Statistical Analysis of Partial Discharge Mitigation Performance of Electret in High Power Density System

Electret-based approach showed its potential to mitigate partial discharge (PD) under pulse width modulated (PWM) voltages. A significant percentage reduction in both maximum PD magnitude and PD repetition rate has been achieved by the inclusion of polyvinylidene fluoride (PVDF) based electret under PWM voltages. Although electrets are fabricated under the same charging condition based on the triode corona charging method, the percentage reduction by the electret showed a stochastic nature. For this reason, in this study, our goal is to develop a statistical model to analyze the performance of electrets that have the same surface charge density in mitigating PD under power electronic switching voltages. A series of PD experiments under square voltage were conducted with uncharged PVDF and electret fabricated under the same charging condition, and percentage reductions in the maximum PD magnitude and PD repetition rate were determined. Two different probability distribution models, normal distribution and Weibull distribution, have been used to characterize the statistical behavior of percentage reduction of PD magnitude and repetition rate when electrets are used. This study investigates the effect of rise time on PD mitigation performance using the Weibull and normal distribution.