电工技术学报2024，Vol.39Issue(20)：6564-6576,6590,14.DOI:10.19595/j.cnki.1000-6753.tces.231323
基于绕组短路冲击响应时频特性的多特征联合形变判定方法
Multi-Feature Joint Deformation Determination Method Based on Time-Frequency Characteristics of Winding Short-Circuit Impulse Response
摘要
Abstract
The transformer will suffer many external short-circuit impact during long-term operation,and the winding will be affected by many accumulations,which will produce irreversible deformation.However,there are still some problems in the study of on-line monitoring of winding mechanical status.The operation of transformer is affected by the accumulative effect,and the relevant studies have not modified the relevant eigenvalues by de-accumulation.The fault diagnosis is mainly aimed at the fundamental frequency vibration signal of the transformer,but the frequency doubling component within 500 Hz is generally present in normal operation,and the transient state contains more higher harmonics.To solve these problems,a feature extraction and deformation determination method based on time-frequency characteristics of shock response of winding is proposed in this paper,which can accurately judge the deformation of winding. Firstly,based on the relative displacement model of the single degree-of-freedom system,the short-circuit shock response spectrum of the winding is constructed,and the distribution law of the vibration shock response of the winding considering the cumulative effect is obtained.The Fourier spectrum and shock response spectrum distribution of the measured signal are compared to determine the frequency analysis range.Secondly,the time-frequency energy distribution of the short-circuit impulse signal is calculated,and the frequency bands of the energy spectrum are divided according to the response distribution characteristics obtained by the impulse response spectrum to offset the influence of the cumulative effect,and the characteristic changes of the relative energy band entropy are obtained,and the weighted entropy increment is calculated.Thirdly,transform the energy spectrum into time-frequency matrix,decompose the signal by singular value decomposition(SVD),get the singular value vector,and calculate its weight according to the distribution characteristics of the singular value,can calculate the fundamental frequency singular value distortion rate of the signal.Finally,the calculated weighted entropy increment and the singular value distortion of fundamental frequency are compared with the measured cumulative microstrain. After converting the shock response spectrum into a planar strip,it can be seen that there is basically no accumulative effect when the short-circuit current is relatively small,so the first four shock response bands do not change significantly.Since the fifth time,due to the accumulative effect,the base-frequency short-circuit impulse response of A and C two-phase winding increases from about 100 Hz to 105.3 Hz and 104.7 Hz respectively,but the high-frequency part does not change significantly.The shock response of the B-phase fundamental short-circuit increases from 101.5 Hz to 107.6 Hz,and the peak distribution of the main response gradually increases to 200～550 Hz.In the range of 550～1 000 Hz,the shock response of the winding is unevenly distributed.According to this,the frequency bands are divided,the accumulative effect is corrected,and the change of weighted entropy is calculated,which is highly correlated with the accumulative microstrain of the winding.However,because the threshold of entropy increment is not easy to judge,and the requirement of data acquisition is high,it can not be missed or miscollected,so the concept of fundamental frequency singular value distortion is proposed,and the distortion rate does not exceed 2.0 when there is no deformation,which can be used as an auxiliary judgment means. Through the analysis of the feature extraction and deformation determination methods proposed in this paper,the following conclusions are drawn:(1)Less high-frequency components in the spectrum can cause a higher level of shock response in the winding,and it is necessary to conduct a comprehensive analysis of signals within 1 000 Hz.(2)Considering the offset degree of shock response points affected by cumulative effects,the relative energy band entropy in different frequency ranges is calculated,which is consistent with the law of winding burst deformation,indicating that it is correlated with winding deformation.(3)The weighted entropy increment of the short-circuit impact signal is calculated and compared with the cumulative microstrain of the winding.The two are linearly correlated.The calculated singular value distortion rate of the short-circuit impact signal does not exceed 2.0 when the winding is not deformed.The combination of the two can accurately predict whether the winding deformation occurs after short-circuit.关键词
短路试验/绕组形变/累积效应/冲击响应/时频矩阵Key words
Short-circuit test/winding deformation/accumulative effect/impact response/time-frequency matrix分类
信息技术与安全科学引用本文复制引用
张子康,耿江海,汪鑫宇,吕安强,高树国..基于绕组短路冲击响应时频特性的多特征联合形变判定方法[J].电工技术学报,2024,39(20):6564-6576,6590,14.基金项目
河北省自然科学基金资助项目(E2021521004). （E2021521004）
