Partial Discharge Localization for a Transformer Based on Frequency Spectrum Analysis

Partial discharge (PD) is a major source of insulation failure in power transformers. The location of a PD source is of crucial importance in both the maintenance and repair of a transformer. This paper applies the knowledge that the poles of a PD current frequency spectrum do not change, whilst the zeros vary with the position of a PD source within the winding. An algorithm based on this approach has been developed for the localization of PDs. The algorithm adopts the well-known ladder network to model the transformer winding, then estimates the parameters of this model from the poles of the PD current frequency spectrum. This provides the necessary information to be able to calculate a PD signal from different source locations within the model. Finally, the position of a PD source can then be estimated by a comparison of the measured and calculated PD signals. Simulation and experimentation results are demonstrated in the paper. 2