An Investigation into the Effect of the Probabilistic Distribution of Lightning Current Amplitude on a Transmission Line Backflashover Rate

Probability distributions of the lightning current amplitude plays an important role on the estimation of transmission lines lightning performance. In this paper, an assessment is made of the effect of two probability functions, related to lightning current waves representative of the lightning activity recorded at Mount San Salvatore (MSS) and Morro do Cachimbo Station (MCS), on the backflashover rate of a 230-kV transmission line. The Alternative Transient Program (ATP) is used to obtain the resulting overvoltages across line insulators and the disruptive effect model is taken into account to compute the critical current value and the line outage rate. The results show that, depending on the critical current level, the probability function considered may lead to significant differences in the lightning performance estimation.