Research on the Failure Process of Oil Paper Insulation of Surface Partial Discharge under Fluctuating DC voltage

Partial discharge along the surface seriously damages the oil-paper insulation performance and ultimately leads to insulation failure, which greatly reduces the safety and reliability of the converter transformer operation. It is important to understand the failure process of oil-paper insulation under partial discharge along the surface to avoid fault occurrence. In this paper, the failure process of oil-paper insulation under partial discharge of pulsating DC and AC voltage is studied. A partial discharge test platform for oil-paper insulation under pulsating DC voltage was built. The partial discharge test of oil-paper insulation along the extremely uneven electric field was simulated by using the needle plate and column plate discharge model. The oilpaper insulation under two kinds of voltages under the extremely uneven electric field was analyzed in depth. The similarities and differences of the failure process and their causes, the insulation design and operation and maintenance recommendations for preventing flashover under the extremely uneven electric field are proposed.