INDUCED VOLTAGE ON AN OVERHEAD LINE DUE TO NEARBY LIGHTNING

Voltage waveshapes induced on an overhead line by nearby lightning return strokes are calculated numerically by solving the transmission line equations using the time domain approach of Agrawal et al. [1] and a finite difference technique. The traveling current source (TCS) model [2] is used to calculate the return stroke vertical and horizontal electric fields, which are the sources for a line voltage, above a perfectly conducting ground plane. Neglecting the effects of finite ground conductivity and lightning channel tortuosity, the horizontal electric field is a result of line elevation only. The effect of the striking point distance and the return stroke current waveshape on the induced voltages are illustrated. The maximum line voltage does not necessarily occur at the point closest to the return stroke channel. The exact location of the maximum voltage along the line depends not only on the closest distance from the striking point to the line but also on lightning current parameters. In the case of a 2000-m-long line and a striking point a distance of 100 m from the line center, almost 90% of the induced voltage at the line terminations is due to the horizontal electric field coupling. © 1990 IEEE