A cable live defect positioning method, device and medium based on resistance-capacitance coupling
By injecting a broadband signal through an RC coupling channel, calculating the complex impedance spectrum of the capacitor, and reconstructing the system impedance spectrum, the access and location problems of the traditional reflection method in cable live-line detection are solved, and high-precision live-line detection of cable defects is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2026-04-29
- Publication Date
- 2026-07-10
AI Technical Summary
Existing traditional positioning reflection methods are difficult to apply directly to live cable detection, and the RC coupling channel will affect the system impedance spectrum and distance domain positioning results.
By injecting a broadband signal through an RC coupling channel, calculating the complex impedance spectrum of the capacitor, reconstructing the system impedance spectrum, performing frequency domain difference calculation and interpolation, and using inverse Fourier transform to obtain the distance domain defect diagnosis function, the live detection of cable defects is realized.
It enables live detection of cable defects without damaging the insulation structure, reducing the difficulty of on-site modification and the risk of detection access, and improving the positioning accuracy.
Smart Images
Figure CN122362006A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of cable live-line detection and defect location technology, and in particular to a method, equipment and medium for locating cable live-line defects based on resistance-capacitance coupling. Background Technology
[0002] Power cables are widely used in power distribution networks, substations, rail transit, petrochemical plants, and large industrial power supply systems. Their operational reliability directly affects power supply safety and equipment stability. During long-term operation, cables are subjected to factors such as heat, electrical and mechanical stress, humid environments, and partial discharge, which can easily lead to defects such as insulation aging, localized water trees, shielding damage, and poor joint contact. If these defects are not detected in their early stages, they may further develop into breakdowns, short circuits, or grounding faults.
[0003] Among existing cable defect location technologies, time-domain reflection and frequency-domain reflection are the most typical reflection location methods. Time-domain reflection typically injects a pulse signal into the out-of-service cable and determines the defect location based on the arrival time of the reflected wave. It has advantages such as simple principle and lightweight equipment, but its location accuracy is easily affected by wavefront distortion, attenuation, and noise. Frequency-domain reflection, on the other hand, measures the input impedance spectrum or reflection coefficient spectrum and then obtains the distance domain response through inverse Fourier transform, offering higher location resolution and bandwidth utilization.
[0004] However, traditional reflection methods are mostly geared towards offline testing scenarios. For live cables, it is difficult for testing equipment to directly connect to the cable core metal, and it must meet requirements for operational safety, insulation isolation, and low intrusion access. Therefore, reflection methods are relatively less used in online and live cable testing. Existing online monitoring methods rely more on partial discharge, sheath current, temperature, dielectric loss, or oscillating waves. These methods can reflect the cable's operating status, but they still have shortcomings in accurate defect location, early identification of weak defects, or accessibility at the cable's head end.
[0005] In field scenarios such as power distribution equipment, switchgear, or cable terminals, an RC coupling channel that maintains insulation isolation from the cable core or busbar can be installed. This channel consists of coupling capacitors, voltage divider resistors, and detection ports, enabling the formation of a broadband signal coupling path without direct contact with the primary conductor. By using this RC coupling channel to superimpose or inject low-energy broadband detection signals onto live cables, it is possible to achieve the safe access required for online detection using the reflection method without damaging the original insulation structure of the power equipment, without power interruption, and without changing the main circuit operation mode.
[0006] However, the RC coupling channel itself introduces series capacitance, voltage divider resistors, and parasitic inductance at the beginning, and its impedance frequency characteristics significantly affect the injected signal and the measured system impedance spectrum. Experiments and simulations both show that when a series capacitor or RC coupling structure exists at the beginning, directly performing an inverse Fourier transform on the system impedance spectrum easily leads to problems such as enhanced beginning response, broadened location peaks, masking of defect peaks, or decreased location sensitivity. Therefore, how to achieve live injection through an RC coupling channel while simultaneously eliminating or reducing the influence of the beginning coupling network on the frequency domain reflection location results is a crucial problem that urgently needs to be solved in the location of live defects in cables. Summary of the Invention
[0007] This application provides a method, device, and medium for locating live defects in cables based on resistance-capacitance coupling, which solves the following technical problems: existing traditional positioning reflection methods are difficult to apply directly to live cable detection and live operating cable cores, and it is difficult to directly connect to the detection signal. The resistance-capacitance coupling channel also affects the system impedance spectrum and distance domain positioning results.
[0008] The embodiments of this application adopt the following technical solutions: On one hand, this application provides a method for locating live defects in cables based on resistance-capacitance coupling, comprising: constructing a resistance-capacitance coupling injection path based on a resistance-capacitance coupling channel that is insulated from the cable core or busbar; calculating and classifying the complex impedance of the resistance-capacitance coupling channel through the resistance-capacitance coupling injection path and based on the presence of capacitance parameters to obtain a channel capacitance impedance spectrum; reconstructing and calculating the system impedance spectrum at the detection port based on the broadband signal in the resistance-capacitance coupling injection path to obtain a cable system impedance spectrum; calculating the frequency domain difference between the cable system impedance spectrum and the channel capacitance impedance spectrum to obtain a compensated cable frequency domain diagnostic impedance spectrum; performing an inverse Fourier transform on the weighted frequency domain spectrum of the interpolated cable frequency domain diagnostic impedance spectrum to obtain a distance domain defect diagnosis function; and performing a judgment process on the cable defect based on the peak value of the diagnosis function through the distance domain defect diagnosis function to obtain a cable defect detection result.
[0009] This application's embodiments utilize an RC coupling channel as the detection signal injection channel, eliminating the need to damage the cable's insulation structure or directly contact the cable core, thus facilitating live-line detection of cable defects. Furthermore, it extends the traditional reflection method from offline detection during power outages to live-line detection scenarios, resolving the difficulty of safely accessing and injecting signals into operating cables. Simultaneously, the high-insulation RC coupling path enables the injection of broadband signals into the cable core with minimal intrusion, reducing the difficulty of on-site modifications and the risks associated with detection access. Moreover, by utilizing the obtained capacitance impedance spectrum of the RC coupling channel and compensating for the system impedance spectrum, the influence of the initial coupling structure on the distance-domain positioning results can be reduced.
[0010] In one feasible implementation, an RC coupling injection path is constructed based on an RC coupling channel that maintains insulation isolation from the cable core or busbar. Specifically, this includes: when the cable under test is in a energized operating state, selecting an RC coupling channel that maintains insulation isolation from the cable core or busbar as the detection signal coupling path; connecting the detection device to the low-voltage side of the RC coupling channel, and injecting a low-energy broadband signal from the detection device through the detection signal coupling path; and constructing the RC coupling injection path based on the detection signal coupling path and the low-energy broadband signal.
[0011] In one feasible implementation, the complex impedance of the RC coupling channel is calculated and classified based on the presence of capacitor parameters through the RC coupling injection path to obtain the channel capacitance impedance spectrum. Specifically, if the capacitor parameters are known to exist, then according to... The complex impedance of the capacitor with known capacitor parameters is obtained. ;in, The imaginary unit; Pi; This is the actual capacitance value of the RC coupling channel; The first in the frequency sweep sequence Frequency values of each frequency point; This refers to the frequency domain sampling point number; if the capacitance parameter is unknown, then according to... The complex impedance of the capacitor with unknown capacitance parameters is obtained. ;in, For the first The impedance amplitude of the RC coupling channel capacitor measured at each frequency point; For the first The impedance phase of the RC coupling channel capacitor measured at each frequency point; Here is the frequency domain sampling point number, and ; The number of sweep points is used; based on the complex impedance of the capacitor with known capacitance parameters and the complex impedance of the capacitor with unknown capacitance parameters, the channel capacitance impedance spectrum is constructed.
[0012] In one feasible implementation, the system impedance spectrum at the detection port is reconstructed based on the broadband signal in the RC coupling injection path to obtain the cable system impedance spectrum. Specifically, this includes: based on... The complex impedance of the cable system is obtained. ;in, For the first The system complex impedance at each frequency point For the first The impedance amplitude of the cable system measured at each frequency point; For the first The phase impedance of the cable system measured at each frequency point; Here is the frequency domain sampling point number, and ; This refers to the number of frequency sweep points; The unit is the imaginary unit; based on the complex impedance of the cable system, the impedance spectrum of the cable system is constructed.
[0013] In one feasible implementation, the frequency domain difference between the impedance spectrum of the cable system and the impedance spectrum of the channel capacitance is calculated to obtain the compensated cable frequency domain diagnostic impedance spectrum, specifically including: according to The frequency domain diagnostic impedance spectrum of the cable was obtained. ;in, The impedance spectrum of the cable system; The impedance spectrum of the channel capacitance is given.
[0014] In one feasible implementation, the interpolated cable frequency domain diagnostic impedance spectrum is subjected to an inverse Fourier transform of the weighted frequency domain spectrum to obtain a distance domain defect diagnosis function. Specifically, this includes: deduplicating and sorting the frequency sequences in the RC coupling channel, and constructing an equally spaced frequency axis from zero to the highest effective frequency; interpolating the cable frequency domain diagnostic impedance spectrum based on the equally spaced frequency axis to obtain a complex spectrum on the equally spaced frequency sequence; selecting the imaginary part of the complex spectrum as the input of the fast inverse Fourier transform; and obtaining the distance domain defect diagnosis function d[n] according to d[n]=|IFFT(|S[k]|W[k])| (1≤n≤NT); where IFFT is the fast inverse Fourier transform; W[k] is the window function weight at the k-th frequency point; NT is the number of distance domain sampling points after the inverse Fourier transform; k is the frequency domain sampling point number; n is the distance domain sampling point number; S[k] is the selected cable frequency domain diagnostic impedance spectrum, and S[k] contains multiple frequency domain diagnostic impedance spectra.
[0015] In one feasible implementation, based on the distance domain defect diagnosis function, and according to The time intervals corresponding to adjacent distance domain sampling points after inverse Fourier transform are obtained. ;in, The frequency interval between adjacent frequency sampling points; For the number of frequency sweep points; according to ,get Cable distance corresponding to each distance domain sampling point ;in, To detect the speed at which a signal propagates in a cable; This represents the sampling point number in the distance domain.
[0016] In one feasible implementation, the cable defect is judged based on the peak value of the diagnostic function using the distance domain defect diagnosis function to obtain the cable defect detection result. Specifically, this includes: constructing a cable distance axis based on the cable distances corresponding to several distance domain sampling points; and detecting and judging the position of the cable distance axis using the peak value of the diagnostic function in the distance domain defect diagnosis function: if the peak value of the diagnostic function is located in the cable end region, the cable defect detection result is determined as an end reflection result; if the peak value of the diagnostic function is located in the middle region of the cable, the cable defect detection result is determined as a local defect result.
[0017] Secondly, embodiments of this application also provide a cable live defect location device based on resistor-capacitor coupling, the device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to execute a cable live defect location method based on resistor-capacitor coupling as described in any of the above embodiments.
[0018] Thirdly, embodiments of this application also provide a non-volatile computer storage medium, wherein the storage medium is a non-volatile computer-readable storage medium, the non-volatile computer-readable storage medium stores at least one program, each program including instructions, and the instructions, when executed by a terminal, cause the terminal to execute a cable live defect location method based on RC coupling as described in any of the above embodiments.
[0019] This application provides a method, device, and medium for locating live defects in cables based on resistive-capacitive coupling. Compared with the prior art, the embodiments of this application have the following beneficial technical effects: 1. Using the RC coupling channel as the detection signal injection channel does not require damaging the cable's insulation structure or directly contacting the cable core, which is beneficial for realizing live detection of cable defects.
[0020] 2. The traditional reflection method is extended from offline detection during power outages to live detection scenarios, solving the problem of the reflection method being difficult to safely access and inject signals into operating cables.
[0021] 3. By utilizing a high-insulation resistance-capacitance coupling path, broadband signals can be injected into the cable core with a low degree of intrusion, reducing the difficulty of on-site modification and the risk of detection access.
[0022] 4. Obtaining the impedance spectrum of the RC coupling channel and compensating for the system impedance spectrum can reduce the influence of the head-end coupling structure on the range domain positioning results. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 A flowchart illustrating a method for locating live defects in cables based on resistance-capacitance coupling, provided in this application embodiment; Figure 2 This is a schematic diagram of a cable live defect location system provided in an embodiment of this application; Figure 3 A comparison diagram of simulation positioning results provided in an embodiment of this application; Figure 4 A comparison diagram of the amplitude-frequency and phase-frequency characteristics of an ideal capacitor model and a measured coupling capacitor provided in an embodiment of this application; Figure 5 This application provides an example of an impedance spectrum comparison diagram between the cable body impedance spectrum, system impedance spectrum, ideal model compensation, and measured coupling capacitance compensation. Figure 6 A comparison diagram of experimental localization results provided in an embodiment of this application; Figure 7 This is a schematic diagram of a cable live defect location device based on RC coupling, provided as an embodiment of this application. Detailed Implementation
[0024] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.
[0025] It should be noted that the cable live defect location system based on RC coupling injection in this application can utilize an RC coupling channel composed of coupling capacitors, voltage divider resistors, and detection ports as the injection and measurement channel for detection signals. The detection equipment is connected to the low-voltage side of the RC coupling channel; the detection equipment generates a broadband signal, which is injected into the live cable core through the RC coupling channel; the capacitance impedance spectrum of the RC coupling channel and the broadband impedance spectrum of the system are obtained; by compensating the RC coupling network at the beginning, a frequency domain spectrum for defect diagnosis is constructed; finally, an inverse Fourier transform is performed on the frequency domain spectrum to obtain the distance domain defect diagnosis function, and the defect location is determined based on the peak position.
[0026] This application provides a method for locating live defects in cables based on resistive-capacitive coupling, such as... Figure 1 As shown, the method for locating live defects in cables based on resistance-capacitance coupling specifically includes steps S101-S106: S101. Based on the RC coupling channel that maintains insulation isolation from the cable core or busbar, an RC coupling injection path is constructed.
[0027] Specifically, when the cable to be tested is in a energized operating state, an RC coupling channel that is insulated from the cable core or busbar is selected as the coupling path for the detection signal.
[0028] Furthermore, the detection equipment is connected to the low-voltage side of the RC coupling channel, and a low-energy broadband signal from the detection equipment is injected for control through the detection signal coupling path. Finally, based on the detection signal coupling path and the low-energy broadband signal, an RC coupling injection path is constructed.
[0029] As a feasible implementation method, Figure 2 This is a schematic diagram of a cable live-line defect location system provided in an embodiment of this application, as shown below. Figure 2 As shown, a resistance-capacitive coupling injection path needs to be constructed first. That is, when the cable under test is in a energized operating state, a resistance-capacitive coupling channel that is insulated from the cable core or busbar is selected as the coupling path for the detection signal. The detection equipment is connected to the low-voltage side of the resistance-capacitive coupling channel, and a low-energy broadband signal is injected into the cable core through this resistance-capacitive coupling path.
[0030] In one embodiment, Figure 2 This is a schematic diagram of a system structure for wideband signal injection into cable cores via a resistor-capacitor coupling channel, as shown below. Figure 2 As shown, in the actual RC coupling channel, the parallel resistance is approximately 10MΩ, which is much larger than the equivalent impedance of the coupling capacitor and cable loop within the test frequency band. Therefore, in broadband signal injection analysis, this parallel resistance has a weak effect on current shunting in the measurement loop. It can be approximated that the measurement loop consists of the test signal source, the signal source internal resistance, the coupling capacitor, and the cable under test connected in series. In the simulation, a live-line detection model is established based on this equivalent series loop, consisting of a 50Ω signal source internal resistance, a 20pF coupling capacitor, a 10kV distribution cable, local defects, and the cable end boundary. The cable length is 100m, with defects set at 20m and 50m, and the cable end is open-circuited. The simulation calculates the location results without and with the RC coupling channel.
[0031] S102. Through the RC coupling injection path, and based on the existence of capacitor parameters, the complex impedance of the RC coupling channel is calculated and classified to obtain the channel capacitance impedance spectrum.
[0032] Specifically, if the capacitance parameters are known, i.e., the capacitance parameters are known, the capacitance impedance spectrum can be directly constructed. Then, according to... The complex impedance of the capacitor with known capacitor parameters is obtained. .in, The imaginary unit; Pi; This is the actual capacitance value of the RC coupling channel; The first in the frequency sweep sequence Frequency values of each frequency point; This represents the frequency domain sampling point number.
[0033] Furthermore, if the capacitance parameters are unknown, that is, when the capacitance parameters are unknown, it is necessary to use an impedance analyzer to measure the impedance spectrum of the coupling channel capacitance, and reconstruct the complex impedance spectrum from the measured amplitude and phase: according to The complex impedance of the capacitor with unknown capacitance parameters is obtained. .in, For the first The impedance amplitude of the RC coupling channel capacitor measured at each frequency point; For the first The impedance phase of the RC coupling channel capacitor measured at each frequency point; Here is the frequency domain sampling point number, and ; This represents the number of sweep points.
[0034] Furthermore, based on the complex impedance of the capacitor with known capacitance parameters and the complex impedance of the capacitor with unknown capacitance parameters, the channel capacitance impedance spectrum is constructed.
[0035] S103. Based on the broadband signal in the RC coupling injection path, the system impedance spectrum at the detection port is reconstructed and calculated to obtain the cable system impedance spectrum.
[0036] Specifically, first according to The complex impedance of the cable system is obtained. .in, For the first The system complex impedance at each frequency point For the first The impedance amplitude of the cable system measured at each frequency point; For the first The phase impedance of the cable system measured at each frequency point; Here is the frequency domain sampling point number, and ; This refers to the number of frequency sweep points; It is the imaginary unit.
[0037] Furthermore, based on the complex impedance of the cable system, the impedance spectrum of the cable system is constructed.
[0038] In one embodiment, it is necessary to measure the impedance spectrum of the cable system, which is achieved by injecting a broadband signal into the cable core through an RC coupling channel and measuring the impedance spectrum of the cable system at the detection port.
[0039] S104. Calculate the frequency domain difference between the impedance spectrum of the cable system and the impedance spectrum of the channel capacitance to obtain the compensated cable frequency domain diagnostic impedance spectrum.
[0040] Specifically, first according to The frequency domain diagnostic impedance spectrum of the cable was obtained. .in, Impedance spectrum of the cable system; This is the channel capacitance impedance spectrum.
[0041] In one embodiment, it is also necessary to construct the cable frequency domain diagnostic impedance spectrum, that is, to reduce the influence of the first-end RC coupling structure on the distance domain positioning results, the above-mentioned frequency domain diagnostic impedance spectrum is constructed.
[0042] S105. Perform an inverse Fourier transform on the weighted frequency domain spectrum of the interpolated cable frequency domain diagnostic impedance spectrum to obtain the distance domain defect diagnostic function.
[0043] Specifically, the frequency sequence in the RC coupling channel is first deduplicated and sorted, and an equally spaced frequency axis is constructed from zero to the highest effective frequency. Then, based on the equally spaced frequency axis, the frequency domain diagnostic impedance spectrum of the cable is interpolated to obtain the complex spectrum on the equally spaced frequency sequence.
[0044] Furthermore, the imaginary part of the complex spectrum is selected as the input of the fast inverse Fourier transform.
[0045] Furthermore, according to The distance domain defect diagnosis function is obtained. .in, For Fast Inverse Fourier Transform; For the first Window function weights at each frequency point; This represents the number of sampling points in the distance domain after the inverse Fourier transform. This refers to the frequency domain sampling point number; This refers to the sampling point number in the distance domain; The selected cable frequency domain diagnostic impedance spectrum, and It includes multiple frequency domain diagnostic impedance spectra, and for example, it also includes: (Measured Coupling Capacitance Compensation Spectrum) (Ideal model compensation spectrum) or (System impedance spectrum).
[0046] In one embodiment, the inverse Fourier transform is needed to obtain the distance domain defect diagnosis function. That is, the frequency sequence is deduplicated and sorted, and a range from 0 to the highest effective frequency is constructed. The frequency axes are then evenly spaced. Interpolation is then performed on the defect diagnosis spectra in each range domain to obtain the complex spectrum over the evenly spaced frequency sequence. Finally, the imaginary part of the spectrum is selected as the IFFT input, and a Chebyshev window is used for weighting. After performing an inverse Fourier transform on the weighted frequency domain spectrum, the range domain defect diagnosis function is obtained.
[0047] Furthermore, it is also necessary to combine the distance domain defect diagnosis function with the sampling interval. and cable propagation speed To construct the subsequent distance axis. First, based on... The time intervals corresponding to adjacent distance domain sampling points after inverse Fourier transform are obtained. .in, The frequency interval between adjacent frequency sampling points; This refers to the number of frequency sweep points. And based on... ,get Cable distance corresponding to each distance domain sampling point .in, To detect the speed at which a signal propagates in a cable, the speed can be obtained by looking up a table based on the cable type. This represents the sampling point number in the distance domain.
[0048] In one embodiment, Figure 3 A simulation positioning result comparison diagram is provided for an embodiment of this application, such as... Figure 3 As shown, simulation results indicate that when performing IFFT on the impedance spectrum of a system containing a first-end RC coupling channel, the impedance spectrum measurement is easily affected by the first-end series capacitor, which leads to the failure of the distance domain diagnostic curve.
[0049] S106. Using the distance domain defect diagnosis function, the cable defect is judged based on the peak value of the diagnosis function to obtain the cable defect detection result.
[0050] Specifically, a cable distance axis is first constructed based on the cable distances corresponding to several distance domain sampling points.
[0051] Furthermore, the cable distance axis position is determined by the peak value of the diagnostic function in the distance domain defect diagnostic function: if the peak value is located at the end of the cable, the cable defect detection result is determined to be an end reflection result. If the peak value is located in the middle of the cable, the cable defect detection result is determined to be a local defect result.
[0052] In one embodiment, the final determination of the cable's live-line test result is as follows: based on the distance domain defect diagnosis function d[x] obtained in step 105, the cable defect is judged: if the peak value of the diagnosis function is located near the end of the cable, it is determined to be an end reflection; if the peak value is located in the middle area of the cable, it is determined to be a local defect.
[0053] In one embodiment, Figure 4 A comparison diagram of the amplitude-frequency and phase-frequency characteristics of an ideal capacitor model and a measured coupling capacitor provided for embodiments of this application (including: (a) amplitude-frequency characteristic comparison diagram and (b) phase-frequency characteristic comparison diagram), as shown. Figure 4 As shown; Figure 5 This application provides an embodiment of the impedance spectrum comparison diagram between the cable body impedance spectrum, system impedance spectrum, ideal model compensation, and measured coupling capacitance compensation (including: (a) amplitude frequency characteristic comparison diagram and (b) phase frequency characteristic comparison diagram). Figure 5 As shown, where Figure 5 This section presents a comparison of the cable's impedance spectrum, system impedance spectrum, and impedance spectra of measured and ideally compensated coupling capacitors. A broadband impedance spectroscopy testing device was used to measure the impedance spectra of individual coupling capacitors and the system impedance spectrum of the coupling capacitors connected in series with the cable. The complex impedance spectrum was reconstructed from the amplitude and phase. The experimental capacitance value was approximately 63 pF; therefore, the measured coupling capacitor impedance spectrum and an ideal 63 pF capacitor model were compared to analyze the impact of the initial coupling capacitor on the cable defect location results.
[0054] In one embodiment, Figure 6 A comparative diagram of experimental positioning results provided for embodiments of this application (including: (a) cable body impedance spectrum, (b) system impedance spectrum, (c) ideal model compensation spectrum, and (d) measured coupling capacitance compensation spectrum), as shown in the figure. Figure 6 As shown, the system impedance spectra are constructed respectively. Measured Coupling Capacitance Compensation Spectrum Compensation spectrum of ideal model Then, an inverse Fourier transform was performed on the frequency domain spectrum to obtain the distance domain defect diagnosis curve. Experimental results show that the measured coupling capacitance compensation spectrum and the ideal capacitance compensation spectrum are both better than the system impedance spectrum for locating open circuits at the end, thus verifying the feasibility of using the RC coupling channel for live cable defect detection.
[0055] As a feasible implementation method, the combined results of experiments and simulations show that: the RC coupling channel can serve as a broadband signal injection path for cable cores, providing access conditions for the application of the reflection method to live cable detection; the RC coupling structure at the beginning affects the localization results of the direct IFFT of the system impedance spectrum; after compensation by measured coupling capacitance or approximate ideal model, the influence of the coupling structure at the beginning can be reduced to a certain extent, improving the identifiability and reliability of the defect localization results.
[0056] In addition, embodiments of this application also provide a method and device for locating live defects in cables based on resistive-capacitive coupling, such as... Figure 7 As shown, the cable live defect location method device 700 based on RC coupling specifically includes: At least one processor 701; and a memory 702 communicatively connected to the at least one processor 701; wherein the memory 702 stores instructions executable by the at least one processor 701 to enable the at least one processor 701 to execute: Based on the RC coupling channel that maintains insulation isolation from the cable core or busbar, an RC coupling injection path is constructed. By using the RC coupling injection path and based on the presence of capacitor parameters, the complex impedance of the RC coupling channel is calculated and classified to obtain the channel capacitance impedance spectrum. Based on the broadband signal in the RC coupling injection path, the system impedance spectrum at the detection port is reconstructed and calculated to obtain the cable system impedance spectrum. The frequency domain difference between the impedance spectrum of the cable system and the impedance spectrum of the channel capacitance is calculated to obtain the compensated cable frequency domain diagnostic impedance spectrum. The interpolated cable frequency domain diagnostic impedance spectrum is subjected to an inverse Fourier transform of the weighted frequency domain spectrum to obtain the distance domain defect diagnosis function. By using the distance domain defect diagnosis function, cable defects are judged based on the peak value of the diagnosis function, and the cable defect detection results are obtained.
[0057] This application's embodiments utilize an RC coupling channel as the detection signal injection channel, eliminating the need to damage the cable's insulation structure or directly contact the cable core, thus facilitating live-line detection of cable defects. Furthermore, it extends the traditional reflection method from offline detection during power outages to live-line detection scenarios, resolving the difficulty of safely accessing and injecting signals into operating cables. Simultaneously, the high-insulation RC coupling path enables the injection of broadband signals into the cable core with minimal intrusion, reducing the difficulty of on-site modifications and the risks associated with detection access. Moreover, by utilizing the obtained capacitance impedance spectrum of the RC coupling channel and compensating for the system impedance spectrum, the influence of the initial coupling structure on the distance-domain positioning results can be reduced.
[0058] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the device and medium embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the description of the method embodiments.
[0059] The devices and media provided in this application are one-to-one with the methods. Therefore, the devices and media also have similar beneficial technical effects as their corresponding methods. Since the beneficial technical effects of the methods have been described in detail above, the beneficial technical effects of the devices and media will not be repeated here.
[0060] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0061] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0062] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0063] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0064] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.
[0065] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.
[0066] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.
[0067] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0068] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of this specification.
Claims
1. A method for locating live defects in cables based on resistive-capacitive coupling, characterized in that, The method includes: Based on the RC coupling channel that maintains insulation isolation from the cable core or busbar, an RC coupling injection path is constructed. Through the aforementioned RC coupling injection path, and based on the presence of capacitor parameters, the complex impedance of the RC coupling channel is calculated and classified to obtain the channel capacitance impedance spectrum. Based on the broadband signal in the RC coupling injection path, the system impedance spectrum at the detection port is reconstructed and calculated to obtain the cable system impedance spectrum. The frequency domain difference between the impedance spectrum of the cable system and the impedance spectrum of the channel capacitance is calculated to obtain the compensated cable frequency domain diagnostic impedance spectrum. The interpolated cable frequency domain diagnostic impedance spectrum is subjected to an inverse Fourier transform of the weighted frequency domain spectrum to obtain the distance domain defect diagnosis function. The cable defect detection result is obtained by using the distance domain defect diagnosis function to perform judgment processing based on the peak value of the diagnosis function.
2. The method for locating live defects in cables based on RC coupling according to claim 1, characterized in that, Based on the RC coupling channel that maintains insulation isolation from the cable core or busbar, an RC coupling injection path is constructed, specifically including: When the cable under test is in a live operating state, select an RC coupling channel that is insulated from the cable core or busbar as the coupling path for the detection signal; The detection device is connected to the low-voltage side of the RC coupling channel, and the low-energy broadband signal in the detection device is injected for control through the detection signal coupling path; Based on the detection signal coupling path and the low-energy broadband signal, the RC coupling injection path is constructed.
3. The method for locating live defects in cables based on resistive-capacitive coupling according to claim 1, characterized in that, Through the aforementioned RC coupling injection path, and based on the presence of capacitor parameters, the complex impedance of the RC coupling channel is calculated and classified to obtain the channel capacitance impedance spectrum, specifically including: If the capacitance parameters are known to exist, then according to The complex impedance of the capacitor with known capacitor parameters is obtained. ;in, The imaginary unit; Pi; This is the actual capacitance value of the RC coupling channel; The first in the frequency sweep sequence Frequency values of each frequency point; This refers to the frequency domain sampling point number; If the capacitance parameter is unknown, then according to The complex impedance of the capacitor with unknown capacitance parameters is obtained. ;in, For the first The impedance amplitude of the RC coupling channel capacitor measured at each frequency point; For the first The impedance phase of the RC coupling channel capacitor measured at each frequency point; Here is the frequency domain sampling point number, and ; This refers to the number of frequency sweep points; The channel capacitance impedance spectrum is constructed based on the complex impedance of the capacitor with known capacitance parameters and the complex impedance of the capacitor with unknown capacitance parameters.
4. The method for locating live defects in cables based on resistive-capacitive coupling according to claim 1, characterized in that, Based on the broadband signal in the RC coupling injection path, the system impedance spectrum at the detection port is reconstructed and calculated to obtain the cable system impedance spectrum, specifically including: according to The complex impedance of the cable system is obtained. ;in, For the first The system complex impedance at each frequency point For the first The impedance amplitude of the cable system measured at each frequency point; For the first The phase impedance of the cable system measured at each frequency point; Here is the frequency domain sampling point number, and ; This refers to the number of frequency sweep points; The imaginary unit; Based on the complex impedance of the cable system, the impedance spectrum of the cable system is constructed.
5. The method for locating live defects in cables based on resistive-capacitive coupling according to claim 1, characterized in that, The frequency domain difference between the impedance spectrum of the cable system and the impedance spectrum of the channel capacitance is calculated to obtain the compensated cable frequency domain diagnostic impedance spectrum, specifically including: according to The frequency domain diagnostic impedance spectrum of the cable was obtained. ;in, The impedance spectrum of the cable system; The impedance spectrum of the channel capacitance is given.
6. The method for locating live defects in cables based on resistive-capacitive coupling according to claim 1, characterized in that, The interpolated cable frequency domain diagnostic impedance spectrum is subjected to an inverse Fourier transform of the weighted frequency domain spectrum to obtain the distance domain defect diagnosis function, which specifically includes: The frequency sequences in the RC coupling channel are deduplicated and sorted, and an equally spaced frequency axis is constructed from zero to the highest effective frequency. Based on the equally spaced frequency axes, the frequency domain diagnostic impedance spectrum of the cable is interpolated to obtain a complex spectrum on the equally spaced frequency sequence. The imaginary part of the complex spectrum is selected as the input of the fast inverse Fourier transform; according to The distance domain defect diagnosis function is obtained. ;in, For Fast Inverse Fourier Transform; For the first Window function weights at each frequency point; This represents the number of sampling points in the distance domain after the inverse Fourier transform. This refers to the frequency domain sampling point number; This refers to the sampling point number in the distance domain; The selected cable frequency domain diagnostic impedance spectrum, and It includes multiple frequency domain diagnostic impedance spectra.
7. The method for locating live defects in cables based on resistive-capacitive coupling according to claim 6, characterized in that, Based on the distance domain defect diagnosis function, and according to The time intervals corresponding to adjacent distance domain sampling points after inverse Fourier transform are obtained. ;in, The frequency interval between adjacent frequency sampling points; This refers to the number of frequency sweep points; according to ,get Cable distance corresponding to each distance domain sampling point ;in, To detect the speed at which a signal propagates in a cable; This represents the sampling point number in the distance domain.
8. The method for locating live defects in cables based on resistive-capacitive coupling according to claim 1, characterized in that, The cable defect detection result is obtained by using the distance domain defect diagnosis function to perform judgment processing based on the peak value of the diagnosis function, specifically including: Based on the cable distances corresponding to several distance domain sampling points, a cable distance axis is constructed; The cable's distance axis is located and determined by the peak value of the diagnostic function in the distance domain defect diagnostic function. If the peak value of the diagnostic function is located in the cable end region, the cable defect detection result is determined as the end reflection result; If the peak value of the diagnostic function is located in the middle region of the cable, the cable defect detection result is determined to be a local defect result.
9. A cable live-line defect location device based on resistive-capacitive coupling, characterized in that, The device includes: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions executable by the at least one processor, enabling the at least one processor to perform a method for locating live cable defects based on RC coupling according to any one of claims 1-8.
10. A non-volatile computer storage medium, characterized in that, The storage medium is a non-volatile computer-readable storage medium that stores at least one program, each program including instructions that, when executed by a terminal, cause the terminal to perform a cable live defect location method based on RC coupling according to any one of claims 1-8.