Transient Overvoltage Simulation Analysis of 1100kV Long Distance GIL

Abstract

Gas-insulated Metal-enclosed Transmission Line (GIL) is a kind of power transmission technology that integrates safety, reliability, environmental friendly. It will be more widely used in power distribution system due to its excellent performance. In this case, the length of GIL would continue to grow. It will bring new challenges to the protection of overvoltage and insulation coordination. Thus, in this paper, based on the practical engineering design, a long-distance GIL simulation model is established by ATP-EMTP. The equivalent capacitance parameters of insulators are calculated by finite element simulation software COMSOL. The influences of insulator configurations (basin-type insulator and tri-post insulator), closing angle, GIL length and residual charge on overvoltage are studied respectively. The configurations with different insulators for the GIL has little effect on the overvoltage. The maximum multiple of operating overvoltage occurs at the end of the GIL pipeline, and relates to the closing phase angle at the same time. Because of the refraction and reflection process of waves, there is no obvious monotonic function relation between the GIL length and the maximum multiple of overvoltage. When the length of GIL is less than 1.5 km, there is no obvious correlation between the maximum multiple of overvoltage and the length of GIL. The maximum multiple of overvoltage is between 2.27 p.u. and 2.3 p.u. after the length of GIL exceeds 1.5 km. The amplitude of the overvoltage increases as residual charge increase. The result could provide design basis for insulation coordination of long distance GIL