Modelling of power lines in lightning incidence calculations

When applying the electrogeometric model to power lines to determine the frequency and characteristics of the collected lightning strokes, the power line has traditionally been represented by a set of horizontal wires, i.e. both the sag of the wires and the existence of the towers have been ignored. This approach has serious shortcomings. The authors eliminate these problems by presenting a computerized solution which takes into consideration the sag of the wires, the existence of the towers, and the inequality of the striking distances to towers and to wires. The solution requires 168 equations for calculating the stroke collection area for a given current amplitude, as compared to the only three equations needed for the horizontal wire representation, and it uses an improved validated electrogeometric model. The features of the program are discussed and some of its results are given