Research On The Determination Of Outdoor Insulation Level For The Transmission Line In Gormu High Altitude Area

Germu Salt Lake lies in Caidamu Basin of Qinghui-Tibet Plateau, which belongs to heavy-pollution area with an altitude of 2800m high. Due to flashovers often happen on HV transmission lines in that area. The 110kV transmission lines for Qinghai-Tibet railway (project II) lies in the roof of the world , with an altitude of 4000m-5000m . At present, the existed rule and specifications for designing 110kV transmission lines could not be used for the design of 110kV transmission lines on the Salt Lake and Qinghai-Tibet railway. Therefore, the determination of the outside insulating level for 110kV transmission line is a key project for the Germu Salt Lake and Qinghai-Tibet area. In the thesis, based on the flashover events due to pollution, weather conditions and the results from the measurement of the salt density on the insulators, the pollution degree of the area of Germu Salt Lake are determined (the pollution degree of Salt Lake is IV, and that of area around the urban is III) . It was found that the reason for flashover happened often in Xiaoming and Xiaobai transmission lines was due to less creepage distance of the insulator string. Based on the investigation on the existed data, a new ruleand some empirical formula are proposed to determine the outdoor insulation level for 110kV transmission lines on Germu Salt Lake area, providing a bases on developing a standard for outdoor insulation design in this area.Based on the above results, a new proposal is presented for the determination of outdoor insulation level of 110kV transmission along with Qinghai-Tibet railway.