CN-121995154-A - Lightning stroke fault positioning method and system based on starting time of action current of lightning arrester

CN121995154ACN 121995154 ACN121995154 ACN 121995154ACN-121995154-A

Abstract

The invention belongs to the field of lightning fault positioning, and provides a lightning fault positioning method and a lightning fault positioning system based on the starting time of action current of a lightning arrester, wherein the lightning arrester action current signal and positioning information are obtained; the method comprises the steps of carrying out wavelet transformation and denoising on an arrester action current signal, calculating the current change rate of the denoised arrester action current signal, extracting mutation characteristics based on the current change rate to obtain candidate starting time, introducing a self-adaptive double-threshold verification mechanism, screening the candidate starting time from two aspects of amplitude characteristics and space-time constraint to determine final action current starting time, comprehensively considering time measurement errors, wave speed fluctuation and positioning synchronization errors, compensating positioning information to obtain corrected positioning information, and carrying out distance calculation and logic judgment of the direction and the same based on the final action current starting time and the corrected positioning information to realize lightning stroke point positioning. The lightning stroke fault point positioning method is high in lightning stroke fault point positioning capability.

Inventors

LIU HONGSHUN
XIAO XIAOLONG
HE DONGXIN
REN FUQIANG
LI QINGQUAN
SHEN YANG
WANG YUQING
CHEN XI
XU KEKE
CHEN YIYUAN
XUE ZHITONG
GUO JIAHAO
FANG XIN

Assignees

山东大学
国网江苏省电力有限公司电力科学研究院

Dates

Publication Date: 20260508
Application Date: 20251226

Claims (10)

1. A lightning stroke fault positioning method based on the starting time of the action current of a lightning arrester is characterized by comprising the following steps: acquiring an action current signal and positioning information of a lightning arrester; Performing wavelet transformation and denoising on the lightning arrester action current signal, and calculating the current change rate of the denoised lightning arrester action current signal; Based on the current change rate, extracting mutation characteristics to obtain candidate starting time, introducing a self-adaptive double-threshold verification mechanism, screening the candidate starting time from two aspects of amplitude characteristics and space-time constraints, and determining final action current starting time; comprehensively considering time measurement errors, wave speed fluctuation and positioning synchronization errors, and compensating positioning information to obtain corrected positioning information; and based on the final action current starting time and the corrected positioning information, performing distance calculation and logic judgment of the direction and the same, and realizing lightning stroke point positioning.
2. A lightning strike fault location method based on an arrester action current start time as claimed in claim 1, wherein the process of wavelet transforming the arrester action current signal comprises: and carrying out time-frequency localization analysis through wavelet transformation, carrying out expansion and translation operation by using the inner product operation of a wavelet basis function and a signal, decomposing the signal into components of different time-frequency windows, and filtering noise components while retaining transient characteristics of current from zero.
3. The lightning fault locating method based on the starting time of the action current of the lightning arrester according to claim 2, wherein the process of performing the scaling and translation operation by using the inner product operation of the wavelet basis function and the signal comprises the steps of performing continuous wavelet transformation on the original current signal i (t) by using db4 wavelet basis ψ (t): In the formula, the scale factor a takes 2 j , j=1, 2, & gt, 5 layers of decomposition are realized, high-frequency noise is captured through small scales a=2, 4, low-frequency signal trend is reserved for large scales a=16, 32, and the translation factor b slides at a sampling interval delta t, so that the time resolution is ensured to be consistent with the original signal.
4. The lightning fault locating method based on the starting time of the action current of the lightning arrester according to claim 1, wherein the process of denoising the action current signal of the lightning arrester comprises the following steps of adopting soft threshold processing to suppress noise for high-frequency coefficient j=1, 2 and 3 layers: the noise standard deviation is estimated sigma=mean (|W T |)/0.6755 by the median value of the high-frequency coefficient, N is the signal length, and after the reconstruction by the wavelet inverse transformation, the signal-to-noise ratio of the denoising signal i' (t) is improved, and the initial edge sharpness distortion rate is reduced.
5. The lightning fault locating method based on the starting time of the action current of the lightning arrester according to claim 1, wherein the process of calculating the current change rate of the denoised action current signal of the lightning arrester comprises the steps of performing first derivative calculation on a current signal i' (t) subjected to wavelet denoising treatment to obtain the current change rate: Δt is the time interval.
6. The lightning fault location method based on the starting time of the action current of the lightning arrester according to claim 5, wherein the step of extracting the abrupt change feature comprises the steps of characterizing the abrupt change feature of the change rate by a second derivative based on the change rate of the current: Δt is the time interval, and the second derivative experiences a zero crossing point from negative to positive, i.e. the theoretical position of the start time.
7. The lightning stroke fault locating method based on the starting time of the action current of the lightning arrester according to claim 1, wherein the self-adaptive double-threshold verification mechanism is introduced, candidate starting time is screened from the aspects of amplitude characteristics and space-time constraint, and the process of determining the final action current starting time comprises the steps of taking the maximum peak value of a signal-free section with a preset duration based on a noise base line I noise of a signal before denoising in the aspect of amplitude threshold verification, and setting the amplitude threshold to be: Combining the lightning current propagation velocity v with the maximum monitoring distance l, defining a time threshold as: Wherein T l is the intrinsic time of lightning intrusion, and T max is the upper limit of the positioning time; the earliest candidate time passing the dual-threshold verification is the effective starting time, and the final action current starting time is determined : 。
8. The lightning stroke fault locating method based on the starting time of the action current of the lightning arrester according to claim 1, wherein the process of compensating the locating information by comprehensively considering the time measurement error, the wave speed fluctuation and the locating synchronization error comprises the following steps: and (3) quantizing and compensating through an error correction formula to obtain a corrected distance s * section: in the time measurement error Mainly related to the current high frequency sensor sampling rate, Taking the time resolution of sensor and wave speed error Mainly related to the change of line parameters, such as wave speed fluctuation caused by high temperature, ice coating and the like of the line, and is determined according to specific conditions The positioning synchronization error delta is related to the performance of the positioning device.
9. The lightning stroke fault positioning method based on the starting time of the action current of the lightning arrester, as set forth in claim 1, is characterized in that the distribution network line one requires at least 2 lightning arrester data, the distribution network line T requires 3 data for a central point lightning arrester and one lightning arrester on two branches respectively, the distribution network cross line requires 4 data for a central point lightning arrester and one lightning arrester on three branches respectively; And a plurality of lightning arrester data exist, and the intersection of the positioning intervals is taken, so that the accuracy of positioning information is further improved.
10. A lightning strike fault location system based on an arrester action current start time, comprising: The data acquisition module is configured to acquire an arrester action current signal and positioning information; the current change rate module is configured to perform wavelet transformation and denoising on the lightning arrester action current signal, and calculate the current change rate of the denoised lightning arrester action current signal; the starting time determining module is configured to extract mutation characteristics based on the current change rate to obtain candidate starting time, introduce a self-adaptive double-threshold verification mechanism, screen the candidate starting time from two aspects of amplitude characteristics and space-time constraint, and determine final action current starting time; The distance correction module is configured to comprehensively consider time measurement errors, wave speed fluctuation and positioning synchronization errors, compensate the positioning information and obtain corrected positioning information; and the lightning stroke point positioning module is configured to perform distance calculation and logic judgment of the direction and the same direction based on the final action current starting time and the corrected positioning information so as to realize the positioning of the lightning stroke point.

Description

Lightning stroke fault positioning method and system based on starting time of action current of lightning arrester Technical Field The invention belongs to the field of lightning fault positioning, and particularly relates to a lightning fault positioning method and system based on the starting time of action current of a lightning arrester. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. In a power system, lightning stroke faults are one of main reasons for causing power failure and equipment damage of a distribution network, and severe accidents such as flashover of a line insulator, breakdown of a transformer winding, explosion of a switch cabinet and the like can be caused by strong lightning overvoltage, so that huge equipment maintenance cost is caused, and great threat is formed to power supply continuity of a power grid and electricity safety of users. As the core equipment of the lightning protection of the power system, the zinc oxide lightning arrester effectively reduces the impact damage of lightning stroke to electrical equipment by releasing lightning current and limiting overvoltage amplitude. However, the action current waveform of the zinc oxide arrester in the lightning stroke process also records key fault information, the current of the zinc oxide arrester always rises rapidly from a zero value at the initial moment, the superposition interference of the power frequency component of the power grid on the transient waveform is avoided, and the arrival time of the lightning current waveform can be reflected more accurately. The existing lightning fault positioning method is mostly dependent on line traveling wave signal analysis or pole tower grounding resistance measurement, but is often faced with difficulties such as power frequency voltage current interference, waveform superposition distortion and the like, and is limited by factors such as complex distribution network topology, multiple line branches and the like. The traditional traveling wave positioning technology needs to capture transient signals rapidly after faults, however, the continuous existence of power frequency components can interfere real waveform characteristics of lightning current, so that time difference calculation deviation occurs in a positioning algorithm, and a grounding resistance method is easily influenced by soil resistivity and topography environment, so that accurate fault point positioning is difficult to realize. Disclosure of Invention In order to solve the problems, the invention provides a lightning stroke fault positioning method and a lightning stroke fault positioning system based on the starting time of the action current of a lightning arrester. According to some embodiments, the present invention employs the following technical solutions: A lightning stroke fault positioning method based on the starting time of an action current of a lightning arrester comprises the following steps: acquiring an action current signal and positioning information of a lightning arrester; Performing wavelet transformation and denoising on the lightning arrester action current signal, and calculating the current change rate of the denoised lightning arrester action current signal; Based on the current change rate, extracting mutation characteristics to obtain candidate starting time, introducing a self-adaptive double-threshold verification mechanism, screening the candidate starting time from two aspects of amplitude characteristics and space-time constraints, and determining final action current starting time; comprehensively considering time measurement errors, wave speed fluctuation and positioning synchronization errors, and compensating positioning information to obtain corrected positioning information; and based on the final action current starting time and the corrected positioning information, performing distance calculation and logic judgment of the direction and the same, and realizing lightning stroke point positioning. As an alternative embodiment, the process of performing wavelet transformation on the lightning arrester action current signal includes: and carrying out time-frequency localization analysis through wavelet transformation, carrying out expansion and translation operation by using the inner product operation of a wavelet basis function and a signal, decomposing the signal into components of different time-frequency windows, and filtering noise components while retaining transient characteristics of current from zero. As a further embodiment, the process of performing scaling and panning operations using the inner product operation of the wavelet basis function and the signal includes performing a continuous wavelet transform on the original current signal i (t) using the db4 wavelet basis ψ (t): In the formula, the scale factor a takes 2 j, j=1, 2, & gt, 5 layers of decompo