A Digital Technique Based On The Wavelet Transform For Partial Discharges Analysis

With ultrawide-band detection of partial discharge (PD) transients the true shape of a PD current pulse can be recorded. It is so possible to achieve more useful information about both sources and causes of PDs and physical processes taking place. However, the recorded signal can be distorted due to external noise, reflections and oscillations, stray elements in the measuring circuit; as a consequence, the extracted information might be meaningless. In this paper a digital technique for a reliable analysis of such PD pulses is suggested. The technique, based on the Wavelet Transform, is able to set the detected pulse free from most of the disturbances affecting its true shape, thus assuring traceability in the measurements carried out on the pulse itself. After a brief remark on theoretical and implementation features of the Wavelet Transform, the proposed technique is described in detail. Experimental results obtained from the application of the proposed technique to actual PD pulses are also given.