A new method of partial discharge localization on transformers via the Karhunen-Loeve-transform

This paper introduces a new method of PD localization in a transformer. For this purpose, the electrical PD signals are decoupled via the transformer-bushings. After digitizing, the energy share of reference signals with known origins in each PD pulse is processed. Therefore, the PD pulse is computed via the Karhunen-Loeve-transform to one spectral component of the obtained spectrum. The quotient of this spectral component and the energy of the PD pulse is used for classifying pulses with different origins. In this way, the procedure is independent of the pulse-charges. The efficiency of this new localization method is demonstrated on signals measured on the coil of a distribution transformer. Another advantage of this method is the possibility of separating PD and pulse shaped noise signals, which is confirmed with signals measured on a distribution transformer and a power transformer. Finally, it is shown that the Karhunen-Loeve-transform also allows a very efficient data reduction of the sampled PD signals