Impact of Temperature on the Transient DC Field Distribution of ±1100 kV UHVDC Wall Bushing

UHV DC wall bushing is the only channel connecting the valve hall and the DC electric field in the converter station. For the epoxy - SF
₆
gas composite insulation wall bushing, the main insulation material is the epoxy/crepe paper core and SF
₆
gas. The transient process of establishing the DC electric field for the wall bushing is impacted by the temperature gradient. In this paper the 3-D temperature field of the wall bushing has been simulated considering the effect of heat conduction, convection and radiation. The simulation results have been confirmed using a temperature rise experiment. The transient process of the wall bushing under the actual operation condition has been simulated using the gas saturation current density method. The temperature impact on space charge density in the core, the surface charge on the interface, and the electric field distribution on the bushing is investigated. In this way a theoretical basis is developed for the optimal design of the bushing that is conductive to the safe operation of the bushing.