Backflashover rate of quadruple-circuit transmission lines due to first and subsequent return strokes

•We evaluate backflashover rate (BFR) of 220/110 kV quadruple-circuit transmission lines due to first and subsequent return stroke.•The subsequent strokes propagate along the first stroke channel may lead more multi-circuit trip-out than the first stroke.•The protection measures of unbalanced insulation and coupling ground wire are effective for BFR due to first and subsequent strokes.

The backflashover rate (BFR) of typical 220/110 kV quadruple-circuit transmission lines due to direct negative first and subsequent return strokes and the effects of common lightning protection measures are quantified. The method based on ATP-EMTP and IEEE electro-geometric model (EGM) is adopted. The results show that the peak current distribution of the first and subsequent stroke has great influence on the BFR. The subsequent strokes propagate along the first stroke channel may lead more multi-circuit trip-out than the first stroke. The influence of tower foot resistance on single and double circuit BFR due to the first stroke is more serious than that due to subsequent strokes. The protection measures of unbalanced insulation, insulation strengthen and coupling ground wire are effective for BFR due to first and subsequent strokes.