Research On Transformer Fault Diagnosis Method Based On Acoustic Signal

Power transformer is an important part of the modern power system,which is related to the stability of the power system and the reliability of the power supply.Most of the transformer accidents are caused by insulation problems.If we can effectively monitor the insulation system of the transformer and detect faults in time,electric accidents caused by transformer insulation problems can be prevented.In all kinds of insulation problems of transformer,discharge is an important cause.When discharge occurs in transformer oil,it will radiate acoustic energy around.These acoustic signals contain information related to the condition of transformers.Therefore,the analysis of transformer acoustic signals can diagnose the operation status of transformers.In this paper,the generation mechanism of the transformer acoustic signal is studied,including the normal running state and the discharge state.Combined with their different characteristics,Fourier transform,wavelet transform and wavelet packet transform are selected to analyze these two kinds of acoustic signals.Then the acoustic signals under normal condition and three simulated spark discharge faults are collected and the difference between their time domain wave-forms and the time frequency analysis results is compared.The frequency spectrum obtained by Fourier transform and the energy spectrum obtained by the wavelet packet transform are proposed to diagnose whether a transformer has discharge faults.On this basis,a method of identifying the type of discharge fault based on the characteristic frequency interval obtained by wavelet transform is further proposed.According to the previous research results,a transformer fault acoustic diagnostic instrument has been developed,which includes amplification module,filter module,AD conversion module and MCU.Experiments on the diagnostic instrument show that the diagnostic instrument can accurately diagnose the discharge faults and the types of faults in the transformer.