Electric Field Simulation on Epoxy Spacer with Nonlinear Conductivity for DC-GIL

Abstract

AbstractThe electrical field distortion at the gas–solid interface is a primary factor to induce flashover and decrease the withstand voltage of the HVDC gas insulated transmission line (GIL). Conventional electrical field homogenization methods such as structure optimization and material modification, have some limitations, thus urgently required to be effectively regulated. We proposed to use nonlinear conductivity composite to suppress field distortion. Electrical field along the conventional and novel spacers under different conditions were calculated based on the measured nonlinear conductivities of epoxy composites at different temperatures. Results show that, in full load conditions, the conductor temperature rise can uniform the electrical field in a certain range, but it will cause field distortion near the ground electrode while overloading. The application of nonlinear conductive epoxy composites can decrease the maximum field by 40% and uniform the electrical field distribution under high temperature gradients. The power loss generated by the leakage current in the spacer increases with temperature, but it can be ignored compared with the conductor current heating. Epoxy composites with nonlinear conductivity can improve the electric field distribution at the gas–solid interface effectively, and are expected to be widely used in DC GIL.