高海拔地区750kV输变电设备外绝缘选取方法及绝缘子选型研究

根据750kV输变电示范工程的需求,对工程可能选取的4种大吨位电瓷绝缘子、4种大吨位玻璃绝缘子和3种不同伞裙结构的高强度、大直径电站支持绝缘子进行了不同海拔高度、多种污秽程度的试验研究;试验研究了硅橡胶复合绝缘子在不同海拔高度的污闪特性;比较了有、无RTV涂层的电站支持绝缘子污闪特性的差别。利用爬电比距法和污耐压法选取了不同污区、不同海拔高度的线路悬式和电站支持绝缘子的外绝缘尺寸,推荐了三层伞和双层伞型线路绝缘子为优选伞型。研究表明硅橡胶复合绝缘子比电瓷和玻璃绝缘子的耐污闪能力优异,建议在高海拔重污区首选复合型绝缘子。

Study on Selection Method of External Insulation and Insulator Type Selection for 750 kV Transmission and Transformation Equipment in High Altitude Area

Polluted external insulation is the controlling factor for the selection of external insulation of the electrical equipments used in the 750 kV transmission lines. The problem has become more serious in high altitude areas with lower air pressure. According to the requirements of the 750 kV demonstration project in China, four types of 210 kN and 300 kN porcelain insulators, four types of 210 kN and 300 kN glass insulators and three kinds of the post insulators with different shed types have been tested in different altitudes and different pollution levels. Meanwhile, the flashover characteristics of the composite insulators in different altitudes have been studied. Comparisons of flashover characteristics between the post insulators covered with RTV or without RTV are carried out. Specific creepage distance method and withstand voltage method are adopted to select the suspension and post insulators in different pollution levels and different altitudes. As a result, the three-shed-suspension insulators and two-shed-suspension insulators are recommended for the transmission lines. The three-shed-post insulators with deep grooves are recommended for the substations. The results have shown that the pollution resistance performances of composite insulators have advantages over that of the porcelain and glass insulators. So they are recommended in high altitude area with heavy pollution.