Modeling the influence of a protective device on PD intensity in cable insulation

The article focuses on the influence of a nonlinear protective device based on metal-oxide varistors on the characteristics of partial discharge (PD) in an insulation defect. The study presents a multifaceted approach, including mathematical modeling and analysis of the processes associated with PD, which helps evaluate the effectiveness of using the protective device (PD) to protect insulation from the negative impact of impulse overvoltages. The study is based on a mathematical model that implements the classical mechanism of partial discharge in a single defect. The protective device, connected in parallel to the studied model, limits the overvoltage, which was simulated using a high-frequency decaying impulse. The simulation was carried out in a multiphysics formulation of the problem, calculating the model using the finite element method, which implements the relationship between current density and Joule heating of the air in the defect. The mathematical model allows obtaining the dependencies of temperature in the defect over time, heating and cooling curves of the defect environment, and PD power at various values of defect diameter and impulse overvoltage multiplicity. The study assessed the influence of the protective device on PD power, and determined the degree of PD power reduction. It demonstrated the possibility of using the protective device to reduce the negative impact of PD on insulation.