Cable fault positioning method and system, electronic equipment and storage medium

Abstract

The invention provides a cable fault positioning method and system, electronic equipment and a storage medium, and the method comprises the steps: obtaining a first traveling wave signal and a second traveling wave signal when a fault traveling wave flows through the two ends of a to-be-detected cable after a fault occurs; respectively filtering the first traveling wave signal and the second traveling wave signal to obtain a first target traveling wave signal and a second target traveling wave signal; performing cross-correlation calculation on the first target traveling wave signal and the second target traveling wave signal; obtaining a time difference between the first arrival time and the second arrival time based on a maximum value of cross-correlation calculation; and obtaining a fault occurrence position based on the time difference. According to the scheme, fault positioning is performed based on the filtered target traveling wave signal, so that the fault positioning precision is improved; and on the other hand, compared with a mode of calculating the time difference according to the trigger time in the related technology, the time difference determined by adopting the cross-correlation calculation mode in the scheme is more accurate, and the fault positioning precision can be further improved.

Description

Technical Field

[0001] The present application relates to the technical field of cable fault location, and in particular to a cable fault location method, system, electronic device and storage medium. Background Art

[0002] With the rapid development of modern society and the continuous increase in electricity demand, high-voltage cables are an important part of the power system, so it is particularly important to ensure the stability of power supply. However, due to the operating environment, the long service life of the cable, aging and other reasons, cable failures often occur, which will inevitably affect the normal operation of the power system. In order to reduce the impact of faults on the power system and improve the reliability of power supply, it is very important to quickly and accurately locate the cable fault point. At present, transmission line fault distance measurement equipment based on the traveling wave principle has been widely used in power systems.

[0003] The two-end ranging method in related technology usually uses the trigger time to calculate the time difference of reaching the two ends of the cable, or performs feature analysis on the time domain and waveform shape of the traveling wave to select fixed feature points to calculate the time difference. Both calculation methods are relatively one-sided and have low positioning accuracy for cable faults. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a cable fault location method, system, electronic device and storage medium to solve the above-mentioned problems.

[0005] In a first aspect, an embodiment of the present application provides a cable fault locating method, the method comprising: obtaining a first traveling wave signal and a second traveling wave signal when a fault traveling wave flows through both ends of a cable to be inspected after a fault occurs; filtering the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal; performing cross-correlation calculation on the first target traveling wave signal and the second target traveling wave signal; obtaining a time difference between a first arrival time and a second arrival time based on the maximum value of the cross-correlation calculation; wherein the first arrival time and the second arrival time are respectively the time when the fault traveling wave arrives at both ends of the cable to be inspected; based on the time difference, obtaining the fault location.

[0006] In the implementation process of the above scheme, the traveling wave signals collected from both ends of the cable to be inspected are filtered to filter out noise and clutter signals, and then the filtered target traveling wave signals are cross-correlated, and the time difference between the traveling wave reaching the two ends of the cable to be inspected is determined based on the maximum value of the cross-correlation calculation, and finally the fault location is determined based on the time difference. On the one hand, fault location based on the filtered target traveling wave signal is conducive to improving the fault location accuracy; on the other hand, compared with the method of calculating the time difference based on the trigger time in the related technology, the time difference determined by the cross-correlation calculation method in the above scheme is more accurate, which is conducive to further improving the fault location accuracy.

[0007] In an implementation of the first aspect, the filtering processing is performed on the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal, including: converting the first traveling wave signal and the second traveling wave signal into the frequency domain to obtain a first spectrum and a second spectrum; extracting an energy concentration band between the first spectrum and the second spectrum; wherein the energy concentration band is used to characterize a frequency band with the highest similarity and / or the most concentrated energy between the first spectrum and the second spectrum; based on the energy concentration band, filtering processing is performed on the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal.

[0008] In the implementation process of the above scheme, the energy concentration band in the traveling wave signal is determined by performing frequency domain modal analysis on the traveling wave signal, thereby filtering out the environmental noise and clutter signals in the traveling wave signal, which is beneficial to improving the extraction accuracy of the target traveling wave signal, and further improving the fault location accuracy of the above cable fault location method.

[0009] In an implementation of the first aspect, the extracting of the energy concentration band between the first spectrum and the second spectrum includes: solving an objective function and determining the energy concentration band in a preset frequency band; wherein the objective function includes a similarity judgment item and / or an energy concentration judgment item; the similarity judgment item is used to characterize the similarity between the first spectrum and the second spectrum in the same preset frequency band; the energy concentration judgment item is used to characterize the degree of energy concentration of the first spectrum and the second spectrum in the same preset frequency band.

[0010] In the process of implementing the above scheme, the energy concentration frequency band is determined by solving the objective function. On the one hand, it is beneficial to improve the extraction accuracy of the energy concentration frequency band, and then improve the fault location accuracy of the above cable fault location method; on the other hand, the objective function can comprehensively consider the similarity and energy concentration degree between the first spectrum and the second spectrum, which is beneficial to further improve the extraction accuracy of the energy concentration frequency band, and then further improve the fault location accuracy of the above cable fault location method.

[0011] In an implementation manner of the first aspect, when the objective function includes the similarity judgment item and the energy concentration judgment item, the objective function also includes a balance coefficient for balancing the similarity judgment item and the energy concentration judgment item.

[0012] In the implementation process of the above scheme, by setting the balance coefficient, the balance between the energy distance discrimination term and the similarity discrimination term can be optimized, which is conducive to more accurate extraction of the energy concentration frequency band, and thus improving the fault location accuracy of the above cable fault location method; on the other hand, by setting the balance coefficient, the above cable fault location method can be applied to more application scenarios, which is conducive to improving the robustness of the above cable fault location method.

[0013] In an implementation of the first aspect, the solving of the objective function and determining the energy concentration band in the preset frequency band include: obtaining a first energy value of the first spectrum and a second energy value of the second spectrum; wherein the first energy value is used to characterize the accumulated energy value of the first spectrum in each of the preset frequency bands; the second energy value is used to characterize the accumulated energy value of the second spectrum in each of the preset frequency bands; normalizing the first energy value and the second energy value to obtain a third energy value and a fourth energy value; calculating the similarity judgment item and / or the energy concentration judgment item based on the third energy value and the fourth energy value; solving the objective function and determining the energy concentration band in the preset frequency band.

[0014] In the implementation process of the above scheme, the normalized accumulated energy value is used to calculate the objective function value, which can eliminate the influence of the energy magnitude difference on the solution process, making the solution result of the objective function more accurate, and thus helping to improve the fault location accuracy of the above cable fault location method.

[0015] In an implementation of the first aspect, the method of obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation includes: normalizing the calculated value of the cross-correlation calculation to obtain the normalized calculated value of the cross-correlation calculation; and obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the normalized calculated value of the cross-correlation calculation.

[0016] In the implementation process of the above scheme, the calculated values ​​of the cross-correlation calculation are normalized to adjust the amplitude of the target traveling wave signal to the same scale, thereby eliminating the influence of the amplitude difference on the cross-correlation result, which is beneficial to improve the accuracy of the cross-correlation judgment and further improve the fault location accuracy of the above cable fault location method.

[0017] In an implementation of the first aspect, the method of obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation includes: judging whether the fault occurs in the cable to be inspected based on the positive or negative condition of the maximum value of the cross-correlation calculation value; if the fault occurs in the cable to be inspected, obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation.

[0018] In the implementation process of the above scheme, judging whether the fault occurs in the cable to be tested by calculating the positive or negative value of the maximum value through cross-correlation is helpful to reduce the amount of invalid calculations, thereby improving the fault location efficiency of the above cable fault location method.

[0019] In a second aspect, an embodiment of the present application provides a fault location system, the system comprising a first traveling wave monitoring device, a second traveling wave monitoring device and a host computer, the first traveling wave monitoring device and the second traveling wave monitoring device are respectively installed at both ends of the cable to be inspected, the first traveling wave monitoring device and the second traveling wave monitoring device are respectively electrically connected to the host computer, wherein:

[0020] The first traveling wave monitoring device and the second traveling wave monitoring device are respectively used to collect the first traveling wave signal and the second traveling wave signal when the fault traveling wave flows through the two ends of the cable to be inspected after the fault occurs, and send the first traveling wave signal and the second traveling wave signal to the host computer;

[0021] The host computer is used to obtain the first traveling wave signal and the second traveling wave signal; filter the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal; perform cross-correlation calculation on the first target traveling wave signal and the second target traveling wave signal; obtain the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation; wherein the first arrival time and the second arrival time are respectively the time when the fault traveling wave arrives at both ends of the cable to be inspected; based on the time difference, obtain the fault location.

[0022] In a third aspect, an embodiment of the present application provides an electronic device, comprising: a processor, a memory, and a communication bus, wherein the processor and the memory communicate with each other through the communication bus; the memory stores computer program instructions that can be executed by the processor, and when the computer program instructions are read and run by the processor, the method provided by the first aspect or any possible implementation of the first aspect is executed.

[0023] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, on which computer program instructions are stored. When the computer program instructions are read and executed by a processor, the method provided by the first aspect or any possible implementation of the first aspect is executed.

[0024] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by practicing the embodiments of the present application. The purpose and other advantages of the present application can be realized and obtained by the structures specifically pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the principle of a double-terminal traveling wave fault location method provided in an embodiment of the present application;

[0027] Figure 2 A schematic diagram of a process for locating a cable fault provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of a first traveling wave signal in a certain scenario provided in an embodiment of the present application;

[0029] Figure 4 A schematic diagram of a second traveling wave signal in a certain scenario provided in an embodiment of the present application;

[0030] Figure 5 A schematic diagram of a cross-correlation calculation value in a certain scenario provided in an embodiment of the present application;

[0031] Figure 6 A schematic diagram of the structure of a cable fault point locating system provided in an embodiment of the present application;

[0032] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] The following will describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0035] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0036] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0037] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0038] An embodiment of the present application provides a cable fault location method, which filters the traveling wave signals collected from both ends of the cable to be inspected, thereby filtering out noise and clutter signals, and then performs cross-correlation calculation on the filtered target traveling wave signals, and determines the time difference between the traveling wave reaching the two ends of the cable to be inspected based on the maximum value of the cross-correlation calculation, and finally determines the fault location based on the time difference. On the one hand, fault location based on the filtered target traveling wave signal is conducive to improving the fault location accuracy; on the other hand, compared with the method of calculating the time difference based on the trigger time in the related art, the time difference determined by the cross-correlation calculation method in the above scheme is more accurate, which is conducive to further improving the fault location accuracy.

[0039] Before introducing the above-mentioned cable fault location method, the principle of the double-terminal traveling wave fault location method involved in the embodiment of the present application is first introduced:

[0040] When a cable fault occurs, a fault traveling wave signal with a large amplitude change will be generated. The two-end traveling wave fault location method generally determines the location of the fault point by the time difference between the fault traveling wave signal reaching the two ends of the cable. Figure 1 Assume that the cable fails at point F, the time when the fault traveling wave signal reaches the traveling wave measurement end A is recorded as t1, and the time when the fault traveling wave signal reaches the traveling wave measurement end B is recorded as t2. The total length of the cable is D, and the propagation rate of the traveling wave is v. The distance L between the fault point and the traveling wave measurement end A is calculated using the double-end traveling wave fault location method. F The method is:

[0041]

[0042] The above t2-t1 is the time difference between the fault traveling wave signal reaching the traveling wave measuring end A and the traveling wave measuring end B. After determining the time difference, the fault point can be located.

[0043] See also Figure 2 A flow chart of a cable fault location method is shown. The cable fault location method provided in the embodiment of the present application can be applied to an electronic device, which may include a physical device such as a server, a PC, a tablet computer or a smart phone, or a virtual device such as a virtual machine or a container. The electronic device may be a single device, a combination of multiple devices, or a cluster of a large number of devices. The above-mentioned cable fault location method may include:

[0044] Step S110: obtaining a first traveling wave signal and a second traveling wave signal when a fault traveling wave flows through both ends of the cable to be inspected respectively after a fault occurs;

[0045] Step S120: filtering the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal;

[0046] Step S130: performing cross-correlation calculation on the first target traveling wave signal and the second target traveling wave signal;

[0047] Step S140: obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation; wherein the first arrival time and the second arrival time are respectively the time when the fault traveling wave reaches both ends of the cable to be inspected;

[0048] Step S150: Based on the time difference, obtain the fault occurrence location.

[0049] The above-mentioned traveling wave refers to the wave state in which the wave propagates forward along the medium after being generated from the wave source, and the waveform keeps moving. When a cable fault occurs, a traveling wave signal with a sudden change in amplitude will be generated at the fault point. Therefore, by monitoring whether a traveling wave signal is generated in the cable, it can be determined whether the cable has a fault.

[0050] The first traveling wave signal and the second traveling wave signal acquired in the above step S110 may be: traveling wave signals sent by traveling wave monitoring devices installed at both ends of the cable to be inspected to the electronic device executing the above cable fault locating method.

[0051] After the fault traveling wave signal is generated at the fault point, due to factors such as electromagnetic interference, equipment noise, and environmental conditions, the fault traveling wave signal will be mixed with some noise signals and clutter signals during the transmission process in the cable to be tested. The purpose of filtering the traveling wave signal in the above step S120 is to filter out part or all of the noise signals and clutter signals, and retain the initial traveling wave signal when the fault traveling wave signal is generated, that is, the target traveling wave signal. The embodiment of the present application filters the traveling wave signal to filter out the noise and clutter signals in the traveling wave signal, or to reduce the influence of the noise and clutter signals on the cable fault location, thereby helping to improve the positioning accuracy of the cable fault location.

[0052] The embodiment of the present application can filter the traveling wave signal in at least the following two ways:

[0053] The first method: using wavelet transform to filter the traveling wave signal;

[0054] Wavelet transform is an effective time-frequency analysis tool that can decompose signals at different time and frequency resolutions. By selecting the appropriate wavelet basis and decomposition layer number, the noise and clutter signals in the traveling wave signal can be separated, thereby extracting the target traveling wave signal.

[0055] The second method is to convert the traveling wave signal into the frequency domain and then perform frequency domain modal analysis. Based on the analysis results, the environmental noise and clutter signals are filtered. For example, the environmental noise and clutter signals are band-pass filtered to obtain the target traveling wave signal.

[0056] Optionally, the above step S120 includes:

[0057] Step S121: converting the first traveling wave signal and the second traveling wave signal into the frequency domain to obtain a first spectrum and a second spectrum;

[0058] Optionally, Fourier transform may be performed on the first traveling wave signal and the second traveling wave signal, so as to convert the first traveling wave signal and the second traveling wave signal from the time domain to the frequency domain, and obtain a first spectrum of the first traveling wave signal and a second spectrum of the second traveling wave signal;

[0059] Step S122: extracting an energy-concentrated frequency band between the first spectrum and the second spectrum; wherein the energy-concentrated frequency band is used to characterize a frequency band with the highest similarity and / or the most concentrated energy between the first spectrum and the second spectrum;

[0060] After a fault occurs, the main components of the first traveling wave signal and the second traveling wave signal are both the target traveling wave signal (i.e., the initial traveling wave signal). Therefore, the energy-concentrated frequency band with the highest similarity or the most concentrated energy between the first spectrum and the second spectrum is more likely to be the frequency band where the target traveling wave signal is located. Therefore, the frequency band where the target traveling wave signal is located can be determined by searching for the energy-concentrated frequency band in the first spectrum and the second spectrum.

[0061] Step S123: Based on the energy concentration frequency band, filter the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal;

[0062] After the energy concentration frequency band is determined, the first traveling wave signal and the second traveling wave signal are band-pass filtered to filter out signals in other frequency bands, thereby obtaining the first target traveling wave signal and the second target traveling wave signal.

[0063] The above scheme determines the energy concentration frequency band in the traveling wave signal by performing frequency domain modal analysis on the traveling wave signal, thereby filtering out the environmental noise and clutter signals in the traveling wave signal, which is beneficial to improving the extraction accuracy of the target traveling wave signal, and further improving the fault location accuracy of the above cable fault location method.

[0064] The method for extracting the energy concentration frequency band in step S122 is introduced below. The embodiment of the present application can extract the energy concentration frequency band in the traveling wave signal in at least the following four ways:

[0065] The first method: by calculating the similarity between the first spectrum and the second spectrum in the same preset frequency band, the preset frequency band whose similarity is greater than a preset similarity threshold is determined as the energy concentration frequency band;

[0066] It can be understood that the traveling wave signal obtained in the above step S110 is generally a discrete signal, and the spectrum data obtained after converting the traveling wave signal into the frequency domain is generally also discrete. Therefore, the similarity between the first spectrum and the second spectrum in each preset frequency band can be calculated by the Euclidean distance between each sampling point.

[0067] Of course, the similarity between the first spectrum and the second spectrum in the same preset frequency band may also be calculated by the degree of deviation of the energy values ​​between the sampling points or the degree of deviation of the total energy values ​​in the preset frequency band.

[0068] The second method: by calculating the value of the energy concentration index, a preset frequency band whose energy concentration index value is greater than a preset index threshold is determined as the energy concentration frequency band;

[0069] For example: taking the preset frequency band as a unit, the energy values ​​of the first spectrum and the second spectrum in each preset frequency band are calculated, and then the energy product between the energy value of the first spectrum in the frequency band and the energy value of the second spectrum in the same preset frequency band is calculated, and then the preset frequency band whose energy product is greater than the preset energy product threshold is determined as the energy concentration band.

[0070] The third method: by calculating the similarity between the first spectrum and the second spectrum in the same preset frequency band and the value of the energy concentration index, the preset frequency band whose similarity is greater than a preset similarity threshold and whose energy product is greater than a preset energy product threshold is determined as the energy concentration frequency band;

[0071] The fourth method is to convert the energy concentration frequency band extraction problem into a target optimization problem, construct and solve the objective function, obtain the optimal solution, and thus determine the energy concentration frequency band;

[0072] Optionally, the above-mentioned step S122 includes: solving the objective function and determining the energy concentration frequency band in the preset frequency band; wherein the objective function includes a similarity judgment item and / or an energy concentration judgment item; the similarity judgment item is used to characterize the similarity between the first spectrum and the second spectrum in the same preset frequency band; the energy concentration judgment item is used to characterize the degree of energy concentration of the first spectrum and the second spectrum in the same preset frequency band.

[0073] Taking the objective function including similarity discriminant and energy aggregation discriminant as an example, the objective function can be in the form of:

[0074]

[0075] Among them, D i is the similarity between the first spectrum and the second spectrum in the i-th preset frequency band; i is the energy product of the first spectrum and the second spectrum in the i-th preset frequency band;

[0076] By solving the nonlinear maximum value of y, the preset frequency band i that maximizes the y value can be obtained, that is, the energy concentration frequency band.

[0077] The above scheme determines the energy concentration frequency band by solving the objective function. On the one hand, it is conducive to improving the extraction accuracy of the energy concentration frequency band, and then improving the fault location accuracy of the above cable fault location method; on the other hand, the objective function can comprehensively consider the similarity and energy concentration degree between the first spectrum and the second spectrum, which is conducive to further improving the extraction accuracy of the energy concentration frequency band, and then further improving the fault location accuracy of the above cable fault location method.

[0078] Optionally, when the objective function includes a similarity judgment item and an energy concentration judgment item, the objective function also includes a balance coefficient for balancing the similarity judgment item and the energy concentration judgment item.

[0079] After setting the balance coefficient, the objective function can be expressed as:

[0080]

[0081] Among them, μ is the balance coefficient used to balance the importance of the similarity discriminant term and the energy aggregation discriminant term.

[0082] In the implementation process of the above scheme, by setting the balance coefficient, the balance between the energy distance discrimination term and the similarity discrimination term can be optimized, which is conducive to more accurate extraction of the energy concentration frequency band, and thus improving the fault location accuracy of the above cable fault location method; on the other hand, by setting the balance coefficient, the above cable fault location method can be applied to more application scenarios, which is conducive to improving the robustness of the above cable fault location method.

[0083] Optionally, the above-mentioned solution of the objective function determines the energy concentration band in the preset frequency band, including: obtaining a first energy value of the first spectrum and a second energy value of the second spectrum; wherein the first energy value is used to characterize the cumulative energy value of the first spectrum in each preset frequency band; the second energy value is used to characterize the cumulative energy value of the second spectrum in each preset frequency band; normalizing the first energy value and the second energy value to obtain a third energy value and a fourth energy value; based on the third energy value and the fourth energy value, calculating a similarity discriminant item and / or an energy concentration discriminant item; solving the objective function to determine the energy concentration band in the preset frequency band.

[0084] The third energy value and the fourth energy value are obtained in the following manner:

[0085]

[0086] Among them, E mi and E si are the third energy value and the fourth energy value respectively; [f 1i ,f 2i ] is the i-th preset frequency band; M[k] and S[k] are the first spectrum and the second spectrum respectively; E T1 and E T2 are the total energy value of the first spectrum and the total energy value of the second spectrum respectively.

[0087] The above scheme uses the normalized accumulated energy value to calculate the objective function value, which can eliminate the influence of energy magnitude difference on the solution process, making the solution result of the objective function more accurate, and thus is conducive to improving the fault location accuracy of the above cable fault location method.

[0088] The scheme for performing cross-correlation calculation in step S130 is introduced below:

[0089] Cross-correlation is a method used to measure the similarity between two signals. For two continuous signals x(t) and y(t), the cross-correlation function R xy (τ) is defined as:

[0090]

[0091] Where, τ is the time delay;

[0092] The filtered first target traveling wave signal and the second target traveling wave signal are represented as m′[n] and s′[n] respectively, where n is the index of the sampling point. Taking the first target traveling wave signal and the second target traveling wave signal both containing N sampling points as an example, the cross-correlation function of the first target traveling wave signal m′[n] and the second target traveling wave signal s′[n] can be defined as:

[0093]

[0094] Wherein, N is the number of sampling points of the first target traveling wave signal and the second target traveling wave signal; p represents the multiple of the time offset relative to the unit sampling duration, taking p=3 as an example, it means that the time offset is 3 times the unit sampling duration.

[0095] The cross-correlation function takes the maximum value R ms (p * ), it means that the second target traveling wave signal s′[n] is offset by p * After that, the similarity with the first target traveling wave signal m′[n] is the highest. At this time, based on p * The time difference between the traveling wave signal reaching the two ends of the cable under test is determined by the unit sampling time.

[0096] It is understandable that since the essence of cross-correlation is to measure the similarity of two signals in the time dimension, when there is a difference in the amplitude magnitude of the two signals, it may affect the judgment result of the cross-correlation, thereby affecting the positioning accuracy of the cable fault location. Based on this, the embodiment of the present application provides the following solution:

[0097] Optionally, the above-mentioned step S140 obtains the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation, including: normalizing the calculated value of the cross-correlation calculation to obtain the normalized calculated value of the cross-correlation calculation; and obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the normalized calculated value of the cross-correlation calculation.

[0098] The method for normalizing the cross-correlation calculation value may be:

[0099]

[0100] Among them, R ms(p)′ is the normalized calculated value of the cross-correlation calculation.

[0101] The above scheme normalizes the calculated values ​​of the cross-correlation calculation, thereby adjusting the amplitude of the target traveling wave signal to the same scale, eliminating the influence of the amplitude difference on the cross-correlation result, which is beneficial to improve the accuracy of the cross-correlation judgment, and further improves the fault location accuracy of the above cable fault location method.

[0102] It is understandable that the double-ended traveling wave fault location method may divide the complete cable into multiple sections of the cable to be tested, and then perform double-ended traveling wave fault location on the multiple sections of the cable to be tested. In this scenario, the fault traveling wave signal detected by the traveling wave monitoring equipment installed at both ends of the cable to be tested may be generated by the fault point in other cables to be tested. At this time, it is necessary to determine whether the fault point is in the section of the cable to be tested. Based on this, the embodiment of the present application provides the following solution:

[0103] Optionally, the above step S140 obtains the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation, including: judging whether the fault occurs in the cable to be inspected based on the positive or negative condition of the maximum value of the cross-correlation calculation value; if the fault occurs in the cable to be inspected, obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation.

[0104] It can be understood that in addition to the positive and negative conditions of the maximum value of the cross-correlation calculation, the location of the fault point is also related to the installation direction of the traveling wave monitoring equipment installed at both ends of the cable to be tested, specifically:

[0105] The first scenario: The traveling wave monitoring devices installed at both ends of the cable to be tested are installed in the same direction;

[0106] When no fault occurs in the cable section to be tested, the currents flowing through the two traveling wave monitoring devices at the same time are in opposite directions;

[0107] When a fault occurs in the cable section to be tested, the current flows from the fault point in the section to the traveling wave monitoring devices installed at both ends of the cable to be tested. At this time, the directions of the currents monitored by the two traveling wave monitoring devices are the same;

[0108] Therefore, in the first scenario, if the maximum value calculated by the cross-correlation is positive, that is, the directions of the traveling wave currents monitored by the two traveling wave monitoring devices are the same, then the fault point is located within the cable section to be tested; if the maximum value calculated by the cross-correlation is negative, that is, the directions of the traveling wave currents monitored by the two traveling wave monitoring devices are opposite, then the fault point is located outside the cable section to be tested.

[0109] The second scenario: the installation directions of the traveling wave monitoring devices installed at both ends of the cable to be tested are inconsistent;

[0110] When no fault occurs in the cable section to be tested, the currents flowing through the two traveling wave monitoring devices at the same time have the same direction;

[0111] When a fault occurs in the cable section to be tested, the current flows from the fault point in the section to the traveling wave monitoring devices installed at both ends of the cable to be tested. At this time, the directions of the currents monitored by the two traveling wave monitoring devices are opposite;

[0112] Therefore, in the second scenario, if the maximum value of the cross-correlation calculation is positive, that is, the directions of the traveling wave currents monitored by the two traveling wave monitoring devices are the same, then the fault point is outside the cable section to be tested; if the maximum value of the cross-correlation calculation is negative, that is, the directions of the traveling wave currents monitored by the two traveling wave monitoring devices are opposite, then the fault point is inside the cable section to be tested.

[0113] The above scheme determines whether the fault is located in the cable to be tested by calculating the positive or negative value of the maximum value through cross-correlation, which is beneficial to reducing the amount of invalid calculations, thereby improving the fault location efficiency of the above cable fault location method.

[0114] The method for obtaining the fault location in step S150 is described below:

[0115] The fault point location can be calculated as:

[0116]

[0117] Where d is the distance between the fault point and a certain traveling wave monitoring device; D is the length of the cable to be tested; v is the traveling wave propagation velocity; p * In order to make R ms The index offset when (p)′ takes the maximum value; t s The unit sampling duration.

[0118] In order to facilitate understanding of the working principle of the above-mentioned cable fault location method, the embodiment of the present application provides a specific application scheme of the above-mentioned cable fault location method in a certain scenario, mainly including:

[0119] Step 1: obtaining a first traveling wave signal and a second traveling wave signal collected by traveling wave monitoring equipment installed at both ends of the cable to be tested;

[0120] The traveling wave monitoring equipment at both ends of the cable to be tested is used to collect the traveling wave signal propagating in the cable to be tested in real time. In addition, to avoid signal distortion and high-frequency signal loss, the high-frequency traveling wave sampling rate is not less than 100MHz, and the sampling time is not less than 1ms. The first traveling wave signal and the second traveling wave signal obtained are respectively as follows: Figure 3 and Figure 4 As shown by the red line segments in , both traveling wave signals are in the time domain, denoted as m[n] and s[n] respectively. Figure 3 and Figure 4The horizontal axis of the coordinate system is time, and the vertical axis is current amplitude.

[0121] Step 2: Use Fourier transform to convert the first traveling wave signal m[n] and the second traveling wave signal s[n] from the time domain to the frequency domain to obtain the first spectrum M[k] and the second spectrum S[k], where 0≤k≤N-1, and N is the number of sampling points of the first traveling wave signal m[n] and the second traveling wave signal s[n];

[0122] Step 3: extracting the energy concentration frequency band;

[0123] In order to ensure the consistency of reflected waves when faults occur at both ends, the energy distribution of the spectrum at both ends is calculated respectively, and the common characteristics of energy aggregation of reflected waves are extracted. The master-slave energy distribution membership function is as follows:

[0124]

[0125] Among them, E mi and E si are the third energy value and the fourth energy value respectively; [f 1i ,f 2i ] is the i-th preset frequency band; M[k] and S[k] are the first spectrum and the second spectrum respectively; E T1 and E T2 are the total energy values ​​of the first spectrum and the total energy values ​​of the second spectrum respectively;

[0126] Extract the frequency band with the highest similarity and the most concentrated energy distribution among the preset frequency bands, and consider using the Euclidean distance D i As a similarity criterion, e i The distribution of energy product, the objective function is as follows:

[0127]

[0128] e i =E mi ×E si

[0129] Wherein, μ is the balance coefficient used to balance the importance of similarity discriminant and energy aggregation discriminant; f i is the center frequency of each i-th preset frequency band;

[0130] By solving the nonlinear maximum value of y, the preset frequency band i that maximizes the y value can be obtained, that is, the energy concentration frequency band.

[0131] Step 4: Bandpass filter the first traveling wave signal m[n] and the second traveling wave signal s[n] to filter out signals in other frequency bands and obtain the first target traveling wave signal m′[n] and the second target traveling wave signal s′[n].

[0132] Step 5: performing cross-correlation calculation on the first target traveling wave signal m′[n] and the second target traveling wave signal s′[n];

[0133] The calculation method can be:

[0134]

[0135] Where N is the number of sampling points of the first target traveling wave signal and the second target traveling wave signal; p represents the time offset relative to the unit sampling time length t s multiples of;

[0136] The cross-correlation calculation results are as follows: Figure 5 As shown, Figure 5 The horizontal axis is the time delay, and the vertical axis is the cross-correlation exchange function value.

[0137] Step 5: Normalize the cross-correlation calculation value:

[0138]

[0139] Among them, R ms (p)′ is the normalized calculated value of the cross-correlation calculation.

[0140] It can be understood that when the signal lengths of the first target signal and the second target signal are M points and N points respectively, the total length of the cross-correlation function calculated should be M+N-1 lengths. In particular, when the signal lengths of both the master and slave ends are N points, the length of the cross-correlation function is 2N-1 lengths, and the time difference range should be [(1-N) / f s , (N-1) / f s ], where f s is the actual traveling wave signal sampling rate.

[0141] Step 6: Based on the positive or negative condition of the maximum value of the cross-correlation calculation value, determine whether the fault occurs in the cable to be inspected;

[0142] In the above scenario, the traveling wave monitoring devices installed at both ends of the cable to be tested are installed in the same direction, so:

[0143]

[0144] Depend on Figure 5 The cross-correlation function value shown in the figure shows that when R ms (p)′ takes the maximum value R ms (p * )′, R ms (p * )′>0, therefore, it is determined that the fault occurs in the cable under test.

[0145] Step 7: Determine the location of the fault point:

[0146] The fault point location can be calculated as:

[0147]

[0148] Where d is the distance between the fault point and a certain traveling wave monitoring device; D is the length of the cable to be tested; v is the traveling wave propagation velocity; p * In order to make R ms The index offset when (p)′ takes the maximum value; t s The unit sampling duration.

[0149] See also Figure 6 The embodiment of the present application is based on the same inventive concept. The embodiment of the present application also provides a cable fault point positioning system 200, which includes: a first traveling wave monitoring device 210, a second traveling wave monitoring device 220 and a host computer 230. The first traveling wave monitoring device 210 and the second traveling wave monitoring device are respectively installed at both ends of the cable to be inspected, and the first traveling wave monitoring device 210 and the second traveling wave monitoring device 220 are respectively electrically connected to the host computer, wherein:

[0150] The first traveling wave monitoring device 210 and the second traveling wave monitoring device 220 are respectively used to collect the first traveling wave signal and the second traveling wave signal when the fault traveling wave flows through the two ends of the cable to be inspected after the fault occurs, and send the first traveling wave signal and the second traveling wave signal to the host computer 230;

[0151] The host computer 230 is used to obtain a first traveling wave signal and a second traveling wave signal; filter the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal; perform cross-correlation calculation on the first target traveling wave signal and the second target traveling wave signal; obtain a time difference between a first arrival time and a second arrival time based on a maximum value of the cross-correlation calculation; wherein the first arrival time and the second arrival time are respectively the times when the fault traveling wave arrives at both ends of the cable to be inspected; and obtain a fault location based on the time difference.

[0152] Figure 7 A schematic diagram of an electronic device provided in an embodiment of the present application. Figure 7 The electronic device 300 includes: a processor 310, a memory 320 and a communication interface 330. These components are interconnected and communicate with each other through a communication bus 340 and / or other forms of connection mechanisms (not shown).

[0153] The memory 320 includes one or more (only one is shown in the figure), which may be, but not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The processor 310 and other possible components may access the memory 320 and read and / or write data therein.

[0154] The processor 310 includes one or more (only one is shown in the figure), which can be an integrated circuit chip with signal processing capabilities. The above-mentioned processor 310 can be a general-purpose processor, including a central processing unit (CPU), a micro controller unit (MCU), a network processor (NP) or other conventional processors; it can also be a special-purpose processor, including a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components.

[0155] The communication interface 330 includes one or more (only one is shown in the figure), which can be used to communicate directly or indirectly with other devices to exchange data. For example, the communication interface 330 can be an Ethernet interface; it can be a mobile communication network interface, such as an interface of a 3G, 4G, or 5G network; or it can be other types of interfaces with data transceiving functions.

[0156] One or more computer program instructions may be stored in the memory 320 , and the processor 310 may read and execute these computer program instructions to implement the cable fault location method and other desired functions provided in the embodiments of the present application.

[0157] Understandably, Figure 7 The structure shown is for illustration only. The electronic device 300 may also include Figure 7 More or fewer components as shown, or with Figure 7 Different configurations shown. Figure 7 Each component shown in the figure can be implemented by hardware, software or a combination thereof. For example, the electronic device 300 can be a single server (or other device with computing processing capabilities), a combination of multiple servers, a cluster of a large number of servers, etc., and can be both a physical device and a virtual device.

[0158] The present application also provides a computer-readable storage medium, which stores computer program instructions. When the computer program instructions are read and executed by a computer processor, the cable fault location method provided by the present application is executed. For example, the computer-readable storage medium can be implemented as Figure 7 The memory 320 in the electronic device 300.

[0159] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0160] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0162] The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A cable fault location method, characterized in that: The method comprises: Acquire a first traveling wave signal and a second traveling wave signal when a fault traveling wave flows through two ends of the cable to be inspected respectively after a fault occurs; Performing filtering processing on the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal; Performing cross-correlation calculation on the first target traveling wave signal and the second target traveling wave signal; Obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation; wherein the first arrival time and the second arrival time are respectively the time when the fault traveling wave arrives at both ends of the cable to be inspected; Based on the time difference, the fault occurrence location is obtained.

2. The cable fault location method according to claim 1, characterized in that: The filtering the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal comprises: Convert the first traveling wave signal and the second traveling wave signal into a frequency domain to obtain a first frequency spectrum and a second frequency spectrum; Extracting an energy-concentrated frequency band between the first spectrum and the second spectrum; wherein the energy-concentrated frequency band is used to characterize a frequency band with the highest similarity and / or the most concentrated energy between the first spectrum and the second spectrum; Based on the energy concentration frequency band, the first traveling wave signal and the second traveling wave signal are filtered respectively to obtain a first target traveling wave signal and a second target traveling wave signal.

3. The cable fault location method according to claim 2, characterized in that: The extracting the energy concentration frequency band between the first spectrum and the second spectrum comprises: Solve the objective function and determine the energy concentration frequency band in the preset frequency band; wherein the objective function includes a similarity judgment item and / or an energy concentration judgment item; the similarity judgment item is used to characterize the similarity between the first spectrum and the second spectrum in the same preset frequency band; the energy concentration judgment item is used to characterize the degree of energy concentration of the first spectrum and the second spectrum in the same preset frequency band.

4. The cable fault location method according to claim 3, characterized in that: When the objective function includes the similarity judgment item and the energy concentration judgment item, the objective function also includes a balance coefficient for balancing the similarity judgment item and the energy concentration judgment item.

5. The cable fault location method according to claim 4, characterized in that: The solving of the objective function and determining the energy concentration frequency band in the preset frequency band include: Obtaining a first energy value of the first spectrum and a second energy value of the second spectrum; wherein the first energy value is used to represent the accumulated energy value of the first spectrum in each of the preset frequency bands; and the second energy value is used to represent the accumulated energy value of the second spectrum in each of the preset frequency bands; Normalizing the first energy value and the second energy value to obtain a third energy value and a fourth energy value; Based on the third energy value and the fourth energy value, calculating the similarity discriminant item and / or the energy concentration discriminant item; Solve the objective function and determine the energy concentration band in the preset frequency band.

6. The cable fault location method according to claim 1, characterized in that: The obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation includes: Normalizing the calculated value of the cross-correlation calculation to obtain a normalized calculated value of the cross-correlation calculation; The time difference between the first arrival time and the second arrival time is obtained based on the maximum value of the normalized calculation value of the cross-correlation calculation.

7. The cable fault location method according to any one of claims 1 to 6, characterized in that: The obtaining the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation includes: Based on the positive or negative condition of the maximum value of the cross-correlation calculation value, judging whether the fault occurs in the cable to be inspected; If a fault occurs in the cable to be inspected, the time difference between the first arrival time and the second arrival time is obtained based on the maximum value of the cross-correlation calculation.

8. A fault location system, characterized in that: The system includes a first traveling wave monitoring device, a second traveling wave monitoring device and a host computer, wherein the first traveling wave monitoring device and the second traveling wave monitoring device are respectively installed at two ends of the cable to be inspected, and the first traveling wave monitoring device and the second traveling wave monitoring device are respectively electrically connected to the host computer, wherein: The first traveling wave monitoring device and the second traveling wave monitoring device are respectively used to collect the first traveling wave signal and the second traveling wave signal when the fault traveling wave flows through the two ends of the cable to be inspected after the fault occurs, and send the first traveling wave signal and the second traveling wave signal to the host computer; The host computer is used to obtain the first traveling wave signal and the second traveling wave signal; filter the first traveling wave signal and the second traveling wave signal respectively to obtain a first target traveling wave signal and a second target traveling wave signal; perform cross-correlation calculation on the first target traveling wave signal and the second target traveling wave signal; obtain the time difference between the first arrival time and the second arrival time based on the maximum value of the cross-correlation calculation; wherein the first arrival time and the second arrival time are respectively the time when the fault traveling wave arrives at both ends of the cable to be inspected; based on the time difference, obtain the fault location.

9. An electronic device, characterized in that: include: A processor, a memory and a communication bus, wherein the processor and the memory communicate with each other via the communication bus; The memory stores program instructions executable by the processor, and the processor can execute the method according to any one of claims 1 to 7 by calling the program instructions.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and when the computer instructions are executed by a computer, the computer is caused to perform the method according to any one of claims 1 to 7.

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