The paper presents a study aimed at evaluating the effect of adjacent tower grounding systems on the backflashover (BFO) in HV overhead lines (OHL) when direct lightning occurs. A detailed ATP-EMTP model of a typical 150 kV – 50 Hz Italian OHL has been implemented in order to simulate BFO: for each tower of the OHL, grounding systems have been simulated by means of a simplified pi- type model, able to reproduce the effects of propagation along the ground conductors and soil ionization phenomena. Results have been compared with those obtained by grounding all towers, except the one struck by lightning, via a constant resistance derived from the 50 Hz tower grounding system equivalent resistance. Comparisons show a negligible effect of adjacent tower grounding systems on BFO simulation at the struck tower, whereas a small effect on the voltage across insulators of the adjacent towers is observed.
Large-scale adoption of a simplified tower grounding model in direct lightning simulation / Gatta, Fabio Massimo; Geri, Alberto; Lauria, Stefano; Maccioni, Marco. - (2014), pp. 1-6. (Intervento presentato al convegno 6th International Conference on Lightning Physics and Effects GROUND 2014&6th LPE tenutosi a Manaus (Brazil) nel May 12th-16th, 2014).