0043] In step 102, the interphase differential mode voltages of the two fault phases are calculated based on the fault recording data.

[0044] In step 103, taking the arc extinguishing of the fault point when the circuit breaker trips after the fault as the starting time, the phase-to-phase differential mode voltage is integrated according to a preset time window to obtain the phase-to-phase differential mode voltage integral value.

[0045] At 104, within a preset time window, if the inter-phase differential mode voltage integral value is continuously less than the preset integral threshold value, or if the inter-phase differential mode voltage integral value is greater than the preset integral threshold value but the number of continuous sampling points is less than the preset number, it is determined that a permanent fault has occurred.

[0046] Preferably, the length of the preset time window T1=2T0, where T0 is the differential mode voltage resonance period.

[0047] Preferably, the preset integral threshold value K=M*T1, wherein M is a preset coefficient; and T1 is the length of a preset time window.

[0048] Preferably, the method further comprises:

[0049] If there are a continuous preset number of inter-phase differential mode voltage integral values ​​greater than or equal to a preset integral threshold value within a preset time window, it is determined that a transient fault occurs.

[0050] The method of the present invention is based on the analysis of the change characteristics of the differential mode voltage after the fault of the UHV transmission line with shunt reactor, and proposes a method for identifying transient and permanent faults of the transmission line based on the integral value of the differential mode voltage. The following describes in detail the difference in the fault characteristics of the differential mode voltage and the fault identification method.

[0051] (1) Differential-mode voltage fault characteristics of UHV transmission lines with shunt reactors

[0052] UHV transmission lines have high voltage levels, large transmission capacity, and long transmission distances, but the capacitance rise effect of long transmission lines is obvious, which limits the transmission capacity and makes the power frequency overvoltage of the lines prominent. Therefore, UHV transmission lines usually use shunt reactors to balance the line-to-ground capacitance and solve the power frequency overvoltage problem.

[0053] Taking the UHV transmission line with shunt reactors on both sides of the line as an example, the concentrated parameter equivalent circuit diagram is as follows: Figure 2 As shown. Where: C0 is the equivalent capacitance of the line to ground; L is the inductance of the shunt reactor; x is the percentage of the length from the fault point to the m side of the line in the total length of the line; u mx 、u nx They are the three-phase voltages on the m and n sides of the line (x=A, B, C); f is the fault point.

[0054] Line differential mode voltage:

[0055]

[0056] When a three-phase short circuit or a two-phase short circuit occurs in the line, the line protection sends a trip command and the circuit breakers on both sides trip. At this time, due to the coupling between the line-to-ground capacitance and the shunt reactor, a residual voltage with attenuated oscillation will appear on the line. Depending on the nature of the fault, when a transient fault or a permanent fault occurs in the line, the differential mode voltage presents different characteristics. Specifically, when a transient fault occurs in the line, after the circuit breakers on both sides trip and the arc at the fault point is extinguished, the circuit breaker is further simplified. Figure 2 Can get as Figure 3As shown in the equivalent circuit diagram, the residual energy on the line-to-ground capacitance and the shunt reactor oscillates back and forth between the line-to-ground capacitance and the equivalent inductance of the reactor, causing the residual voltage to appear as follows Figure 4 The “beat frequency characteristic” shown in the figure; when a permanent fault occurs in the line, its simplified equivalent circuit diagram is as follows Figure 5 At this time, the parallel circuit of the line-to-ground capacitance and the equivalent inductance of the reactor is short-circuited, and the residual voltage of the line decays rapidly, as shown in Figure 1. Figure 6 Therefore, based on this characteristic, the differential mode voltage integral value can be used to identify transient and permanent faults in the line.

[0057] (2) Methods for identifying transient and permanent faults in UHV transmission lines with shunt reactors

[0058] According to (1), the present invention uses the comparison result between the fault phase differential mode voltage integral value and the threshold value to identify the transient fault or permanent fault of the line, as follows:

[0059] B1) First read the fault recording data of the instantaneous values ​​of the three-phase voltage after the UHV transmission line with shunt reactor fails, and confirm the two fault phases.

[0060] B2) Perform Fourier decomposition on the instantaneous voltage value of the fault phase, and calculate the differential mode voltage of the fault phase according to formula (1).

[0061] B3) Considering that when a transient fault occurs in a UHV transmission line with a shunt reactor, the differential mode voltage exhibits a "beat frequency" resonance characteristic and the resonance period T0 is relatively long. In order to eliminate the voltage integral value fluctuation to the greatest extent, a time window with a period of T1 is used, and the differential mode voltage U is measured with the arc extinguishing at the fault point after the fault when the circuit breaker trips. α , U β or U γ Perform sliding window integration and calculate the differential mode voltage integral value dU α ,dU β or dU γ Among them, T1 can be determined according to the differential mode voltage resonance period T0, and usually T1 = 2T0. To simplify the calculation, the window length can be taken as 10ms.

[0062] B4) Compare the differential mode voltage integral value of the fault phase with the preset integral threshold value K. If there are N consecutive sampling points with the phase-to-phase differential mode voltage integral value greater than or equal to the preset integral threshold value K within a preset time window, it is determined that a transient fault has occurred; within a preset time window, if the differential mode voltage integral value of the fault phase is continuously less than the preset integral threshold value, or at the same time, the fault phase differential mode voltage integral value is greater than the preset integral threshold value K but does not meet the requirement that N consecutive sampling points are higher than the threshold K, it is determined to be a permanent fault. Among them, the integral threshold value K is related to the integral time window T1, K = M * T1; wherein M is a preset coefficient; T1 is the length of the preset time window. In a 10ms time window, M is 5, then the threshold value K can be 50, and the threshold value can be appropriately lowered when the line length is short; the specific value of N is related to the sampling frequency of the protection device, usually N = 5 at a sampling rate of 1000Hz.

[0063] According to B1) to B4), based on the actual fault recording data of a permanent fault of two phases BC in a certain line, the following can be calculated: Figure 7 The three-phase differential mode U α , U β , U γ , and Figure 8 The three-phase differential mode voltage integral value dU α ,dU β ,dU γ .

[0064] according to Figure 8 The calculation results show that the fault phase differential mode voltage U β Integral value dU β If the value is continuously less than the threshold value, the identification result is a permanent fault, which verifies the accuracy of the instantaneous and permanent fault type identification of the UHV transmission line with shunt reactor proposed in the present invention.

[0065] Fig. 9 FIG. 9 is a schematic diagram of a permanent fault identification system 900 for an ultra-high voltage AC transmission line according to an embodiment of the present invention. Fig. 9 As shown, the permanent fault identification system 900 for an ultra-high voltage AC transmission line provided in an embodiment of the present invention includes: a fault phase determination unit 901 , an inter-phase differential mode voltage calculation unit 902 , and an integral value calculation unit 903 .

[0066] Preferably, the fault phase determination unit 901 is used to obtain fault recording data of instantaneous values ​​of three-phase voltage after a fault of an ultra-high voltage transmission line with a shunt reactor, and determine two fault phases where interphase faults occur based on the fault recording data.

[0067] Preferably, the phase-to-phase differential mode voltage calculation unit 902 is used to calculate the phase-to-phase differential mode voltages of the two faulty phases based on the fault recording data.

[0068] Preferably, the integral value calculation unit 903 is used to perform sliding window integration on the phase-to-phase differential mode voltage according to a preset time window, taking the arc extinguishing of the fault point when the circuit breaker trips after the fault as the starting time, to obtain the phase-to-phase differential mode voltage integral value.

[0069] Preferably, the fault identification unit 904 is used to determine that a permanent fault has occurred if, within a preset time window, the inter-phase differential mode voltage integral value is continuously less than a preset integral threshold value, or if the inter-phase differential mode voltage integral value is greater than the preset integral threshold value but the number of continuous sampling points is less than a preset number.

[0070] Preferably, the length of the preset time window T1=2T0, where T0 is the differential mode voltage resonance period.

[0071] Preferably, the preset integral threshold value K=M*T1, wherein M is a preset coefficient; and T1 is the length of a preset time window.

[0072] Preferably, the fault identification voltage 904 is also used for:

[0073] If there are a continuous preset number of inter-phase differential mode voltage integral values ​​greater than or equal to a preset integral threshold value within a preset time window, it is determined that a transient fault occurs.

[0074] The UHV AC transmission line permanent fault identification system 900 of the embodiment of the present invention corresponds to the UHV AC transmission line permanent fault identification method 100 of another embodiment of the present invention, and will not be described in detail herein.

[0075] Based on 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 any step of a method for identifying permanent faults in an ultra-high voltage AC transmission line.

[0076] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0077] The computer-readable storage medium described above; and

[0078] One or more processors are used to execute the program in the computer-readable storage medium.

[0079] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0080] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of said means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0081] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented 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.

[0082] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0083] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0084] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does 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 identifying permanent faults in ultra-high voltage AC transmission lines, characterized in that: The method comprises: Obtaining fault recording data of instantaneous values ​​of three-phase voltages after a fault of an ultra-high voltage transmission line with a shunt reactor, and determining two fault phases where interphase faults occur based on the fault recording data; Calculate the interphase differential mode voltage of the two fault phases based on the fault recording data; Taking the arc extinguishing of the fault point after the circuit breaker trips after the fault as the starting time, performing sliding window integration on the phase-to-phase differential mode voltage according to a preset time window to obtain an integral value of the phase-to-phase differential mode voltage; Within a preset time window, if the inter-phase differential mode voltage integral value is continuously less than the preset integral threshold value, or if the inter-phase differential mode voltage integral value is greater than the preset integral threshold value but the continuous number of sampling points is less than the preset number, it is determined that a permanent fault has occurred.

2. The method according to claim 1, characterized in that The length of the preset time window is T1=2T0, where T0 is the differential mode voltage resonance period.

3. The method according to claim 1, characterized in that The preset integral threshold value K=M*T1; wherein M is a preset coefficient; and T1 is the length of a preset time window.

4. The method according to claim 1, characterized in that The method further comprises: If there are a continuous preset number of inter-phase differential mode voltage integral values ​​greater than or equal to a preset integral threshold value within a preset time window, it is determined that a transient fault occurs.

5. A permanent fault identification system for ultra-high voltage AC transmission lines, characterized in that: The system comprises: A fault phase determination unit is used to obtain fault recording data of instantaneous values ​​of three-phase voltage after a UHV transmission line with a shunt reactor fails, and determine two fault phases where interphase faults occur based on the fault recording data; A phase-to-phase differential mode voltage calculation unit, used for calculating the phase-to-phase differential mode voltage of the two fault phases based on the fault recording data; An integral value calculation unit is used to perform sliding window integration on the phase-to-phase differential mode voltage according to a preset time window, taking the arc extinguishing at the fault point when the circuit breaker trips after the fault as the starting time, to obtain an integral value of the phase-to-phase differential mode voltage; The fault identification unit is used to determine that a permanent fault has occurred if, within a preset time window, the inter-phase differential mode voltage integral value is continuously less than a preset integral threshold value, or if the inter-phase differential mode voltage integral value is greater than the preset integral threshold value but the number of continuous sampling points is less than a preset number.

6. The system according to claim 5, characterized in that The length of the preset time window is T1=2T0, where T0 is the differential mode voltage resonance period.

7. The system according to claim 5, characterized in that The preset integral threshold value K=M*T1; wherein M is a preset coefficient; and T1 is the length of a preset time window.

8. The system according to claim 5, characterized in that The fault identification voltage is also used for: If there are a continuous preset number of inter-phase differential mode voltage integral values ​​greater than or equal to a preset integral threshold value within a preset time window, it is determined that a transient fault occurs.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

10. An electronic device, characterized in that: include: The computer readable storage medium as claimed in claim 9; as well as One or more processors are used to execute the program in the computer-readable storage medium.

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