±660kV HVDC输电线路典型杆塔绕击性能评估

Lightning Shielding Failure Analysis of ±660kV HVDC Transmission Lines Typical Tower

±660 kV高压直流输电线路是世界上首条该电压等级的线路,对其耐雷性能研究至关重要。已有研究表明改进的EGM是所有计算线路绕击跳闸率模型中较为精确的模型。利用改进的EGM,考虑雷电对导线、地线和大地三者击距的差异、风偏影响、地形影响和导线工作电压影响等,基于典型杆塔对我国±660 kV高压直流输电线路进行绕击性能分析。仿真结果表明,在相同地面倾角时,考虑导线工作电压的绕击跳闸率大约是不考虑导线工作电压的2倍,因此计算中必须考虑导线工作电压。随着风速和地面倾角的增大,绕击跳闸率呈加速度增长。当地面倾角大于20°,风速大于20 m/s时,杆塔为ZP2711的线路绕击跳闸率超过指标要求0.1次/100 km.a,因此ZP2711杆塔适用于在内陆平原地区使用。而JP2711杆塔在地面倾角小于30°,风速小于30 m/s时绕击跳闸率都达标,因此可以在沿海以及山区地带选用。

＋660 kV HVDC transmission line is the first line in the world whose vohage grade is ＋660 kV. An investigation of lightning protection performance for ＋660 kV HVDC transmission llne is critical. Studies have shown that the improved EGM is the most accurate method among all that used to calculate lightning shielding failure rate. In this paper,an improved EGM is proposed to evaluate the lightning shielding failure rate of 4-660 kV HVDC transmission line. The striking distances to phase conductors, shield wires and ground are differentiated. Furthermore, the influences of ground obliquity, wind deflection and operating voltage of phase conductors are taken into account. The simulation results based on classic tower show that the lightning shielding failure rate considering line operating voltage is about multiple of that without considering line operating voltage under the same ground obliquity. Also ,the shielding failure rate accelerates with the increase of the ground obliquity and the wind speed. When the ground obliquity is more than 20 and the wind speed is more than 20 m/s,the transmission line with tower ZP2711 exceeds the indicator 0.1 times/100km.a. So the ZP2711 tower should be used in the inland and plains. Instead,when the ground obliquity is less than 30 and the wind speed is less than 30 m/s,the lightning shielding failure rate of the transmission line with tower JP2711 tower is satisfied. So the JP2711 tower can be selected in the coastal and mountainous areas.