中文摘要：

特高压直流输电在国内外均没有设计、建设和运行经验。根据我国云广±800kV特高压直流工程建设的需要，该文以5种不同结构型式的超、特高压直流复合绝缘子短样为试品，在人工雾室试验研究了试品的人工污闪特性，分析了试品绝缘子污闪电压与盐密、气压的关系。结果表明，直流复合绝缘子短样污闪电压（Uf）的污秽程度影响特征指数（α）与伞裙结构和材质有关，其值为0．25-0．3，小于瓷和玻璃绝缘子绝缘子，即坼受污秽程度的影响较小，在污秽严重地区，复合绝缘子具有优势：坼的气压影响特征指数n与绝缘子材质、结构、污秽程度等有关，对于直流复合绝缘子，n值为0．5-0．8，大于瓷绝缘子，在高海拔地区，复合绝缘子不具有优势。根据该文试验结果，采用样品绝缘子E，±800kV特高压直流输电线路在轻污秽、海拔1000m及以下地区的基本电弧距离应不小于8．16m，爬电距离应不小于30．2m。

英文摘要：

There is no design, construction and operating experience of the UHV DC transmission lines both at home and abroad. To meet the demands of the construction of the Yun-Guang ±800kV UHV DC transmission line, the artificial pollution flashover performance （PFP） of the short samples of 5 kinds of UHV/EHV DC composite insulators are investigated. The influences of salt deposit density （SDD） and atmospheric pressure （P） on the PFP of the test insulators are analyzed. The research results show that the a, characterizing the influence of SDD on the flashover voltages （Uf） of the short samples of the DC composite insulators, is related with the configuration and the material of the insulator shed. The a, between 0.25 and 0.3, is smaller than those of porcelain and glass insulators. That is to say, the influence of SDD on the Uf of the DC composite insulators is relatively little. In the severe pollution regions, the composite insulators have certain advantages. The n characterizing the influence of P on the Uf of the DC composite insulators is related with the configuration and the material of the insulator shed and the SDD. The n, between 0.5 and 0.8, is larger than those of porcelain insulators. Therefore, in the high altitude regions, the composite insulators have no advantages. Based on the test results, if insulator sample E is selected for the 4- 800kV UHV DC transmission line, the basic arc distance should be no less than 8.16m and the creepage distance no less than 30.2m.