Wavelet based partial discharge image de-noising

In this paper, the application of wavelet de-noising to partial discharge (PD) phase resolved images obtained during on-line measurements on a 6 kV motor is presented. The basic principles of wavelet de-noising analysis, as well as examples of hard- and soft de-noising thresholding are reported. For the purposes of decomposition, the Daubechies wavelet and wavelet packs at different levels were applied. The efficiency of the enhancement was measured by using a mean square signal-to-noise ratio.