Parameter Optimization of Nonlinear Conductivity Material for ±500 kV GIL Spacer

Regulating the electric field distribution is one of the critical problems for the development of HVDC gas insulated transmission lines (GIL). In this study, the surface nonlinear conductivity (SNC) spacer was applied to relax the electric field distortions caused by a metal particle or a polarity reversal voltage in a ±500 kV DC-GIL. Results indicated impressive behaviors of the SNC spacer in regulating surface charge and electric field distributions. To get better performances, the regulation effect, the loss property and the transient response of the SNC spacer were 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 keeps growing while increasing the nonlinear parameters. The time constant was defined to evaluate the transient response of spacers, and a lower time constant leads to a lower over-shoot of electric field under polarity reversal voltages. Finally, the parameter optimization of the SNC spacer was achieved by drawing a parameter map after fixing relevant indexes.