Study on pressure spread characteristics of arc fault in critical area of UHV oil-filled equipment

Large-scale oil-filled equipment such as AC transformers, converter transformers and reactors are important equipment in UHV transmission systems. However, the sudden pressure rise caused by arc faults will cause explosions of oil-filled equipment, which seriously threatens the safe and stable operation of the power system. The tap-changer and ascending flange are the critical areas of UHV oil-filled equipment, with a higher probability of internal arc faults than the rest of the equipment. In order to clarify the pressure spread characteristics of tap-changers and ascending flanges during arc fault, the pressure distribution characteristics were analyzed based on finite element simulation. Based on the gas-liquid two-phase flow model and the compressible model, the generation and transmission of pressure waves were simulated, and the pressure distribution law and evolution process at different times were analyzed after arc energy was loaded at different fault locations. The results show that the pressure near the fault point is the highest, and the pressure peak decreases significantly with the increase of distance. The time to reach the peak pressure of different parts is obviously different, which shows the feasible to judge the arc fault location based on the pressure distribution characteristics of multiple monitoring points.