Research on the Overheating Fault of HVDC Wall Bushing and its Dignosis Strategies Based on CFD

Resin impregnated paper (RIP) wall bushing is the only channel connecting the valve hall to the outdoor DC field. It carries full voltage, full current and strong mechanical stress in long-term operation. Long-term thermal expansion and contraction causes the electrical contact wear of the outdoor part to be very serious, and it is prone to overheating failure. The local overheating will accelerating the fretting wear and corrosion, which will decrease the insulation and mechanical performance of RIP core. The byproduct also may fall out and distort the electrical field. Therefore, it is vital to maintain the overheating faulted bushing in time. In this paper, firstly the 3-dimentional finite element model of ±500kV DC wall bushing including connect structure was established. Then the thermal field distribution of wall bushing with the contact fingers with different degrees of deterioration were simulated. The correspondence between the temperature of the fault point and the temperature of the sheath were established. Finally, the correspondence were successfully applied to maintain a faulted wall bushing before destructive overheating fault occurs. This research can provide a basis for monitoring the overheating fault of the bushing with an infrared camera.