基于非均匀网格技术的山体周围不同位置处配网耦合雷电过电压快速计算研究

Fast Calculation of Lightning Overvoltage Coupled with Distribution Network at Different Positions Around Mountains Based on Non-Uniform Grid Technology

架空线路往往存在于非平坦地表,比如周围存在山体,利用常规FDTD手段较难准确的计算出非平坦地表上架空线耦合雷电过电压问题。因此,笔者提出利用非均匀网格划分技术,在闪电通道、山体位置处采用较小的网格,在其余空间区域采用较大的网格,同时对于山体-空气不同介质区域采用共形介质理论进行处理,不仅能避免计算耗时,同时能更精确的表达闪电通道、山体等情况,主要研究山体周围不同位置处配电线路耦合雷电过电压变化趋势,研究表明:建立的非均匀FDTD网格算法具有较好的精度;山体使架设其上的配电线路雷电过电压峰值增强44%;由于反射波的作用,山体对架设其附近的配电线路雷电过电压峰值增强2.7%;由于雷电电磁场及其架空线的相互作用,使架设峡谷的配电线路雷电过电压增强3倍。因此,在实际配网线路规划研究工作中,估算山区环境中架空输电线路上的感应过电压值并进行相关防雷设计时,必须要结合山体地形影响因子。

Overhead lines usually exist on non-flat ground,such as surrounding mountains. It is difficult to accurately calculate the coupling lightning overvoltage of overhead lines on non-flat ground by conventional FDTD methods. Therefore,non-uniform mesh generation technology is proposed,which uses smaller mesh in lightning channel and mountain location,and uses bigger mesh in other space areas. At the same time,the conformal medium theory is adopted to deal with different medium area of mountain air,which can not only avoid the calculation time-consuming,but also can express more accurately.Lightning channel,mountain and other conditions,the main study of the distribution line around the mountain coupling lightning overvoltage trends at different locations,the results show that the proposed non-uniform FDTD grid algorithm has a good accuracy;the mountain makes the distribution line installed on the peak lightning overvoltage increased by 44%;due to the role of reflected waves,The peak value of lightning overvoltage of distribution lines near the mountain is increased by 2. 7%,and the lightning overvoltage of distribution lines near the valley is increased by 3 times due to the interaction of lightning electromagnetic field and overhead lines. Therefore,when estimating the Induced overvoltage on overhead transmission lines in mountainous areas and designing lightning protection,it is necessary to consider the influence factors of mountain topography.