Partial discharge location in power transformer windings using the wavelet Laplace function

Abstract

Insulation system conditions in power transformers can be evaluated by means of partial discharge (PD) analyses. In fact, PD analysis is used to detect premature damage in transformer insulation system to avoid catastrophic faults. Detection and location of PD is a complex problem and has been widely studied by several researchers. A new method for PD location in transformer windings based on Wavelet Laplace (WL) is developed in this paper. First, the PD reference signals are obtained from a lumped parameter model (RLC) and those signals are used to determine the WL parameters, then PD signals are analyzed using the WL and each PD reference signal is replaced by its envelope wavelet transform (EWT) coefficients. Then, if a PD signal occurred in any section of the winding, its location will be defined by Hellinger distance between the EWT coefficients and the new PD reference signals. Results are discussed for PD along the winding and between sections of the winding.