雷电参数与地形结合的输电线路绕击闪络率计算

Calculation of the Transmission Line Shielding Failure Trip Rate by Combination the Lightning Parameters and Terrain Parameters

雷击是输电线路非计划停运的主要原因,对于500 kV以上线路,绕击是雷击的主要类型。目前在绕击计算中,线路的雷电活动情况和地形地貌对绕击性能的影响没有得到很好的结合,为此,给出一种线路雷电参数与地形相结合的线路绕击跳闸率计算方法。首先以一档线路为基准,距线路中心及两端杆塔距离为d的范围为杆塔雷电参数统计区域,得到杆塔的落雷密度,以距线路走廊中心及两端杆塔距离为d的范围内为统计区域,得到雷电流幅值概率密度;再次以近似相等的距离将线路走廊离散化,得到垂直线路走廊方向的辅助点,根据离散点与辅助点之间的高差与距离,得到绕击计算的地面倾角;最后对电气几何模型进行改进,得到雷电参数与地形相结合的输电线路绕击计算方法。该方法更能反映输电线路的实际情况,可为差异化防雷服务。

Lightning strike is the main cause resulting to non-planned outage of the transmission lines, and to line with rated voltage of 500 kV and above, Shielding failure caused by lightning is the main type. Currently, the impact of lightning parameter and terrain parameters has not been a good combination in the lighting shielding failure. Therefore, a calculation method of the trip rate caused by lightning strike based on lightning parameters and terrain is given. First, the lightning density statistical area of tower is away from a span transmission line from the center and at both end within the distance d; and the lightning current amplitude probability density statistical area of tower is away from the transmission line corridor center and at both end tower within the distance d. Secondly, the corridor is discrete by approximately equal distance, in order to get the auxiliary points at a vertical direction of the line. It can calculate the ground terrain according the height and distance between the discrete points and auxiliary points. Finally, the transmission lines shielding failure rate can be calculated through improving the electrical geometric model which combination with the lighting parameter and terrain. This method is better to reflect the actual situation of the transmission line, and can provide technical support for the differentiation lighting protection.