低气压下特高压直流污秽复合绝缘子覆冰闪络特性

复合绝缘子耐污性能好，我国在建的云广±800 kV直流特高压线路将采用复合绝缘子，但该线路面临覆冰和高海 拔的影响。该文在人工气候室模拟高海拔的低气压研究了2种不同伞型结构的染污复合绝缘子直流冰闪特性。结果表明：特高压直流复合绝缘子冰闪电压随冰厚和污秽程度增加均呈幂函数规律下降，2种绝缘子冰厚影响特征指数分别为0.246、0.212，污秽影响特征指数则分别为0.174 2、0.178 4。而冰闪电压与高海拔低气压之间满足幂函数关系，其气压影响特征指数与绝缘子型式、覆冰状态和覆冰量、污秽程度等有关。在中等覆冰条件下，五三型结构复合绝缘子具有较好的覆冰电气性能。在严重覆冰条件下，复合绝缘子伞裙结构对直流冰闪电压的影响不明显。

Icing Flashover Performance of UHV DC Composite Insulators at Low Atmospheric Pressure

The newly building ±800 kV ultra high voltage (UHV) transmission lines in China will adopt the composite insulator for its excellent preventing pollution performance, which face with the multi influence of ice and high altitude. The paper studies the DC icing flashover performance of two different shed configurations of polluted composite insulators at low air pressure simulated by the multifunction artificial climate chamber. The test results show that the DC icing flashover voltage may depress by power function rule with the ice thickness and the pollution increasing, the exponent describing the influence of ice thickness is 0.246 and 0.212 separately and the exponent describing the influence of pollution is 0.174 2 and 0.178 4 for the two types of insulators. The relationship between DC ice flashover voltage and air pressure meets power function and the value of the exponent describing the influence of air pressure depends on the configuration of insulator, icing state, icing level and pollution. The electric performance of five-three type icing composite insulator is better under middle icing condition. In severe icing condition, the influence of shedding construction of composite insulators on DC icing flashover voltage is slight.