A New Threshold Function for De-noising Partial Discharge Signal Based on Wavelet Transform

The Partial Discharge (PD) signals, which are characterized by high frequency current pulses, are strongly coupled with external noise. In on-site PD measurement de-noising this PD signal from noisy environment is one of the major challenges. This paper proposes a new nonlinear threshold function for de-noising PD signal using wavelet transform (WT) technique. This new threshold function is continuous as the soft threshold function and also uses the unused coefficients (i.e. which are less than threshold value) which are set to zero in different threshold function. This method first applied on two different type PD signals with White Gaussian Noise (WGN) and simulation results shows that new threshold function can give better performance by changing the variable parameter. Improved signal to noise ratio (SNR) and correlation coefficient indicate that the performance of this method is better than other de-noising technique. Finally, a field detected signal is tested and the de-noised signal indicates that method is effective and efficient for this application.