A power distribution network phase-to-phase fault location method under double-ended data asynchronization condition
By installing electrical quantity acquisition devices at the beginning and end of the distribution network lines and using the full-cycle Fourier algorithm to calculate electrical quantity phasors, the problems of insufficient single-end impedance ranging accuracy and two-point grounding fault ranging of different phases in the distribution network are solved, and accurate fault ranging is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHONGQING CHUANDONG ELECTRIC POWER GRP
- Filing Date
- 2023-12-25
- Publication Date
- 2026-08-04
AI Technical Summary
Existing single-ended impedance ranging methods for distribution networks are not accurate enough when new energy sources are connected, and traditional methods cannot accurately measure two-point grounding faults of different phases, resulting in the inability to accurately locate the fault.
Electrical quantity acquisition devices are installed at the beginning and end of the ranging line. The full-cycle Fourier algorithm is used to calculate the electrical quantity phasors, the phase-to-phase current difference and the phase voltage phasors. The distance is measured by substituting the corresponding fault ranging formula according to the fault condition and location.
It enables accurate measurement of the location of simple phase-to-phase faults and two-point grounding faults of different phases even when the data at both ends are not synchronized, effectively addressing the impact of distributed energy access and improving ranging accuracy.
Smart Images
Figure CN117890724B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power system protection and control, and specifically relates to a method for locating phase-to-phase faults in a distribution network under conditions of asynchronous data at both ends. Background Technology
[0002] With the construction of new power systems, the scale of distribution networks is gradually increasing, and the penetration rate of new energy sources is rising year by year. This leads to an increased probability of faults, and accurate algorithms can effectively improve fault repair speed and ensure the reliability of power supply. Traditional single-ended impedance ranging is affected by changes in the impedance of the load on the opposite side. The integration of new energy sources makes it difficult to accurately calculate the impedance of the load on the opposite side, making single-ended impedance ranging insufficient to meet the requirements. Protection and ranging methods based on multi-ended information have good performance in multi-source networks. By adding a measurement unit to introduce dual-ended information, the problems of single-ended impedance ranging being greatly affected by changes in the impedance on the opposite side and insufficient ranging accuracy can be effectively solved. However, this method usually has high requirements for equipment sampling synchronization conditions, requiring the construction of dedicated communication channels to achieve strict time synchronization, which is costly.
[0003] Meanwhile, the distribution network has a complex structure with numerous branch lines, resulting in a relatively high probability of single-phase grounding faults. To ensure the stability and continuity of power supply, the distribution network typically adopts a neutral point non-effective grounding structure. After a single-phase grounding fault occurs in the system, it can continue to operate for 1 to 2 hours. During this time, the voltage of the non-faulty phase rises, making it easy for insulation breakdown to occur at weak points in the line insulation, forming a two-point grounding fault with different phases. Traditional distribution network ranging algorithms cannot achieve the ranging of two-point faults with different phases.
[0004] Therefore, it is evident that existing single-ended impedance ranging methods in distribution networks suffer from significant susceptibility to load impedance variations and insufficient ranging accuracy. While dual-ended impedance ranging can effectively address the shortcomings of single-ended methods, its implementation is constrained by distribution network construction costs, making it difficult to guarantee strict data synchronization between the two ends. Furthermore, existing ranging algorithms cannot accurately locate two-point grounding faults with different phases. Therefore, researching impedance ranging methods based on asynchronous dual-ended data has significant theoretical and practical implications. Summary of the Invention
[0005] The purpose of this application is to provide a method for locating phase-to-phase faults in distribution networks under the condition of asynchronous data at both ends, which solves the problems of insufficient accuracy of single-end impedance locating in distribution networks and inability to accurately measure the location of two-point grounding faults of different phases in the prior art.
[0006] This invention is achieved through the following technical solution: a method for locating phase-to-phase faults in a distribution network under conditions of asynchronous data at both ends, comprising:
[0007] S1: Electrical quantity acquisition devices are installed at the beginning and end of the ranging line, respectively;
[0008] S2: The full-cycle Fourier algorithm is used to calculate the electrical phasors at the beginning and end of the line after the fault;
[0009] S3: Calculate the phase current difference between the beginning and end points based on the phase current phasors at the beginning and end points respectively;
[0010] S4: Calculate the phase voltage phasor at the end based on the zero-sequence voltage phasor and line voltage phasor at the end;
[0011] S5: Based on the fault condition and location, substitute the two-terminal electrical quantities into the corresponding fault location formula to perform fault location.
[0012] In one possible implementation, the electrical quantity acquisition devices set at the beginning and end of the ranging line respectively include: the measuring devices set at the beginning and end of the line have the ability to measure line voltage, phase current, zero-sequence voltage and zero-sequence current, and also have the ability to measure waveforms and transmit data.
[0013] In one possible implementation, the full-cycle Fourier algorithm is used to calculate the electrical phasors at the beginning and end of the line after the fault. The electrical phasors include: line voltage phasors, phase current phasors, zero-sequence voltage phasors, and zero-sequence current phasors at the beginning and end.
[0014] In one possible implementation, the method for calculating the phase-to-phase current difference between the beginning and end points based on the phase current phasors of the beginning and end points is as follows:
[0015] Method for calculating phase-to-phase current at the beginning:
[0016] Method for calculating interphase current at the end:
[0017] in These represent the phase currents at the measuring points at the beginning of the ranging line. These represent the phase currents at the measuring points at the ends of the ranging line. These represent the phase-to-phase current difference values at the measuring points at the beginning of the ranging line. These represent the phase-to-phase current difference at the measuring point at the end of the ranging line.
[0018] In one possible implementation, the method for calculating the phase voltage phasor of the terminal based on the zero-sequence voltage phasor and the line voltage phasor is as follows:
[0019] Method for calculating the phase voltage at the end:
[0020] in These represent the phase voltages at the measuring points at the end of the ranging line. These represent the line voltages calculated using the full-cycle Fourier algorithm at the measurement points at the end of the line. This represents the zero-sequence voltage calculated using the full-cycle Fourier algorithm at the measurement point at the end of the line.
[0021] In one possible implementation, the fault location is determined by substituting the two-terminal electrical quantities into the corresponding fault location formula based on the fault condition and fault location. The fault condition and fault location include: a phase-to-phase fault occurring between the beginning and end of the fault location; a phase-to-ground fault occurring between the beginning and end of the fault location; a two-point ground fault occurring between opposite phases, with both fault points located between the beginning and end of the fault location; and a two-point ground fault occurring between opposite phases, with one fault point located between the beginning and end of the fault location and the other located downstream of the end of the fault location.
[0022] In one possible implementation, the dissimilar phase two-point grounding fault is: after a single-phase grounding fault occurs on the line, the system continues to operate, and a single-phase grounding fault occurs on another phase in the line, forming a different point phase-to-phase fault, which is called a dissimilar phase two-point grounding fault.
[0023] In one possible implementation, the fault location is determined by substituting the two-terminal electrical quantities into the corresponding fault location formula, which is:
[0024] For line faults involving phase-to-phase and phase-to-ground faults, with the fault points located between the beginning and end of the line, the distance measurement formula is:
[0025] Im(F1(l1))=0
[0026] A two-point ground fault of opposite phases occurs on the line, with both fault points located between the beginning and end of the line. The distance measurement formula is:
[0027]
[0028] A phase-to-phase fault has one location between the beginning and end of the line, and another location downstream of the end of the line. The distance measurement formula is:
[0029]
[0030] Where Re represents taking the real part of the function, Im represents taking the imaginary part of the function, F represents the ranging function, and l1 and l2 represent the distance between the fault point and the beginning of the ranging line. When a simple phase-to-phase fault or a phase-to-ground fault occurs, l1 and l2 are equal.
[0031] In one possible implementation, the expression for the ranging function F is:
[0032]
[0033] in This indicates the line voltage at the beginning of the ranging line. This indicates the line voltage at the end of the ranging line; This indicates the phase-to-phase current difference at the beginning of the line. Z represents the phase-to-phase current difference at the end of the line; Z1 is the unit positive sequence impedance of the line, Z m Z is the unit mutual impedance of the line. S L is the unit self-impedance of the line. MN Let F1 be the total length of the ranging line. For ranging functions F1 and F2, the subscripts x, y, and z can take three phase sequences: a, b, and c. When an AB phase-to-phase fault occurs, x and y take phase sequences a and b, respectively, and z takes phase sequence c. When a BC phase-to-phase fault occurs, x and y take phase sequences b and c, respectively, and z takes phase sequence a. When an AC phase-to-phase fault occurs, x and y take phase sequences a and c, respectively, and z takes phase sequence b. For ranging function F3, the subscripts x1, y1, and z1 can take three phase sequences: a, b, and c. When the downstream fault phase at the end of the ranging line is phase A, z1 takes phase sequence a, and x1 and y1 take phase sequences b and c, respectively. When the downstream fault phase at the end of the ranging line is phase B, z1 takes phase sequence b, and x1 and y1 take phase sequences a and c, respectively. When the downstream fault phase at the end of the ranging line is phase C, z1 takes phase sequence c, and x1 and y1 take phase sequences a and b, respectively.
[0034] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0035] This invention provides a method for locating phase-to-phase faults in distribution networks under conditions of asynchronous data at both ends. It effectively solves the problem of insufficient accuracy of traditional single-end impedance locating in distribution networks under the current situation of new energy access. It can accurately realize the locating of simple phase-to-phase faults and the locating of two-point grounding faults of different phases, effectively cope with the access of distributed energy, and is not affected by asynchronous data sampling and transition resistance. Attached Figure Description
[0036] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:
[0037] Figure 1 This is a flowchart illustrating a method for determining interphase fault location in a distribution network under conditions of asynchronous data at both ends, as provided in an embodiment of this application.
[0038] Figure 2 The diagram shows a time-phase fault network where all fault points are located within the ranging line area, as provided in the embodiments of this application.
[0039] Figure 3This is a schematic diagram of a two-point grounding fault with different phases when one fault point is located within the ranging line area and the other point is located downstream of the end of the ranging line, as provided in the embodiments of this application.
[0040] Figure 4 A simple active power distribution network model diagram containing distributed photovoltaics is provided for the embodiments of this application. Detailed Implementation
[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.
[0042] Example
[0043] like Figure 1 As shown, this application provides a method for locating phase-to-phase faults in a distribution network under asynchronous data sampling conditions after a phase-to-phase fault occurs. The method includes:
[0044] S1: Electrical quantity acquisition devices are installed at the beginning and end of the ranging line, respectively;
[0045] S2: The full-cycle Fourier algorithm is used to calculate the electrical phasors at the beginning and end of the line after the fault;
[0046] S3: Calculate the phase current difference between the beginning and end points based on the phase current phasors at the beginning and end points respectively;
[0047] S4: Calculate the phase voltage phasor at the end based on the zero-sequence voltage phasor and line voltage phasor at the end;
[0048] S5: Based on the fault condition and location, substitute the two-terminal electrical quantities into the corresponding fault location formula to perform fault location.
[0049] This application proposes a method for locating phase-to-phase faults in distribution networks under conditions of asynchronous two-terminal voltage and current information after a phase-to-phase fault. This method can accurately locate simple phase-to-phase faults and two-point grounding faults of different phases, effectively addressing the integration of distributed energy resources and is unaffected by asynchronous data sampling and transition resistance.
[0050] In one possible implementation, the electrical quantity acquisition devices set at the beginning and end of the ranging line respectively include: the measuring devices set at the beginning and end of the line have the ability to measure line voltage, phase current, zero-sequence voltage and zero-sequence current, and also have the ability to measure waveforms and transmit data.
[0051] In one possible implementation, the full-cycle Fourier algorithm is used to calculate the electrical phasors at the beginning and end of the line after the fault. The electrical phasors include: line voltage phasors, phase current phasors, zero-sequence voltage phasors, and zero-sequence current phasors at the beginning and end.
[0052] In one possible implementation, the method for calculating the phase-to-phase current difference between the beginning and end points based on the phase current phasors of the beginning and end points is as follows:
[0053] Method for calculating phase-to-phase current at the beginning:
[0054] Method for calculating interphase current at the end:
[0055] in These represent the phase currents at the measuring points at the beginning of the ranging line. These represent the phase currents at the measuring points at the ends of the ranging line. These represent the phase-to-phase current difference values at the measuring points at the beginning of the ranging line. These represent the phase-to-phase current difference at the measuring point at the end of the ranging line.
[0056] In one possible implementation, the method for calculating the phase voltage phasor of the terminal based on the zero-sequence voltage phasor and the line voltage phasor is as follows:
[0057] Method for calculating the phase voltage at the end:
[0058] in These represent the phase voltages at the measuring points at the end of the ranging line. These represent the line voltages calculated using the full-cycle Fourier algorithm at the measurement points at the end of the line. This represents the zero-sequence voltage calculated using the full-cycle Fourier algorithm at the measurement point at the end of the line.
[0059] In one possible implementation, the fault location is determined by substituting the two-terminal electrical quantities into the corresponding fault location formula based on the fault condition and fault location. The fault condition and fault location include: a phase-to-phase fault occurring between the beginning and end of the fault location; a phase-to-ground fault occurring between the beginning and end of the fault location; a two-point ground fault occurring between opposite phases, with both fault points located between the beginning and end of the fault location; and a two-point ground fault occurring between opposite phases, with one fault point located between the beginning and end of the fault location and the other located downstream of the end of the fault location.
[0060] like Figure 2 As shown in the figure, the fault points provided in this application embodiment are all located within the ranging line area, which is a schematic diagram of the inter-phase fault network. In the figure, L... MNMN represents the total length of the ranging line, and l1 and l2 represent the distances from the fault point to the measuring point at the beginning M of the ranging line, respectively. Based on the fault location and type, the fault network diagram for the line is as follows: a phase-to-phase fault located between the beginning and end of the ranging line; a phase-to-ground fault located between the beginning and end of the ranging line; or a two-point ground fault of opposite phases located between the beginning and end of the ranging line. Figure 2 As shown, l1 and l2 are equal when a simple phase-to-phase fault occurs.
[0061] like Figure 3 As shown in the figure, this application embodiment provides a schematic diagram of a two-point grounding fault with opposite phases when one fault point is located within the ranging line area and the other point is located downstream of the end of the ranging line. In the figure, L... MN MN represents the total length of the ranging line, and l1 and l2 represent the distances from the fault point to the measuring point at the beginning M of the ranging line, respectively. A two-point ground fault of opposite phases occurs on the line, with one fault located between the beginning and end of the ranging line, and the other located downstream of the end of the ranging line. A schematic diagram of the fault network is shown below. Figure 3 As shown.
[0062] In one possible implementation, the dissimilar phase two-point grounding fault is: after a single-phase grounding fault occurs on the line, the system continues to operate, and a single-phase grounding fault occurs on another phase in the line, forming a different point phase-to-phase fault, which is called a dissimilar phase two-point grounding fault.
[0063] like Figure 2 and Figure 3 As shown, when a two-point grounding fault of different phases occurs in the system, there are two fault points in the system, and the two fault distances l1 and l2 need to be solved separately.
[0064] In one possible implementation, the fault location is determined by substituting the two-terminal electrical quantities into the corresponding fault location formula, which is:
[0065] For line faults involving phase-to-phase and phase-to-ground faults, with the fault points located between the beginning and end of the line, the distance measurement formula is:
[0066] Im(F1(l1))=0
[0067] A two-point ground fault of opposite phases occurs on the line, with both fault points located between the beginning and end of the line. The distance measurement formula is:
[0068]
[0069] For a two-point ground fault with different phases, one point is located between the beginning and end of the line, and the other point is located downstream of the end of the line. The distance measurement formula is:
[0070]
[0071] Where Re represents taking the real part of the function, Im represents taking the imaginary part of the function, F represents the ranging function, and l1 and l2 represent the distance between the fault point and the beginning of the ranging line. When a simple phase-to-phase fault or a phase-to-ground fault occurs, l1 and l2 are equal.
[0072] like Figure 2 As shown, when a phase-to-phase fault or a phase-to-ground fault occurs at point 1 or 2 on the line, and the fault point is located within the ranging area of the line, the ranging function F1 is used for fault ranging. The ranging formula is:
[0073] Im(F1(l1))=0
[0074] like Figure 2 As shown, when a two-point ground fault of opposite phase occurs at points 1 and 2 on line, and both fault locations are within the ranging area of the line, the ranging function F2 is used for fault ranging. The ranging formula is:
[0075]
[0076] like Figure 3 As shown, when a two-point ground fault of opposite phase occurs at points 1 and 2 on the line, and one fault is located between the beginning and end of the ranging line, while the other is located downstream of the end of the ranging line, ranging functions F2 and F3 are used for fault ranging. The ranging formula is:
[0077]
[0078] In one possible implementation, the expression for the ranging function F is:
[0079]
[0080] in This indicates the line voltage at the beginning of the ranging line. This indicates the line voltage at the end of the ranging line; This indicates the phase-to-phase current difference at the beginning of the line. Z represents the phase-to-phase current difference at the end of the line; Z1 is the unit positive sequence impedance of the line, Z m Z is the unit mutual impedance of the line. S L is the unit self-impedance of the line. MNLet F1 be the total length of the ranging line. For ranging functions F1 and F2, the subscripts x, y, and z can take three phase sequences: a, b, and c. When an AB phase-to-phase fault occurs, x and y take phase sequences a and b, respectively, and z takes phase sequence c. When a BC phase-to-phase fault occurs, x and y take phase sequences b and c, respectively, and z takes phase sequence a. When an AC phase-to-phase fault occurs, x and y take phase sequences a and c, respectively, and z takes phase sequence b. For ranging function F3, the subscripts x1, y1, and z1 can take three phase sequences: a, b, and c. When the downstream fault phase at the end of the ranging line is phase A, z1 takes phase sequence a, and x1 and y1 take phase sequences b and c, respectively. When the downstream fault phase at the end of the ranging line is phase B, z1 takes phase sequence b, and x1 and y1 take phase sequences a and c, respectively. When the downstream fault phase at the end of the ranging line is phase C, z1 takes phase sequence c, and x1 and y1 take phase sequences a and b, respectively.
[0081] Data is collected by electrical quantity acquisition devices at both ends of the ranging line, and the phasors of electrical quantities at both ends are calculated using the full-cycle Fourier algorithm. The phase-to-phase current difference at both ends and the phase voltage phasor at the end are calculated respectively. According to the fault situation and fault location, the electrical quantities at both ends are substituted into the corresponding fault ranging formula to perform phase-to-phase fault ranging. If it is a simple summation fault, the ranging function F1 is used for phase-to-phase fault ranging; if it is a two-point grounding fault of different phases, and both fault points are located within the ranging line area, the ranging function F2 is used for phase-to-phase fault ranging; if one fault point is located within the ranging line area and the other point is located downstream of the end of the ranging line, the ranging functions F1 and F3 are used to measure the distance between the two fault points respectively.
[0082] To verify the effectiveness and reliability of the protection method proposed in this invention, PSCAD / EMTDC software was used to establish... Figure 4 The simulation model shown is a simple 10kV active distribution network with an ungrounded neutral point. Line L... MN This is a ranging line, with a 2MW distributed photovoltaic (DG) system connected to its end, incorporating negative sequence suppression strategies. The line's unit self-impedance Z... S = (0.144+j0.779)Ω / km, unit mutual impedance Zm = (0.109+j0.271)Ω / km, the distance measuring line length MN is set to 5km, the total line length is 10km, and (f1,f2,f3) represent the fault locations respectively.
[0083] Algorithm verification was performed for different fault locations and fault types. The fault was set in phase BC of the ranging line, with the end data lagging behind the beginning data by 72°. The ranging results under different fault conditions are shown in Table 1 and Table 2.
[0084] Table 1. Results of phase-to-phase fault and phase-to-phase ground fault location.
[0085]
[0086] Table 2. Results of Distance Measurement for Two-Point Ground Faults with Different Phases
[0087]
[0088] Simulation results show that the proposed method for measuring phase-to-phase faults in distribution networks under asynchronous dual-end data conditions can accurately measure simple phase-to-phase faults and two-point grounding faults of different phases, effectively addressing the integration of distributed energy resources.
[0089] This application provides a method for phase-to-phase fault location in distribution networks under conditions of asynchronous data at both ends. It effectively solves the problem of insufficient accuracy of traditional single-end impedance location in distribution networks under the current situation of new energy access. It can accurately realize simple phase-to-phase fault location and two-point grounding fault location of different phases, effectively cope with the access of distributed energy, and is not affected by asynchronous data sampling and transition resistance.
[0090] The above specific embodiments further illustrate the purpose, technical solution and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A method for fault location of phase-to-phase fault in distribution network in case of double-ended data mis-synchronization, characterized in that, Includes the following steps: S1: Electrical quantity acquisition devices are installed at the beginning and end of the ranging line, respectively; S2: The full-cycle Fourier algorithm is used to calculate the electrical phasors at the beginning and end of the line after the fault; S3: Calculate the phase current difference between the beginning and end points based on the phase current phasors at the beginning and end points respectively; S4: Calculate the phase voltage phasor at the end based on the zero-sequence voltage phasor and the line voltage phasor at the end; S5: Based on the fault condition and fault location, substitute the two-terminal electrical quantities into the corresponding fault location formula to perform fault location; The fault location formula in S5 is: For line faults involving phase-to-phase and phase-to-ground faults, with the fault points located between the beginning and end of the line, the distance measurement formula is: A two-point ground fault of opposite phases occurs on the line, with both fault points located between the beginning and end of the line. The distance measurement formula is: A phase-to-phase fault has one location between the beginning and end of the line, and another location downstream of the end of the line. The distance measurement formula is: Where Re represents taking the real part of the function, Im represents taking the imaginary part of the function, F represents the ranging function, and l1 and l2 represent the distance between the fault point and the beginning of the ranging line. When a simple phase-to-phase fault or a phase-to-ground fault occurs, l1 and l2 are equal. The expression for the distance measurement function F is: in This indicates the line voltage at the beginning of the ranging line. This indicates the line voltage at the end of the ranging line; This indicates the phase-to-phase current difference at the beginning of the line. This indicates the phase-to-phase current difference at the end of the line; Z1 is the line unit positive sequence impedance, Z m Z is the unit mutual impedance of the line. S L is the unit self-impedance of the line. MN Let F1 be the total length of the ranging line. For ranging functions F1 and F2, the subscripts x, y, and z take the three phase sequences a, b, and c. When an AB phase-to-phase fault occurs, x and y take the phase sequences a and b respectively, and z takes the phase sequence c. When a BC phase-to-phase fault occurs, x and y take the phase sequences b and c respectively, and z takes the phase sequence a. When an AC phase-to-phase fault occurs, x and y take the phase sequences a and c respectively, and z takes the phase sequence b. For ranging function F3, the subscripts x1, y1, and z1 take the three phase sequences a, b, and c. When the downstream fault phase at the end of the ranging line is phase A, z1 takes the phase sequence a, and x1 and y1 take the phase sequences b and c respectively. When the downstream fault phase at the end of the ranging line is phase B, z1 takes the phase sequence b, and x1 and y1 take the phase sequences a and c respectively. When the downstream fault phase at the end of the ranging line is phase C, z1 takes the phase sequence c, and x1 and y1 take the phase sequences a and b respectively.
2. The method for fault location of distribution network in case of loss of synchro¬ nization of both ends of data according to claim 1, characterized in that, The electrical quantity acquisition devices installed at the beginning and end of S1 include the ability to measure line voltage, phase current, zero-sequence voltage and zero-sequence current, and also have the ability to measure, record waveforms and transmit data.
3. The method for fault location of distribution network in case of double-ended data out-of- synchronization according to claim 1, characterized in that, The electrical phasors calculated using the full-cycle Fourier algorithm in S2 include: line voltage phasors at the beginning and end, phase current phasors, zero-sequence voltage phasors, and zero-sequence current phasors.
4. The method for fault location of distribution network in case of loss of synchro¬ nous data of both ends according to claim 1, characterized in that, The method for calculating the phase-to-phase current difference between the beginning and end points in S3 is as follows: Head-end phase current calculation method: Terminal-to-terminal current calculation method: in These represent the phase currents at the measuring points at the beginning of the ranging line. These represent the phase currents at the measuring points at the ends of the ranging line. These represent the phase-to-phase current difference values at the measuring points at the beginning of the ranging line. These represent the phase-to-phase current difference at the measuring point at the end of the ranging line.
5. The method for fault location of distribution network in case of loss of synchro¬ nous data of both ends according to claim 1, characterized in that, The method for calculating the phase voltage phasor at the end in S4 based on the zero-sequence voltage phasor and line voltage phasor at the end is as follows: End phase voltage calculation method: in These represent the phase voltages at the measuring points at the end of the ranging line. These represent the line voltages calculated using the full-cycle Fourier algorithm at the measurement points at the end of the line. This represents the zero-sequence voltage calculated using the full-cycle Fourier algorithm at the measurement point at the end of the line.
6. The method for determining inter-phase fault location in a distribution network under conditions of asynchronous data at both ends, as described in claim 1, is characterized in that... The fault conditions and locations in S5 include: a phase-to-phase fault occurring between the beginning and end of the ranging line; a phase-to-ground fault occurring between the beginning and end of the ranging line; a two-point ground fault of different phases occurring between the beginning and end of the ranging line; and a two-point ground fault of different phases occurring between the beginning and end of the ranging line, with one fault located between the beginning and end of the ranging line and the other located downstream of the end of the ranging line.
7. The method of claim 6, wherein A two-point grounding fault with different phases is a fault between different phases that occurs when a single-phase grounding fault occurs on a line and the system continues to operate, and a single-phase grounding fault occurs on another phase of the line.