CN-122017498-A - Cable accessory partial discharge detection method

CN122017498ACN 122017498 ACN122017498 ACN 122017498ACN-122017498-A

Abstract

The invention discloses a cable accessory partial discharge detection method, which belongs to the technical field of electric measurement and comprises the steps of injecting a preset detection signal into a cable accessory insulation system, synchronously collecting induction signals through a built-in sensing array to generate a multichannel mixed induction signal, coherently demodulating the multichannel mixed induction signal by taking the detection signal as a reference standard, separating and extracting modulation components of the detection signal to construct an initial modulation component matrix, analyzing multidimensional modulation characteristics of the initial modulation component matrix to generate a spatial modulation characteristic tensor, extracting a primary discharge pulse waveform characteristic set from the multichannel mixed induction signal, and fusing the spatial modulation characteristic tensor and the primary discharge pulse waveform characteristic set to output a partial discharge diagnosis report. The active injection detection signal and the passive monitoring primary pulse are combined, and the spatial modulation characteristic and the waveform characteristic are fused for joint analysis, so that the sensitive, reliable detection and accurate positioning of the partial discharge of the cable accessory can be realized.

Inventors

LIU TIE
YANG GUOHE
Xie Huilan
XU JINGJING

Assignees

浙江登然电力科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260415

Claims (10)

1. A method for detecting partial discharge of a cable accessory, the method comprising: Injecting a preset detection signal into the cable accessory insulation system, synchronously acquiring induction signals through the built-in sensing array, and generating a multichannel mixed induction signal; performing coherent demodulation on the multichannel mixed induction signal by taking the detection signal as a reference standard, separating and extracting modulation components of the detection signal, and constructing an initial modulation component matrix; Analyzing the multidimensional modulation characteristic of the initial modulation component matrix to generate a spatial modulation characteristic tensor; extracting a primary discharge pulse waveform characteristic set from the multichannel mixed induction signal; And fusing the spatial modulation characteristic tensor and the primary discharge pulse waveform characteristic set, performing joint analysis and decision, and outputting a partial discharge diagnosis report.
2. The method for detecting partial discharge of a cable accessory according to claim 1, wherein the injecting a preset detection signal into the cable accessory insulation system and synchronously collecting induction signals through the built-in sensor array, and generating a multi-channel mixed induction signal comprises: A built-in sensing array is arranged in an insulating layer of the cable accessory or at a preset key interface; Between the high-voltage conductor of the cable accessory and the grounding layer, superposing the detection signal on the operating power frequency voltage through a perturbation signal coupling unit; controlling the frequency, amplitude and phase of the detection signal to enable the amplitude to be lower than the operating power frequency voltage and the frequency to be in a preset accessory structure characteristic frequency band; And synchronously acquiring voltage or current signals induced by the built-in sensing array, amplifying and digitizing the voltage or current signals, and generating time-aligned multichannel mixed induction signals.
3. The method according to claim 2, wherein the perturbation signal coupling unit comprises a high pass filter and an isolation transformer, so as to ensure that the detection signal can be injected into the high voltage side and block the power frequency power current.
4. The method for detecting partial discharge of a cable accessory according to claim 2, wherein coherently demodulating the multi-channel mixed induction signal with the detection signal as a reference, separating and extracting modulation components of the detection signal, and constructing an initial modulation component matrix comprises: generating a local reference signal with the same frequency and phase as the detection signal as a reference standard; multiplying each path of signal in the multichannel mixed induction signal with the local reference signal respectively to obtain mixed signals; carrying out low-pass filtering on each path of mixed signals to filter high-frequency carrier components, and extracting low-frequency baseband signals containing amplitude and phase change information to serve as detection signal modulation components of corresponding channels; and arranging the modulation components of the detection signals of all channels according to the channel sequence to form an initial modulation component matrix.
5. The method of claim 4, wherein analyzing the multi-dimensional modulation signature of the initial modulation component matrix to generate a spatial modulation signature tensor comprises: performing time domain analysis on the initial modulation component matrix, and calculating amplitude fluctuation variance and phase jump times of the modulation components of the detection signals of each channel to generate an amplitude-phase disturbance vector; Performing frequency domain analysis on the initial modulation component matrix, calculating the energy duty ratio of a preset subharmonic component in the detection signal modulation component of each channel, and generating a harmonic distortion vector; And carrying out spatial interpolation and gridding on the amplitude-phase disturbance vector and the harmonic distortion vector of each channel at the same moment by combining the spatial position information of the built-in sensing array to form a three-dimensional data body capable of reflecting the spatial distribution of the modulation characteristic, and obtaining a spatial modulation characteristic tensor.
6. The method of claim 5, wherein extracting the set of native discharge pulse waveform features from the multi-channel hybrid induction signal comprises: Digitally filtering the multichannel mixed induction signal, and separating out signal components with frequency bands higher than the frequency of the detection signal to obtain a high-pass filtered signal; performing threshold comparison and pulse recognition on the high-pass filtering signal, and capturing transient pulse waveforms exceeding a preset noise baseline; And extracting peak amplitude, pulse width, rising edge time and pulse repetition rate from each captured transient pulse waveform to form a primary discharge pulse waveform characteristic set.
7. The method of claim 6, wherein the fusing the spatial modulation feature tensor and the native discharge pulse waveform feature set for joint analysis and decision, and outputting a partial discharge diagnostic report comprises: Based on expected disturbance modes of different types of partial discharge events on medium characteristics and corresponding relations with the characteristics of the primary discharge pulse waveform, establishing a physical association rule base; Matching in the physical association rule base according to the spatial distribution mode of the spatial modulation characteristic tensor at the current moment, primarily deducing the discharge type and the possible area, and generating a primary deduced result; based on the preliminary inference result, matching is carried out in the physical association rule base, and an inference waveform feature set is obtained; Verifying whether the pulse characteristics of the primary discharge pulse waveform feature set coincide with the pulse characteristics of the inferred waveform feature set; if the verification is passed, combining the primary discharge pulse waveform feature set and the spatial modulation feature tensor to generate a partial discharge diagnosis report containing discharge type, confidence level, intensity level and approximate region; if the verification is not passed, a conflict resolution mechanism is started.
8. The method of claim 7, wherein if the verification is not passed, starting a conflict resolution mechanism comprises: If the verification is not passed, the data acquisition time length is increased, the frequency or the amplitude of the detection signal is adjusted, and the primary discharge pulse waveform characteristic set is re-extracted; analyzing the characteristic change of the re-extracted original discharge pulse waveform characteristic set and the original discharge pulse waveform characteristic set extracted in the previous time to obtain conflict characteristics; and comparing the conflict characteristics with a preset historical case library to obtain candidate diagnosis results and corresponding confidence degrees.
9. A cable accessory partial discharge detection method as defined in claim 4, characterized in that the method further comprises: Injecting detection signals after the cable accessories are installed and in a discharge-free state, and collecting background response signals through the built-in sensing array; The detection signal modulation component is compared with the background response signal to eliminate the inherent deviation caused by the structural asymmetry of the accessory itself.
10. A cable accessory partial discharge detection system, the system comprising: The active excitation module is used for injecting a preset detection signal into the cable accessory insulation system, synchronously collecting induction signals through the built-in sensing array and generating a multichannel mixed induction signal; The signal demodulation module is used for coherently demodulating the multichannel mixed induction signal by taking the detection signal as a reference standard, separating and extracting a detection signal modulation component, and constructing an initial modulation component matrix; The signal processing module is used for analyzing the multidimensional modulation characteristic of the initial modulation component matrix and generating a spatial modulation characteristic tensor; The signal extraction module is used for extracting a primary discharge pulse waveform characteristic set from the multichannel mixed induction signal; and the decision module is used for fusing the spatial modulation characteristic tensor and the primary discharge pulse waveform characteristic set, carrying out joint analysis and decision, and outputting a partial discharge diagnosis report.

Description

Cable accessory partial discharge detection method Technical Field The invention relates to the technical field of electrical measurement, in particular to a cable accessory partial discharge detection method. Background Cable accessories are critical connecting components in power cabling, and the quality of their insulation directly affects the operational reliability of the overall cable system. Partial discharge phenomenon is an important early sign for representing the insulation degradation of the cable accessory, so that partial discharge detection on the cable accessory becomes an effective technical means for evaluating the insulation state and preventing faults. The existing cable accessory partial discharge detection technology mainly depends on passive monitoring means such as a pulse current method, an ultrahigh frequency method or an ultrasonic method. These methods typically capture transient pulse current, electromagnetic wave or acoustic wave signals generated by the partial discharge activity itself through external or internal sensors, and further infer the intensity and type of discharge by analyzing the amplitude, phase, frequency, etc. characteristics of these passive signals. However, these passive monitoring methods have certain limitations. They are sensitive to external electromagnetic interference and site noise, and are prone to false alarms or missed detection. For partial discharge which occurs early in the insulating medium and has weak intensity, the generated signal is often annihilated in background noise, and is difficult to reliably capture and identify. Furthermore, based on the feature analysis of a single type of passive signal, it is sometimes difficult to accurately distinguish between the types of discharges of different mechanisms, and the spatial positioning capability of the discharge points is often limited. Disclosure of Invention In order to solve the problems, the invention provides a cable accessory partial discharge detection method, which combines active injection detection signals with passive monitoring primary pulses, combines spatial modulation characteristics with waveform characteristics for joint analysis, and can realize sensitive, reliable detection and accurate positioning of the cable accessory partial discharge. The above object can be achieved by the following scheme: A cable accessory partial discharge detection method includes injecting a preset detection signal into a cable accessory insulation system, synchronously collecting induction signals through a built-in sensing array to generate a multichannel mixed induction signal, coherently demodulating the multichannel mixed induction signal by taking the detection signal as a reference standard, separating and extracting modulation components of the detection signal to construct an initial modulation component matrix, analyzing multi-dimensional modulation characteristics of the initial modulation component matrix to generate a spatial modulation characteristic tensor, extracting a primary discharge pulse waveform characteristic set from the multichannel mixed induction signal, fusing the spatial modulation characteristic tensor and the primary discharge pulse waveform characteristic set, carrying out joint analysis and decision, and outputting a partial discharge diagnosis report. The method comprises the steps of injecting a preset detection signal into an insulation system of a cable accessory, synchronously collecting induction signals through a built-in sensing array, distributing the built-in sensing array at the inside of an insulation layer of the cable accessory or at a preset key interface, superposing the detection signal onto an operation power frequency voltage between a high-voltage conductor and a ground layer of the cable accessory through a perturbation signal coupling unit, controlling the frequency, amplitude and phase of the detection signal to enable the amplitude to be lower than the operation power frequency voltage and the frequency to be in a preset accessory structure characteristic frequency band, synchronously collecting voltage or current signals induced by the built-in sensing array, amplifying and digitizing the voltage or current signals, and generating a time-aligned multichannel mixed induction signal. Optionally, the perturbation signal coupling unit includes a high pass filter and an isolation transformer, so as to ensure that the detection signal can be injected into the high voltage side and block the power frequency power current. The method comprises the steps of taking a detection signal as a reference standard, carrying out coherent demodulation on the multichannel mixed induction signal, separating and extracting detection signal modulation components, and constructing an initial modulation component matrix, wherein the initial modulation component matrix comprises the steps of generating local reference signals which are the same in frequency and p