Studies on Partial Discharge Simulation Based on a Stochastic Model Considering the Variation of Discharge Area and Temperature of the Void Surface

Abstract

A model based on the Finite Difference Method (FDM) is proposed for simulation of Partial Discharge (PD) Patterns in which four parameters are considered, viz. the critical field intensity for partial discharge occurrence E c , residual field intensity E r , critical field intensity for discharge propagation along the void surface (E s ) and size of the void. Though different models on PD have been developed by the researchers with various assumptions, this model is proposed assuming that the probability of Partial Discharge occurrence after each polarity inversion (zero-crossing) of the voltage waveform to be less in comparison with that near the peak of the voltage wave along with the consideration that the temperature of the void surface gets changed with the aging of the insulator. This work attempts to show the effect of both E s and size of the void on Partial Discharge as the discharge quantity at any instant is not only a function of E c , E r but also depends upon E s and void size. In this paper, Plane-Plane electrode system is considered and the void taken is a rectangular parallelepiped. PD simulations for different sizes of void inside the dielectric are carried out with constant E c and E s , considering occurrence of partial discharge and residual field to be stochastic in nature. The inception and extinction of PD, shape of PD patterns in relation to released charge amplitude, and the amount of charge, which is released during PD for different void sizes, are studied and reported in this paper. An attempt is also made to show the changes in the phase resolved plots due to growth of the void due to aging of the insulator.