Traveling wave location method and device for multi-branch faults in distribution network based on time difference matrix data fitting

Abstract

The present invention discloses a method and device for locating traveling waves of multi-branch faults in a distribution network based on time difference matrix data fitting. The method comprises: a distribution network has multiple trunk lines with multiple branches, each trunk line is decomposed into multiple lines with only single branches; for each trunk line, simulated fault points are set at the beginning and end of the line respectively, and the difference between the initial traveling wave arrival time at the beginning and end of the line and at the end of each branch relative to the beginning and end is calculated, thereby constructing an endpoint reference time difference matrix S corresponding to the trunk line. k When a real fault occurs in the distribution network, the fault traveling wave time difference matrix G is constructed in the same way k ; For each trunk line S k and G k A first-order relationship fitting is performed. If the relationship matches, the main line is determined to be normal; otherwise, it is faulty. For a faulty main line, the faulty branch is determined based on the distance between the data pair and the linear function line. Finally, the fault point of the faulty branch is located. This invention effectively improves the accuracy of multi-branch fault location.

Description

Technical Field

[0001] The present invention belongs to the technical field of power protection, and in particular relates to a method for locating multi-branch fault traveling waves in a distribution network based on time difference matrix data fitting. Background Art

[0002] With the continuous improvement of my country's urbanization level and the expansion of urban scale, modern society's demand for electricity is also growing. As more and more loads are connected to the power grid, multi-branch distribution lines achieve the goal of supplying power from multiple sources and receiving power from multiple loads. However, the complex structure of distribution networks makes fault location difficult. In particular, when a branch of a multi-branch distribution line fails, traditional multi-branch fault location algorithms cannot meet the requirements of high-precision fault location in multi-branch distribution power grid systems. Therefore, to improve power supply reliability and ensure efficient power supply services, it is crucial to be able to promptly and accurately locate the fault point when a multi-branch distribution line fails.

[0003] Fault traveling wave location is divided into single-ended traveling wave location and double-ended traveling wave location. Single-ended traveling wave location locates the fault based on the time required for the traveling wave to transmit back and forth multiplied by the wave velocity of the traveling wave. However, due to the folding and reflection of the traveling wave generated at the point of wave impedance discontinuity, it will interfere with the determination of the reflected traveling wave head. Since the distribution network contains a large number of branches and overhead-cable hybrid lines, the reliability of the single-ended traveling wave location method is greatly reduced and is not suitable for engineering applications. Double-ended traveling wave location uses the time difference between the absolute moments when the initial traveling wave generated by the fault point reaches both ends of the line to achieve fault location. However, the traveling wave detection device is generally installed at the end of the line, not at the branch. Therefore, the double-ended location method is difficult to directly apply to multi-branch distribution network systems. Summary of the Invention

[0004] The present invention provides a method and device for locating multi-branch fault traveling waves in a distribution network based on time difference matrix data fitting, which locates multi-branch fault lines in the distribution network by fitting the time difference matrix, thereby effectively improving the multi-branch fault locating accuracy.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] A traveling wave location method for multi-branch faults in a distribution network based on time difference matrix data fitting, comprising:

[0007] Step 1: The distribution network has multiple trunk lines with multiple branches, which are decomposed into m lines with only single branches;

[0008] Step 2: For each trunk line with only a single branch: (1) Set a simulated fault point at the head end of the line, use a traveling wave acquisition device to calibrate the initial traveling wave arrival time at the head end and the end end of the line and the end end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the end end, and record it as the reference time difference relative to the end end of the line; (2) Set a simulated fault point at the end end of the line, use a traveling wave acquisition device to calibrate the initial traveling wave arrival time at the head end and the end end of the line and the end end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the head end, and record it as the reference time difference relative to the head end of the line; (3) For each trunk line k, construct the endpoint reference time difference matrix S corresponding to the trunk line based on all the corresponding reference time differences relative to the head end and the end end of the line. k ;

[0009] Step 3: When a real fault occurs in the distribution network, for each trunk line with only a single branch: use the traveling wave acquisition device to calibrate the initial traveling wave arrival time at the beginning and end of the line and at the end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the beginning, and calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the end, and construct the fault traveling wave time difference matrix G for each trunk line based on all the corresponding differences. k ;

[0010] Step 4: For each trunk line k, calculate the endpoint reference time difference matrix S k and the fault traveling wave time difference matrix G k Perform a function relationship fitting, if the matrix S k With G k If the linear function relationship is matched, the trunk line k is judged to be normal, otherwise the trunk line k is judged to be faulty;

[0011] Step 5: For the main line with fault, based on the head end, the end end and the end end of each branch in the matrix S k and G k The distance between the data pair and the linear function line determines the fault branch;

[0012] Step 6: Use the time quantity to locate the fault point of the fault branch.

[0013] Furthermore, the endpoint reference time difference matrix S k and the fault traveling wave time difference matrix G k The construction method is:

[0014] When a simulated fault point is set at the head end of any line j with only a single branch, the initial traveling wave arrival times of each node in line j are: t′ at the head end of line j j，1 , the end of each branch of line j is t′ j，2 , t′ j，3,…,t′ j，n-1 , the end t′ of line j j，n When a simulated fault point is set at the end of line j with only a single branch, the initial traveling wave arrival times of each node in line j are: t″ at the beginning of line j j，1 , the end of each branch of line j is t″ j，2 , t″ j，3 ,…,t″ j，n-1 , the end t″ of line j j，n ; Then the endpoint reference time difference matrix S of the trunk line k k for:

[0015]

[0016] When a real fault occurs in the distribution network, the initial traveling wave arrival times of each node in any line j with only a single branch are: t″′ at the head end of line j j，1 , the end of each branch of line j is t″′ j，2 , t″′ j，3 ,…,t″′ j，n-1 , the end t″′ of line j j，n ; Then the fault traveling wave time difference matrix G of trunk line k is k for:

[0017]

[0018] Furthermore, the least square method is used to fit the linear function relationship y=a+bx, and the matrix S k With G k The conditions for matching a linear function relationship are:

[0019]

[0020] Where b is the slope deviation, a is the displacement deviation; (x i ,y i ) is the matrix S k With G k The data pair consisting of the i-th element in ; is the matrix S k The arithmetic mean of all elements in , y is the matrix G k The arithmetic mean of all elements in .

[0021] Furthermore, in step 5, the endpoint corresponding to the data pair that is farthest from the linear function line is determined to be the fault branch.

[0022] Furthermore, in step 6, let the endpoint corresponding to the fault branch be D3, select the other two endpoints D4 and D5 closest to the fault branch of the faulty main line, and the time when the initial fault traveling wave reaches the endpoints D3, D4 and D5 respectively The fault point in the fault branch can be located using the double-ended traveling wave location principle according to the following formula:

[0023]

[0024]

[0025]

[0026] Where, e, f, and g are the branch nodes from endpoints D3, D4, and D5 to the main line, respectively; x′ is the distance from the fault point to the branch node e calculated using endpoints D3 and D4; V is the traveling wave velocity; The shortest distance from branch node e to branch node f to endpoint D4; is the distance from branch node e to endpoint D3; is the shortest distance from branch node e to branch node g to endpoint D5; x″ is the distance from the fault point to branch node e calculated using endpoints D3 and D5; x is the average distance from the fault point to branch node e.

[0027] A traveling wave location device for multi-branch faults in a distribution network based on time difference matrix data fitting, comprising:

[0028] The line decomposition module is used to: decompose multiple trunk lines with multiple branches in the distribution network into m lines with only single branches;

[0029] The endpoint reference time difference matrix construction module is used for: for each trunk line with only a single branch: (1) setting a simulated fault point at the head end of the line, using a traveling wave acquisition device to calibrate the initial traveling wave arrival time at the head end and the end end of the line and the end end of each branch, calculating the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival at the end, and recording it as the reference time difference relative to the end end of the line; (2) setting a simulated fault point at the end end of the line, using a traveling wave acquisition device to calibrate the initial traveling wave arrival time at the head end and the end end of the line and the end end of each branch, calculating the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival at the head end, and recording it as the reference time difference relative to the head end of the line; (3) for each trunk line k, constructing the endpoint reference time difference matrix S corresponding to the trunk line based on all the corresponding reference time differences relative to the head end and the end end of the line. k ;

[0030] The fault traveling wave time difference matrix construction module is used to: when a real fault occurs in the distribution network, for each trunk line with only a single branch: use the traveling wave acquisition device to calibrate the initial traveling wave arrival time at the beginning and end of the line and the end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival at the beginning, and calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival at the end, and construct the fault traveling wave time difference matrix G for each trunk line based on all the corresponding differences k ;

[0031] The main line fault judgment module is used to: for each main line k, calculate the reference time difference matrix S of its endpoints k and the fault traveling wave time difference matrix G k Perform a function relationship fitting, if the matrix S k With G k If the linear function relationship is matched, the trunk line k is judged to be normal, otherwise the trunk line k is judged to be faulty;

[0032] The branch line fault judgment module is used to: for the main line with a fault, based on the head end and the end end and each branch end in the matrix S k and G k The distance between the data pair and the linear function line determines the fault branch;

[0033] The fault point location module is used to locate the fault point of the fault branch using time quantity.

[0034] Beneficial effects

[0035] This method utilizes a fault location method that combines traveling wave ranging with time difference matrix data fitting to transform the complex multi-branch line fault location problem into a dual-end fault location problem, decomposing the multi-branch line into a single-branch line. Based on the different transmission characteristics of the initial traveling wave head on the fault line and the non-fault line, a baseline time difference matrix for the decomposed trunk line endpoints and a fault time difference matrix are constructed. The time difference variation between the fault line and the non-fault line before and after the fault is thoroughly analyzed. Based on the variation of the elements in the matrices before and after the fault, the least squares method is introduced to fit the data of the two matrices. The optimal linear function match between the two matrices is found, and the fault branch section is determined. This method is suitable for accurately locating fault points on multi-branch power distribution lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flowchart of the positioning method described in an embodiment of the present application;

[0037] Figure 2 This is a network structure topology diagram of a 10kV distribution network described in an embodiment of the present application;

[0038] Figure 3 It will Figure 2 The main line 1 in the figure is decomposed into two lines 1-1 and 1-2 as shown in (a) and (b) respectively;

[0039] Figure 4 It will Figure 2 The main line 2 in FIG. 2 is decomposed into two lines 2-1 and 2-2 as shown in (a) and (b) respectively. DETAILED DESCRIPTION

[0040] The following is a detailed description of an embodiment of the present invention. This embodiment is based on the technical solution of the present invention, provides a detailed implementation method and a specific operation process, and further explains the technical solution of the present invention.

[0041] This embodiment provides a method for locating multi-branch fault traveling waves in a distribution network based on time difference matrix data fitting. Figure 1 As shown, the following steps are included:

[0042] Step 1: Decompose the multi-branch distribution grid lines.

[0043] In a 10kV distribution network, when a fault occurs in a branch of a multi-branch distribution line, the fault traveling wave propagates along the entire distribution network and is refracted and reflected at each branch node and line end. Therefore, the transient traveling wave from the non-faulty branch and the initial traveling wave at the fault point are refracted and reflected at each branch node. The fault traveling wave extracted by the fault traveling wave device is a mixed waveform after multiple refractions and reflections. The fault traveling wave detection device has difficulty identifying the initial wave head of the fault traveling wave, and its calibrated initial traveling wave arrival time is inaccurate, resulting in inaccurate initial fault point location. Therefore, the multi-branch line is decomposed and simplified into a topology with only a single branch line. This transforms the complex multi-branch line fault location problem into a two-terminal network fault location problem. First, the fault section is located, and then the two-terminal traveling wave location principle is used to accurately locate the fault point.

[0044] like Figure 2 The multi-branch distribution network shown in the figure is decomposed into n trunk lines, where trunk line 1 and trunk line 2 are decomposed into Figure 3 and Figure 4 The circuit shown has only a single branch (ie, each decomposed branch has a T-shaped branch structure).

[0045] Step 2: Construct endpoint reference time difference matrix for each trunk line.

[0046] The transmission characteristics of fault traveling waves on fault lines and non-fault lines are different: Figure 3As shown in Figure 1, when a fault occurs at point f1, the source of the traveling wave on the fault line is the fault point. The initial traveling wave propagates from the fault point to the entire distribution network at the speed of light. Different fault point locations and transmission paths result in regular variations in the traveling wave time differences in the matrix. The initial traveling wave on the non-fault line originates from the fault line, and the source of the fault traveling wave can be considered the busbar. Therefore, the transmission path of the initial traveling wave on the non-fault line is unaffected by the location of the fault point, meaning that the initial traveling wave time differences on the non-fault line remain the same as before the fault. Therefore, ignoring detection errors, the elements in the baseline time difference matrix S and the fault time difference matrix G for the non-fault line endpoints are exactly equal. However, since the simulated fault point on the fault line differs from the actual fault point, the elements of the two matrices differ. When a real fault occurs on the busbar, the busbar can be considered the source of the traveling wave for both the fault line and the non-fault line. Therefore, every element in the matrices S and G for all lines is equal. Based on the arrival time of the initial traveling wave head, the variation pattern of the elements in matrices S and G is as follows:

[0047]

[0048] Where k, i = 1, 2, 3…n.

[0049] If the elements in matrices S and G of all lines are the same, it is determined to be a busbar fault.

[0050] Based on the above time difference matrix positioning principle, this step 2 first constructs a reference matrix for comparison of each trunk line, namely the endpoint reference time difference matrix:

[0051] For any line j with only one branch on each trunk line: (1) Set a simulated fault point at the head end of the line and use the traveling wave acquisition device to calibrate the initial traveling wave arrival time t′ at the head end of the line. j，1 , the initial traveling wave arrival time t′ at the end j，n , and the initial traveling wave arrival time t′ at the end of each branch j，2 , t′ j，3 ,…,t′ j，n-1 ; Then calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the end, and record it as the reference time difference relative to the end of the line; (2) Set a simulated fault point at the end of the line, and use the traveling wave acquisition device to calibrate the initial traveling wave arrival time t" at the head end of the line j，1 , the initial traveling wave arrival time at the end is t″ j，n , and the initial traveling wave arrival time t″ at the end of each branch j，2 , t″ j，3 ,…,t″ j，n-1; Then calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the head end, and record it as the reference time difference relative to the head end of the line; (3) For each trunk line k, construct the endpoint reference time difference matrix S corresponding to the trunk line based on all the corresponding reference time differences relative to the head end and the end end of the line k for:

[0052]

[0053] Step 3: Construct the fault traveling wave time difference matrix.

[0054] When a real fault occurs in the distribution network, for each trunk line with only a single branch: use the traveling wave acquisition device to calibrate the initial traveling wave arrival time t″′ at the head end of the line j，1 , the initial traveling wave arrival time t″′ at the end j，n , and the initial traveling wave arrival time t″′ at the end of each branch j，2 , t″′ j，3 ,…,t″′ j，n-1 Calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the head end, and calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the end end. For each trunk line, construct the fault traveling wave time difference matrix G according to all the corresponding differences. k :

[0055]

[0056] Step 4: Select the main line fault line.

[0057] From the above principles, it can be seen that under ideal conditions, the matrix S and matrix G of the non-fault line are the same. However, in actual operation, various measurement errors may occur. For example, the traveling wave acquisition device may be affected by interference, lightning strikes, high-frequency signals, and other factors, resulting in errors in identifying the initial traveling wave head of the fault, resulting in varying degrees of error in the calibration of the arrival time of the initial traveling wave head. Therefore, the least squares method is introduced for a single fitting to reduce the impact of the error.

[0058] This embodiment performs segment positioning based on least squares data fitting. The principle of least squares data fitting is: based on a set of two-dimensional data, that is, a number of points on a plane, it is required to determine a univariate function y=f(x), that is, a curve, so that these points are as close as possible to the overall curve. This is data fitting, referred to as curve fitting, and the purpose is to establish an effective formula between the dependent variable y and the independent variable x. The least squares method (also known as the least squares method) is a mathematical optimization technique. The linear least squares method can reflect whether the data is a linear relationship. It finds the best function match for the data by minimizing the sum of squares of the errors. The least squares method can be used to easily obtain unknown data and minimize the sum of squares of the errors between the obtained data and the actual data.

[0059] The linear least squares method uses the linear relationship between x and the corresponding Y, expressed as y = a + bx. The undetermined constants a and b in the equation become the linear regression coefficients, and a and b also reflect the intercept and slope of the line. Fitting involves determining the regression coefficients a and b based on the measured data, hoping to determine a and b that will keep the data points as close to the line as possible and minimize the deviation. Since deviations can vary in size, both positive and negative, the formula for the deviation is as follows:

[0060]

[0061] When s in the above formula is minimum, the corresponding a and b are the coefficients of the fitted curve.

[0062] The first-order fitting relationship found by the least squares method must satisfy the matrix S k and G k With straight line S k and G k =a+bS k If the following expression is satisfied after one fitting, the matrix S is called k and G k If the line meets the first straight line fitting, the line is judged as a non-fault line, otherwise it is a fault line. The given conditions are:

[0063]

[0064] Where b is the slope deviation, a is the displacement deviation; (x i ,y i ) is the matrix S k With G k The data pair consisting of the i-th element in ; is the matrix S k The arithmetic mean of all elements in , is the matrix G k The arithmetic mean of all elements in .

[0065] Step 5: Branch line fault selection. For the main line with fault, based on the head end and the end end as well as the branch end in the matrix S k and G k The distance between the data pair and the linear function line is used to determine the fault branch.

[0066] for example Figure 3 When a fault occurs at f3 in (a), the initial traveling wave of the fault propagates from the branch node e to both ends of the line at the speed of light. Starting from node e, all nodes a, b, and c have the same corresponding elements in matrices S1 and G1. The nodes with equal elements form a set A = {a, b, c}. Starting from node e, all nodes f have the same corresponding elements in matrices S1 and G1. The nodes with equal elements form a set B = {f}. Get the complement of the union of sets A and B. is the complement symbol. Therefore, we can obtain that the complement set H1 only contains node e, that is, the faulty node is e and the faulty segment is e-D3.

[0067] However, in actual branch line fault determination, even if a branch line is not a fault branch, due to the existence of various measurement errors, its value in the matrix S k With G k It is impossible for them to be exactly the same, so this embodiment selects the fault branch line based on the distance between the data pair and the fitting line: the endpoint corresponding to the data pair farthest from the linear function line is determined to be the fault branch.

[0068] Step 6: Locate the fault point.

[0069] The fault traveling wave head is transmitted along the shortest path. The first wave head information obtained by the traveling wave detection device is the time it takes for the traveling wave generated by the fault point to be directly transmitted to the point. This positioning method simply uses time to locate the fault. The technical difficulty lies in accurately determining the fault interval. In order to obtain a correct fault interval positioning algorithm, the present invention first decomposes the trunk line with multiple branches into multiple lines with only single branches. Figure 3 、 Figure 4 shown.

[0070] When it appears Figure 2 In the case of the fault shown in (a), taking the fault point f3 as an example, the two endpoints D4 and D5 closest to the endpoint D3 are selected. The time when the initial traveling wave of the fault reaches the endpoints D3, D4, and D5 are respectively The fault point can be accurately located using the double-ended traveling wave positioning principle as shown in the following formula:

[0071]

[0072]

[0073]

[0074] Where: x′ is the distance between the fault point and the branch node e calculated using the endpoints D3 and D4; V is the speed of the traveling wave; is the shortest distance from node e to f to endpoint D4; is the distance from node e to endpoint D3; is the shortest distance from node e to node f to endpoint D5; x″ is the distance from the fault point to branch node e calculated using endpoints D3 and D5; x is the average distance from the fault point to branch node e, which is the precise location of the fault point.

[0075] This invention utilizes a fault location method that combines traveling wave ranging with time difference matrix data fitting to transform the complex multi-branch line fault location problem into a dual-end fault location problem, decomposing the multi-branch line into a line with only a single branch. Based on the different transmission characteristics of the initial traveling wave head on the fault line and the non-fault line, a decomposed trunk line endpoint reference time difference matrix and a fault time difference matrix are constructed. The time difference variation between the fault line and the non-fault line before and after the fault is thoroughly analyzed. Based on the variation of the elements in the matrix before and after the fault, the least squares method is introduced to fit the data of the two matrices, finding the optimal linear function match between the two matrices and determining the fault branch section. This method does not consider the traveling wave velocity and is applicable to multi-branch power distribution lines.

[0076] The above embodiments are preferred embodiments of the present application. Ordinary technicians in this field can also make various changes or improvements on this basis. Without departing from the overall concept of the present application, these changes or improvements should fall within the scope of protection required by the present application.

Claims

1. A method for locating multi-branch fault traveling waves in a distribution network based on time difference matrix data fitting, characterized in that: include: Step 1: The distribution network has multiple trunk lines with multiple branches, which are decomposed into m lines with only single branches; Step 2: For each trunk line with only a single branch: (1) set a simulated fault point at the head end of the line, use a traveling wave acquisition device to calibrate the initial traveling wave arrival time at the head end and the end end of the line and at the end end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the end end, and record it as the reference time difference relative to the end end of the line; (2) A simulated fault point is set at the end of the line, and the initial traveling wave arrival time at the beginning and end of the line and at the end of each branch is calibrated using a traveling wave acquisition device. The time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival at the beginning is calculated and recorded as the reference time difference relative to the beginning of the line. (3) For each trunk line k with only a single branch, all the corresponding reference time differences relative to the beginning and end of the line are used to construct the endpoint reference time difference matrix S corresponding to the trunk line. k ; Step 3: When a real fault occurs in the distribution network, for each trunk line with only a single branch: use the traveling wave acquisition device to calibrate the initial traveling wave arrival time at the beginning and end of the line and at the end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the beginning, and calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the end, and construct the fault traveling wave time difference matrix G for each trunk line based on all the corresponding differences. k ; Step 4: For each trunk line k, calculate the endpoint reference time difference matrix S k and the fault traveling wave time difference matrix G k Perform a function relationship fitting, if the matrix S k With G k If the linear function relationship is matched, the trunk line k is judged to be normal, otherwise the trunk line k is judged to be faulty; Step 5: For the main line with fault, based on the head end, the end end and the end end of each branch in the matrix S k and G k The distance between the data pair and the linear function line determines the fault branch; Step 6: Use the time quantity to locate the fault point of the fault branch.

2. The method for locating multi-branch faults in a distribution network according to claim 1, characterized in that: Endpoint reference time difference matrix S k and the fault traveling wave time difference matrix G k The construction method is: When a simulated fault point is set at the head end of any line j with only a single branch, the initial traveling wave arrival times of each node in line j are: j ′, 1, the end of each branch of line j t j ′,2,t j ′,3,…,t j ′, n-1 , the end t of line j j ′, n When a simulated fault point is set at the end of line j with only a single branch, the initial traveling wave arrival times of each node in line j are: j ″, 1, the end of each branch of line j t j ″,2,t j ″,3,…,t j ″, n-1 , the end t of line j j ″, n ; Then the endpoint reference time difference matrix S of the trunk line k k for: When a real fault occurs in the distribution network, the initial traveling wave arrival times of each node in any line j with only a single branch are: t j ″′, 1, the end of each branch of line j t j ″′,2,t j ″′,3,…,t j ″′, n-1 , the end t of line j j ″′, n ; Then the fault traveling wave time difference matrix G of trunk line k is k for:

3. The method for locating multi-branch faults in a distribution network according to claim 1, characterized in that: The least squares method is used to fit the linear function relationship y=a+bx, and the matrix S k With G k The conditions for matching a linear function relationship are: Where b is the slope deviation, a is the displacement deviation; (x i ,y i ) is the matrix S k With G k The data pair consisting of the i-th element in ; is the matrix S k The arithmetic mean of all elements in , is the matrix G k The arithmetic mean of all elements in .

4. The method for locating multi-branch faults in a distribution network according to claim 1, characterized in that: In step 5, the endpoint corresponding to the data pair that is farthest from the linear function line is determined to be the fault branch.

5. The method for locating multi-branch faults in a distribution network according to claim 1, characterized in that: In step 6, let the endpoint corresponding to the fault branch be D3, select the other two endpoints D4 and D5 closest to the fault branch of the faulty main line, and the time when the initial fault traveling wave reaches the endpoints D3, D4 and D5 respectively The fault point in the fault branch can be located using the double-ended traveling wave location principle according to the following formula: Where, e, f, and g are the branch nodes from endpoints D3, D4, and D5 to the main line, respectively; x′ is the distance from the fault point to the branch node e calculated using endpoints D3 and D4; V is the traveling wave velocity; The shortest distance from branch node e to branch node f to endpoint D4; is the distance from branch node e to endpoint D3; is the shortest distance from branch node e to branch node g to endpoint D5; x″ is the distance from the fault point to branch node e calculated using endpoints D3 and D5; x is the average distance from the fault point to branch node e.

6. A device based on the method for locating multi-branch faults in a distribution network according to claim 1, characterized in that: include: The line decomposition module is used to: decompose multiple trunk lines with multiple branches in the distribution network into m lines with only single branches; The endpoint reference time difference matrix construction module is used to: for each trunk line with only a single branch: (1) set a simulated fault point at the head end of the line, use a traveling wave acquisition device to calibrate the initial traveling wave arrival time at the head end and the end end of the line and the end end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the end end, and record it as the reference time difference relative to the end end of the line; (2) Set up a simulated fault point at the end of the line, use the traveling wave acquisition device to calibrate the initial traveling wave arrival time at the beginning and end of the line and at the end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival time at the beginning, and record it as the reference time difference relative to the beginning of the line; (3) For each trunk line k, construct the endpoint reference time difference matrix S corresponding to the trunk line based on all the corresponding reference time differences relative to the beginning and end of the line k ; The fault traveling wave time difference matrix construction module is used to: when a real fault occurs in the distribution network, for each trunk line with only a single branch: use the traveling wave acquisition device to calibrate the initial traveling wave arrival time at the beginning and end of the line and the end of each branch, calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival at the beginning, and calculate the time difference of each initial traveling wave arrival time relative to the initial traveling wave arrival at the end, and construct the fault traveling wave time difference matrix G for each trunk line based on all the corresponding differences k ; The main line fault judgment module is used to: for each main line k, calculate the reference time difference matrix S of its endpoints k and the fault traveling wave time difference matrix G k Perform a function relationship fitting, if the matrix S k With G k If the linear function relationship is matched, the trunk line k is judged to be normal, otherwise the trunk line k is judged to be faulty; The branch line fault judgment module is used to: for the main line with a fault, based on the head end and the end end and each branch end in the matrix S k and G k The distance between the data pair and the linear function line determines the fault branch; The fault point location module is used to locate the fault point of the fault branch using time quantity.

7. The device according to claim 6, characterized in that The main line fault judgment module adopts the least square method to fit the linear function relationship y=a+bx, and the matrix S k With G k The conditions for matching a linear function relationship are: Where b is the slope deviation, a is the displacement deviation; (x i ,y i ) is the matrix S k With G k The data pair consisting of the i-th element in ; is the matrix S k The arithmetic mean of all elements in , is the matrix G k The arithmetic mean of all elements in .

8. The device according to claim 6, characterized in that The branch line fault determination module determines that the branch corresponding to the endpoint of the data pair farthest from the linear function line is a faulty branch.

9. The device according to claim 6, characterized in that The fault point location module uses the double-end traveling wave location principle to locate the fault point in the fault branch, specifically: Assume that the endpoint corresponding to the fault branch is D3, and select the other two endpoints D4 and D5 that are closest to the fault branch of the faulty main line. The time when the initial fault traveling wave reaches the endpoints D3, D4 and D5 are respectively Then the average distance x between the fault point and the branch node e is calculated according to the following formula: Where, e, f, and g are the branch nodes from endpoints D3, D4, and D5 to the main line, respectively; x′ is the distance from the fault point to the branch node e calculated using endpoints D3 and D4; V is the traveling wave velocity; The shortest distance from branch node e to branch node f to endpoint D4; is the distance from branch node e to endpoint D3; is the shortest distance from branch node e to branch node g to endpoint D5; x″ is the distance from the fault point to branch node e calculated using endpoints D3 and D5.

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