Research on the Mesoscopic Range Based on the Effect of Terrains on Lightning Distribution

The difference in ground flash density is studied under various terrains. It is found that a large error occurs when using a single ground flash density value to calculate the lightning trip-out rate of transmission lines in mountainous areas. This is because terrains have a greater effect on the ground flash density within a certain range. This range is larger than microscopic terrain ranging from tens to a few hundred meters, but smaller than macroscopic terrain ranging from tens to hundreds of kilometers or more. Therefore, the concepts of mesoscopic terrain and mesoscopic range are proposed in this paper. An approximation method for finding the probability model of the lightning distribution is proposed. It is found that the probability model of the lightning distribution changes from a uniform distribution to a non-uniform distribution during the transition from flatland to mountain. Furthermore, a method for determining the mesoscopic range is proposed using the maximum, minimum, and average values of ground flash density. The mesoscopic terrain concept proposed in this paper aids in further studies on the differences in lightning distribution and lightning performance between different areas, and offers theoretical support for improving the accuracy of lightning protection calculations in power systems.