Research On Vibration Signal Analysis And State Diagnosis Method Of Transformer On-load Tap-changer

The on-load tap-changer(OLTC)is the core component of the transformer to realize the voltage regulation operation,and its operating state has an important influence on the operating state of the transformer.The state of the OLTC can be diagnosed by analyzing the vibration signal generated when the OLTC operates,which is also easy to implement in the field.Aiming at the problems existing in the current OLTC state diagnosis by vibration signals and the actual engineering needs,this paper based on the features of OLTC,combined with the research results in the fields of modern signal analysis,anomaly detection,pattern recognition,etc.,carries out the transformer OLTC vibration signal analysis and state diagnosis method.The main research contents are:(1)The acquisition and preprocessing methods of OLTC vibration signals are studied.By comparing and analyzing the detection results of multiple measuring points,an acceleration sensor arrangement scheme is proposed to facilitate the detection of the OLTC body state and the transmission mechanism state.The common noise of OLTC vibration signal is analyzed,and the OLTC vibration signal denoising algorithm based on Wiener filter is proposed.The relationship between OLTC vibration signal and OLTC action timing is analyzed.The waveform characteristics of vibration signal in different action stages of OLTC are analyzed.The OLTC vibration signal stage division method based on Teager operator and dual–threshold is designed,and based on this method,the consistency of parallel OLTC action time is detected.(2)The characteristic extraction method of OLTC vibration signal is studied.Aiming at the typical characteristics of OLTC vibration signal,a characteristic extraction method based on CEEMD for OLTC vibration signal is proposed.An OLTC vibration signal characteristic extraction method based on S-transform-SVD is proposed.An OLTC vibration signal characteristic extraction method based on GHM multi-wavelet transform is proposed.Characteristic parameters such as time-frequency domain partition line,time-frequency matrix coefficient of variation,and the gravity of singular vector are proposed.The changes of the characteristic parameters when the OLTC in different states are analyzed.(3)The OLTC state diagnosis method based on vibration signal is studied.An OLTC abnormal state detection method based on local anomaly factor is proposed.Based on the comparison between the sample to be tested and the normal sample set,the severity of the abnormal state is found and determined.An OLTC fault pattern recognition method based on least squares support vector machine is proposed.The field application research of OLTC state diagnosis method was carried out.Based on the analysis of OLTC working principle,the vibration signals of different working positions are classified.The results of field experiments verify the effectiveness of the proposed OLTC state diagnosis method.