Cable fault positioning method, device, system and medium

Abstract

The embodiment of the invention provides a cable fault positioning method, device and system and a medium. The method comprises the steps that a signal generator is controlled to send a reference signal to a to-be-detected cable, a signal acquisition device is controlled to perform signal acquisition on the to-be-detected cable to obtain a reflected signal, and the reference signal has different frequencies in different time displacement intervals; carrying out preprocessing and time-frequency domain conversion processing on the reference signal and the reflection signal to respectively obtain a reference time-frequency spectrum and a reflection time-frequency spectrum; determining the time delay of the reflection signal relative to the reference signal according to the reference time-frequency spectrum and the reflection time-frequency spectrum; and determining a fault point position of the to-be-detected cable according to the time delay and the signal propagation speed of the to-be-detected cable. The method is used for achieving the effect of improving the fault point positioning precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power systems, and particularly relates to a cable fault positioning method, device, system and medium. BACKGROUND

[0002] In the power system, the cable as an important power transmission medium, its safety and reliability are directly related to the stability and continuity of power supply. With the acceleration of urbanization, more and more power cables are buried underground, which although improves the aesthetics and safety of the power system, but also increases the difficulty of cable fault detection and positioning.

[0003] In recent years, with the rapid development of signal processing technology, sensor technology and automation technology, cable fault detection and positioning technology has made significant progress. Especially the fault positioning method based on signal reflection principle, such as time domain reflection method and traveling wave method, is widely used because of its simple operation and rapid positioning. However, in the processing of complex cable network and multi-fault point scene, the frequency spectrum of different fault points often overlaps, which makes it difficult to achieve accurate positioning of fault points.

[0004] Therefore, there is an urgent need for a cable fault positioning method with higher time-frequency analysis accuracy of signals. SUMMARY

[0005] The cable fault positioning method, device, system and medium provided by the embodiments of the present application can improve the accuracy of cable fault positioning.

[0006] In a first aspect, the embodiments of the present application provide a cable fault positioning method, comprising:

[0007] a control signal generator sends a reference signal to a to-be-detected cable, and a signal acquisition device acquires a reflected signal by controlling signal acquisition of the to-be-detected cable, wherein the frequency of the reference signal is different in different time displacement intervals;

[0008] the reference signal and the reflected signal are both preprocessed and time-frequency domain conversion processed to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively;

[0009] According to the reference time-frequency spectrum and the reflected time-frequency spectrum, the time delay of the reflected signal relative to the reference signal is determined;

[0010] According to the time delay and the signal propagation speed of the to-be-detected cable, the fault point position of the to-be-detected cable is determined.

[0011] In a possible implementation, the reference signal is a phase-coded array signal generated based on a quadrature frequency-time mapping matrix;

[0012] The phase encoding array signal comprises a plurality of time slots, each time slot corresponds to a unique frequency, and the frequency-time displacement vectors of any two time slots are not repeated.

[0013] In a possible implementation, the reference signal and the reflected signal are both preprocessed and converted in time-frequency domain to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively, including:

[0014] The reflected signal is denoised and filtered, and the processed reflected signal is aligned with the reference signal in the time axis to obtain a preprocessed reference signal and a preprocessed reflected signal, respectively.

[0015] The preprocessed reference signal and the preprocessed reflected signal are both converted in frequency domain to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively.

[0016] In a possible implementation, the preprocessed reference signal and the preprocessed reflected signal are both converted in frequency domain to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively, including:

[0017] The preprocessed reference signal and the preprocessed reflected signal are both converted in frequency domain to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively, including:

[0018] The function formula of the Hanning window is used to calculate the weight value of each signal point in each time frame.

[0019] The signal intensity of each signal point in each time frame is multiplied by the corresponding weight value to obtain a weighted signal point sequence corresponding to each time frame.

[0020] For each time frame, the weighted signal sequence corresponding to the time frame is converted in frequency domain by using the discrete Fourier transform to obtain a frequency spectrum corresponding to the time frame.

[0021] The frequency spectrums of different time frames are sorted in time sequence to form a time-frequency spectrum.

[0022] The time-frequency spectrum includes a reference time-frequency spectrum and the reflected time-frequency spectrum.

[0023] In a possible implementation, the reference time-frequency spectrum and the reflected time-frequency spectrum are used to determine the time delay of the reflected signal relative to the reference signal, including:

[0024] The reference time-frequency spectrum and the reflected time-frequency spectrum are cross-correlated to obtain a cross-correlation matrix.

[0025] performing two-dimensional peak detection on the cross-correlation matrix, and determining a time point corresponding to a maximum peak in the detection result as the time delay.

[0026] In a possible implementation, the cross-correlation calculation on the reference time-frequency spectrum and the reflected time-frequency spectrum to obtain the cross-correlation matrix comprises:

[0027] For each time point, a product of a value of the reference time-frequency spectrum and a conjugate complex of a value of the reflected time-frequency spectrum at different frequency points corresponding to the time point is calculated to obtain the product at different frequencies corresponding to the time point;

[0028] The products at each frequency are added and summed to obtain a cross-correlation value corresponding to the time point.

[0029] The cross-correlation matrix is constructed according to the cross-correlation values corresponding to different time points.

[0030] In a possible implementation, the determination of the fault point position of the to-be-detected cable according to the time delay and a signal propagation speed of the to-be-detected cable comprises:

[0031] Half of a product of the time delay and the signal propagation speed is determined as a distance of the fault point relative to a terminal of the to-be-detected cable to obtain the position of the fault point.

[0032] In a second aspect, an embodiment of the present application provides a cable fault positioning device, comprising:

[0033] a control module configured to control a signal generator to send a reference signal to a to-be-detected cable, and control a signal acquisition device to acquire a signal of the to-be-detected cable to obtain a reflected signal, the reference signal having different frequencies in different time displacement intervals;

[0034] a processing module configured to perform preprocessing and time-frequency domain conversion processing on the reference signal and the reflected signal to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively;

[0035] a first determination module configured to determine a time delay of the reflected signal relative to the reference signal according to the reference time-frequency spectrum and the reflected time-frequency spectrum;

[0036] a second determination module configured to determine a fault point position of the to-be-detected cable according to the time delay and a signal propagation speed of the to-be-detected cable.

[0037] In a possible implementation, the reference signal in the control module is a phase-coded array signal generated based on a quadrature frequency time mapping matrix.

[0038] The phase encoding array signal comprises a plurality of time slots, each time slot corresponds to a unique frequency, and the frequency-time displacement vectors of any two time slots are not repeated.

[0039] In a possible implementation, the processing module comprises:

[0040] The first processing unit is configured to perform denoising and filtering processing on the reflection signal, and align the processed reflection signal with the reference signal on a time axis to obtain a preprocessed reference signal and a preprocessed reflection signal, respectively.

[0041] The second processing unit is configured to perform frequency domain conversion processing on the preprocessed reference signal and the preprocessed reflection signal to obtain a reference time-frequency spectrum and a reflection time-frequency spectrum, respectively.

[0042] In a possible implementation, the second processing unit is specifically configured to:

[0043] The preprocessed reference signal and the preprocessed reflection signal are subjected to frame processing based on a Hanning window to obtain a plurality of time frames; each time frame comprises a plurality of signal points, and the overlap rate of signal points between adjacent windows is greater than a preset threshold.

[0044] The weight value of each signal point in each time frame is calculated by using a function formula of the Hanning window.

[0045] The signal intensity of each signal point in each time frame is multiplied by the corresponding weight value to obtain a weighted signal point sequence corresponding to each time frame.

[0046] For each time frame, the frequency domain conversion processing is performed on the weighted signal sequence corresponding to the time frame by using a discrete Fourier transform to obtain a frequency spectrum corresponding to the time frame.

[0047] The frequency spectrums of different time frames are sorted in time sequence to form a time-frequency spectrum.

[0048] The time-frequency spectrum comprises a reference time-frequency spectrum and the reflection time-frequency spectrum.

[0049] In a possible implementation, the first determination module comprises:

[0050] The calculation unit is configured to perform cross-correlation calculation on the reference time-frequency spectrum and the reflection time-frequency spectrum to obtain a cross-correlation matrix.

[0051] The detection unit is configured to perform two-dimensional peak detection on the cross-correlation matrix, and determine the time point corresponding to the maximum peak in the detection result as the time delay.

[0052] In a possible implementation, the calculation unit is specifically configured to:

[0053] For each time point, a product of a value of the reference time-frequency spectrum and a conjugate complex of a value of the reflection time-frequency spectrum at different frequency points corresponding to the time point is calculated to obtain the product at different frequencies corresponding to the time point;

[0054] The products at each frequency are summed to obtain a cross-correlation value corresponding to the time point;

[0055] The cross-correlation matrix is constructed according to the cross-correlation values corresponding to different time points.

[0056] In a possible implementation, the second determining module is specifically configured to:

[0057] Half of a product of the time delay and the signal propagation speed is determined as a distance of the fault point relative to the cable terminal to be detected, to obtain the position of the fault point.

[0058] In a third aspect, an embodiment of the present application provides a processing device, comprising a memory and a processor.

[0059] The memory stores computer execution instructions.

[0060] The processor executes the computer execution instructions stored in the memory, so that the processor executes the first aspect and / or various possible implementations of the first aspect.

[0061] In a fourth aspect, an embodiment of the present application provides a fault positioning system of a cable, comprising a processing device, a signal generator and a signal acquisition device, wherein

[0062] The signal generator is configured to send a reference signal to a cable to be detected in response to an indication of the processing device, and the reference signal has different frequencies in different time displacement intervals.

[0063] The signal acquisition device is configured to collect signals of the cable to be detected in response to an indication of the processing device, and obtain a reflection signal corresponding to the reference signal.

[0064] The processing device is configured to perform preprocessing and time-frequency domain conversion processing on the reference signal and the reflection signal, to obtain a reference time-frequency spectrum and a reflection time-frequency spectrum, respectively.

[0065] The time delay of the reflection signal relative to the reference signal is determined according to the reference time-frequency spectrum and the reflection time-frequency spectrum.

[0066] The position of a fault point of the cable to be detected is determined according to the time delay and a signal propagation speed of the cable to be detected.

[0067] In a fifth aspect, an embodiment of the present application provides a computer readable storage medium, the computer readable storage medium storing computer execution instructions, the computer execution instructions being executed by a processor to implement the first aspect and / or various possible implementation manners of the first aspect.

[0068] In a sixth aspect, an embodiment of the present application provides a computer program product, comprising a computer program, the computer program being executed by a processor to implement the first aspect and / or various possible implementation manners of the first aspect.

[0069] The cable fault positioning method, device, system and medium provided by the embodiment of the present application can send reference signals with different frequencies in different time displacement intervals to the cable to be detected through the control signal generator, and control the signal acquisition device to collect signals of the cable to be detected to obtain reflected signals. Then, the reference signals and the reflected signals are both preprocessed and time-frequency domain conversion processed to obtain reference time-frequency spectrum and reflected time-frequency spectrum respectively. According to the reference time-frequency spectrum and the reflected time-frequency spectrum, the time delay of the reflected signals relative to the reference signals is determined. According to the time delay and the signal propagation speed of the cable to be detected, the position of the fault point of the cable to be detected is determined. Based on the time-varying characteristics of the reference signals, different fault points can be effectively distinguished in the case that there are multiple fault points in the cable, and the problem of spectral aliasing in the effective signal analysis stage is solved, so that the time-frequency resolution is improved, and high-precision fault positioning of different faults in a complex cable environment is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0070] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present application and, together with the description, serve to explain the principles of the application.

[0071] Figure 1 A flowchart of a cable fault positioning method provided by the first embodiment of the present application;

[0072] Figure 2 A structural diagram of a cable fault positioning system provided by the first embodiment;

[0073] Figure 3 A time-frequency spectrum diagram of a phase-coded array signal provided by the embodiment;

[0074] Figure 4 A ambiguity function diagram of a phase-coded array signal provided by the embodiment;

[0075] Figure 5 A structural diagram of a cable fault positioning device provided by the third embodiment of the present application;

[0076] Figure 6A structural schematic diagram of a processing device for the present application is provided.

[0077] The specific embodiments of the present application have been shown by the above-described drawings, and will be described in more detail hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0078] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The same numbers are used in different drawings to represent the same or similar elements. The embodiments described in the following exemplary embodiments are not meant to represent all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the appended claims.

[0079] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described again in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

[0080] Figure 1 A flowchart of a cable fault positioning method provided by Embodiment One of the present application is shown in FIG. 1, and the method comprises the following steps. Figure 1

[0081] S101, a control signal generator sends a reference signal to a cable to be detected, and controls a signal acquisition device to acquire signals of the cable to be detected to obtain a reflected signal, wherein the frequency of the reference signal is different in different time displacement intervals.

[0082] In this step, the reference signal needs to be injected into the cable to be detected by the signal generator, and the reflected signal in the cable needs to be acquired by the signal acquisition device, wherein the reflected signal can be the reflected signal returned by the reference signal at the terminal of the cable, or the signal returned by the reference signal at different fault points.

[0083] ​It should be noted that the collected reflection signal can be the reflection signal of one fault point, or can include the reflection signals of multiple fault points. Since the reference signal used in the present application is a signal with different frequencies in different time displacement intervals, it is used to distinguish the reflection signals returned by different fault points to avoid the case of spectral aliasing. Therefore, in the case of multiple fault point reflection signals, the reflection signals of different fault points can be accurately divided, and the method provided in the present application (including steps S102 to S104) can be used for accurate fault positioning.

[0084] Optionally, to ensure the accuracy of signal collection, the signal generator and the signal collection device need to be calibrated before this step. The calibration step includes: adjusting the signal generator and the signal collection device to make them well grounded to reduce electromagnetic interference in the test process; using a standard cable (a cable with known length and no fault) to calibrate the time deviation between the signal transmission time of the signal generator and the starting time of the collection timing of the signal collection device to be less than a preset time difference, for example, 0.5 ns, 1 ns, etc.

[0085] Optionally, the injection power of the reference signal can be adjusted according to the characteristics of the cable to be detected (such as the cross-sectional area, length, insulation material, aging degree, and core structure of the cable) to avoid the case of signal overload.

[0086] In one possible implementation, to recover the original signal from the sampling signal without distortion, the sampling frequency of the signal collection device can be set to be greater than or equal to twice the highest power of the reference signal. For example, when the highest frequency of the reference signal is 13.5 MHz, the sampling frequency of the signal collection device can be set to be ≥27 MS / s.

[0087] In one possible implementation, to avoid omission of the sampling signal, the sampling duration of the signal collection device covers the time for the signal to go back and forth in the full length of the cable to be detected, which can be determined according to the propagation speed of the signal in the cable to be detected. For example, if the time for the signal to go back and forth in the full length of a 200 m cable is 1.3 μs, the collection duration of the signal collection device can be set to be 2 μs.

[0088] S102, pre-process and time-frequency domain conversion process are performed on the reference signal and the reflection signal, respectively to obtain reference time-frequency spectrum and reflection time-frequency spectrum.

[0089] In this step, in order to improve the quality of time-frequency analysis, it is necessary to first preprocess the reference signal and the reflected signal to eliminate interference and noise in the signal (such as electromagnetic interference, cable self-loss noise) and highlight the characteristics of the effective signal, and make the reference signal and the reflected signal comparable. Further, both the preprocessed signals need to be processed by frequency domain conversion to extract the characteristics (i.e. signal intensity) of the signals at different time points and frequency points, so as to obtain the time-frequency spectrum corresponding to the reference signal (i.e. reference time-frequency spectrum) and the time-frequency spectrum corresponding to the reflected signal (i.e. reflected time-frequency spectrum).

[0090] Among them, the frequency domain conversion processing refers to the process of converting the time domain signal into the frequency domain signal through digital transformation. For example, Fourier transform, fast Fourier transform, short-time Fourier transform, wavelet transform, Hilbert-Huang transform, etc. can be used to process the reference signal and the reflected signal by frequency domain conversion. The specific means of frequency domain conversion are not limited in this application.

[0091] The time-frequency spectrum refers to a signal spectrum that integrates time, frequency and signal intensity information. The time-frequency spectrum includes time-frequency points, and the value of each time-frequency point represents the corresponding time point and the signal intensity at the time point. The reference time-frequency spectrum can clearly show the frequency component distribution of the reference signal at different time points; the reflected time-frequency spectrum can reflect the characteristics of the reflected signal in the time and frequency dimensions, including the time-frequency changes caused by the fault point reflection and other information.

[0092] It should be understood that through the processing of this step, the time-frequency characteristics of the reference signal and the reflected signal are effectively extracted and presented in the form of time-frequency spectrum, providing a basis for subsequent fault point positioning analysis in the time-frequency domain, which helps to more accurately identify and locate the defects in the cable.

[0093] For example, the preprocessing process includes filtering, removing direct current components, and synchronizing correction, etc. The application does not make specific limitations.

[0094] S103, according to the reference time-frequency spectrum and the reflected time-frequency spectrum, determine the time delay of the reflected signal relative to the reference signal.

[0095] In this step, since the reference time-frequency spectrum can represent the known reference, i.e. the time-frequency characteristics of the reference signal injected into the cable, and the reflected time-frequency spectrum is a delayed response, i.e. the time-frequency characteristics of the signal reflected by the fault point, by comparing the position difference of the characteristics in the time-frequency dimension, i.e. the time delay of the reflected signal relative to the reference signal.

[0096] Among them, the reflected signal relative to the reference signal can be understood as the time difference between the reflected signal and the reference signal.

[0097] S104, determining the fault point position of the cable to be detected according to the time delay and the signal propagation speed of the cable to be detected.

[0098] In this step, the position of the fault point can be obtained by distance calculation according to the signal delay and the signal propagation speed in the cable to be detected.

[0099] The signal propagation speed in the cable to be detected can be obtained according to the standard manual of the cable, or can also be obtained according to the time delay of the cable to be detected at a known distance, that is, calculated by the formula VoP=2L / τ0, wherein VoP represents the signal propagation speed, L represents the known distance (such as 200m), and τ0 represents the time delay of the cable to be detected at the known distance (that is, the delay time of the reflected signal returned at the known distance relative to the reference signal).

[0100] In a possible implementation, half of the product of the time delay and the signal propagation speed is determined as the distance of the fault point relative to the terminal of the cable to be detected, and the position of the fault point is obtained.

[0101] That is, the distance l of the fault point relative to the terminal of the cable to be detected can be calculated by the formula: l=VoP·τ / 2, wherein τ represents the time delay obtained this time.

[0102] Further, Figure 2 A structural schematic diagram of the cable fault positioning system provided by the embodiment one is shown in FIG. 1, which includes a processing device 201, a signal generator 202 and a signal acquisition device 203. Figure 2

[0103] The signal generator 202 is configured to send a reference signal to the cable to be detected in response to the indication of the processing device 201, and the frequency of the reference signal is different in different time displacement intervals.

[0104] The signal acquisition device 203 is configured to collect signals of the cable to be detected in response to the indication of the processing device 201, and obtain reflected signals corresponding to the reference signal.

[0105] The processing device 201 is configured to pre-process and perform time-frequency domain conversion processing on the reference signal and the reflected signal, respectively, to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum; determine a time delay of the reflected signal relative to the reference signal according to the reference time-frequency spectrum and the reflected time-frequency spectrum; and determine the fault point position of the cable to be detected according to the time delay and the signal propagation speed of the cable to be detected.

[0106] It should be noted that the specific form of the signal generator and the signal acquisition device is not limited in the present application.

[0107] ​As a specific example, the signal generator is, for example, a generator that can send a signal of an arbitrary waveform; and the signal acquisition device is, for example, a digital fluorescence oscilloscope.

[0108] In the test of the cable to be detected by using the above system, a T-shaped connector can be used to connect the signal generator to one end of the cable to be detected for reference signal injection, and the signal acquisition device is connected to the third port of the T-shaped connector for synchronous acquisition of the reflected signal.

[0109] The cable fault positioning method and system provided by the embodiments of the present application can send reference signals with different frequencies in different time displacement intervals to the cable to be detected, and acquire signals of the cable to be detected to obtain reflected signals. Then, the reference signals and the reflected signals are both preprocessed and time-frequency domain conversion processed to obtain reference time-frequency spectrum and reflected time-frequency spectrum respectively. According to the reference time-frequency spectrum and the reflected time-frequency spectrum, the time delay of the reflected signal relative to the reference signal is determined. According to the time delay and the signal propagation speed of the cable to be detected, the position of the fault point of the cable to be detected is determined. Based on the time-varying characteristics of the reference signal, different fault points can be effectively distinguished in the case where there are multiple fault points in the cable, and the problem of spectral aliasing in the effective signal analysis stage is solved, thereby improving the time-frequency resolution and achieving high-precision fault positioning of different faults in a complex cable environment.

[0110] Further, the second embodiment of the present application provides a cable fault positioning method. Based on the above embodiment, the implementation of each step in the above embodiment is further described in detail. The second embodiment specifically includes the following contents.

[0111] Step 1: controlling the signal generator to send a reference signal to the cable to be detected, and controlling the signal acquisition device to acquire signals of the cable to be detected to obtain reflected signals;

[0112] The reference signal is a phase-coded array signal generated based on an Orthogonal Frequency Time Mapping Matrix (OFTM). The phase-coded array signal includes multiple time slots, each time slot corresponds to a unique frequency, and the frequency-time displacement vectors of any two time slots are not repeated.

[0113] Specifically, the time slot refers to a time unit obtained by equally dividing the time axis, and each time slot corresponds to a time displacement and a frequency. To ensure that the signals of different fault points have unique identifiable characteristics, different time slots need to correspond to unique frequencies, and the frequency-time displacement vectors of any two time slots are not repeated (i.e., the frequency-time displacement combination of the time slot is unique).

[0114] OFTM is used to build a one-to-one correspondence between time slots and frequency indexes, i.e., to assign a unique frequency to each time slot. Here, the bijective function is f:{1,2,...,N}→{1,2,...,N}).

[0115] It should be understood that the phase-coded array signal is a signal with a unique time-frequency mapping, which is generated by a quadrature frequency-time mapping matrix. Each time slot of the designed signal corresponds to a unique frequency, and the frequency-time displacement vectors of any two time slots are not repeated. This signal design can effectively avoid spectral aliasing and energy leakage, improve the accuracy of time-frequency analysis of the signal, and thus achieve high-precision fault location in a complex cable environment. In addition, using the unique time-frequency mapping and optimized ambiguity function of the phase-coded array, high-precision fault location can be achieved even under severe propagation effects.

[0116] As a specific example, the expression of the phase-coded array signal is as follows:

[0117]

[0118] where s(t) represents the instantaneous amplitude of the signal at time point t; N represents the number of time slots, i.e., the dimension of the coded array, for example, 8; A i represents the signal amplitude of the i-th time slot, and to ensure the stability of the signal, for example, the signal amplitudes under different time slots are all set to 1V; f m represents the preset minimum frequency, for example, 6.5MHz; represents the step size between the frequencies corresponding to adjacent time slots, for example, 1MHz; f(i) represents the frequency (i.e., the frequency index) corresponding to the i-th time slot, which is determined according to OFTM; T represents the duration of each time slot, for example, 100ns.

[0119] Optionally, the phase-coded array signal can be replaced by a linear frequency modulation (LFM) signal. The LFM signal has a linear frequency change with time, has good time-frequency resolution, and can provide rich frequency information, which is suitable for cable fault location. Through the LFM signal, the recognition ability of the reflected signal can be improved, and the accuracy of fault location can be enhanced.

[0120] Optionally, the phase-coded array signal can be replaced by a pseudo-random binary sequence (PRBS) signal. The PRBS signal has good autocorrelation and anti-interference ability, which is suitable for complex cable fault detection. Through the PRBS signal, the anti-interference ability of the signal can be improved, and the robustness of fault location can be enhanced.

[0121] Step 2: Pre-process and time-frequency domain conversion are performed on the reference signal and the reflection signal to obtain a reference time-frequency spectrum and a reflection time-frequency spectrum, respectively. Specifically, the following steps 2.1-2.2 are included.

[0122] Step 2.1: Denoising and filtering are performed on the reflection signal, and the processed reflection signal is aligned with the reference signal on the time axis to obtain a pre-processed reference signal and a pre-processed reflection signal.

[0123] In this step, in order to ensure the reliability of the signal for time-frequency analysis, denoising and filtering are performed on the reflection signal to remove noise interference in the signal. Further, in order to ensure the comparability between the reference signal and the reflection signal, the processed reflection signal is aligned with the reference signal on the time axis to obtain a pre-processed reference signal and a pre-processed reflection signal.

[0124] Optionally, band-pass filtering can be performed on the collected reflection signal to remove low-frequency interference (such as 50Hz power frequency) and high-frequency noise (such as >15MHz electromagnetic radiation). For example, the passband width is 6.5-13.5MHz.

[0125] Specifically, the reflection signal can be aligned with the reference signal on the time axis by the starting time mark of the reference signal to ensure the consistency of the time reference for subsequent time-frequency analysis.

[0126] Step 2.2: Frequency domain conversion is performed on the pre-processed reference signal and the pre-processed reflection signal to obtain a reference time-frequency spectrum and a reflection time-frequency spectrum, respectively.

[0127] In this step, frequency domain conversion is performed on the pre-processed reference signal and the pre-processed reflection signal to obtain a reference time-frequency spectrum indicating the time-frequency characteristics of the reference signal and a reflection time-frequency spectrum indicating the time-frequency characteristics of the reflection signal, respectively.

[0128] In one possible implementation, the reference time-frequency spectrum and the reflection time-frequency spectrum can be obtained by steps 2.2.1-2.2.5, including:

[0129] Step 2.2.1: The pre-processed reference signal and the pre-processed reflection signal are framed based on the Hanning window to obtain a plurality of time frames.

[0130] Each time frame includes a plurality of signal points (i.e., sampling points of the signal), and the overlap rate of the signal points between adjacent time frames is greater than a preset threshold.

[0131] In this step, first, the Hanning window is selected to frame the signal, and a plurality of time frames are obtained to split the long time domain signal into short time frames for analysis, effectively dealing with the time-varying characteristics of the frequency characteristics of the non-stationary signal, avoiding the problem that the overall Fourier transform of the long signal cannot reflect the local time-varying characteristics, thereby ensuring that the reflection signal and the reference signal can more accurately extract the time-frequency characteristics of the signal.

[0132] Specifically, the frame processing refers to dividing the discrete time domain signal into a plurality of short time frames according to a fixed window length (the number of signal points contained in each frame).

[0133] In addition, the overlap rate of signal points between adjacent time frames needs to be set to be greater than a preset threshold. For example, the preset threshold is 50%, for example, the first time frame includes the first 256 signal points, and the second time frame includes the 129th to 384th signal points. This setting can reduce the information loss between adjacent time frames, ensure that the signal can be continuously captured in time when the signal is frame processed, avoid missing key time-frequency characteristics due to too large window interval, and thus retain good time-frequency resolution.

[0134] In actual application, the window length can be set to be the same as the duration T of the time slot of the signal, for example, 100 ns. Correspondingly, when the preset threshold is 50%, each time frame overlaps 50 ns.

[0135] It should be understood that the Hanning window can achieve a good balance between time resolution and frequency resolution, reduce spectral leakage, and be more suitable for capturing the time-frequency characteristics of non-stationary signals, so as to improve the accuracy of the time-frequency characteristics of the reference signal and the reflection signal.

[0136] Step 2.2.2: The function formula of the Hanning window is used to calculate the weight value of each signal point in each time frame.

[0137] Step 2.2.3: Multiply the signal intensity of each signal point in each time frame by the corresponding weight value to obtain the weighted signal point sequence of each time frame.

[0138] In the above two steps, the Hanning window is used to weight the signal points in each time frame to obtain the weighted signal point sequence of each time frame, wherein the weighted signal point sequence is the sequence of weighted signal points.

[0139] The function formula of the Hanning window is:

[0140] In the above formula, k represents the signal point index in the time frame, and is taken from [0, N-1]; N represents the window length.

[0141] Step 2.2.4: For each time frame, perform frequency domain transformation on the weighted signal sequence of the time frame using discrete Fourier transform to obtain the frequency spectrum corresponding to that time frame.

[0142] In this step, a short-time Discrete Fourier Transform is performed on each time frame to convert it into the frequency domain, thereby obtaining the frequency spectrum corresponding to each time frame. The frequency spectrum is used to indicate the correspondence between the frequency domain of the signal and the signal strength (i.e., amplitude or energy).

[0143] Step 2.2.5: Sort the frequency spectra of different time frames in chronological order to form a time spectrum.

[0144] The time spectrum includes the reference time spectrum and the reflection time spectrum.

[0145] In this step, after performing the above-mentioned framing, windowing, and frequency domain transformation processes on both the preprocessed reference signal and the preprocessed reflection signal, the corresponding reference time spectrum and reflection time spectrum can be obtained.

[0146] The method provided in this implementation, through optimized signal processing, reduces spectral leakage due to the smoothing characteristics of the Hanning window, and improves time resolution by setting the window overlap rate, thereby more accurately capturing the local time-frequency characteristics of non-stationary signals. It can effectively cope with attenuation and dispersion effects in cables, improve the robustness of the method, and correspondingly enhance the ability to identify weak fault signals. It reduces the dependence of signal identification on cable length and fault type, improves the adaptability of the method, and thus flexibly copes with various complex cable fault situations, including faults with multiple fault points and different impedance types, thereby improving the practicality and scalability of the method.

[0147] Figure 3 This is a schematic diagram of the time spectrum of the phase-coded array signal provided in this embodiment, as shown below. Figure 3 As shown, the time-frequency distribution of the signal exhibits a sparse and orthogonal discrete distribution, indicating that the time-frequency pattern of the signal has high recognizability, providing a clear basis for subsequent extraction of time delay. In addition, the sparse time-frequency distribution concentrates the signal energy at specific time-frequency points, which is highly distinguishable from randomly distributed noise energy, effectively improving the anti-interference capability of this scheme.

[0148] Step 3: Determine the time delay of the reflected signal relative to the reference signal based on the reference time spectrum and the reflected time spectrum. This specifically includes steps 3.1-3.2:

[0149] Step 3.1: Perform cross-correlation calculation on the reference time spectrum and the reflection time spectrum to obtain the cross-correlation matrix.

[0150] Step 3.2: Perform two-dimensional peak detection on the cross-correlation matrix, and determine the time point corresponding to the maximum peak in the detection results as the time delay.

[0151] In the above two steps, cross-correlation analysis needs to be performed on the reference time-frequency spectrum and the reflected time-frequency spectrum to obtain the time delay. Specifically, first, the similarity of the two signals at different time points is calculated to obtain a cross-correlation matrix, where the cross-correlation matrix is a matrix representing the similarity of the two signals in the time dimension; then, by means of two-dimensional peak detection, the time point corresponding to the maximum value in the matrix is determined as the time delay of the reflected signal compared with the reference signal.

[0152] Wherein, cross-correlation analysis is a method for measuring the similarity between two signals, which determines the time delay between them by calculating the correlation degree between them. In cable fault location, cross-correlation analysis can be used to calculate the time delay between the reference signal and the reflected signal, so as to determine the location of the fault point. This method can reduce the influence of signal attenuation and dispersion, thereby effectively improving the accuracy of fault location.

[0153] In one possible implementation, the cross-correlation matrix can be obtained by using the following steps 3.1.1 to 3.1.2:

[0154] Step 3.1.1: For each time point, the product of the value of the reference time-frequency spectrum and the conjugate complex of the value of the reflected time-frequency spectrum at different frequency points corresponding to the time point is calculated to obtain the product at different frequencies corresponding to the time point; the products at each frequency are summed to obtain the cross-correlation value corresponding to the time point.

[0155] Wherein, the cross-correlation value is used to represent the similarity between the reference signal and the reflected signal at the corresponding time point.

[0156] Specifically, the cross-correlation value of the tth time point The calculation formula is as follows:

[0157]

[0158] Wherein, represents the value of the reference signal at time point t and frequency point f; represents the conjugate complex of the value at time point t and frequency point f.

[0159] Step 3.1.2: According to the cross-correlation values corresponding to different time points, a cross-correlation matrix is constructed.

[0160] In this step, the constructed cross-correlation matrix includes the cross-correlation values corresponding to different time points.

[0161] In one possible implementation, the pre-processed reflected signal and the pre-processed reference signal can be input into a pre-trained model, and the similarity of the features of the two signals is captured by the model to output the delay time corresponding to the reflected signal.

[0162] Optionally, the model performs feature extraction and classification using machine learning algorithms (such as support vector machines, random forests) or deep learning algorithms (such as convolutional neural networks). Among them, the support vector machine is an effective classifier that can handle high-dimensional data and is suitable for classification and identification of fault features. Through the support vector machine, the accuracy and robustness of fault positioning can be improved. In addition, the random forest is an ensemble learning method based on decision trees, which has high classification accuracy and anti-overfitting ability. Through the random forest, complex fault features can be effectively processed, and the precision of fault positioning can be improved.

[0163] Step 4: According to the time delay and the signal propagation speed of the cable to be detected, the fault point position of the cable to be detected is determined.

[0164] The implementation of this step has been described in detail in the previous embodiment, and will not be repeated here.

[0165] Optionally, to avoid the influence of random errors on the accuracy of the fault position, the method in steps 1 to 4 can be repeatedly executed to test and obtain multiple fault point positions, and the final fault point is determined by averaging.

[0166] The cable fault positioning method provided in this embodiment can effectively avoid spectral aliasing and energy leakage by using a phase-coded array signal with unique time-frequency mapping as a reference signal, improving the time-frequency analysis accuracy of the signal. Further, by preprocessing and processing based on the Hanning window and the discrete Fourier transform, the time-frequency features of the signal are more accurately captured, which can effectively cope with the attenuation and dispersion effects in the cable, improve the robustness of the method, and reduce false positives and false negatives. At the same time, the cross-correlation analysis method provided in this scheme can effectively; in addition, the use of short-time Fourier transform and cross-correlation analysis in this scheme has a simple processing process, short calculation time, and can quickly complete fault positioning, meeting the real-time requirement.

[0167] Further, the technical effects provided by the present scheme are verified and described as follows:

[0168] The ambiguity function is used to evaluate the correlation of the signal under time delay (τ) and frequency offset (v). It measures the similarity between the signal and its delayed and frequency offset version, helping to analyze the performance of the signal in the reflection measurement. The specific formula is:

[0169]

[0170] Where: τ is the time delay, corresponding to the target range. v is the frequency offset, corresponding to the Doppler effect of the target (in cable reflection measurement, this can be analogous to the frequency-dependent attenuation and dispersion of the cable).

[0171] Figure 4 A schematic diagram of the ambiguity function of the phase-coded array signal provided by the embodiment is shown in FIG. 3. Figure 3 As shown in the figure, the ambiguity function presents a "pin-like" structure, with a narrow and clear peak, and the side lobes are effectively suppressed. This feature enables the signal to accurately estimate the target position in the presence of frequency offset, thereby achieving high-precision fault positioning.

[0172] As can be seen, based on the signal characteristics of the method provided by the embodiment, accurate positioning of the cable fault can be ensured.

[0173] Figure 5 A structural schematic diagram of the cable fault positioning device provided by Embodiment Three of the present application is shown in FIG. 4. Figure 5 As shown in the figure, the cable fault positioning device 30 provided by the embodiment includes:

[0174] A control module 301, configured to control a signal generator to send a reference signal to a cable to be detected, and control a signal acquisition device to collect signals of the cable to be detected to obtain a reflection signal, the reference signal having different frequencies in different time displacement intervals;

[0175] A processing module 302, configured to perform preprocessing and time-frequency domain conversion processing on the reference signal and the reflection signal, to obtain a reference time-frequency spectrum and a reflection time-frequency spectrum, respectively;

[0176] A first determination module 303, configured to determine a time delay of the reflection signal relative to the reference signal according to the reference time-frequency spectrum and the reflection time-frequency spectrum;

[0177] A second determination module 304, configured to determine a fault point position of the cable to be detected according to the time delay and a signal propagation speed of the cable to be detected.

[0178] In a possible implementation, the reference signal in the control module 301 is a phase-coded array signal generated based on a quadrature frequency-time mapping matrix;

[0179] The phase-coded array signal includes a plurality of time slots, each time slot corresponding to a unique frequency, and the frequency-time displacement vectors of any two time slots are not repeated.

[0180] In a possible implementation, the processing module includes:

[0181] The first processing unit is configured to perform denoising and filtering on the reflection signal, and align the processed reflection signal with the reference signal on a time axis to obtain a preprocessed reference signal and a preprocessed reflection signal respectively.

[0182] The second processing unit is configured to perform frequency domain conversion on the preprocessed reference signal and the preprocessed reflection signal to obtain a reference time-frequency spectrum and a reflection time-frequency spectrum respectively.

[0183] In a possible implementation, the second processing unit is specifically configured to:

[0184] frame the preprocessed reference signal and the preprocessed reflection signal based on a Hanning window to obtain a plurality of time frames; each time frame includes a plurality of signal points, and the overlap rate of signal points between adjacent windows is greater than a preset threshold;

[0185] calculate the weight value of each signal point in each time frame by using a function formula of the Hanning window;

[0186] multiply the signal intensity of each signal point in each time frame by the corresponding weight value to obtain a weighted signal point sequence corresponding to each time frame;

[0187] perform frequency domain conversion on the weighted signal sequence corresponding to each time frame by using a discrete Fourier transform to obtain a frequency spectrum corresponding to the time frame;

[0188] sort the frequency spectrums of different time frames in time sequence to form a time-frequency spectrum;

[0189] The time-frequency spectrum includes the reference time-frequency spectrum and the reflection time-frequency spectrum.

[0190] In a possible implementation, the first determination module 303 includes:

[0191] The calculation unit is configured to perform cross-correlation calculation on the reference time-frequency spectrum and the reflection time-frequency spectrum to obtain a cross-correlation matrix;

[0192] The detection unit is configured to perform two-dimensional peak detection on the cross-correlation matrix, and determine the time point corresponding to the maximum peak in the detection result as the time delay.

[0193] In a possible implementation, the calculation unit is specifically configured to:

[0194] for each time point, calculate the product of the conjugate complex of the value of the reference time-frequency spectrum and the value of the reflection time-frequency spectrum at different frequency points corresponding to the time point to obtain the product at different frequencies corresponding to the time point;

[0195] sum the product at each frequency to obtain the cross-correlation value corresponding to the time point;

[0196] According to the cross-correlation values corresponding to different time points, a cross-correlation matrix is constructed.

[0197] In a possible implementation, the second determining module 304 is specifically configured to:

[0198] Half of the product of the time delay and the signal propagation speed is determined as the distance of the fault point from the cable terminal to be detected, to obtain the position of the fault point.

[0199] The cable fault positioning apparatus provided in the embodiment can execute the method provided in the method embodiment, and has similar implementation principles and technical effects, which will not be repeated here.

[0200] Figure 6 A structural schematic diagram of a processing device is provided for the present application. As shown in the figure, Figure 6 The processing device 40 provided in the embodiment includes at least one processor 401 and a memory 402. Optionally, the device 40 further includes a communication component 403. The processor 401, the memory 402 and the communication component 403 are connected through a bus 404.

[0201] In the specific implementation process, the at least one processor 401 executes the computer execution instructions stored in the memory 402, so that the at least one processor 401 executes the above-mentioned method.

[0202] The specific implementation process of the processor 401 can refer to the above-mentioned method embodiment, which has similar implementation principles and technical effects, and will not be repeated here.

[0203] In the above-mentioned embodiments, it should be understood that the processor can be a central processing unit (CPU for short), and can also be other general-purpose processors, digital signal processors (DSP for short), application specific integrated circuits (ASIC for short) and the like. The general-purpose processor can be a microprocessor, or the processor can also be any conventional processor and the like. The steps of the method disclosed in the application can be directly embodied as the execution of the hardware processor, or executed by the combination of the hardware and software modules in the processor.

[0204] The memory can include a read-only memory and a random access memory. The memory can be a volatile memory or a nonvolatile memory, or can include both volatile and nonvolatile memory. Among them, the nonvolatile memory can include a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically EPROM (EEPROM), or a flash memory. The volatile memory can include a random access memory (RAM) used as an external cache. By way of example, and not limitation, many forms of RAM are available. For example, a static random access memory (SRAM), a dynamic random access memory (DRAM), a synchronous dynamic random access memory (SDRAM), a double data rate synchronous dynamic random access memory (DDR SDRAM), an enhanced SDRAM (ESDRAM), a sync link DRAM (SLDRAM), and a direct Rambus RAM (DR RAM) can be used.

[0205] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of the present application does not limit to only one bus or one type of bus.

[0206] The present application also provides a computer program product, comprising a computer program, which, when executed, implements the above method.

[0207] The present application also provides a computer-readable storage medium, which stores computer execution instructions, and when the computer execution instructions are executed, the above method is implemented.

[0208] The above-mentioned readable storage medium can be realized by any type of volatile or non-volatile storage device or a combination thereof, such as SRAM, EEPROM, EPROM, PROM, ROM, magnetic storage, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0209] An exemplary readable storage medium is coupled to the processor, so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be an integral part of the processor. The processor and the readable storage medium can be located in an ASIC. Of course, the processor and the readable storage medium can also exist as discrete components in the device.

[0210] The division of units is only a logical functional division, and in actual implementation, there can be another division manner, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0211] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0212] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit.

[0213] If the functions are realized in the form of software functional units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the part of the present application that essentially contributes to the prior art or the part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method of each embodiment of the present application. The foregoing storage medium includes various storage media that can store program codes, such as a U disk, a mobile hard disk, a ROM, a RAM, a magnetic disk or an optical disk.

[0214] Those skilled in the art can understand that all or part of the steps of the above-mentioned method embodiments can be completed by program instruction related hardware. The foregoing program can be stored in a computer readable storage medium. The program, when executed, performs steps including the above-mentioned method embodiments; and the foregoing storage medium includes various media capable of storing program codes, such as ROM, RAM, magnetic disk, or optical disk.

[0215] The above embodiments are only preferred embodiments for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Any equivalent replacement or transformation of the present application made by those skilled in the art based on the present application is within the protection scope of the present application.

[0216] Finally, it should be noted that other embodiments of the present application will readily occur to those skilled in the art upon consideration of the specification and practice of the present disclosure. The present application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such further uses of the application as come within the scope of the present application, the scope of the present application being defined by the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Claims

1. A method of fault locating in a cable, characterized by, The method comprises the following steps: A control signal generator sends a reference signal to a cable to be detected, and controls a signal acquisition device to collect signals of the cable to be detected to obtain a reflected signal, the reference signal having different frequencies in different time displacement intervals; The reference signal and the reflected signal are both preprocessed and converted into time-frequency domain to obtain a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively; According to the reference time-frequency spectrum and the reflected time-frequency spectrum, a time delay of the reflected signal relative to the reference signal is determined; According to the time delay and a signal propagation speed of the cable to be detected, a fault point position of the cable to be detected is determined.

2. The method of claim 1, wherein, The reference signal is a phase-coded array signal generated based on a quadrature frequency-time mapping matrix; The phase-coded array signal comprises a plurality of time slots, each time slot corresponding to a unique frequency, and the frequency-time displacement vectors of any two time slots being different from each other.

3. The method according to claim 1 or 2, characterized in that, The preprocessing and time-frequency domain conversion of the reference signal and the reflected signal to obtain the reference time-frequency spectrum and the reflected time-frequency spectrum, respectively, comprises the following steps: The reflected signal is denoised and filtered, and the processed reflected signal is aligned with the reference signal on a time axis to obtain a preprocessed reference signal and a preprocessed reflected signal, respectively; The preprocessed reference signal and the preprocessed reflected signal are both converted into frequency domain to obtain the reference time-frequency spectrum and the reflected time-frequency spectrum, respectively.

4. The method of claim 3, wherein, The frequency domain conversion of the preprocessed reference signal and the preprocessed reflected signal to obtain the reference time-frequency spectrum and the reflected time-frequency spectrum, respectively, comprises the following steps: For the preprocessed reference signal and the preprocessed reflected signal, a plurality of windows are obtained through frame processing based on a Hanning window, wherein each window comprises a plurality of signal points, and the overlap rate of the signal points between adjacent windows is greater than a preset threshold; The weight value of each signal point in each time frame is calculated by using the function formula of the Hanning window; The signal intensity of each signal point in each time frame is multiplied by the corresponding weight value to obtain a weighted signal point sequence corresponding to each time frame; For each time frame, the frequency domain conversion of the weighted signal sequence corresponding to the time frame is performed by using a discrete Fourier transform to obtain a frequency spectrum corresponding to the time frame; The frequency spectrums of different time frames are sorted in time sequence to form a time-frequency spectrum; The time-frequency spectrum comprises the reference time-frequency spectrum and the reflected time-frequency spectrum.

5. The method according to claim 1 or 2, characterized in that, The determination of the time delay of the reflected signal relative to the reference signal based on the reference time-frequency spectrum and the reflected time-frequency spectrum comprises the following steps: The cross-correlation calculation of the reference time-frequency spectrum and the reflected time-frequency spectrum is performed to obtain a cross-correlation matrix; The two-dimensional peak value of the cross-correlation matrix is detected, and the time point corresponding to the maximum peak value in the detection result is determined as the time delay.

6. The method of claim 5, wherein, The cross-correlation calculation of the reference time-frequency spectrum and the reflected time-frequency spectrum to obtain the cross-correlation matrix comprises the following steps: For each time point, the product of the conjugate complex of the value of the reference time-frequency spectrum and the value of the reflected time-frequency spectrum at different frequency points corresponding to the time point is calculated to obtain the product at different frequencies corresponding to the time point. Sum up the products at each frequency to obtain a cross-correlation value corresponding to the time point; According to the cross-correlation values corresponding to different time points, the cross-correlation matrix is constructed.

7. The method according to claim 1 or 2, characterized in that, The method further comprises: The product of the time delay and the signal propagation speed is halved to determine the distance of the fault point from the terminal of the cable under test, thereby obtaining the position of the fault point.

8. A processing device, characterized by The method further comprises: A memory and a processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor executes the method according to any one of claims 1-7.

9. A fault location system for a cable, characterized by The method further comprises: A processing device, a signal generator, and a signal acquisition device, wherein The signal generator is configured to send a reference signal to the cable under test in response to an instruction from the processing device, the reference signal having different frequencies in different time displacement intervals; The signal acquisition device is configured to collect signals from the cable under test in response to an instruction from the processing device, thereby obtaining reflected signals corresponding to the reference signal; The processing device is configured to pre-process and perform time-frequency domain conversion on both the reference signal and the reflected signal, thereby obtaining a reference time-frequency spectrum and a reflected time-frequency spectrum, respectively; According to the reference time-frequency spectrum and the reflected time-frequency spectrum, a time delay of the reflected signal relative to the reference signal is determined. According to the time delay and the signal propagation speed of the cable under test, a position of a fault point of the cable under test is determined.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are executed by the processor to implement the method according to any one of claims 1-7.

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