Study on Lightning Intrusion Overvoltage of Traction Substation at High Altitude

Qinghai-Tibet Railway is located at high altitude areas, whose altitude ranges from 2828 meters to 5072 meters. The lightning impulse withstand levels of transmission lines in those areas is quite different due to the different altitudes, which leads to various wave shapes of overvoltage. Therefore, we intend to adopt a regulations method to modify the insulation strength of transmission lines at high altitudes. And the magnitudes of overvoltage on main electrical equipment at different altitudes and their changes with altitude were compared and analyzed. In this paper, firstly, the flashover voltage of the insulator string at different altitudes is modified, to obtain the 50% discharge voltage of the insulator string at different altitudes. Secondly, we established several numerical models of the arrester, tower, insulator string, lightning current, and equipment in the station. Observations and studies of lightning phenomena indicate that lightning has the phenomenon of multiple discharges in one breakdown process. Finally, the overvoltage of lightning intrusion waves at different altitudes and under different lightning impact waves was calculated respectively, and the law of lightning overvoltage of main equipment under different altitudes is obtained.