青藏铁路110 kV输电线路全程3/4处于高海拔冻土地带,该地区特有的雷电活动规律和土壤地质状况对输电线路的雷电防护效果有着很大的影响,需要在防雷设计中予以考虑。通过对高海拔冻土地带气候地质特点的统计分析,得出在这一地区进行输电线路防雷设计应该考虑土壤融冻层出现季节与雷电活动时间基本一致的气候特点,充分利用融冻层的低电阻率特性,确保输电线路的防雷可靠性。依据这一原理提出了在高海拔冻土地带进行输电线路防雷设计的一般过程和具体措施,包括耐雷水平和接地电阻的确定、接地体结构尺寸的选择以及一些改进措施的比较等。对青藏铁路格尔木-拉萨段110 kV输电线路的计算表明,提出的设计方法可以满足输电线路雷击跳闸率的要求。
The 3/4 length of the 110 kV transmission line along the Qinghai-Tibet Railway passes mrougn the high altitude permafrost region, so the lightning activity and the soil geological condition of these regions will greatly affect the lightning protection function of the transmission line, and this should be considered in the design process. On the basis of the statistical analysis of the climate and geological features of high altitude permafrost regions, it is proposed that the lightning protection design of transmission lines should consider the time consistency between the thawing season and the lightning activity time, making full use of the low resistivity characteristics of the thawing layer to ensure the reliability of the lightning protection of transmission lines. Thereby, a general process and some specific measures of lightning protection design for transmission lines in high altitude permafrost region are put forward, including the determination of the lightning withstand current and the tower grounding resistance, the selection of the grounding structure and size, and the comparison of some improvement measures. The calculations on the 110 kV transmission line for the Golmud-Lhasa section of the Qinghai-Tibet railway have shown that the proposed design way can meet the requirements of the stroke trip-out rate of transmission lines.