Evaluation of lightning performance on transmission system sag

Abstract

A lightning stroke causes current injection into transmission lines at the point of contact. The lightning performance can be difficult to understand without using simulation programs. PSCAD is powerful software was selected to develop the appropriate data required to investigate this phenomena. In this paper, a model of 500 kV transmission line is developed when lightning stroke hits the shield wire directly at the mid-span sag location of transmission line. This study emphasizes on lightning performance when stroke hits either top of transmission tower or position of maximum sag locations between towers. In addition, the effects of lightning strokes on overvoltage along transmission system are studied. The results revealed that the sag of transmission line has a considerable influence on fast transient flashover and induced voltages occurrences across line insulators as well as phase lines.