A Fault Location Method and System for Transmission Cables Based on the Differential Iteration Method

Abstract

The present invention provides a method for fault location of transmission cables based on the differential iteration method, which includes receiving the actual monitoring signals of all fault monitoring devices, and determining that all fault monitoring devices with fault power frequency characteristics are fault location devices and the shortest lines; on each shortest line, respectively extract the initial actual time when the fault traveling wave signal arrives, and calculate the traveling wave speed; set each shortest line as an equally divided line; obtain the current equally divided line and divide it into N equal parts, and simulate and calculate the initial theoretical times of N + 1 fault traveling wave signals on the current equally divided line; compare the two initial theoretical times when the N + 1 fault traveling wave signals respectively arrive with the corresponding two initial actual times, iteratively calculate all equally divided lines, and output the fault point that meets the predetermined conditions screened out in the last iteration as the final fault point. Implementing the present invention can solve the problem of low fault location accuracy in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission line management, and particularly to a transmission cable fault location method and system based on a differential iteration method. Background Art

[0002] In the prior art, there are various transmission cable fault location methods, including impedance location method and traveling wave location method. Among them, the impedance location method has large ranging errors and is affected by the arc resistance at the fault point, the power supply impedance, the voltage, the transformation errors of voltage and current transformers, and the line asymmetry, etc. It is difficult to obtain accurate zero-sequence parameters, which may cause incorrect accurate positioning results; the traveling wave location method is affected by factors such as the line length, wave velocity, and different architecture modes of the line, resulting in propagation attenuation and distortion, etc., reducing the accuracy, making the fault location results always difficult to meet the requirements of on-site operation. Therefore, there are still deficiencies in the accurate judgment of transmission cable faults and it needs to be improved.

[0003] In order to solve the problem of low fault location accuracy in the prior art, it is necessary to propose a new transmission cable fault location method, which can improve the ability of fault diagnosis and rapid location of transmission cable lines, solve the long-existing problems such as difficult line patrol and high operation and maintenance labor intensity of transmission cables, shorten the fault power outage time, improve the maintenance efficiency, and provide technical support for the emergency repair and power supply guarantee of transmission cables. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide a transmission cable fault location method and system based on a differential iteration method, which can solve the problem of low fault location accuracy in the prior art.

[0005] To solve the above technical problem, the embodiments of the present invention provide a transmission cable fault location method based on a differential iteration method, and the method includes the following steps:

[0006] S1. Receive the signals actually monitored by all preset fault monitoring devices on the transmission line, and determine that the fault monitoring devices carrying the fault power frequency characteristics in the signals are all the required fault location devices, and further determine the shortest line to which each two fault location devices belong in the preset transmission line topology diagram;

[0007] S2. On each shortest line, respectively extract the initial actual moments when the fault traveling wave signals arrive at the corresponding two fault location devices, and calculate the traveling wave velocity of the fault traveling wave signals corresponding to each shortest line in combination with the preset total length of each shortest line;

[0008] S3. Set each shortest line as an evenly divided line;

[0009] S4. Obtain the current evenly divided line, perform N equal divisions to obtain both ends of the current evenly divided line and N - 1 evenly divided points, all of which are marked as fault points. Then, combined with the total length of the current evenly divided line and the corresponding traveling wave velocity, simulate and calculate the initial theoretical moments when the fault traveling wave signals generated by the N + 1 fault points on the current evenly divided line reach the corresponding two fault location devices respectively; where N is a positive integer greater than 1.

[0010] S5. On the current evenly divided line, compare the two initial theoretical moments of each fault traveling wave signal with the corresponding two initial actual moments. According to the comparison results, when it is determined that the preset iteration end condition is not satisfied, among the N + 1 fault points on the current evenly divided line, screen out the fault points that meet the predetermined conditions. Further, on the current evenly divided line, determine the smallest line interval formed by the selected fault points and their adjacent left and right fault points. After setting the determined smallest line interval as the current evenly divided line, return to step S4.

[0011] S6. If it is determined that the iteration end condition is satisfied according to the comparison results, end the iterative calculation of the current evenly divided line, extract the next shortest line as the current evenly divided line, and then return to step S4.

[0012] S7. After the iterative calculations of all the shortest lines are completed, output the fault points screened out in the last iteration on each shortest line and determine them as the final fault points.

[0013] Among them, the fault monitoring devices are installed on the distribution boxes at each line node of the transmission line.

[0014] Among them, the iteration end condition is that the difference between the time difference formed between the two initial theoretical moments when a certain fault traveling wave signal arrives and the time difference formed between the corresponding two initial actual moments is less than the preset threshold.

[0015] Among them, the predetermined condition is that the time difference formed between the two initial theoretical moments when a certain fault traveling wave signal arrives is the closest to the time difference formed between the corresponding two initial actual moments, and the difference between the two is greater than the preset threshold.

[0016] The embodiment of the present invention also provides a transmission cable fault location system based on the differential iteration method, including:

[0017] A line screening unit, configured to receive all the signals actually monitored by the preset fault monitoring devices on the transmission line, determine that the fault monitoring devices carrying the fault power frequency characteristics in the signals are all the required fault location devices, and further determine the shortest line to which each two fault location devices belong in the preset transmission line topology diagram.

[0018] A traveling wave velocity calculation unit, configured to extract, on each shortest line, the initial actual arrival times of the fault traveling wave signal at the corresponding two fault location devices respectively, and calculate the traveling wave velocity of the fault traveling wave signal on each shortest line in combination with the preset total length of each shortest line;

[0019] An equalized line setting unit, configured to set each shortest line as an equalized line;

[0020] A simulation initial theoretical time calculation unit, configured to obtain the current equalized line, perform N equal divisions, so that both ends of the current equalized line and N - 1 equal division points are recorded as fault points, and simulate and calculate the initial theoretical arrival times of the fault traveling wave signals generated by the N + 1 fault points on the current equalized line at the corresponding two fault location devices respectively in combination with the total length of the current equalized line and the corresponding traveling wave velocity; where N is a positive integer greater than 1;

[0021] A current equalized line iterative calculation unit, configured to compare the two initial theoretical times of each fault traveling wave signal with the corresponding two initial actual times on the current equalized line, and when it is determined according to the comparison result that the preset iteration end condition is not satisfied, screen out the fault points that meet the predetermined conditions among the N + 1 fault points on the current equalized line, further determine the smallest line interval formed by the selected fault points and their adjacent left and right fault points on the current equalized line, and after setting the determined smallest line interval as the current equalized line, return to the simulation initial theoretical time calculation unit;

[0022] A next equalized line iterative calculation unit, configured to end the iterative calculation of the current equalized line if it is determined according to the comparison result that the iteration end condition is satisfied, extract the next shortest line as the current equalized line, and then return to the simulation initial theoretical time calculation unit;

[0023] A fault result output unit, configured to output the fault points screened out in the last iteration on each shortest line after the iterative calculations of all shortest lines are completed, and recognize them as the final fault points.

[0024] Wherein, the fault monitoring devices are installed on the distribution boxes at each line node of the transmission line.

[0025] Wherein, the iteration end condition is that the difference between the time difference formed between the two initial theoretical arrival times of a certain fault traveling wave signal and the time difference formed between the corresponding two initial actual arrival times is less than a preset threshold.

[0026] Wherein, the predetermined condition is that the time difference formed between the two initial theoretical arrival times of a certain fault traveling wave signal and the time difference formed between the corresponding two initial actual arrival times are the closest, and the difference between the two is greater than the preset threshold.

[0027] Implementing the embodiments of the present invention has the following beneficial effects:

[0028] In the present invention, multiple fault monitoring devices are distributed and installed on the transmission cable line. When a fault occurs, the change characteristics of power frequency parameters are used to determine the fault location device and its affiliated fault interval (such as the shortest line). The traveling wave signals on all fault monitoring devices are collected to record the initial time when the fault traveling wave signal arrives. Further, by simulating the fault point position, the fault point position is continuously iteratively divided into N equal parts, and the final fault location result is obtained, thereby solving the problem of low fault location accuracy in the prior art, improving the ability of fault diagnosis and rapid location of the transmission cable line, solving the long-existing problems of difficult line patrol and high operation and maintenance labor intensity of the transmission cable, shortening the fault power outage time, improving the maintenance efficiency, and providing technical support for the emergency repair and power supply guarantee of the transmission cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still belongs to the scope of the present invention.

[0030] Figure 1 It is a flowchart of a transmission cable fault location method based on the differential iteration method provided by the embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the fault device interval in the transmission line topology diagram in a transmission cable fault location method based on the differential iteration method provided by the embodiment of the present invention;

[0032] Figure 3 It is a schematic structural diagram of a transmission cable fault location system based on the differential iteration method provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings.

[0034] As Figure 1 shown, in the embodiment of the present invention, a transmission cable fault location method based on the differential iteration method is provided. The method includes the following steps:

[0035] Step S1: Receive the signals actually monitored by all preset fault monitoring devices on the transmission line, and determine that the fault monitoring devices with fault power frequency characteristics carried in the signals are all required fault location devices. Further, in the preset transmission line topology diagram, determine the shortest line to which each two fault location devices belong.

[0036] Step S2: On each shortest line, respectively extract the initial actual moments when the fault traveling wave signals arrive at the corresponding two fault location devices, and combine the preset total length of each shortest line to calculate the traveling wave speed of the fault traveling wave signal corresponding to each shortest line.

[0037] Step S3: Set each shortest line as an evenly divided line.

[0038] Step S4: Obtain the current evenly divided line, perform N equal divisions, so that both ends of the current evenly divided line and N - 1 evenly divided points are recorded as fault points. Combine the total length of the current evenly divided line and the corresponding traveling wave speed, and simulate and calculate the initial theoretical moments when the fault traveling wave signals generated by the N + 1 fault points on the current evenly divided line arrive at the corresponding two fault location devices; where N is a positive integer greater than 1.

[0039] Step S5: On the current evenly divided line, compare the two initial theoretical moments of each fault traveling wave signal with the corresponding two initial actual moments. According to the comparison results, when it is determined that the preset iteration end condition is not met, among the N + 1 fault points on the current evenly divided line, screen out the fault points that meet the predetermined conditions. Further, on the current evenly divided line, determine the smallest line interval formed by the selected fault points and their adjacent left and right fault points. After setting the determined smallest line interval as the current evenly divided line, return to Step S4.

[0040] Step S6: If it is determined that the iteration end condition is met according to the comparison results, end the iterative calculation of the current evenly divided line, extract the next shortest line as the current evenly divided line, and then return to Step S4.

[0041] Step S7: After the iterative calculations of all shortest lines are completed, output the fault points screened out in the last iteration on each shortest line and determine them as the final fault points.

[0042] Specifically, before Step S1, the fault monitoring devices are installed on the distribution boxes at each line node of the transmission line.

[0043] In step S1, first, receive the signals actually monitored by all preset fault monitoring devices on the transmission line; second, determine the fault monitoring device at the fault point through the power frequency characteristics of the fault. Therefore, all the fault monitoring devices carrying the power frequency characteristics of the fault in the signals are the required fault location devices; finally, in the preset transmission line topology diagram, determine the fault device interval, so as to further determine the shortest line to which every two fault location devices belong, for subsequent rapid fault location.

[0044] It should be noted that the fault interval can be a two-terminal interval and a multi-terminal interval; as Figure 2 shown, the main line 2# and the main line 3# are two-terminal intervals, and the main line 3#, the main line 4#, and the XX line 5# are multi-terminal intervals. At this time, if the multi-terminal interval is the fault device interval, then a shortest line is formed between every two of the main line 3#, the main line 4#, and the XX line 5#, for a total of three shortest lines.

[0045] In step S2, first, by reading the time when the fault monitoring device receives the fault traveling wave signal, the initial actual time when the fault traveling wave signal arrives at the two fault location devices corresponding to each shortest line can be extracted; second, from the transmission line topology diagram, the preset total length of each shortest line can be read. Then, by calculating the distance divided by the total time (the sum of the two initial actual times), the traveling wave speed V of the fault traveling wave signal corresponding to each shortest line is obtained. It should be noted that the initial actual time is the time when the fault traveling wave signal generated by the actual fault point first arrives at the fault location device, and this time can be accurately measured or calculated.

[0046] In step S3, for the convenience of iteration, each shortest line is set as an equally divided line.

[0047] In step S4, taking an equally divided line as an example, according to the line length L of the current equally divided line, it is divided into N equal parts, obtaining N + 1 fault points, and the preset fault division position is the Nm-th position (0 ≤ m ≤ N).

[0048] Since the line length L of the current equally divided line is known, the length of each equal division is L / N. And since the traveling wave speed V has been calculated in step S2, by dividing the distance by the speed, the initial theoretical times when the fault traveling wave signals generated by the N + 1 fault points on the current equally divided line arrive at the corresponding two fault location devices are simulated and calculated. For example, the initial theoretical time of the first equal division point is L / (N*V), and L*(N - 1) / (N*V).

[0049] In step S5, first, calculate the time difference △T formed between the initial actual times; then, calculate the time difference △T formed between the two initial theoretical times when each fault traveling wave signal arrives. i / ; Next, set the iteration end condition as the time difference △T formed between two initial theoretical arrival times of a certain fault traveling wave signal i / and the time difference △T formed between the corresponding two initial actual arrival times is less than the preset threshold ε; Then, if △T i / - △T > ε, the iteration end condition is not satisfied, and among the N + 1 fault points on the current equally divided line, the fault points that meet the predetermined conditions are selected; where the predetermined condition is that the time difference △T formed between two initial theoretical arrival times of a certain fault traveling wave signal i / is the closest to the time difference △T formed between the corresponding two initial actual arrival times, that is, among the N + 1 △T i / s, △T i / ≈ △T is the best; Finally, on the current equally divided line, determine the smallest line interval formed by the selected fault point and its adjacent left and right fault points (i.e., the total length of 2L / N), and after setting the determined smallest line interval as the current equally divided line, return to step S4.

[0050] It can be understood that the iteration end condition can also be set according to the distance difference and distance accuracy, which is subject to the actual design and will not be elaborated here.

[0051] And so on, divide 2L / N into N equal parts again, each part is 2L / N / N,..., and then analyze until △T i / - △T < ε.

[0052] In step S6, on the current equally divided line, if △T i / - △T < ε, end the iterative calculation of the current equally divided line, extract the next shortest line as the current equally divided line, and then return to step S4;

[0053] In step S7, after the iterative calculations of all the shortest lines are completed, output the fault points screened in the last iteration on each shortest line and determine them as the final fault points.

[0054] As Figure 3 shown, in an embodiment of the present invention, a power transmission cable fault location system based on a differential iteration method is provided, including:

[0055] A line screening unit 110 is configured to receive signals actually monitored by all preset fault monitoring devices on a transmission line, and determine that the fault monitoring devices carrying fault power frequency characteristics in the signals are all required fault location devices. Further, in a preset transmission line topology diagram, the shortest lines to which every two fault location devices belong are determined;

[0056] A traveling wave speed calculation unit 120 is configured to respectively extract the initial actual moments when a fault traveling wave signal arrives at corresponding two fault location devices on each shortest line, and calculate the traveling wave speed of the fault traveling wave signal corresponding to each shortest line in combination with the preset total length of each shortest line;

[0057] An equal - divided line setting unit 130 is configured to set each shortest line as an equal - divided line;

[0058] A simulation initial theoretical moment calculation unit 140 is configured to obtain the current equal - divided line, perform N - equal - division, so that both ends of the current equal - divided line and N - 1 equal - division points are recorded as fault points. And in combination with the total length of the current equal - divided line and the corresponding traveling wave speed, simulate and calculate the initial theoretical moments when the fault traveling wave signals generated by N + 1 fault points on the current equal - divided line arrive at corresponding two fault location devices respectively; where N is a positive integer greater than 1;

[0059] A current equal - divided line iterative calculation unit 150 is configured to compare the two initial theoretical moments of each fault traveling wave signal with the corresponding two initial actual moments on the current equal - divided line. And according to the comparison result, when it is determined that the preset iteration end condition is not satisfied, among the N + 1 fault points on the current equal - divided line, fault points meeting a predetermined condition are screened out. Further, on the current equal - divided line, the smallest line interval formed by the screened fault points and their left and right adjacent fault points is determined. And after setting the determined smallest line interval as the current equal - divided line, return to the simulation initial theoretical moment calculation unit 140;

[0060] A next equal - divided line iterative calculation unit 160 is configured to, if it is determined that the iteration end condition is satisfied according to the comparison result, end the iterative calculation of the current equal - divided line, extract the next shortest line as the current equal - divided line, and then return to the simulation initial theoretical moment calculation unit 140;

[0061] A fault result output unit 170 is configured to, after the iterative calculations of all shortest lines are completed, output the fault points screened out in the last iteration on each shortest line and recognize them as the final fault points.

[0062] Among them, the fault monitoring devices are installed on the distribution boxes at each line node in the transmission line.

[0063] Wherein, the iteration end condition is that the difference between the time difference formed between two initial theoretical moments when a certain fault traveling wave signal arrives and the time difference formed between the corresponding two initial actual moments is less than a preset threshold value.

[0064] Wherein, the predetermined condition is that the time difference formed between two initial theoretical moments when a certain fault traveling wave signal arrives is the closest to the time difference formed between the corresponding two initial actual moments, and the difference between the two is greater than the preset threshold value.

[0065] Implementing the embodiments of the present invention has the following beneficial effects:

[0066] The present invention solves the problem of low fault location accuracy in the prior art by distributively installing multiple fault monitoring devices on a transmission cable line, and when a fault occurs, using the change characteristics of power frequency parameters to determine the fault location device and its corresponding fault interval (such as the shortest line), collecting the traveling wave signals on all fault monitoring devices to record the initial time when the fault traveling wave signal arrives, and further by simulating the fault point position, continuously iterating and equally dividing into N equal parts according to the fault point position to finally locate the fault result, thereby improving the ability of fault diagnosis and rapid location of the transmission cable line, solving the long-existing problems of difficult line patrol and high maintenance labor intensity of the transmission cable, shortening the fault power outage time, improving the maintenance efficiency, and providing technical support for the emergency repair and power supply guarantee of the transmission cable.

[0067] It should be noted that in the above system embodiments, the included system units are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the functional units are only for the convenience of mutual distinction and do not limit the protection scope of the present invention.

[0068] Those of ordinary skill in the art can understand that all or part of the steps in implementing the above method embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, optical disc, etc.

[0069] The above-disclosed are only the preferred embodiments of the present invention, and of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A transmission cable fault location method based on the differential iteration method, characterized in that, The method includes the following steps: S1. Receive the signals actually monitored by all preset fault monitoring devices on the transmission line, and determine that the fault monitoring devices carrying the fault power frequency characteristics in the signals are all required fault location devices. Further, in the preset transmission line topology diagram, determine the shortest line to which each two fault location devices belong; S2. On each shortest line, respectively extract the initial actual moments when the fault traveling wave signals reach the corresponding two fault location devices, and combine the preset total length of each shortest line to calculate the traveling wave speed of the fault traveling wave signal in each shortest line; S3. Set each shortest line as an evenly divided line; S4. Obtain the current evenly divided line, divide it into N equal parts, and mark the two ends of the current evenly divided line and the N - 1 evenly divided points as fault points. Combine the total length of the current evenly divided line and the corresponding traveling wave speed, and simulate and calculate the initial theoretical moments when the fault traveling wave signals generated by the N + 1 fault points on the current evenly divided line reach the corresponding two fault location devices; where N is a positive integer greater than 1; S5. On the current evenly divided line, compare the two initial theoretical moments of each fault traveling wave signal with the corresponding two initial actual moments. According to the comparison result, when it is determined that the iteration end condition is not met, among the N + 1 fault points on the current evenly divided line, screen out the fault points that meet the predetermined conditions. Further, on the current evenly divided line, determine the smallest line interval formed by the screened fault points and their left and right adjacent fault points. After setting the determined smallest line interval as the current evenly divided line, return to step S4; S6. If it is determined that the iteration end condition is met according to the comparison result, end the iterative calculation of the current evenly divided line, extract the next shortest line as the current evenly divided line, and then return to step S4; S7. After the iterative calculations of all the shortest lines are completed, output the fault points screened in the last iteration on each shortest line and determine them as the final fault points.

2. The transmission cable fault location method based on the differential iteration method according to claim 1, wherein The fault monitoring devices are installed on the distribution boxes at each line node of the transmission line.

3. The transmission cable fault location method based on the differential iteration method according to claim 2, wherein The iteration end condition is that the difference between the time difference formed between the two initial theoretical moments when a certain fault traveling wave signal arrives and the time difference formed between the corresponding two initial actual moments is less than a preset threshold.

4. The transmission cable fault location method based on the differential iteration method according to claim 3, characterized in that The predetermined condition is that the time difference formed between the two initial theoretical moments when a certain fault traveling wave signal arrives and the time difference formed between the corresponding two initial actual moments are the closest, and the difference between the two is greater than the preset threshold.

5. A transmission cable fault location system based on the differential iteration method, characterized in that, It includes: A line screening unit, configured to receive the signals actually monitored by all preset fault monitoring devices on the transmission line, and determine that the fault monitoring devices carrying the fault power frequency characteristics in the signals are all required fault location devices. Further, in the preset transmission line topology diagram, determine the shortest line to which each two fault location devices belong; A traveling wave velocity calculation unit is configured to respectively extract the initial actual arrival times of the fault traveling wave signals at the corresponding two fault location devices on each shortest line, and calculate the traveling wave velocity of the fault traveling wave signals in each shortest line in combination with the preset total length of each shortest line. An equal-division line setting unit is configured to set each shortest line as an equal-division line. A simulation initial theoretical time calculation unit is configured to obtain the current equal-division line, perform N equal divisions to obtain the two ends of the current equal-division line and N - 1 equal-division points, all of which are marked as fault points, and simulate and calculate the initial theoretical arrival times of the fault traveling wave signals generated by the N + 1 fault points on the current equal-division line at the corresponding two fault location devices in combination with the total length of the current equal-division line and the corresponding traveling wave velocity; where N is a positive integer greater than 1. A current equal-division line iterative calculation unit is configured to, on the current equal-division line, compare the two initial theoretical times of each fault traveling wave signal with the corresponding two initial actual times, and according to the comparison result, when it is determined that the preset iteration end condition is not satisfied, screen out the fault points that meet the predetermined conditions among the N + 1 fault points on the current equal-division line, further determine the smallest line interval formed by the screened fault points and their adjacent left and right fault points on the current equal-division line, and after setting the determined smallest line interval as the current equal-division line, return to the simulation initial theoretical time calculation unit. A next equal-division line iterative calculation unit is configured to, if it is determined that the iteration end condition is satisfied according to the comparison result, end the iterative calculation of the current equal-division line, extract the next shortest line as the current equal-division line, and then return to the simulation initial theoretical time calculation unit. A fault result output unit is configured to, after the iterative calculations of all the shortest lines are completed, output the fault points screened in the last iteration on each shortest line and determine them as the final fault points.

6. The transmission cable fault location system based on the differential iteration method according to claim 5, characterized in that, The fault monitoring devices are installed on the distribution boxes at each line node of the transmission line.

7. The transmission cable fault location system based on the differential iteration method according to claim 6, characterized in that, The iteration end condition is that the difference between the time difference formed between the two initial theoretical arrival times of a certain fault traveling wave signal and the time difference formed between the corresponding two initial actual arrival times is less than a preset threshold.

8. The transmission cable fault location system based on the differential iteration method according to claim 7, characterized in that, The predetermined condition is that the time difference formed between the two initial theoretical arrival times of a certain fault traveling wave signal and the time difference formed between the corresponding two initial actual arrival times are the closest, and the difference between the two is greater than the preset threshold.

Images