| Transmission lines is an important part of the power system.With the development of power system technology,power grid is kept been adjusted and complicatedin recent years,and of the linesput into operation increased year by year,hence the safe operation of transmission linesdraws more attention.Statistics show that many power system accidents were caused by transmission line failure,andthe transmission line failure it is mostly caused by lightning,and a greater proportion of which occur on the lines setting up in the mountains.Several critical technical problems of the lightning protection in the mountain were analysed in this paper.Based on the applicatio n of theory stduty,the 220 k V transmission line projects of Wenfeng-Gubei,Lu’an,Anhui were designed.In terms of the routine selection in the montain,to achieve the appropriate investment control,and effective improvement of operatiron security,the elemantary data,such as lightning weather and characteristic parameters were studied,which according with the routine selection scheme authorized by the local planning department.The avoidation of bad geological section and optimization of transmission line election in the high altitude area were studied,with taking the tower location election and avoidation of lightning strike zone,zone were taken into consideration.By employing the operation experience of transmission lines,the design parameters of conductors,earth wire prevent wave 、 bird damage and insulation coordination were studied,and a set desi gn parameters were put forward.In terms of lightning protection of transmission lines,the characteristic parameters of towers,including topography、ground inclination、elevation were concluded,and the shielding failure flashover rate 、 back stroking rate and lightning trip rate were calculated;the flashover characteristic under lightning were analysed,and the flashover risk level were evaluated by differential analysis,and locate the towers with a high risk level of lightning flashover.For the tower with high risk of lightning flashover,several lightning protection methods were compared to inprove the reliability of transmission lines,including ins tallation of controble lightning rod on one side,optimization of conduct wires arrangement and reduction in tower height,reduction of the earthing resistance by vertical grounding devices,utilization of cap insulators,etc. |
