220 kV输电线路跨江段防雷措施研究

Study on Lightning Protection Measures of 220 kV Transmission Line Section Across River

输电线路中的大跨越线路悬挂高度更高,地面的屏蔽作用减弱,线路更易遭受雷击,为保证线路安全运行,必须对大跨越档距防雷进行特殊设计。文中针对吉安井冈山水电站220 k V送出工程跨赣江部分进行了防雷的综合设计,通过建立EMG三维电气几何模型,分析计算了侧向避雷针长度与保护距离之间的关系以及架设避雷线短针后的绕击率;通过建立雷击暂态模型,仿真分析了接地电阻和耦合地线对雷击过电压的影响。研究结果表明:塔头上的侧向避雷针长度为3 m时,保护的距离为21 m,线路上加装1.2 m短侧针可将线路绕击率降低93.2%;降低接地电阻是减小反击过电压的最直接有效措施,但在土壤电阻率较高地区,通过架设耦合地线分流能更有效的减小反击过电压。

Due to the higher suspension height of large cross section,the ground shielding effective is weaker than the common section,large cross transmission lines are easily hit by lightning.In order to ensure the safe operation of power transmission,the lightning protection of large cross section must be specially designed.In this paper,a comprehensive lightning protection design has provided for the 220 kV electrical power transmission line project of Jing Gangshan hydropower station across Gan river section.By establishing the EMG 3 D electrical geometry model,the relationship between side lightning rod length and protection distance is analyzed and the transmission line shielding failure rate is calculated.By establishing lightning transient model,the influence of ground resistance and coupled ground line on lightning overvoltage is simulated and analyzed.It is shown that,when the length of side lightning rod on tower head is 3 m,the protection distance is 21 m;the shielding failure rate can be reduced 93.2%by installation of 1.2 m short side pins on the lines;reducing grounding resistance is the most direct and effective measure to reduce reverse overvoltage,but in high soil resistivity area reverse overvoltage can be reduced more effectively by setting up couplinggroundwire.