Investigation of the Relative Impact of Negative and Positive Lightning Strokes for Establishing the Lightning Performance of Extra High Voltage Transmission Lines

The impact of negative and positive strokes on the lightning performance of HVAC and HVDC transmission lines due to backflashover is assessed based on results provided by systematic computational simulations with typical configurations of 500 kV transmission lines. Traditional cumulative peak current distributions of negative first, subsequent, and positive strokes were assumed, along with representative current waveforms of such events. The obtained results indicated that lightning outage rate is mainly defined by negative first strokes, and that the contribution of subsequent strokes and positive strokes on such rate becomes relevant just for low values of tower-footing grounding resistance. Furthermore, the contribution of subsequent strokes is slightly more important for the…