Fault Location Method, System, Terminal and Storage Medium for Photovoltaic T-Connected Distribution Network

Abstract

A fault location method, system, terminal and storage medium for a photovoltaic T-connected distribution network determine the relative position relationship between the fault point and the photovoltaic power source according to the voltage and current information in the positive sequence additional network of the fault. Then, a fault location equation is formed based on the positive sequence voltage and current, and electrical quantities at multiple moments are used as data sources for regression calculation. When the double-ended data is asynchronous, the Levenberg-Marquardt method is used to calculate the fault distance. The present invention does not require a separate measurement device to be added at the grid connection point of the photovoltaic power source. During the process of accurate fault location, only the voltage and current at both ends of the T-connected line need to be measured, and the double-ended data does not need to be strictly synchronized.

Description

Technical Field

[0001] The present invention belongs to the field of operation and maintenance of distribution networks, and particularly relates to a method, a system, a terminal and a storage medium for fault location in a photovoltaic T-connected distribution network. Background Art

[0002] As a bridge connecting users and the power system, the safe and stable operation of the distribution network is closely related to the quality of people's lives. With the proposal of the "dual carbon" goal, distributed power sources dominated by photovoltaics have gradually been connected to the distribution network, forming an active distribution network. An accurate and fast fault location method can provide a basis for staff to patrol the line, so as to repair faults in time and shorten the power outage time.

[0003] There are mainly two methods for fault location: the traveling wave method and the impedance method. The traveling wave method is mostly used in transmission networks with long lines, few branches, precise synchronization, and high sampling frequencies; the impedance method calculates the impedance of the fault loop from the measured voltage and current at the fault moment. In a multi-branched distribution system, it is difficult to accurately distinguish true and false fault points. In traditional methods, a quadratic distance measurement equation is written based on the principle that the reactive power consumed by the fault point transition resistance is zero, and the fault distance is calculated iteratively. Or, in view of the possible blind area of the single-end distance measurement method, the double-end synchronous data measured by the μPMU is used to calculate the fault distance. The double-end distance measurement method has high accuracy and is not affected by the transition resistance and the impedance at the opposite end in principle. Or a distributed parameter is used to establish a distance measurement model, and the fault of the T-connected transmission line is located by measuring the voltages and currents at three ends.

[0004] Chinese Patent CN114675135A, "Distribution Network T-Type Line Fault Location Method and System Based on Model Optimization Solution", discloses a T-type line fault location method and system. The ill-conditioned situation of the distance measurement equation is analyzed through the condition number, and the objective function and constraint conditions based on the fault components are respectively constructed according to the parameter range and the relationship between voltage and current, and an optimization model is established and solved to obtain the fault location and line parameters. However, the fault location method described in this patent requires the use of a micro synchronous phasor measurement unit μPMU and requires strict synchronization. The distance measurement method described in this patent can achieve fault location without the need for a micro synchronous phasor measurement unit.

[0005] Although great progress has been made in the existing methods for fault section location and fault location in distribution networks, further research is still needed for the case where DGs are connected to the distribution network in a T-connected manner. The existing fault location methods mainly calculate the fault distance through three-terminal synchronous electrical quantities, and most of the fault location methods are for the case of T-connection in transmission networks. However, it is uneconomical to build a three-terminal optical fiber channel for the distribution network, and some areas do not have the conditions to build an optical fiber channel. Summary of the Invention

[0006] To address the deficiencies in the existing technology, the present invention provides a fault location method, system, terminal, and storage medium for a photovoltaic T-connected distribution network. The relative position relationship between the fault point and the photovoltaic power source (PV) is determined based on the voltage and current information in the positive-sequence additional network of the fault. Subsequently, a fault location equation is formed using the positive-sequence voltage and current, and the electrical quantities at multiple moments are used as data sources for regression calculation. When the double-ended data is asynchronous, the Levenberg-Marquardt method is employed to calculate the fault distance. The present invention is not affected by the fault location, transition resistance, or intermittency of the photovoltaic power source, and has low requirements for synchronization.

[0007] The present invention adopts the following technical solutions.

[0008] A fault location method for a photovoltaic T-connected distribution network includes the following steps:

[0009] Step 1, collect the positive-sequence voltage fault component and positive-sequence current fault component at both ends of the line to determine the relative position between the fault point and the photovoltaic power source;

[0010] Step 2, establish a fault location equation set based on the electrical quantity relationship at both ends of the fault branch;

[0011] Step 3, introduce a synchronous transmission error angle to establish a nonlinear objective equation;

[0012] Step 4, perform multivariate nonlinear regression iterative analysis using the Levenberg-Marquardt algorithm.

[0013] Preferably, Step 1 includes the following steps:

[0014] Step 1.1, collect the positive-sequence voltage fault component and positive-sequence current fault component at the power supply side of the line and positive-sequence current fault component

[0015] collect the positive-sequence voltage fault component MN+ and positive-sequence impedance Z of the line from the load side to the T connection point of the photovoltaic power source NO+ ;

[0016] Step 1.3, under non-fault conditions, construct the positive-sequence component balance equations for the line from the power supply side to the T connection point of the photovoltaic power source and the line from the load side to the T connection point of the photovoltaic power source;

[0017] Step 1.4, use the relationship between the positive-sequence components of the line from the power supply side to the T connection point of the photovoltaic power source and the positive-sequence components of the line from the load side to the T connection point of the photovoltaic power source to determine the relative position between the fault point and the photovoltaic power source.

[0018] In Step 1.3, in the non-fault state, the lines from the power supply side to the T connection point of the photovoltaic power supply and the lines from the load side to the T connection point of the photovoltaic power supply satisfy the following relationship:

[0019]

[0020] In the formula, is the positive-sequence voltage fault component on the power supply side of the line; is the positive-sequence current fault component on the power supply side; Z MN+ is the positive-sequence impedance of the line from the power supply side to the T connection point N of the photovoltaic power supply; Z NO+ is the impedance of the line from the load side to the T connection point N of the photovoltaic power supply; is the positive-sequence voltage fault component on the load side of the line; is the positive-sequence current fault component on the load side.

[0021] In Step 1.4, if the positive-sequence components of the line from the power supply side to the T connection point of the photovoltaic power supply and the positive-sequence components of the line from the load side to the T connection point of the photovoltaic power supply satisfy the following relational formula:

[0022]

[0023] Then it is determined that the fault point is on the line from the power supply side to the T connection point of the photovoltaic power supply.

[0024] In Step 1.4, if the positive-sequence components of the line from the power supply side to the T connection point of the photovoltaic power supply and the positive-sequence components of the line from the load side to the T connection point of the photovoltaic power supply satisfy the following relational formula:

[0025]

[0026] Then it is determined that the fault point is on the line from the load side to the T connection point of the photovoltaic power supply.

[0027] Preferably, in Step 2, the current on the left side of the photovoltaic power supply can be estimated by the current on the O side and the output current at the photovoltaic power supply end:

[0028]

[0029] Among them, is the estimated value of the positive-sequence current injected by the photovoltaic power supply and the X side into the fault point; is the positive-sequence current on the O side of the line; is the estimated value of the d-axis current injected by the photovoltaic power supply; is the estimated value of the q-axis current injected by the photovoltaic power supply, and The values of both can be estimated through the voltage and the low-voltage ride-through control strategy; θN is the phase angle of the voltage ; is the reference power factor angle.

[0030] The reference power factor angle has the following calculation formula:

[0031]

[0032] Preferably, step 3 includes:

[0033] Step 3.1, collect the positive-sequence voltage and positive-sequence current at the power supply side of the line, the positive-sequence voltage and positive-sequence current

[0034] at the load side, jδ and introduce the phase shift e

[0035] caused by the synchronization error angle to construct a ranging equation.

[0036]

[0037] In the formula, is the positive-sequence voltage at side M, is the positive-sequence current at side M, Z MN+ is the positive-sequence impedance of line MN, α is the ratio of the distance from the left end of the fault location to the full length of the line, is the positive-sequence voltage at side N, δ is the transmission error angle, is the positive-sequence current at side N, is the output current of the photovoltaic power source estimated according to the voltage at the photovoltaic access point and the low-voltage ride-through control strategy.

[0038] Take the real part and imaginary part of the ranging equation respectively, and simplify to obtain the following non-linear expressions:

[0039] y = Acosδ + Bsinδ + Cαcosδ + Dαsinδ + Eα

[0040] When taking the real part, there is:

[0041]

[0042] When taking the imaginary part, there is:

[0043]

[0044] A photovoltaic T-connected distribution network fault ranging system includes a model construction module and a non-linear analysis module.

[0045] The model construction module determines the relative position between the fault point and the photovoltaic power source, establishes a fault location equation set, and based on double-ended sampling, introduces a synchronous transmission error angle to establish a non-linear objective equation;

[0046] The non-linear analysis module performs multiple linear regression iterative analysis based on the Levenberg-Marquardt algorithm, and obtains the fault distance according to the results output by the model construction module.

[0047] The beneficial effects of the present invention are as follows. Compared with the prior art,

[0048] 1. The present invention does not require a separate measurement device to be added at the PV connection point. During the process of accurate fault location, only the voltage and current at both ends of the T-connected line need to be measured, and the double-ended data does not need to be strictly synchronized.

[0049] 2. The simulation test of the present invention proves that the method has good ranging accuracy. Description of the Drawings

[0050] Figure 1 It is a flow chart of a fault location method for a photovoltaic T-connected distribution network according to the present invention;

[0051] Figure 2 It is an equivalent schematic diagram of an active distribution network in a T-connected form. Detailed Embodiments

[0052] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only a part of the embodiments of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0053] A fault location method for a photovoltaic T-connected distribution network is based on the structure as Figure 2 shown. The photovoltaic power source PV is connected to the active distribution network in a T-connected manner. S on the left represents the system power source upstream of the fault point f, and X on the right represents the system power source downstream of the fault point f. Assume that a three-phase short circuit fault occurs inside the line MN, and α is the fault location parameter, representing the ratio of the distance from the fault point f to the bus M to the total length of the line MN.

[0054] As Figure 1 shown, the method specifically includes the following steps:

[0055] Step 1, collect the positive sequence voltage fault component and the positive sequence current fault component at both ends of the line, and determine the relative position between the fault point and the photovoltaic power source.

[0056] If a fault occurs at the grid connection point, the positive-sequence voltage fault component and positive-sequence current fault component at both ends satisfy the following relationship:

[0057]

[0058] In the formula, is the positive-sequence voltage fault component on the M side of the line; is the positive-sequence current fault component on the M side; Z MN+ is the positive-sequence impedance of the line from the M side to the PV connection point N; Z NO+ is the impedance of the line from the N side to the PV connection point N; is the positive-sequence voltage fault component on the O side of the line; is the positive-sequence current fault component on the O side. Adding a "+" at the lower right corner of voltage, current, and impedance indicates the power-frequency positive-sequence electrical quantity.

[0059] When a fault occurs in the MN branch:

[0060]

[0061] When a fault occurs in the NO branch:

[0062]

[0063] Step 2: Establish a fault location ranging equation set according to the electrical quantity relationship at both ends of the fault branch.

[0064] Assume that a fault occurs in the MN branch. The positive-sequence voltage at the grid connection point is expressed according to Kirchhoff's voltage law as:

[0065]

[0066] In the formula, is the positive-sequence voltage at N; is the positive-sequence voltage at O; is the positive-sequence current at O; Z NO+ is the positive-sequence impedance between the lines NO.

[0067] The current on the left side of the PV can be estimated by the current on the O side and the output current of the PV terminal:

[0068]

[0069] In the formula: is the estimated value of the positive-sequence current injected by the PV and X side into the fault point; is the positive-sequence current on the O side of the line; is the estimated value of the d-axis current injected by the PV; is the estimated value of the q-axis current injected by the PV, and The values can all be estimated through the voltage and the low voltage ride-through control strategy; θN is the voltage phase angle; is the reference power factor angle, and its calculation formula is:

[0070]

[0071] When the distribution line can achieve double-end synchronous sampling, the following relationships exist for the electrical quantities at both ends:

[0072]

[0073] Step 3: Introduce the synchronous transmission error angle and establish a non-linear objective equation.

[0074] In actual engineering, it is difficult for the distribution network to achieve precise synchronization. Let the synchronization error angle be δ, and the ranging equation can be expressed as:

[0075]

[0076] In the formula, is the positive sequence voltage on the M side, is the positive sequence current on the M side, Z MN+ is the positive sequence impedance of the line MN, α is the ratio of the distance from the fault location to the left end of the line to the total length of the line, is the positive sequence voltage on the N side, δ is the transmission error angle, is the positive sequence current on the N side, is the output current of the photovoltaic power source estimated based on the voltage at the photovoltaic access point and the low voltage ride-through control strategy.

[0077] Taking the real part and the imaginary part of the above formula respectively and simplifying, the following non-linear expressions are obtained:

[0078] y = Acosδ + Bsinδ + Cαcosδ + Dαsinδ + Eα

[0079] When taking the real part, there is:

[0080]

[0081] When taking the imaginary part, there is:

[0082]

[0083] In the formula, is the positive sequence voltage on the M side, is the positive sequence current on the M side, Z MN+ is the positive sequence impedance of the line MN, α is the ratio of the distance from the fault location to the left end of the line to the total length of the line, is the positive-sequence voltage on the N side, δ is the transmission error angle, is the positive-sequence current on the N side, is the output current of the PV power source estimated according to the voltage at the PV connection point and the low-voltage ride-through control strategy.

[0084] After taking the real part and the imaginary part, they are used as the data sources for nonlinear regression at the same time, and the nonlinear regression algorithm is used for iteration to obtain the fault distance α.

[0085] Step 4, perform multivariate nonlinear regression iterative analysis using the Levenberg-Marquardt algorithm.

[0086] The Levenberg-Marquardt (LM) algorithm, as the most widely used nonlinear least squares method, has the advantages of both the gradient descent method and the Gauss-Newton method, and has a fast convergence speed. The general expression of multivariate nonlinear regression is:

[0087] y i = f i (x i1 , x i2 , …, x im , a1, a2, … a n )

[0088] In the formula, f is a nonlinear function; x i1 , x i2 , …, x im represents the m independent variables of the i-th data, represented by the vector x; a1, a2, … a n represents the n parameters to be solved, represented by the vector a. Let the total number of data sources be G, and the loss function is expressed as the sum of the squares of the residuals (the difference between the estimated value and the actual value) of each data:

[0089]

[0090] In the formula, represents the dependent variable of the i-th data in the data source.

[0091] Taking a j as an example, the loss function is differentiated with respect to the parameter to be solved:

[0092]

[0093] The above formula is represented using the Jacobian matrix:

[0094] 2EJ = 0

[0095] In the formula, E is the error row vector, representing the difference between the estimated value and the actual value, with 1 row and G columns. J is the Jacobian matrix, with G rows and n columns, that is:

[0096]

[0097] If the gradient descent method is used to iteratively find the minimum value of the loss function, the descent speed is very fast when far from the minimum value, but slow near the minimum value. The Gauss-Newton method has good convergence near the minimum value, but has a high dependence on the initial value. The LM algorithm has the advantages of both the gradient descent method and the Gauss-Newton method by adding a damping factor μ. Let the initial value of the parameter to be solved be a k , and the iterative formula is:

[0098]

[0099] where k is the number of iterations, I is the identity matrix, and g k is the negative gradient direction. A relatively large μ is selected in the initial stage of iteration, which is equivalent to the gradient descent method; μ is relatively small in the later stage of iteration, which is equivalent to the Gauss-Newton method.

[0100]

[0101]

[0102] The present invention can utilize the measurement information at multiple moments to solve the fault location parameter α, so it has high fault location accuracy. A 10 kV active distribution network simulation model is established using Matlab / Simulink to calculate the fault location parameter α. The results of multiple simulations show that the fault location error can be controlled within an error range of 1%.

[0103] A photovoltaic T-connected distribution network fault location system includes a model construction module and a non-linear analysis module.

[0104] The model construction module determines the relative position between the fault point and the photovoltaic power source, establishes a fault location equation set, and based on double-ended sampling, introduces a synchronous transmission error angle to establish a non-linear objective equation;

[0105] The non-linear analysis module performs multiple linear regression iterative analysis based on the Levenberg-Marquardt algorithm, and solves the fault distance according to the results output by the model construction module.

[0106] The present disclosure may be a system, method, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions thereon for causing a processor to implement various aspects of the present disclosure.

[0107] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium may be, for example—but not limited to—an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a memory stick, a floppy disk, a mechanically encoded device, such as a punched card or raised structures in grooves storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage medium used herein is not construed as an instantaneous signal itself, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagated through a waveguide or other transmission medium (e.g., an optical pulse through an optical fiber cable), or an electrical signal transmitted through a wire.

[0108] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to various computing / processing devices, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network may include a copper transmission cable, an optical fiber transmission, a wireless transmission, a router, a firewall, a switch, a gateway computer, and / or an edge server. The network adapter or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0109] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine - related instructions, microcode, firmware instructions, state - setting data, or source code or object code written in any combination of one or more programming languages, including object - oriented programming languages such as Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" language or similar programming languages. The computer - readable program instructions may be executed entirely on the user's computer, partially on the user's computer, executed as a stand - alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., through the Internet using an Internet service provider). In some embodiments, by using the state information of the computer - readable program instructions to customize an electronic circuit, such as a programmable logic circuit, a field - programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit can execute the computer - readable program instructions to implement various aspects of the present disclosure.

[0110] 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 them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A fault location method for a photovoltaic T-connected distribution network, characterized in that, It includes the following steps: Step 1: Collect the positive-sequence voltage fault component and positive-sequence current fault component at both ends of the line, and determine the relative position between the fault point and the photovoltaic power source; Step 2: Establish a fault location equation set according to the electrical quantity relationship at both ends of the fault branch; Step 3, collect the positive-sequence voltage on the line power supply side and the positive-sequence current , the positive-sequence voltage on the load side and the positive-sequence current , the estimated value of the photovoltaic power supply current ; introduce the phase shift caused by the synchronous transmission error angle , and construct the ranging equation as follows: Wherein, is the positive sequence impedance of the line, is the ratio of the distance from the left end of the line at the fault location to the total length of the line, is the synchronous transmission error angle; Take the real part and imaginary part of the ranging equation respectively, and simplify to obtain the following non-linear objective equation: When taking the real part, there is: When taking the imaginary part, there is: Step 4, after obtaining the real part and the imaginary part, simultaneously use them as the data source for non-linear regression, and perform multivariate non-linear regression iterative analysis using the Levenberg-Marquardt algorithm, and then obtain .

2. A photovoltaic T-connected distribution network fault location method according to claim 1, characterized in that: Step 1 includes: Step 1.1, collect the positive-sequence voltage fault component on the power supply side of the line and the positive-sequence current fault component ; collect the positive-sequence voltage fault component on the load side of the line and the positive-sequence current fault component ; Step 1.2, based on the method of grounding and pressurizing, obtain the positive sequence impedance of the line from the power supply side to the T-joint of the photovoltaic power supply and the positive sequence impedance of the line from the load side to the T-joint of the photovoltaic power supply ; Step 1.3: In the non-fault state, construct the positive-sequence component balance equations for the line from the power source side to the T connection point of the photovoltaic power source and the line from the load side to the T connection point of the photovoltaic power source; Step 1.4: Use the relationship between the positive-sequence components of the line from the power source side to the T connection point of the photovoltaic power source and the positive-sequence components of the line from the load side to the T connection point of the photovoltaic power source to determine the relative position between the fault point and the photovoltaic power source.

3. A photovoltaic T-connected distribution network fault location method according to claim 2, characterized in that: In step 1.3, in the non-fault state, the line from the power source side to the T connection point of the photovoltaic power source and the line from the load side to the T connection point of the photovoltaic power source satisfy the following relationship: Wherein, is the positive-sequence voltage fault component on the line power supply side; is the positive-sequence current fault component on the power supply side; is the positive-sequence impedance of the line from the power supply side to the T connection point N of the photovoltaic power source; is the impedance of the line from the load side to the T connection point N of the photovoltaic power source; is the positive-sequence voltage fault component on the line load side; is the positive-sequence current fault component on the load side.

4. A photovoltaic T-connected distribution network fault location method according to claim 2, characterized in that: In step 1.4, if the positive-sequence components of the line from the power source side to the T connection point of the photovoltaic power source and the positive-sequence components of the line from the load side to the T connection point of the photovoltaic power source satisfy the following relational expression: Then determine that the fault point is on the line from the power source side to the T connection point of the photovoltaic power source.

5. A photovoltaic T-connected distribution network fault location method according to claim 2, characterized in that: In step 1.4, if the positive-sequence components of the line from the power source side to the T connection point of the photovoltaic power source and the positive-sequence components of the line from the load side to the T connection point of the photovoltaic power source satisfy the following relational expression: Then determine that the fault point is on the line from the load side to the T connection point of the photovoltaic power source.

6. A photovoltaic T-connected distribution network fault location method according to claim 1, characterized in that: In step 2, the electrical quantities at both ends have the following relationship: is the positive-sequence voltage on the M side, is the positive-sequence current on the M side, is the positive-sequence impedance of line MN, is the ratio of the distance from the left end of the line at the fault location to the total length of the line, is the positive-sequence voltage on the N side; The current on the left side of the photovoltaic power source can be estimated by the current on the O side and the output current at the photovoltaic power source end; Among them, is the estimated value of the positive-sequence current injected by the photovoltaic power source and the X-side fault point; is the positive-sequence current on the O side of the line; is the estimated value of the d-axis current injected by the photovoltaic power source; is the estimated value of the q-axis current injected by the photovoltaic power source, and The values of both can be estimated through the voltage and the low-voltage ride-through control strategy; is the phase angle of the voltage ; is the reference power factor angle.

7. A photovoltaic T-connected distribution network fault location method according to claim 6, characterized in that: The reference power factor angle The calculation formula is as follows: 。 8. A photovoltaic T-connected distribution network fault location system, characterized in that, It includes a model construction module and a non-linear analysis module: The model construction module collects the positive-sequence voltage fault component and positive-sequence current fault component at both ends of the line to determine the relative position between the fault point and the photovoltaic power source; according to the electrical quantity relationship at both ends of the fault branch, a fault location equation set is established; the positive-sequence voltage at the power source side of the line is collected and the positive-sequence current , the positive-sequence voltage at the load side and the positive-sequence current , the estimated value of the photovoltaic power source current ; introducing the phase shift caused by the synchronous transmission error angle , the constructed ranging equation is: Wherein, is the positive sequence impedance of the line, is the ratio of the distance from the left end of the line at the fault location to the total length of the line, is the synchronous transmission error angle; Take the real part and imaginary part of the ranging equation respectively, and simplify to obtain the following non-linear objective equation: When taking the real part, there is: When taking the imaginary part, there is: The non-linear analysis module is used to, after taking the real part and the imaginary part, simultaneously serve as the data source for non-linear regression, and perform multivariate non-linear regression iterative analysis using the Levenberg-Marquardt algorithm, so as to obtain .

9. A terminal includes a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is used to operate according to the instructions to execute the steps of the method according to any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it realizes the steps of the method according to any one of claims 1-7.

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