不同串型设计条件下的特高压交流同塔双回线路雷电性能

Lightning Performance of UHVAC Double-circuit Transmission Lines on the Same Tower Under Different Design Conditions of Insulator String

为准确评估1 000 k V特高压同塔双回线路在不同绝缘子串型下的雷电性能,基于电磁暂态程序(EMTP)和电气几何模型(EGM),分别对特高压同塔双回线路在"I"型、"V"型绝缘子串设计条件下的反击和绕击性能进行了仿真研究。并分析了不同的杆塔最小空气间隙距离、塔高、接地电阻、地面倾斜角对线路雷电性能的影响,提出了最佳优化设计方案。最后,结合"皖电东送"工程的设计、运行情况,对比研究了"V"串线路与"I"串线路的雷电性能。结果表明,与"I"串线路相比,"V"串线路更易出现导线对上横担放电闪络,且反击闪络率也略高,但2者的绕击闪络率相差不大。此外,"V"串线路的防雷薄弱点在于其易出现导线对上横担的放电闪络,而"I"串线路的防雷薄弱点在于其易出现导线对下横担的放电闪络。工程设计中可针对2种串型线路各自的雷电薄弱点进行防雷优化设计。

In order to accurately assess the lightning performance of 1 000 k V ultra-high voltage（UHV） double-circuit transmission lines on the same tower with different configurations of insulator strings, we studied the back flashover performance and the shielding failure performance of the transmission lines with I-shape and V-shape of insulator strings based on simulations using the electro-magnetic transient program（EMTP） and the improved elector-geometrical model（EGM）. We also analyzed the effects of the minimum air gap distance to line, length, ground resistance, and ground tilt angle of tower on the lightning performance of lines, and proposed an optimized design scheme of tower. Finally, on the basis of design and operation experience of ‘Huainan—Shanghai 1 000 k V transmission line＇ project, we compared the lightning performance of transmission lines with ‘I＇ strings and ‘V＇ strings. The results show that, compared with the lines with ‘I＇ strings, lines with ‘V＇ strings are more likely to have lightning flashover on upper cross-arms, and higher back flashover trip-out rate, though the shielding failure trip-out rates of these two types are almost the same. The weakness of lightning protection for lines with ‘V＇ strings appears to be the probable lightning flashover on the upper cross-arms of towers, while for lines with ‘I＇ strings, it becomes the probable lightning flashover on the nether cross-arms. Therefore, in engineering design, the lightning protection measures of these two types of lines can be optimized according to their weakness, respectively.