A Multi-Time-Sequence Signal Correction Method and System for Cable Defect Location Based on Waveform Features

Abstract

This invention relates to the field of power equipment condition monitoring and fault diagnosis technology, specifically disclosing a method and system for locating cable defects based on waveform characteristics using multi-time-series signal correction. The method includes: deploying at least two monitoring points at the cable joint; deploying a first acquisition module and a second acquisition module sharing the same clock source and time reference synchronization at each monitoring point to obtain multi-timestamp sequences and waveform data, respectively; correcting the multi-timestamp sequences based on the waveform data to obtain a true multi-timestamp sequence; pairing the rising and falling edges of the true multi-timestamp sequence according to time order to form a complete pulse cycle; calculating the center point of each cycle to obtain the time difference; and verifying the time difference through a multi-cycle consistency check, then solving the double-end ranging formula to obtain the cable defect location. This invention can accurately and quickly locate high-voltage cable defects using defect signals, ensuring power system safety and reducing operation and maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of power equipment condition monitoring and fault diagnosis technology, and in particular to a method and system for locating cable defects based on waveform characteristics and multi-time-series signal correction. Background Technology

[0002] During long-term operation, high-voltage cables may fail due to insulation aging, manufacturing defects, or mechanical damage. Defect signals typically appear before these signals occur. Accurately and quickly locating the defect using these signals is crucial for ensuring power system safety and reducing operation and maintenance costs. Currently, cable defect location technologies primarily rely on traveling wave methods, time-domain reflectometry, and partial discharge detection methods.

[0003] However, existing technologies generally suffer from the following problems: First, there is a contradiction between sampling rate and recording duration. High sampling rates can capture the transient traveling wave fronts generated by defects, improving time measurement accuracy. However, limited by storage depth and data processing capabilities, their continuous sampling duration is usually short, making it easy to miss intermittent defects or fail to simultaneously acquire the long-term evolution trend of defects. Low sampling rates, while supporting longer continuous recording times, lack sufficient time resolution, making it difficult to accurately locate defects. Second, the triggering mechanism is singular, resulting in severe information loss. Conventional detection systems often trigger recording only when the signal first exceeds a threshold, and then stop recording or only record the peak value for a period of time, leading to the loss of key features such as multiple reflections and oscillations in the defect waveform. These multiple threshold exceedance points contain rich time delay information, which is crucial for accurate location and defect type identification. Third, there is the attenuation and distortion of pulse signals. Timestamps triggered by thresholds achieve high time accuracy when triggering the same waveform, but signal attenuation or distortion inevitably occurs during signal propagation in cables, especially for high-frequency pulses, whose rising edges are steep and require extremely high time measurement accuracy. Amplitude attenuation can cause a shift in the threshold exceedance time. Relying solely on the timestamps of a single trigger threshold at both ends of the signal will inevitably introduce errors, making it impossible to accurately locate the defect. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and system for locating cable defects based on waveform characteristics and multi-time-sequence signal correction. The method corrects multiple timestamps based on pulse waveforms, enabling accurate and rapid location of cable defects.

[0005] On the one hand, a method for locating cable defects based on waveform characteristics using multi-time-series signals is provided, including: At least two monitoring points are deployed at the cable joint. At each monitoring point, a first acquisition module and a second acquisition module that share the same clock source and time reference synchronization are deployed to obtain multi-time stamp sequences and waveform data, respectively. Based on the waveform data, the multi-timestamp sequence is corrected to obtain a true multi-timestamp sequence; the rising and falling edges of the true multi-timestamp sequence are paired in chronological order to form a complete pulse cycle, and the center point of each cycle is calculated. The time difference is calculated based on the center point; and the time difference is tested through a multi-period consistency test to obtain the time difference that passes the test. The location of the cable defect is obtained by calculating the time difference between the inspection and the time difference using the double-ended distance measurement formula.

[0006] Preferably, the first acquisition module is a multi-timestamp acquisition module, used to record the rising edge and falling edge of the pulse when they pass the threshold, so as to obtain a multi-timestamp sequence.

[0007] Preferably, the second acquisition module is a waveform acquisition module, which is triggered synchronously with the first acquisition module and is used to continuously acquire waveform data.

[0008] Preferably, the step of correcting the multi-timestamp sequence based on the waveform data to obtain a true multi-timestamp sequence involves: using the current amplitude s[n] and s[n+1] of the corresponding sampling points in the waveform data to verify whether the points that have passed the threshold are true; if both s[n] and s[n+1] are greater than or less than the threshold, it is determined that the timestamps recorded at points n and n+1 are caused by high-frequency noise and are therefore discarded; if s[n] and s[n+1] are located on both sides of the preset threshold, then it is a true multi-timestamp sequence and is retained.

[0009] Preferably, the calculation of the center point is specifically as follows: when the pulse waveform is symmetrical about the peak value, the center point of each cycle of the entire pulse is calculated; When the pulse waveform is asymmetrical, calculate the equivalent center point of each cycle of the entire pulse and take the equivalent center point as the center point.

[0010] Preferably, the calculation of the time difference based on the center point specifically involves subtracting the timestamp center point sequence of the first end and the timestamp center point sequence of the second end of the pulse signal to obtain the time difference of the center point of each cycle.

[0011] Preferably, the step of calculating the time difference of the inspection based on the double-end ranging formula to obtain the cable defect location is as follows: multiply the time difference by the pulse wave velocity, sum the product with the total length of the cable, and then divide the sum by 2 to obtain the distance from the defect to the corresponding monitoring end, thereby obtaining the defect location.

[0012] On the other hand, a multi-time-series signal correction cable defect location system based on waveform characteristics is provided, including: an acquisition module, at least two monitoring points are deployed at the cable joint, and a first acquisition module and a second acquisition module that share the same clock source and time reference synchronization are deployed at each monitoring point to obtain multi-time stamp sequences and waveform data respectively; The signal correction module corrects the multi-timestamp sequence based on the waveform data to obtain a true multi-timestamp sequence; it pairs the rising and falling edges of the true multi-timestamp sequence in chronological order to form a complete pulse cycle, and calculates the center point of each cycle. The verification module calculates the time difference based on the center point; and verifies the time difference through a multi-period consistency check to obtain the time difference that passes the check. The positioning module calculates the time difference between passing the inspection based on the double-end distance measurement formula to obtain the location of the cable defect.

[0013] Furthermore, an electronic device is also provided, including: Memory, used for non-transitory storage of computer-readable instructions; and Processor, for executing the computer-readable instructions, When the computer-readable instructions are executed by the processor, they perform the method described in the first aspect above.

[0014] In another aspect, a storage medium is also provided for non-transitory storage of computer-readable instructions, wherein when the non-transitory computer-readable instructions are executed by a computer, the method described in the first aspect is performed.

[0015] The above technical solution has the following advantages or beneficial effects: This invention combines a high-precision multi-timestamp acquisition module with a waveform recording acquisition module, ensuring that the two modules are strictly consistent at the first trigger moment. The waveform recording is used to verify the authenticity of the multi-timestamp and eliminate false triggers caused by noise. By utilizing the symmetry of the pulse and calculating the midpoint of the rising and falling edges, the timest offset caused by signal attenuation and distortion during propagation is eliminated, thereby enabling rapid and accurate location of cable defects. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1 The overall process of the method of the present invention Figure 1 ; Figure 2 The overall process of the method of the present invention Figure 2 . Detailed Implementation

[0018] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the invention. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] In this embodiment of the invention, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of this invention, "multiple" refers to two or more.

[0021] Furthermore, to facilitate a clear description of the technical solutions of the embodiments of the present invention, the terms "first" and "second" are used in the embodiments of the present invention to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0022] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0023] Example 1 Please see Figure 1 This invention provides a method for locating cable defects based on waveform features using multi-time-series signal correction, specifically including: S1: Deploy at least two monitoring points at the cable joint. At each monitoring point, deploy a first acquisition module and a second acquisition module that share the same clock source and time reference synchronization to obtain multi-timestamp sequences and waveform data, respectively. The first acquisition module is a multi-timestamp acquisition module, which is used to record the rising edge and falling edge of the pulse when they pass the threshold to obtain a multi-timestamp sequence; the second acquisition module is a waveform recording acquisition module, which is triggered synchronously with the first acquisition module and is used to continuously acquire waveform data.

[0024] At the cable joint, a sheath current grounding wire is led out, allowing the sheath current to be collected. Therefore, this invention arranges two or more monitoring points at the cable joint, with each monitoring point containing 8 channels to collect the main cable operating current and the sheath grounding current, respectively. The sampling rate is 50 MHz, collecting data in 1 ms increments.

[0025] Suppose a defect point in the cable generates a high-frequency pulse current signal at time t=0, and its waveform can be expressed as:

[0026] in, The pulse center frequency, The initial amplitude, Let T be the attenuation coefficient and T be the pulse duration. The pulse propagates to both ends of the cable at a velocity of v, and the pulse waveform is approximately symmetrical about the peak value of each cycle.

[0027] Each monitoring point is equipped with two parallel acquisition modules, namely the first acquisition module and the second acquisition module. These two modules share the same clock source and time reference for synchronization.

[0028] The first acquisition module is a multi-timestamp acquisition module, and the second acquisition module is a waveform recording acquisition module.

[0029] like Figure 2 As shown, a threshold is manually preset. After the multi-timestamp acquisition module and the waveform acquisition module are installed and deployed, they continuously acquire current signals in real time, but do not store the acquired data. They cyclically check whether the signal amplitude exceeds the preset threshold. When the current signal amplitude exceeds the preset threshold, a trigger signal is generated by a hardware comparator, activating the two acquisition modules to save the acquired data. The multi-timestamp acquisition module records the time points when the threshold is exceeded, while the waveform acquisition module acquires waveform data.

[0030] Multi-timestamp acquisition module: When the signal amplitude changes from below the threshold to above the threshold, a rising edge timestamp is recorded. When the signal amplitude changes from above the threshold to below the threshold, a falling edge timestamp is recorded. This module records all threshold-crossing moments during the entire pulse period, forming a high-precision timestamp sequence.

[0031] Waveform acquisition module: This module shares the same trigger event with the multi-timestamp acquisition module. Similarly, when the signal first exceeds the threshold, the waveform acquisition module is triggered to continuously acquire 1ms of waveform data, including 0.2ms before the trigger and 0.8ms after the trigger.

[0032] It should be noted that the same triggering event is triggered by the same threshold, the same signal, and the same clock source to ensure that waveform recording trigger acquisition and multi-timestamp trigger acquisition use the same signal. The multi-timestamp acquisition module and the waveform recording acquisition module share the same threshold.

[0033] The multi-timestamp acquisition module provides the precise timestamps of all threshold-crossing points during the entire pulse period, but not the waveform amplitude; the waveform recording acquisition module provides continuous waveform sampling points, with timestamps increasing at a fixed sampling interval Ts = 1 / fs (fs is the sampling frequency). The trigger start point of the waveform recording acquisition module (i.e., the first threshold-crossing point) is the same as the first rising edge time of the multi-timestamp acquisition module. Strictly consistent.

[0034] S2: Based on the waveform data, the multi-timestamp sequence is corrected to obtain a real multi-timestamp sequence; the rising and falling edges of the real multi-timestamp sequence are paired in chronological order to form a complete pulse cycle, and the center point of each cycle is calculated.

[0035] The multi-timestamp acquisition module records the precise time of each threshold crossing point. and The waveform acquisition module provides a timestamp for each sampling point. Where n is the number of points after the sampling is triggered. It is possible to determine which two sampling points each threshold point falls between, i.e., to find n such that... And extract the current amplitude corresponding to the two sampling points.

[0036] By using the current amplitudes s[n] and s[n+1] of the corresponding sampling points in the waveform recording, it is possible to verify whether the threshold point is real, and to eliminate false triggers caused by noise. Under the condition that the waveforms at both ends of the monitoring point are consistent, the pseudo timestamps caused by noise can be eliminated.

[0037] Based on waveform data, the multi-timestamp sequence is corrected to obtain the true multi-timestamp sequence. Specifically, the current amplitudes s[n] and s[n+1] of the corresponding sampling points in the waveform data are used to verify whether the points that have passed the threshold are true. If both s[n] and s[n+1] are greater than or less than the threshold, it is determined that the timestamps recorded at the nth and n+1th points are caused by high-frequency noise and are removed. If s[n] and s[n+1] are located on both sides of the preset threshold, they are true multi-timestamp sequences and are retained.

[0038] This invention locates each threshold-crossing moment in a multi-timestamp sequence between adjacent sampling points in waveform data, and corrects the data based on the amplitude of the sampling points to obtain a true multi-timestamp sequence.

[0039] Furthermore, after obtaining the real multi-timestamp sequence, the rising and falling timestamps of the real multi-timestamp sequence are paired according to time order to form a complete pulse cycle, and the center point of each cycle is calculated.

[0040] The calculation of the center point is as follows: when the pulse waveform is symmetrical about the peak, calculate the center point of each cycle of the entire pulse; when the pulse waveform is asymmetrical, calculate the equivalent center point of each cycle of the entire pulse and take the equivalent center point as the center point.

[0041] Rising and falling edges recorded by the multi-timestamp module are naturally paired in chronological order, each pair ( A complete cycle is formed by the pulse. If the pulse has M complete cycles, then i = 1, 2, ..., M. For each monitoring point, the multi-timestamp module records the rising edge timestamp sequence of the entire pulse. and falling edge timestamp sequence For the first The cycle has 1, and the center point (i.e., the moment when the peak of the cycle occurs) is defined as:

[0042] When the pulse waveform is symmetrical about the peak, the center point is equal to the peak moment and is not affected by amplitude attenuation.

[0043] If the pulse undergoes distortion during propagation, such as a slower rising edge and a steeper falling edge, the waveform will exhibit an asymmetrical shape. The equivalent center point of each cycle is then calculated as the center point.

[0044] Where start and end are the indices of the sampling points within the threshold interval of the i-th period, respectively.

[0045] S3: Calculate the time difference based on the center point; and verify the time difference through a multi-period consistency test to obtain the time difference that passes the test.

[0046] The time difference is calculated based on the center point; specifically, the time difference of the center point sequence of the timestamps at the first end and the second end of the pulse signal is taken as the difference to obtain the time difference of the center point of each cycle. The time difference of the center point of each cycle is approximately equal to a constant.

[0047] For pulse signals generated by the same defect, when the pulse is not distorted, the waveforms received at the monitoring points at both ends of the pulse signal, A and B, have the same oscillation period. The timestamp center point sequence at A... and the timestamp center point sequence of the B end The time difference at the center point of the i-th cycle is approximately equal to a constant, which is the time difference of the pulse propagating from the defect point to the monitoring points at ends A and B. : i=1,2,…,M Similarly, when the pulse is not distorted, the waveform is asymmetrical. The equivalent center point of each cycle is calculated and used as the center point to calculate the time difference between the monitoring points at end A and end B.

[0048] Observing the data collected from actual cables reveals that problems such as noise or local waveform distortion may occur. There will be some differences. In order to suppress errors, this invention proposes a multi-period consistency check, which is specifically as follows: 1) Calculate all Standard deviation ,if If the pulse waveform is less than a preset threshold (5ns), it is considered complete and symmetrical. The average value is used as the final time difference; 2) If a certain Deviation from the mean by more than 3 If it is an outlier, it will be removed and then averaged again. 3) If If all are abnormal and the number of valid periods is less than 2, only the first timestamp that exceeds the threshold will be used, and a low confidence level will be given.

[0049] The time difference between multiple pulse cycles is checked and corrected by multi-cycle consistency testing, thereby suppressing errors.

[0050] S4: Calculate the time difference between the inspection and the defect location of the cable based on the double-ended distance measurement formula.

[0051] The method involves calculating the time difference between the inspection and the cable defect location based on the double-end distance measurement formula. Specifically, the time difference between the inspection and the pulse wave velocity are multiplied, the product is summed with the total length of the cable, and the sum is divided by 2 to obtain the distance from the defect to the corresponding monitoring end, thus obtaining the cable defect location.

[0052] The formula for two-end distance measurement is:

[0053] Where L is the total length of the cable between monitoring points A and B, i.e., the total length of the cable between end A and end B; v is the wave velocity.

[0054] Example 2 This embodiment provides a multi-time-series signal correction cable defect location system based on waveform characteristics, including: The acquisition module deploys at least two monitoring points at the cable joint. At each monitoring point, a first acquisition module and a second acquisition module are deployed, sharing the same clock source and time reference synchronization, to obtain multi-timestamp sequences and waveform data, respectively. The signal correction module corrects the multi-timestamp sequence based on the waveform data to obtain a true multi-timestamp sequence; it pairs the rising and falling edges of the true multi-timestamp sequence in chronological order to form a complete pulse cycle, and calculates the center point of each cycle. The verification module calculates the time difference based on the center point; and verifies the time difference through a multi-period consistency check to obtain the time difference that passes the check. The positioning module calculates the time difference between passing the inspection based on the double-end distance measurement formula to obtain the location of the cable defect.

[0055] Example 3 This embodiment also provides an electronic device, including: one or more processors, one or more memories, and one or more computer programs; wherein, the processor is connected to the memory, and the one or more computer programs are stored in the memory. When the electronic device is running, the processor executes the one or more computer programs stored in the memory to cause the electronic device to perform the method described in Embodiment 1.

[0056] Example 4 This embodiment also provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, complete the method described in Embodiment 1.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for locating cable defects based on waveform characteristics using multi-time-series signals, characterized in that, include: At least two monitoring points are deployed at the cable joint. At each monitoring point, a first acquisition module and a second acquisition module that share the same clock source and time reference synchronization are deployed to obtain multi-time stamp sequences and waveform data, respectively. Based on the waveform data, the multi-timestamp sequence is corrected to obtain the true multi-timestamp sequence; The rising and falling edges of the real multi-timestamp sequence are paired in chronological order to form a complete pulse cycle, and the center point of each cycle is calculated. The time difference is calculated based on the center point; The time difference is then tested using a multi-period consistency test, and the time difference that passes the test is obtained. The location of the cable defect is obtained by calculating the time difference between the inspection and the time difference using the double-ended distance measurement formula.

2. The cable defect location method based on waveform characteristics using multi-time-series signal correction as described in claim 1, characterized in that, The first acquisition module is a multi-timestamp acquisition module, used to record the rising edge and falling edge of the pulse when they pass the threshold, so as to obtain a multi-timestamp sequence.

3. The cable defect location method based on waveform characteristics using multi-time-series signal correction as described in claim 1, characterized in that, The second acquisition module is a waveform acquisition module, which is triggered synchronously with the first acquisition module and is used to continuously acquire waveform data.

4. The cable defect location method based on waveform characteristics using multi-time-series signal correction as described in claim 1, characterized in that, The step of correcting the multi-timestamp sequence based on the waveform data to obtain a true multi-timestamp sequence is as follows: using the current amplitude s[n] and s[n+1] of the corresponding sampling points in the waveform data to verify whether the threshold points are true. If both s[n] and s[n+1] are greater than or less than the threshold, then the timestamps recorded at point n and point n+1 are determined to be caused by high-frequency noise and are removed; if s[n] and s[n+1] are located on both sides of the preset threshold, then they are real multi-timestamp sequences and are retained.

5. The cable defect location method based on waveform characteristics using multi-time-series signal correction as described in claim 1, characterized in that, The calculation of the center point is as follows: when the pulse waveform is symmetrical about the peak value, calculate the center point of each cycle of the entire pulse; When the pulse waveform is asymmetrical, calculate the equivalent center point of each cycle of the entire pulse and take the equivalent center point as the center point.

6. The cable defect location method based on waveform characteristics using multi-time-series signal correction as described in claim 1, characterized in that, The time difference is calculated based on the center point; specifically, the time difference of the center point of each cycle is obtained by subtracting the timestamp center point sequence of the first end and the timestamp center point sequence of the second end of the pulse signal.

7. The method for locating cable defects based on waveform characteristics using multi-time-series signals as described in claim 1, characterized in that, The method of calculating the time difference of the inspection based on the double-end ranging formula to obtain the cable defect location is as follows: multiply the time difference by the pulse wave velocity, sum the product with the total length of the cable, and then divide the sum by 2 to obtain the distance from the defect to the corresponding monitoring end, thereby obtaining the defect location.

8. A multi-time-series signal correction cable defect location system based on waveform characteristics, characterized in that, include: The acquisition module deploys at least two monitoring points at the cable joint. At each monitoring point, a first acquisition module and a second acquisition module are deployed, sharing the same clock source and time reference synchronization, to obtain multi-timestamp sequences and waveform data, respectively. The signal correction module corrects the multi-timestamp sequence based on the waveform data to obtain the true multi-timestamp sequence; The rising and falling edges of the real multi-timestamp sequence are paired in chronological order to form a complete pulse cycle, and the center point of each cycle is calculated. The verification module calculates the time difference based on the center point; The time difference is then tested using a multi-period consistency test, and the time difference that passes the test is obtained. The positioning module calculates the time difference between passing the inspection based on the double-end distance measurement formula to obtain the location of the cable defect.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for locating cable defects based on waveform features according to any one of claims 1 to 7.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for locating cable defects based on waveform features according to any one of claims 1 to 7.

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