直流瓷绝缘子长串高海拔覆冰闪络特性

DC Flashover Performance of Ice-covered Porcelain Insulator Strings Under High Altitude Conditions

为了给超特高压直流输电线路外绝缘选择和运行维护提供基础数据，以典型直流瓷绝缘子XZP－210长串为研究对象，在大型多功能人工气候室试验研究了污秽、覆冰、高海拔综合复杂环境下的直流闪络特性。试验结果表明：XZP－210覆冰绝缘子串直流冰闪50％闪络电压眠慨与串长基本呈线性关系；不同海拔高度下，弘㈣随覆冰厚度和污秽程度增加均呈幂函数规律下降，冰厚影响的特征指数在0．182～0．208之间，污秽程度影响特征指数在0．175～0．191之间；气压对％0％的影响特征指数n在0．404－0．462之间；临界闪络电流Ic随污秽程度的增大呈幂函数规律增大，其指数在0．629-0．678之间；厶随着气压的降低而减小，与气压比呈幂函数规律，指数在0．512～0．538之间。

In order to obtain the basic data for the design and maintenance of insulators used in UHV/EHV transmission lines, the DC flashover performance of typical insulator strings XZP-210 were studied under the combined conditions of surface pollution, icing and high altitude in the multi-function artificial climate chamber. Based on the test results, the relationships between the flashover voltage and the insulator length as well as the environmental factors were obtained. Test results show that the average flashover voltage （U50%） of ice-covered XZP-210 insulator strings is almost in linear relationship with the string length, and decreases with the increase of the ice thickness and pollution severity in power function rule at various altitudes. The characteristic exponent describing the influence degree of ice thickness, and pollution severity is 0.182-0.208 and 0.175-0.191 respectively. The characteristic exponent describing the influence degree of air pressure is from 0.404 to 0.462. The critical flashover current lc increases in power function rule with the increase of pollution severity, and the range of the characteristic exponent is from 0.629 to 0.678. Moreover, Ic decreases with the decrease of air pressure, and it presents the power function rule along with the ratio of air pressure. And the range of the characteristic exponent is from 0.512 to 0.538.