应用改进的电气几何模型分析500 kV同塔双回输电线路雷电绕击性能

利用电气几何模型(electro-geometric model,EGM)分析超高压及以下电压等级的输电线路雷电绕击性能时,因没有考虑风速以及周围植被的影响,取得的结果与运行经验不一致,针对此,提出改进的EGM,进一步分析风速的变化、击距系数对线路和绕击跳闸率的影响。结果表明:随着杆塔高度的增加,绕击跳闸率增加;当地面倾角增大时,绕击跳闸率呈非线性上升,地面倾角小于15°时对绕击率的影响不大,地面倾角大于15°时绕击率呈倍数增加;当风速小于5 m/s时,其对线路的绕击率的影响不大,当风速大于5m/s时绕击率明显增加。最后得出结论,在分析500kV同杆双回线路耐雷性能时应该考虑风速、周围植被的影响,才能使分析结果更符合实际情况。

Analysis on Lightning Shielding of 500 kV One-tower Double-circuit Transmission Lines by Using Improved Electrical Geometric Model

Due to ignorance of influences of wind speed and surrounding plants during analysis of lightning shielding of UHV- and-below transmission lines by using electro-geometric model （EGM）, the conclusion is in unconformity with practical oper- ational experiences. Therefore, improved EGM is proposed to further analyze influence of wind speed change and striking distance factor on shielding failure trip-out rate. The result demonstrates that shielding failure trip-out rate is proportional to heights of poles and towers; shielding failure trip-out rate escalates in nonlinear trend when the ground angle increases; in- fluence on shielding failure rate is insignificance when the ground angle is smaller than 15~ and shielding failure rate increases exponentially in the opposite case; in case wind speed is less than 5 m/s, it does not have much influence on shielding failure rate while shielding failure rate increases prominently in the opposition case. The conclusion is that influence of wind speed and surrounding plants should be taken into consideration during analysis of lightning shielding of 500 kV one-tower double circuit transmission lines so that the analysis result can be more practical.