De-noising of partial discharge signals detected at a 400kV power transformer

摘要

Partial discharge signals generated atrntransformer winding are subjected to electrical noisernwhilst propagating from the site of origin to thernmeasuring terminals. If this electrical noise, whichrnmay be caused by various sources, is cancelled out byrnpost processing the collected data, fairly cleanerrnsignals may be obtained for further analyses. Waveletrnde-noising method for partial discharge signalsrndetected on-site at a 400kV/275kV, 500MVA, autotransformerrnis examined in this paper. The paperrndiscusses various noise sources present on-site and thernsuperiority of wavelet de-noising method as comparedrnto conventional filtering. While giving a shortrntheoretical background on de-noising using wavelets,rnthe paper also presents some de-noising resultsrnobtained with different wavelet basis functions, levelsrnof decomposition and soft and hard thresholding.