Modeling of Partial Discharge for Solid Insulation

In high voltage (HV) electrical power systems; varieties of materials (solid, liquid and gaseous) are used for insulation purpose to protect the early failure in High Voltage power equipment. Most of the insulating materials are not perfect in all respect and contain some impurities. The presence of air bubble is one of such impurities in insulating materials which is highly undesirable. Insulation of the HV power equipment gradually degrades due to the cumulative effect of electrical, chemical and thermal stress and aging. Due to the high voltage stress, the weak zone inside the insulator causes partial discharge (PD).This deteriorates the insulator. In this paper, an electrical circuit model of the solid insulator with void is used to study the PD activity leading to breakdown inside the insulator. Among the models (namely the capacitive model and induced charge concept model), the capacitive model is adopted in present work. The Simulink capacitive model implemented, effectively demonstrates the partial discharge process. The model is used to study and demonstrate the effect of the permittivity of cavity/impurity and breakdown inception voltage level of the impurity.