Modelling of cycle to cycle behaviour for partial discharge events within a spherical cavity in a solid dielectric material by using Finite Element Analysis

A partial discharge (PD) analysis method that can be used to observe cycle to cycle behaviour of PD activity is to plot PD charge magnitude and voltage of PD occurrence against phase angle for certain numbers of cycles of the applied voltage. The advantage of this method is it gives a better picture of PD activity behaviour in terms of the sequence of discharge events. In this paper, the cycle to cycle behaviour of experimental measurements of PD in a spherical cavity within a solid dielectric material has been obtained and compared with simulation results from a PD model. The paper includes the description of the development of the model using the Finite Element Analysis (FEA) method. The model can effectively reproduce the PD cycle to cycle behaviour of the experiment. Through analyzing the cycle to cycle behaviour of PD events, understanding of the physical mechanisms involved in PD activity can be obtained, such as the effects of initial electron generation rate, charge decay and temperature change between consecutive discharges.