Identification and Detection of Partial Discharge and Electrical Breakdown within a Cavity by using Wavelet Transform under AC Condition

Abstract: In high voltage system, the measurement of partial discharge (PD) is used in the assessment of an insulation system. Through modelling the PD process, a better understanding of the phenomenon may be evaluated. In this paper, a model for a cavity within a dielectric material has been developed and tested by using MATLAB environment. The model has been used to study the effect of various applied voltages on the cavity. The measurements were performed for different amplitudes of the applied voltage. The measured results show that PD is strongly influenced by various conditions such as applied voltages, frequencies and the type of the cavity. The cycle to cycle behavior of PD events, discharge phase and magnitude distributions, numbers of PDs per cycle, total charge magnitude per cycle for each set have been obtained and analyzed. The test results from the PD model have been studied and analyzed. It is found that certain model parameters are dependent on the applied voltage, frequencies and cavity conditions. Parameters that clearly affect PD activity can be readily identified.

Keywords: Partial Discharge, Corona Discharge, Surface Discharge, Treeing & Tracing, Void, Cavity, Wavelet Transform, Signal Energy, Breakdown.