A method for accurate fault location in distribution network based on distributed traveling wave detection

Abstract

The present invention provides a method for accurately locating distribution network faults based on distributed traveling wave detection, the method comprising the following steps: S1: configuring a traveling wave monitoring unit; S2: real-time monitoring of faults in the distribution network through the traveling wave monitoring unit; S3: filtering other types of interference traveling waves except for the fault traveling wave signal, identifying and selecting the fault traveling wave; S4: calibrating the time point of the traveling wave head; S5: calculating the minimum propagation time of the traveling wave from each node to each end point, the end points are the ends of the two ends of the main line of the distribution network and the ends of the branch line, and the nodes are all intermediate nodes except the end points; S6: presetting the fault point and calculating the Pearson coefficient r of the time array; S7: traversing the fault point, and judging the actual position of the fault point in turn based on the calculated Pearson coefficient r. The present invention aims at the problem that the distribution network architecture is complex, the faults occur frequently, and the current technology is difficult to accurately locate the faults, and realizes the accurate fault location of the distribution network based on the traveling wave positioning method.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network fault location, and in particular to a distribution network fault accurate location method based on distributed traveling wave detection. Background Art

[0002] The distribution network has a complex grid structure, many line branches, a changeable operating environment, and frequent faults. Single-phase grounding faults account for more than 80% of the total number of faults in the medium-voltage distribution network, and two-phase or three-phase short circuits are mostly developed from single-phase grounding. Fault line selection and fault distance measurement for single-phase grounding are of great significance for quickly troubleshooting faults and improving power grid reliability. However, my country's medium-voltage distribution network mostly adopts a neutral point non-effective grounding operation mode, and the single-phase grounding fault current is small, which brings difficulties to fault line selection and distance measurement. At present, many studies have been devoted to solving the fault line selection and distance measurement of small current grounding systems, but due to the complex fault characteristics and grid structure of the distribution network, the current method is difficult to properly handle special fault conditions such as high-resistance grounding, small fault closing angle grounding, mixed lines and branch line faults. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for accurately locating distribution network faults based on distributed traveling wave detection. In view of the problems that the distribution network architecture is complex, faults occur frequently, and it is difficult to accurately locate faults with current technology, accurate fault location of the distribution network is achieved based on the traveling wave positioning method.

[0004] To achieve the above-mentioned object of the invention, the present invention provides a method for accurately locating distribution network faults based on distributed traveling wave detection, the method comprising the following steps:

[0005] S1: Configure the traveling wave monitoring unit;

[0006] S2: Real-time fault monitoring of the distribution network through the traveling wave monitoring unit;

[0007] S3: Filtering other types of interference traveling waves except the fault traveling wave signal, identifying and selecting the fault traveling wave;

[0008] S4: calibrate the time point of the traveling wave head;

[0009] S5: Calculate the minimum propagation time of the traveling wave from each node to each endpoint, the endpoints are the ends of the main line of the distribution network and the ends of the branch line, and the nodes are all intermediate nodes except the endpoints;

[0010] S6: preset the fault point and calculate the Pearson coefficient r of the time array;

[0011] S7: Traverse the fault points and determine the actual positions of the fault points in turn based on the calculated Pearson coefficient r.

[0012] It should be noted that the traveling wave monitoring unit configured in S1 is specifically configured for each endpoint, wherein the traveling wave monitoring unit has a built-in power supply module, a traveling wave voltage sensor, a traveling wave current sensor, a high-precision GPS / Beidou synchronization clock, a 4G communication unit and a collection unit, and the traveling wave monitoring unit is used for real-time collection of line fault power frequency voltage and current, traveling wave voltage and traveling wave current signals.

[0013] It should be noted that the specific steps of S2 include:

[0014] S201: The traveling wave monitoring unit captures line voltage and current changes in real time;

[0015] S202: Collect fault power frequency voltage and current and high frequency traveling wave voltage and current signals;

[0016] S203: Marking a high-precision GPS / Beidou synchronized clock on the signal collected in the previous step;

[0017] S204: Upload the marked signal to the backend central station.

[0018] The specific steps of S3 include:

[0019] S301: Set the low-pass cutoff frequency fp1 and the high-pass cutoff frequency fp2, the units of fp1 and fp2 are Hz; the filter order is n1;

[0020] S302: Frequency normalization, as shown in the following formula:

[0021]

[0022] Among them, w1 is the parameter after the normalization of the low-pass cutoff frequency parameter, w2 is the parameter after the normalization of the high-pass cutoff frequency parameter, F s is the sampling rate;

[0023] S303: Calculate the filter coefficient matrix b(n):

[0024] n∈[0,n1], when hour,

[0025]

[0026] when hour,

[0027] S304: Perform zero-phase shift filtering.

[0028] It should be further explained that the specific steps of S304 include:

[0029] S341: Input filter coefficient matrix and shape to be filtered;

[0030] S342: Perform the first filtering;

[0031] S343: performing data flipping on the data after the first filtering, wherein the data flipping is to sequentially swap the array from the beginning to the end;

[0032] S344: Perform a second filtering;

[0033] S345: performing a second data flip on the data after the second filtering;

[0034] S346: Output result;

[0035] Among them, the formulas for the first filtering and the second filtering are exactly the same, and the specific formulas are as follows:

[0036] y(n)=b(1)x(n)+b(2)x(n-1)+...+b(n1+1)x(n-n1)

[0037] Where x(n) is the shape to be filtered, and y(n) is the result after filtering.

[0038] It should be noted that the specific steps of S4 include:

[0039] S401: Perform multi-wavelet packet transformation on each traveling wave, and determine the arrival time of the traveling wave head by modulus maximum method, so as to obtain the arrival time corresponding to each traveling wave monitoring unit;

[0040] S402: Find the minimum value from the arrival times corresponding to the traveling wave monitoring units obtained in S401;

[0041] S403: Subtract the minimum value from all arrival times to obtain a time array T based on the measured traveling wave:

[0042] T=[T A ,T B ,....T U ]

[0043] Among them, one element in array T is 0, and the rest of the elements are greater than 0.

[0044] The specific steps of S5 include:

[0045] S501: Find the shortest path from each node to each endpoint, and bring the shortest path into the line basic data query to obtain the lengths L1, L2, ..., L of the N types of wire materials included in the path. n And the traveling wave speed V1, V2, ..., V in each material wire n ;

[0046] S502: Obtain the minimum propagation time t of the traveling wave from each node to each endpoint 最小 , where the minimum propagation time t of a traveling wave from node to node, from node to endpoint, and from endpoint to endpoint is 最小 The specific formulas are:

[0047]

[0048] Assume that the shortest path from node P to endpoint D is P—M—N—O—D, and M, N, and O are the intermediate nodes on the shortest path. Then the minimum propagation time of the traveling wave from P to D is:

[0049]

[0050] Among them, L i is the length of the wire of the i-th material in the shortest path from node P to endpoint D, V i It is the speed of the traveling wave in the wire of the i-th material in the shortest path from the node P to the endpoint D.

[0051] The specific steps of S6 include:

[0052] S601: Using the traversal method, calculate the time T required for the preset fault point to reach each endpoint monitoring terminal in turn i ′, where i represents the i-th endpoint. Let the line be A-M-C, where A and C are endpoints, M is a node in the line A-M-C, and the fault point is located at endpoint A. Then the time it takes for the traveling wave to reach endpoint A is T A ' = 0, the time taken to reach the endpoint C is T C ′=t AM +t MC , where t AM is the minimum propagation time of the traveling wave from A to M, t MC is the minimum propagation time of the traveling wave from M to C, t AM ,t MC Solved by step S5;

[0053] S602: According to S601, T is obtained in sequence B ′、T D ′、T E ′, ...., T U ′, find T A ′、T B ′, ...., T U ′, and T A ′、T B ′, ...., T U ′ is deducted from the minimum value, that is, it is reset to zero, and the time array T′=[T A ″, T B ″, ..., TU ″], where T A ″、T B ″、....、T U ″ is T A ′、T B ′, ...., T U 'The result after zeroing;

[0054] S603: Calculate the Pearson coefficient r of T and T′. The specific formula is:

[0055]

[0056] It should be noted that the specific steps of S7 include:

[0057] S701: Setting threshold r set , 0 <r set <1;

[0058] S702: Check in sequence, if r≥r set , then the fault point endpoint A preset in S6 is the real fault point; if r≤r set , then the second fault point needs to be preset. Since the first preset fault point is endpoint A, when traversing, first complete the traversal of all suspected fault points on line AM until the Pearson coefficient of the suspected fault point is found, and the Pearson coefficient satisfies r≥r set , that is, the point is the real fault point, otherwise proceed to S703;

[0059] S703: If all preset fault points on the AM do not satisfy r≥r set , then traverse the next line segment and repeat steps S1 to S7 until the real fault point is found. If all lines are traversed and there is still no condition that satisfies r≥r set If the preset fault point is found, it is determined that the fault is not on this line.

[0060] It should be further explained that the specific steps of completing the traversal of all suspected fault points of line AM in S702 include:

[0061] S721: Set the length step dl, set the distance from the endpoint Adl on the line segment AM as the second preset fault point, and according to the steps of S5 and S6, calculate the time required for the preset fault point to reach each endpoint monitoring terminal in turn, and finally calculate the Pearson coefficient r based on the measured traveling wave time array;

[0062] S722: Determine whether the Pearson coefficient r of the preset fault point satisfies r≥r set, if it is satisfied, the second preset fault point is the actual fault point. Otherwise, it is necessary to further traverse the line segment AM until the traversal of the entire line segment AM is completed. For the last preset fault, if its distance from point M is less than dl, the last preset fault point on AM is point M.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] The present invention provides a method for accurately locating distribution network faults based on distributed traveling wave detection. The method performs real-time fault monitoring on the distribution network by configuring a traveling wave monitoring unit, and solves the problem of accurately locating distribution network faults based on a traveling wave positioning method. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0066] Figure 1 It is a schematic diagram of the overall process of a method for accurately locating distribution network faults based on distributed traveling wave detection provided by an embodiment of the present invention.

[0067] Figure 2 It is a schematic diagram of a typical complex distribution network structure provided by an embodiment of the present invention.

[0068] Figure 3 It is a schematic diagram of the process of zero phase shift filtering provided by an embodiment of the present invention.

[0069] Figure 4 It is a diagram showing the calculation effect of a fault moment of certain measured data provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0070] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The enumerated embodiments are only used to explain the present invention but not to limit the scope of the present invention.

[0071] The distribution network is generally a complex network structure including multiple T-connections and cable-overhead mixed racks. Figure 1 This embodiment provides a method for accurately locating distribution network faults based on distributed traveling wave detection, the method comprising the following steps:

[0072] S1: Configure the traveling wave monitoring unit;

[0073] S2: Real-time fault monitoring of the distribution network through the traveling wave monitoring unit;

[0074] S3: Filtering other types of interference traveling waves except the fault traveling wave signal, identifying and selecting the fault traveling wave;

[0075] S4: calibrate the time point of the traveling wave head;

[0076] S5: Calculate the minimum propagation time of the traveling wave from each node to each endpoint, the endpoints are the ends of the main line of the distribution network and the ends of the branch line, and the nodes are all intermediate nodes except the endpoints;

[0077] S6: preset the fault point and calculate the Pearson coefficient r of the time array;

[0078] S7: Traverse the fault points and determine the actual positions of the fault points in turn based on the calculated Pearson coefficient r.

[0079] Exemplarily, when the method is implemented to accurately locate distribution network faults, there are two situations, namely, the situation where all branch line terminals are equipped with monitoring terminals and the situation where some branch line terminals are not equipped with monitoring terminals.

[0080] Reference Figure 2 , when all branch line end points are equipped with monitoring terminals:

[0081] The first step is to configure the traveling wave monitoring unit at both ends of the main line of the distribution network and the ends of all branches. The traveling wave monitoring unit has a built-in power supply module, a traveling wave voltage sensor, a traveling wave current sensor, a GPS / Beidou synchronization clock, a 4G communication unit, a collection unit, etc., which can collect the line fault power frequency voltage and current, traveling wave voltage and traveling wave current signals in real time, and transmit the collected signals to the remote central station through 4G, and realize unified analysis and processing at the central station, and output the final fault diagnosis results. For the convenience of subsequent description, each endpoint (the ends of the main line and the ends of the branch line) and the node (all intermediate nodes except the endpoint) are numbered in sequence by English letters, where A, B, C...L are endpoints, and M, N...U are nodes.

[0082] The second step is to conduct real-time fault monitoring. When a fault occurs, the power frequency voltage and power frequency current of the entire line will change. In addition, at the moment of the fault, a high-frequency traveling wave is generated at the fault point and propagates along the line from the fault point to the entire distribution network. The monitoring unit captures the line voltage and current changes, triggers the collection of fault power frequency voltage and current and high-frequency traveling wave voltage and current signals in real time, and marks the collected signals with a high-precision GPS / Beidou clock, which is finally uploaded to the background center station.

[0083] Then, in the third step, because the fault monitoring unit uploads the fault traveling wave signal, it often mixes other types of interference traveling waves, so the fault traveling wave signal should be identified and selected. When the fault traveling wave is generated, the line voltage suddenly changes, and the traveling wave corresponding to the voltage mutation time point is the fault traveling wave.

[0084] It should be noted that the present invention realizes accurate identification of voltage mutation points through positive and negative FIR zero-phase shift filtering, and the filter is a bandpass filter, specifically:

[0085] Set the low-pass cutoff frequency fp1, unit: Hz; high-pass cutoff frequency fp2, unit: Hz; filter order is n1;

[0086] Perform frequency normalization:

[0087] Among them, w1 is the parameter after the normalization of the low-pass cutoff frequency parameter, w2 is the parameter after the normalization of the high-pass cutoff frequency parameter, F s is the sampling rate;

[0088] Calculate the filter coefficient matrix b(n):

[0089] n∈[0,n1], when hour,

[0090]

[0091] when hour,

[0092] It should be noted that after the filter coefficient matrix is ​​calculated, zero phase shift filtering can be performed on this basis. Figure 3 , zero-phase-shift filtering includes the following steps:

[0093] Input filter coefficient matrix and shape to be filtered;

[0094] Perform the first filtering;

[0095] The data after the first filtering is flipped, and the data flipping is to replace the array from the beginning to the end, such as the original array x[n] = {1,2,3}, and after flipping, it becomes {3,2,1};

[0096] Perform a second filtering;

[0097] Perform a second data flip on the data after the second filtering;

[0098] Output the result;

[0099] Among them, the formulas for the first filtering and the second filtering are exactly the same, and the specific formulas are as follows:

[0100] y(n)=b(1)x(n)+b(2)x(n-1)+...+b(n1+1)x(n-n1)

[0101] Where x(n) is the shape to be filtered, and y(n) is the result after filtering.

[0102] Reference Figure 4 , Figure 4 This is the filtering effect of a measured case. After the fault time point is confirmed by this method, the traveling wave within 0.5ms before and after the fault time point is taken as the reference, and the traveling wave within 0.5ms before and after is the traveling wave at the fault time point.

[0103] Then, in the fourth step, after extracting the traveling waves at the time of the fault, each traveling wave is transformed by multi-wavelet packet, and the arrival time of the traveling wave head is determined by the modulus maximum method, which must be accurate to 0.1μs, thereby obtaining the arrival time TA, TB, TC...TU corresponding to the traveling waves of each monitoring unit. Find the minimum value among these moments, and subtract the minimum value from all moments to obtain a time array based on the measured traveling wave, as follows:

[0104] T=[T A ,T B ,....T U ], obviously one element in array T is 0, and the rest of the elements are greater than 0.

[0105] Then the fifth step is to Figure 1 Take the example of a traveling wave from node P to endpoint D. Obviously, the shortest path is P→M→N→O→D. Connect the path into a straight line and bring in the basic line data. Assume that the path contains N kinds of wires such as overhead bare wires, insulated wires, cables, etc. In actual lines, N is generally less than or equal to 3. The lengths corresponding to each material are L1, L2, ..., L n , the speed of the traveling wave in each material wire is V1, V2, ..., V n The length parameter can be obtained through the line record data, and the traveling wave velocity can be obtained through offline measurement or on-site verification and other methods.

[0106] Then the shortest time for the traveling wave to travel from node P to node D, that is, the minimum propagation time, is:

[0107]

[0108] The minimum time from any other node to any endpoint can be obtained in the same way, thereby obtaining a series of minimum propagation time parameters. In order to save subsequent calculation time, in actual engineering applications, the above basic parameter calculations can be completed as soon as the line data is confirmed, and stored in the central station, and can be directly called during calculation.

[0109] Then in the sixth step, preset the fault point and calculate the time array correlation coefficient. Obviously, Figure 1 The line can be considered as a series of line segments such as AM, MN, NC, etc. The line fault may be located on any line segment or on a non-line segment, such as other lines sharing the busbar.

[0110] The traversal method is used to calculate the time required for the preset fault point to reach each endpoint monitoring terminal in turn. Taking line segment AM as an example,

[0111] Assume that the fault point is at endpoint A, then the time it takes for the traveling wave to reach endpoint A is T A ' = 0, the time taken to reach the endpoint C is T C ′=t AM +t MC , where t AM is the minimum propagation time of the traveling wave from A to M, t MC is the minimum propagation time of the traveling wave from M to C, t AM ,t MC Solve by step S5, and get T B ′、T D ′、T E ′, ...., T U ′, find T A ′、T B ′, ...., T U ′, and T A ′、T B ′, ...., T U ′ is deducted from the minimum value, that is, it is reset to zero, and the time array T′=[T A ″, T B ″, ..., T U ″], where T A ″、T B ″、....、T U ″ is T A ′、T B ′, ...., T U ' is the result after zeroing; then calculate the Pearson coefficient r of T and T', the specific formula is:

[0112]

[0113] The last seventh step is to set the threshold r set , 0 <r set <1, in practice, it is recommended to set rset to between 0.90 and 0.98. set , then the fault point endpoint A preset in step 6 is the real fault point. If r≤r set, then the second fault point needs to be preset. Since the first preset fault point is endpoint A, when traversing, first complete the traversal of all suspected fault points on line AM. Set the length step dl. If it is a pure overhead bare wire, dl is recommended to be 40-50m. If it is an overhead insulated wire or cable, dl is recommended to be 20-25m. On line segment AM, the second preset fault point is dl away from endpoint A. According to the fifth and sixth steps, the time required for the preset fault point to reach each endpoint monitoring terminal is calculated in turn, and finally the Pearson coefficient based on the measured traveling wave time array is obtained. Similarly, it is determined whether the coefficient r≥r is satisfied. set If the condition is met, the second preset fault point is the actual fault point. Otherwise, it is necessary to further traverse the line segment AM until the traversal of the entire line segment AM is completed. For the last preset fault, if its distance from point M is less than dl, the last preset fault point on AM is point M.

[0114] According to the above traversal rules, when all preset fault points on AM do not satisfy r≥r set , then traverse the next line segment, such as MN, MP or MR. If a point satisfies r≥r set If the condition is met, then this point is a fault point and no subsequent traversal process is required. If there is no preset fault point that meets this condition after the entire line traversal is completed, it is determined that the fault is not on this line.

[0115] Reference Figure 2 , when monitoring terminals are not installed at the ends of some branch lines:

[0116] In actual engineering applications, there may be situations where monitoring terminals are not installed at the ends of some branches. Figure 2 Take the example for explanation. The difference is that after removing the monitoring terminals of endpoints I and J, the line segments PQ, QI, and QJ are monitoring blind areas, and the remaining area line segments are normal monitoring segments. If the fault point occurs in the normal segment, the fault point on segment AM is still located at point Y as an example. At this time, after the fault traveling wave starts from point Y, the shortest path to endpoint H is YMPH, which is the same as when there are monitoring terminals at I and J. The shortest paths to the remaining endpoints are also the same as when there are monitoring terminals at I and J. The only difference is that there are 2 fewer elements in the shortest time array, and the PQ, QI, and QJ segments do not participate in the above calculation process, which is equivalent to removing the PQ, QI, and QJ segments from the network.

[0117] If the fault point occurs in any of the three segments PQ, QI, and QJ, take point Z on segment QJ as an example. After the fault occurs at point Z, the fault wave propagates to the entire network. It must first pass through the two line segments ZQ and QP, and then be diverted from point P to both sides, further propagating to the subsequent nodes, and finally captured by each monitoring terminal. Assuming that it takes time t0 for the fault point to propagate from point Z to point P, for each endpoint monitoring terminal, when the fault wave at point Z propagates to point P after t0, the subsequent process is exactly the same as the propagation path of the fault at point P, that is, for each monitoring terminal, the fault at point Z is completely equivalent to the fault at point P after a delay of t0, and t0 will be eliminated in the zeroing process. According to the above processing flow, when the fault point occurs in the three blind line segments PQ, QI, and QJ, the final positioning result is the fault at point P.

[0118] Therefore, in actual applications, when the monitoring terminal is not installed at the end of some branches, all line segments between the branch and the branch with the monitoring terminal or the nearest connection node of the main line are removed and not considered. Figure 4 Taking the case as an example, it is obvious that the nearest connection node is point P. At this time, PI and QJ should be removed during calculation. If the fault occurs at any position on the PI and QJ branches, the fault location result is at point P. When the fault occurs at other positions, it is the same as the situation where all branch end nodes are equipped with monitoring terminals. Based on this principle, in actual engineering applications, comprehensive considerations such as construction convenience, economy, and line patrol requirements can be fully combined. Monitoring terminals may not be configured for some short branches and easy-to-patrol locations, which can save investment while ensuring the positioning effect.

[0119] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for accurately locating distribution network faults based on distributed traveling wave detection, characterized in that: The method comprises the following steps: S1: Configure the traveling wave monitoring unit; S2: Real-time fault monitoring of the distribution network through the traveling wave monitoring unit; S3: Filtering other types of interference traveling waves except the fault traveling wave signal, identifying and selecting the fault traveling wave. The specific steps include: S301: Set the low-pass cutoff frequency fp1 and the high-pass cutoff frequency fp2, the units of fp1 and fp2 are Hz; the filter order is n1; S302: Frequency normalization, as shown in the following formula: Among them, w1 is the parameter after the normalization of the low-pass cutoff frequency parameter, w2 is the parameter after the normalization of the high-pass cutoff frequency parameter, F s is the sampling rate; S303: Calculate the filter coefficient matrix b(n): n∈[0,n1], when hour, when hour, S304: Perform zero phase shift filtering, the specific steps include: S341: Input filter coefficient matrix and shape to be filtered; S342: Perform the first filtering; S343: performing data flipping on the data after the first filtering, wherein the data flipping is to sequentially swap the array from the beginning to the end; S344: Perform a second filtering; S345: performing a second data flip on the data after the second filtering; S346: Output result; Among them, the formulas for the first filtering and the second filtering are exactly the same, and the specific formulas are as follows: y(n)=b(1)x(n)+b(2)x(n-1)+...+b(n1+1)x(n-n1) In the formula, x(n) is the shape to be filtered, and y(n) is the result after filtering; S4: calibrate the time point of the traveling wave head, the specific steps include: S401: Perform multi-wavelet packet transformation on each traveling wave, and determine the arrival time of the traveling wave head by modulus maximum method, so as to obtain the arrival time corresponding to each traveling wave monitoring unit; S402: Find the minimum value from the arrival times corresponding to the traveling wave monitoring units obtained in S401; S403: Subtract the minimum value from all arrival times to obtain a time array T based on the measured traveling wave: T=[T A ,T B ,....T U ] Among them, one element in array T is 0, and the rest of the elements are greater than 0; S5: Calculate the minimum propagation time of the traveling wave from each node to each endpoint, the endpoints are the ends of the main line of the distribution network and the ends of the branch line, and the nodes are all intermediate nodes except the endpoints; S6: Preset the fault point and calculate the Pearson coefficient r of the time array. The specific steps include: S601: Using the traversal method, calculate the time T required for the preset fault point to reach each endpoint monitoring terminal in turn i ′, where i represents the i-th endpoint. Let the line be A-M-C, where A and C are endpoints, M is a node in the line A-M-C, and the fault point is located at endpoint A. Then the time it takes for the traveling wave to reach endpoint A is T A ' = 0, the time taken to reach the endpoint C is T C ′=t AM +t MC , where t AM is the minimum propagation time of the traveling wave from A to M, t MC is the minimum propagation time of the traveling wave from M to C, t AM ,t MC Solved by step S5; S602: According to S601, T is obtained in sequence B ′、T D ′、T E ′, ...., T U ′, find T A ′、T B ′, ...., T U ′, and T A ′、T B ′, ...., T U Subtract the minimum value from the average value, that is, return to zero, and get the time array T'=[T A ″, T B ″, ..., T U ″], where T A ″、T B ″、....、T U ″ is T A ′、T B ′, ...., T U 'The result after zeroing; S603: Calculate the Pearson coefficient r of T and T′. The specific formula is: S7: Traverse the fault points and determine the actual positions of the fault points in turn based on the calculated Pearson coefficient r.

2. The method for accurately locating distribution network faults based on distributed traveling wave detection according to claim 1 is characterized in that: The configuration of the traveling wave monitoring unit in S1 specifically configures the traveling wave monitoring unit for each endpoint. The traveling wave monitoring unit has a built-in power supply module, a traveling wave voltage sensor, a traveling wave current sensor, a high-precision GPS / Beidou synchronous clock, a 4G communication unit and a collection unit. The traveling wave monitoring unit is used to collect the line fault power frequency voltage and current, traveling wave voltage and traveling wave current signals in real time.

3. The method for accurately locating distribution network faults based on distributed traveling wave detection according to claim 2 is characterized in that: The specific steps of S2 include: S201: The traveling wave monitoring unit captures line voltage and current changes in real time; S202: Collect fault power frequency voltage and current and high frequency traveling wave voltage and current signals; S203: Marking a high-precision GPS / Beidou synchronized clock on the signal collected in the previous step; S204: Upload the marked signal to the backend central station.

4. The method for accurately locating distribution network faults based on distributed traveling wave detection according to claim 3 is characterized in that: The specific steps of S5 include: S501: Find the shortest path from each node to each endpoint, and bring the shortest path into the line basic data query to obtain the lengths L1, L2, ..., L of the N types of wire materials included in the path. n And the traveling wave speed V1, V2, ..., V in each material wire n ; S502: Obtain the minimum propagation time t of the traveling wave from each node to each endpoint 最小 , where the minimum propagation time t of a traveling wave from node to node, from node to endpoint, and from endpoint to endpoint is 最小 The specific formulas are: Assume that the shortest path from node P to endpoint D is P—M—N—O—D, and M, N, and O are the intermediate nodes on the shortest path. Then the minimum propagation time of the traveling wave from P to D is: Among them, L i is the length of the wire of the i-th material in the shortest path from node P to endpoint D, V i is the speed of the traveling wave in the wire of the i-th material in the shortest path from node P to endpoint D.

5. The method for accurately locating distribution network faults based on distributed traveling wave detection according to claim 4 is characterized in that: The specific steps of S7 include: S701: Setting threshold r set , 0 <r set <1; S702: Check in sequence, if r≥r set , then the fault point endpoint A preset in S6 is the real fault point; if r≤r set , then the second fault point needs to be preset. Since the first preset fault point is endpoint A, when traversing, first complete the traversal of all suspected fault points on line AM until the Pearson coefficient of the suspected fault point is found, and the Pearson coefficient satisfies r≥r set , that is, the point is the real fault point, otherwise proceed to S703; S703: If all preset fault points on the AM do not satisfy r≥r set , then traverse the next line segment and repeat steps S1 to S7 until the real fault point is found. If all lines are traversed and there is still no condition that satisfies r≥r set If the preset fault point is found, it is determined that the fault is not on this line.

6. A method for accurately locating distribution network faults based on distributed traveling wave detection according to claim 5, characterized in that: The specific steps of completing the traversal of all suspected fault points of line AM in S702 include: S721: Set the length step dl, set the distance from the endpoint Adl on the line segment AM as the second preset fault point, and according to the steps of S5 and S6, calculate the time required for the preset fault point to reach each endpoint monitoring terminal in turn, and finally calculate the Pearson coefficient r based on the measured traveling wave time array; S722: Determine whether the Pearson coefficient r of the preset fault point satisfies r≥r set , if it is satisfied, then the second preset fault point is the actual fault point. Otherwise, further traverse on line segment AM until the traversal of the entire line segment AM is completed. For the last preset fault, if its distance from point M is less than dl, then the last preset fault point on AM is point M.

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