微地形下输电线路绕击闪络率的计算方法

Calculation of Shielding Failure Flashover Rate of Transmission Line Under Micro-topography Condition

为反映地形、导线及地线高度的变化对绕击性能的影响,提出了一种获取输电线路微地形及导线、地线与地面的相对位置的方法,并在此基础上计算输电线路杆塔的绕击闪络率。首先沿线路方向将输电走廊进行近似等分,利用地理信息软件得到各分段的海拔高度和地面倾角这2个微地形参数;其次根据导线、地线的特性,结合各分段海拔高度,得到任意分段处导线、地线与地面的实际相对位置,最后以电气几何模型(electrical geometry model,EGM)为基础,计算各分段及各杆塔的绕击闪络率。以某500 kV线路为例,计算其实际微地形下输电线路杆塔的绕击闪络率,结果表明该方法不仅能够反映输电线路的绕击范围,而且能够得到输电线路容易遭受雷击的杆塔;遭受过雷击的杆塔位于易击区间,证明了该方法的有效性。

To reflect the effects of changes in terrain, height of ground wires and conductors on the shielding failure performance, a method of indentifying the micro-topography and the relative position among the wire, the ground wire and the ground was proposed. On this basis, the shielding failure flashover rate was calculated. First of all, the transmission line corridor was approximately divided into equal segments, and the altitude of each point and the ground elevation were obtained by using Google Earth software. Secondly, according to the characteristics of lead and the altitude of each point, the relative position among the ground wire, the conductor wire and the ground was obtained. Lastly, based on the electrical geometry model, the shielding failure flashover rate of each segment and each tower was calculated. Taking a 500 kV transmission line as an example, the shielding failure flashover rate under the actual micro-topography condition was calculated. The results show that this method can reflect changes of the shielding failure flashover rate along the span, and figure out which towers are easy to be suffered from lightning stroke along the entire transmission line. Comparing the operation data, it can be seen that lightning strikes take place in the easy-stroke inter-zone, which proves the effectiveness of the proposed method.