kV, 220 kV, 500 kV and 1 000 kV transmission lines caused by the first stroke, subsequent stroke through the same and

different return stroke channels with first stroke was analyzed based on EMTP and improved electrogeometric model

(EGM). The effect of peak current distribution and waveform, tower height and shielding angle were analyzed. The results

show that the peak current distribution of the first and subsequent stroke has a significant impact on the SFOR while the

current front time of the first and subsequent stroke has little effect. The subsequent stroke of  different return

stroke channel has a significant impact on the transmission line with a voltage class of less than 500 kV but has little

influence on the UHV transmission line. The effects of subsequent stroke of the 500 kV transmission line is worth

considering. In the condition of none SFOR owing to the first stroke and the subsequent stroke of different return stroke

channel, the SFOR may still occur due to the same subsequent stroke of the return stroke channel.