Research of Pollution Level Prediction and Bushing External Insulation Design of Qinghai ± 800kV Converter Station

The ultrahigh altitude, complex environment and other problems of Qinghai converter station bring great challenges to the equipment selection and the external insulation design in the construction of UHV converter station project. The external insulation design of UHV DC transmission mainly depends on the contamination performance of insulators under working voltage, and the contamination performance includes the natural contamination accumulation performance of insulators and the flash-over performance of contaminated insulators. First, the accurate prediction of pollution level of the area where the converter station site is located is the primary premise of the external insulation design of the converter station. This paper investigates the meteorological and industrial pollution sources and the situations about operation of power transmission and transformation equipment in Hainan Tibetan Autonomous Prefecture, Qinghai Province, especially in the proposed ±800 kV Qinghai converter station site and its surrounding areas, and predicts the contamination accumulation level of AC insulators in the site and its surrounding areas. On this basis, the pollution level of DC field equipment of converter station is further predicted according to the prediction of DC/AC pollution accumulation ratio. Then, aiming at the problem of difficult selection of large-diameter bushing equipment in Qinghai station, a typical bushing is selected to carry out the experimental study on flash-over performance, and the rule of flash-over characteristics of bushing is obtained. Finally, in consideration of the altitude correction of the converter station, this paper puts forward suggestions on the configuration of external insulation of the bushing of Qinghai converter station, which provides a basis for the external insulation design in the construction of Qinghai converter station project.