Equivalence between Triangular and Heidler Functions for Calculations of Lightning Overvoltages on Transmission Lines

This paper presents a study of the resulting overvoltages on the insulator strings of a 230 kV transmission line, taking into consideration two different models for the lightning currents: Heidler and triangular functions. The analysis was carried out considering only direct strokes to the tower and several grounding conditions. The main objective of the work is to find the front time of a triangular function that results on the same overvoltage peak produced by a Heidler function considering the same current peak. Thus, an equivalence equation between the front times is determined, providing a simplified method for the modelling and simulation of lightning currents. The main advantage of using this equivalency is the reduction of the computational efforts demanded in a series of simulations.