Application of wavelet transforms denoising in acoustic emission detection of polluted insulator discharge

This paper studies how to use wavelet transform method to purify and denoise in acoustic emission monitoring of polluted insulator discharge. Based on numerous acoustic emission experiments of polluted insulators discharge, the common characteristics of acoustic emission wave emitted from polluted insulators discharge are summarized. And an effective method to select best wavelet basis is proposed based on wavelet transform of acoustic emission signals. Then the appropriate wavelet function is chosen. And frequency analysis of acoustic emission signals is realized using wavelet transform with optimal wavelet function of rbio3.9. Characteristic frequency bands are extracted to reconstruct the signal, and then duplicate wavelet decomposition is applied to reduce noise of reconstructed signal. Two examples using wavelet analysis to denoise in acoustic emission signals are given. Experimental result shows that the reliability of separating the signal from noise is improved and noise influence on acoustic emission signal is reduced effectively after using wavelet transform method.