Backflashover simulation of HV transmission lines with concentrated tower grounding

For high voltage (HV) transmission lines (TLs) the backflashover phenomenon can occur when lightning strikes a tower or a shield wire (SW). In this paper, the backflashover phenomenon of typical HV-TLs has been studied. The simulation code, based on ATP/EMTP program, accounts for both the discharge process between the arcing horns of insulator strings, by means of a leader progression model and the non-linear transient behaviour of tower grounding systems consisting of vertical rod(s). The lightning current ranges, causing back flash in a 161 kV-50 Hz single circuit line with two grounded SWs, have been investigated in detail. Numerical results of the investigations are in good agreement with actual behavior of the studied TL.