耦合地线架设位置及根数对500/220kV同塔4回线路防雷特性影响

架设耦合地线是一种有效降低线路反击跳闸率的防雷措施。为探讨不同耦合地线架设位置对不同回线路的耐雷性能所造成的影响,针对500/220kV同塔4回线路进行分析计算,分别在不同高度横担中央处架设单根或双根耦合地线,比较其保护范围及效果。同时也对不同耦合地线架设位置对应的杆塔、避雷线和耦合地线的分流系数以及导线和避雷线间的耦合系数进行了分析比较,以确定耦合地线在不同位置安装时,其改善线路防雷性能的机理。研究表明:耦合地线离线路越近,对其保护越好,单根耦合地线对应的分流系数可达2%～7%,架设双根耦合地线时分流可达5%～14%,架设耦合地线可以有效地增大耦合系数。

Influence of Mounting Location and Number of Coupling Ground Wires on Characteristic of Lightning Protection for 500/220kV Quadruple-circuit Transmission Line on Same Tower

Mounting coupling ground wire is an effective lightning protection measure to reduce trip-out rate of back flashover,however,various mounting positions of coupling ground wire have different impacts on the lightning protection characteristics of transmission lines,especially the multi-circuit lines.We compared their protecting effect of setting single or two grounding wires in the middle of cross-arms at different heights,and analyzed the effects of mounting coupling ground wire on the center of different cross-arm aimed at 500/220 kV quadruple-circuit transmission lines.Moreover,in order to explore the mechanism of coupling grounding wires improving the protection characteristics in transmission lines,we compared and discussed the shunt coefficients of tower,ground wire and coupling ground wire and the coupling coefficient in the condition of various mounting positions.The results indicate that the effect of protecting conductor wire is better when the coupling ground wire is closer to the conductor.The shunt coefficient of single coupling ground wire can reach 2%~7%,and the shunt coefficient of double coupling ground wires can reach 5%~14%.Mounting coupling grounding wires can effectively increase the coupling coefficient.