Effect of tower modeling on the minimum backflashover current of overhead transmission lines

The evaluation of the lightning performance of overhead transmission lines necessitates the estimation of the minimum lightning current causing backflashover of line insulation. In the present study an assessment is made on the effects of transmission tower modelling upon the minimum backflashover current of typical 150 kV and 400 kV overhead lines with the aid of ATP-EMTP simulations. Several tower models, classified in three categories namely vertical lossless single-phase frequency-independent distributed parameter line models, multiconductor models and multistory models, were employed in simulations. Simulation results indicate that tower modelling, affecting the computed overvoltages arising across line insulators, influences the minimum backflashover current and the phase insulator…