This paper calculates and researches on lightning protection performance of back striking and influence factors for typical towers of 750 kV single circuit and double circuit transmission lines by ATP-EMTP.With towers using multi-wave impedance model and considering factors such as propagation velocity of the lightning wave through the tower

height of tower and grounding resistance etc

a statistical method determines lightning protection performance of back striking for 750 kV supernigh voltage transmission line.Research results show that the effect of propagation velocity of the lightning wave through the tower shouldn’t be neglected;along with the reduction of both tower height and surge grounding resistance

the back striking withstand performance enhances;the effect of the arrangement manner of line and lines distance on the back striking withstand performance is very little;only trip-out rate of back flashover of single circuit of the tower of ZB329 and ZGU315 exceeds anticipation lightning trip-out rate

so it is necessary to seriously calculate and research on lightning protection performance of back striking for transmission line when 750 kV transmission lines be constructed.