The Evaluation of Transmission Line Modeling on Lightning Performance Considering Surger Arresters: Impact in the Energy and Backflashover Rates

This paper investigates the impact of transmission line parameter calculation formulations on surge arrester performance in response to lightning strikes. This evaluation consists of comparing power and energy dissipated in surge arresters, as well as critical currents and line backflashover rates. The lightning performance of surge arrester installed in a typical Brazilian 138 kV transmission line is assessed by simulations in ATP software, while transmission line parameters are calculated in 3 different ways, namely: (i) Carson formulation, (ii) Nakagawa formulation considering the electrical parameters of the ground constant with the frequency, and (iii) Nakagawa formulation considering the frequency-dependent characteristics of the soil. Taking as reference the results determined by Carson’s formulation (since this formulation is the most used in programs for calculating transients, such as ATP), it is shown that Nakagawa’s formulations considering both constant and frequency-dependent soil parameters can lead to differences for the cases of unprotected lines, partially protected (lightning arresters in one or two phases) and fully protected (lightning arresters in all phases), resulting in an inaccurate prevision of insulation failure, leading to an increase in the backflashover rate.