Design of ±400kV DC Line Arrester in High Altitude Area

Abstract

The ±400 kV transmission linefrom Chaidam,Qinghai to Lhasa, Tibet (Chaidam-Lhasaline) is the main power receiving channel of Tibet Power Grid, and also the first DC transmission line over the world crossing 5 000 m altitude region. In order to improve its ability to withstand the risk of lightning damage effectively, the structure type and technical parametersof the line arrester used in this line was analyzed according to current technical standards for AC/DC line arresters and high-altitude environmental requirements. The key technical parameters of ±400 kV DC line arrester were designed, calculated and verifiedwith tests. Its key technical parameters are: rated voltage 480 kV, nominal discharge current 20 kA, lightning impulse discharge voltage ≤ 2 100 kV, residual voltage ≤ 960 kV, unified specific creepage distance ≥ 32.5 mm/kV, DC wet withstand voltage 480 kV, polymer lightning impulse discharge withstand voltage 1 344 kV, and polymer DC wet withstand voltage also 480 kV. In addition, the unified air series gap distance is 2.8~3.2 m. Development of ±400 kV DC line arrester fills the technical gap of high-altitude DC line arrester, laying a foundation for popularization and application of the arrester on ±400 kV Chaidam-Lhasa line.