Spectral method for localization of multiple partial discharges in dielectric insulation of hydro-generator coils: Simulation and experimental results

Abstract

A methodology based on spectral analysis for localization of multiple partial discharges in dielectric region of hydro-generator coils is proposed. This pinpointing of multiple discharges aims to provide means for performing diagnosis of insulating regions of the coil. A numerical model of the structure was developed by using the finite-difference time-domain method (FDTD-3D) to solve Maxwell's equations. Transient voltage associated with partial discharges that occurs at different positions of the coil is calculated at specific point and its spectrum is used to perform the diagnosis. In 90% of simulations, accurate estimates of simultaneous discharges location were obtained. Physical phenomena allowing the development of the methodology are assessed numerically and experimentally. Finally, a localized artificial PD injection schema is proposed and used for validating our numerical results and physical analysis.