CN-122017674-A - High-voltage cable sheath fault diagnosis method, device, equipment and medium

CN122017674ACN 122017674 ACN122017674 ACN 122017674ACN-122017674-A

Abstract

The embodiment of the application provides a fault diagnosis method, device, equipment and medium for a high-voltage cable sheath. The method comprises the steps of firstly collecting sheath voltage-to-ground time sequence data and sheath circulation time sequence data under dynamic working conditions of load current change of a main cable, then constructing sheath voltage frequency domain parameters according to the sheath voltage-to-ground time sequence data, then constructing sheath circulation time domain parameters according to the sheath circulation time sequence data, and finally matching the sheath voltage frequency domain parameters and the sheath circulation time domain parameters with fault mode characteristics in a preset fault mode library to obtain a fault diagnosis result of the sheath. By the method, the influence of the absolute value of the load on the steady-state measured value is avoided, and the accuracy of the fault diagnosis result is improved.

Inventors

XU YINGCHUN
WANG XIAOFENG
CHENG XIANGMAO
LIN RUNJIE
CHEN CHENG
HUANG KAIJIE
Wu Zhichuo
HUANG PEIFENG
WU CHAOHANG
HUANG WEIYUE

Assignees

广东电网有限责任公司潮州供电局

Dates

Publication Date: 20260512
Application Date: 20260228

Claims (10)

1. A method for diagnosing faults of a high-voltage cable sheath, comprising the steps of: Collecting sheath-to-ground voltage time sequence data and sheath circulation time sequence data under the dynamic working condition of main cable load current change; constructing sheath voltage frequency domain parameters according to the sheath voltage to ground time sequence data; Constructing sheath circulation time domain parameters according to the sheath circulation time sequence data; and matching the sheath voltage frequency domain parameter and the sheath circulating current time domain parameter with fault mode characteristics in a preset fault mode library to obtain a fault diagnosis result of the sheath.
2. The method of claim 1, wherein the collecting sheath-to-ground voltage and sheath circulation timing data under dynamic conditions of main cable load current variation comprises: monitoring the change process of the main cable load current, and calculating the second derivative of the main cable load current; identifying inflection point moments when sign inversion occurs to the second derivative; and triggering the acquisition operation within a preset delay time after the inflection point moment.
3. The method of claim 1, wherein constructing sheath voltage frequency domain parameters from the sheath-to-ground voltage timing data comprises: Performing frequency domain transformation on the time sequence data of the voltage of the protective layer to the ground, and extracting phase information of at least two frequency components near the resonance frequency; Calculating the phase angle relation between the phase information and constructing a phase angle sequence; Performing phase space reconstruction on the phase angle sequence to obtain a track, and calculating a Lyapunov exponent of the track and a sample entropy of the phase angle sequence; And taking the Lyapunov exponent and the sample entropy as vector components to form sheath voltage frequency domain parameters.
4. The method of claim 1, wherein said constructing sheath flow time domain parameters from said sheath flow time series data comprises: Performing multi-scale decomposition on the sheath circulation time sequence data to obtain a fast-scale component and a slow-scale component; respectively analyzing the fast scale component and the slow scale component, calculating a cross-correlation coefficient and determining a fusion weight; fusing the fast scale component and the slow scale component according to the fusion weight to obtain an instantaneous envelope; Fitting the instantaneous envelope with a theoretical response model, and extracting the deviation as a sheath circulation time domain parameter, wherein the theoretical response model is established based on the material conductivity of the sheath, the geometric dimension of the sheath and the equivalent capacitance between the sheath and the ground.
5. The method of claim 4, wherein after constructing the sheath circulation time domain parameter, the method further comprises: Acquiring sheath circulation time sequence data of a reference cable arranged adjacent to the main cable; analyzing signal processing is carried out on sheath circulation time sequence data of the reference cable, and a reference instantaneous envelope is obtained; and calculating the form matching degree between the instantaneous envelope of the main cable and the reference instantaneous envelope as a comparison parameter of the main cable.
6. A method according to claim 3, wherein before said matching of said sheath voltage frequency domain parameter and said sheath circulating current time domain parameter with fault pattern features in a pre-set fault pattern library, the method further comprises: reversely pushing an equivalent impedance complex value of the sheath grounding loop at the resonance frequency according to the Lyapunov exponent and the sample entropy in the sheath voltage frequency domain parameter; reversely pushing the equivalent impedance time domain response of the sheath grounding loop according to the deviation in the sheath circulation time domain parameter; Performing inverse transformation on the complex value of the equivalent impedance to obtain a time domain equivalent impedance response; And comparing the coincidence degree of the time domain equivalent impedance response and the equivalent impedance time domain response to serve as a coincidence parameter of the protective layer.
7. The method of claim 1, wherein matching the sheath voltage frequency domain parameter and the sheath circulating current time domain parameter to fault pattern features in a pre-set fault pattern library comprises: constructing sheath voltage frequency domain parameters, sheath circulating current time domain parameters, spatial distribution parameters, thermal coupling parameters, comparison parameters and consistency parameters into multidimensional feature vectors; Calculating the space distance between the multidimensional feature vector and each fault mode feature in a preset parameter space in a preset fault mode library; selecting a fault type corresponding to the fault mode characteristic of the minimum space distance as a preliminary diagnosis result; The method comprises the steps of obtaining multidimensional feature vectors of a protective layer at a plurality of past diagnosis moments to form a track; Analyzing the position relation between the moving direction of the track and each fault mode characteristic in a preset parameter space in a preset fault mode library, and determining fault evolution information; And outputting the preliminary diagnosis result and the fault evolution information as a fault diagnosis result.
8. A high voltage cable sheath fault diagnosis apparatus, comprising: The acquisition module is used for acquiring the sheath ground voltage time sequence data and the sheath circulation time sequence data under the dynamic working condition of the load current change of the main cable; The first construction module is used for constructing sheath voltage frequency domain parameters according to the sheath voltage to ground time sequence data; The second construction module is used for constructing sheath circulation time domain parameters according to the sheath circulation time sequence data; And the processing module is used for matching the sheath voltage frequency domain parameter and the sheath circulating current time domain parameter with fault mode characteristics in a preset fault mode library to obtain a fault diagnosis result of the sheath.
9. An electronic device is characterized by comprising a memory and a processor; The memory stores computer-executable instructions; The processor executing computer-executable instructions stored in the memory, causing the processor to perform the method of any one of claims 1-7.
10. A computer readable storage medium having stored therein computer executable instructions which when executed by a processor are adapted to carry out the method of any one of claims 1-7.

Description

High-voltage cable sheath fault diagnosis method, device, equipment and medium Technical Field The application relates to the technical field of power equipment state monitoring, in particular to a high-voltage cable sheath fault diagnosis method, device, equipment and medium. Background The high-voltage cable is core power transmission equipment in a power system and is widely applied to urban power grids, industrial power supply and remote power transmission scenes. The cable sheath is taken as an important component of the cable structure, and the grounding state of the cable sheath is directly related to the safety and stability of the operation of the cable. The ground fault of the protective layer can cause local overheating, insulation aging acceleration and even cable breakdown accidents, and the safety of a power grid is seriously threatened. In the operation and maintenance of the power system, the high-voltage cable sheath needs to be monitored in real time and fault diagnosis is performed so as to early warn the potential risk in advance. Therefore, a multi-dimensional characteristic analysis method based on the response characteristics of the sheath in the dynamic load change process is needed to realize high-precision and anti-interference sheath fault diagnosis and ensure the reliable operation of the power system. The existing high-voltage cable sheath fault diagnosis method is mainly based on the voltage-current amplitude relation under the steady-state working condition. Specifically, through collecting sheath voltage to ground and circulation signal under the steady operating mode of cable load, calculate voltage to current's amplitude ratio or phase difference to compare with preset threshold value, judge whether the sheath has the earth fault. However, the schemes in the prior art are deficient in terms of accuracy and reliability. Disclosure of Invention The embodiment of the application provides a fault diagnosis method, device, equipment and medium for a high-voltage cable sheath, which are used for solving the problems of insufficient accuracy and reliability in the prior art. In a first aspect, an embodiment of the present application provides a method for diagnosing a fault of a high-voltage cable sheath, including: Collecting sheath-to-ground voltage time sequence data and sheath circulation time sequence data under the dynamic working condition of main cable load current change; constructing sheath voltage frequency domain parameters according to the sheath voltage to ground time sequence data; Constructing sheath circulation time domain parameters according to the sheath circulation time sequence data; and matching the sheath voltage frequency domain parameter and the sheath circulating current time domain parameter with fault mode characteristics in a preset fault mode library to obtain a fault diagnosis result of the sheath. In one possible implementation manner, the collecting sheath ground voltage and sheath circulation time sequence data under the dynamic working condition that the load current of the main cable changes includes: monitoring the change process of the main cable load current, and calculating the second derivative of the main cable load current; identifying inflection point moments when sign inversion occurs to the second derivative; and triggering the acquisition operation within a preset delay time after the inflection point moment. In one possible implementation manner, the constructing sheath voltage frequency domain parameters according to the sheath voltage to ground time sequence data includes: Performing frequency domain transformation on the time sequence data of the voltage of the protective layer to the ground, and extracting phase information of at least two frequency components near the resonance frequency; Calculating the phase angle relation between the phase information and constructing a phase angle sequence; Performing phase space reconstruction on the phase angle sequence to obtain a track, and calculating a Lyapunov exponent of the track and a sample entropy of the phase angle sequence; And taking the Lyapunov exponent and the sample entropy as vector components to form sheath voltage frequency domain parameters. In one possible implementation manner, the constructing a sheath circulation time domain parameter according to the sheath circulation time sequence data includes: Performing multi-scale decomposition on the sheath circulation time sequence data to obtain a fast-scale component and a slow-scale component; respectively analyzing the fast scale component and the slow scale component, calculating a cross-correlation coefficient and determining a fusion weight; fusing the fast scale component and the slow scale component according to the fusion weight to obtain an instantaneous envelope; Fitting the instantaneous envelope with a theoretical response model, and extracting the deviation as a sheath circulation time domain parameter, whe