Electric field regulation and parameter optimization of surface nonlinear conductivity spacer for 500 kV DC-GIL

In this paper, the surface nonlinear conductivity (SNC) spacer is proposed to regulate the electric field in a 500 kV DC-GIL, whose effects are verified by assigning a temperature gradient, a rough electrode, a metal particle and a polarity reversal voltage in the simulation model. The results show impressive behavior of the SNC spacer in suppressing surface charge and electric field distortion. To obtain a better performance, the regulation effect, the loss property and the transient response of the SNC spacer are explored by varying the ohmic surface conductivity and the nonlinear coefficient. The electric field utilization factor of the SNC spacer has a saturation region, but the surface loss increases with increases in the nonlinear parameters. Reducing the time constant of the SNC spacer restrains the electric field over-shoot under voltage polarity reversal. The parameter optimization of the SNC spacer is achieved by drawing a parameter map after fixing relevant indexes.