Partial discharge localization in transformers using UHF detection method

The location of a partial discharge (PD) source inside a transformer can be determined from the time differences of arrival (TDOA) between signals that are captured by an array of UHF sensors. The TDOA can be acquired from the received PD waveforms. In this paper, three different methods of acquiring the TDOA from the PD waveforms are discussed. The time difference can be calculated either by taking the first peak of the signal as the arrival instant, or from the cross-correlation of the PD waveforms, or by applying the similarity function to the plots of the PD signals cumulative energy. Computation algorithms for determining the TDOA automatically are introduced so that possible bias from human interpretation is avoided. The presence of noise and its effect on the accuracy of the PD localization will also be presented. Experimental results show the first-peak method has higher accuracy than the two other methods. The application of signal denoising further improves the localization accuracy.