Modelling of aged cavities for partial discharge in power cable insulation

In this study, the ageing process of cavities in solid insulation of power cables is divided into three stages, and for each stage a circuit model is proposed. Each of these circuit models preserves the basic characteristics of the cavity under the circumstances of the corresponding stage and provides the expected behaviour of generated partial discharge (PD) pulses. This set of models simulate cavity wall effects, the non-uniformity of internal electrical field and charge deployed on the wall surfaces with considering the existence of electronegative gases according to the requirements of the three defined ageing stages. Finally, the simulation results, in the forms of phase resolved PD patterns are presented showing good agreement with the published experimental measurements drawn from accelerated ageing process setups.