Fluid-Kinetic Model for Numerical Simulation of Gas-Solid Insulation Surface Discharge

The study aimed at a Power electronics transformer (PET). The high-frequency power transformer (HFPT) has a gas-solid insulation system, and Surface discharge considers the main reasons for the failure insulation. The research on the mechanism and simulation model of surface discharge is still incomplete. A plasma model of air-surface discharge under negative pulsed electrical stress in plasma with a needle-bar electrode structure was established to study the development process of surface discharge of air-polyimide insulation. Based on the theory of fluid dynamics and kinetic approach, this model couples the particle transport equation, momentum equation, energy equation, Poisson equation, and plasma chemical reaction together and fully considers the surface reaction of the PI film and the secondary electrons caused by high-energy particle bombardment PI surface during launch. Instead of involving hundreds of particle reactions in air emissions, in this model, a set of simplified reactions are used to correctly describe the generation and destruction of charged substances under the background of dry air, which significantly reduces the complexity of the model. Therefore, the finite element method and log formulation are introduced to solve the model, avoiding the unreasonable situation of negative particle density in the solid solution process.