An optimal wavelet filtering method for noise suppression of PD measured signal and its location in power transformer winding

In this paper a method for selecting optimal wavelet is introduced, which is implemented for evaluating electrical measured partial discharges on a 66 kV/25 MVA fully interleaved winding of a power transformer. Applying wavelet transform to a signal produces a wavelet detail coefficient distribution throughout the for generating coefficients with maximal values. The basic idea of this method is described and applications to partial discharge studies are explored. The paper demonstrates that the wavelet based de-noising method proposed in the paper can he employed in extracting the PD pulses from the measured signal successfully to provide enhanced information and further infer the original site of the PD pulse through capacitive ratio method.