The lightning protection performance of back striking for double-circuit transmission line based on the distributed transmission line tower model

In order to make the calculation of lightning protection more precisely than the traditional methods, a distributed transmission line tower model of double-circuit transmission lines is constructed. The lightning protection performance of back striking for AC 500kV double-circuit transmission lines is described in details in this paper. A statistical method is utilized considering the magnitude and polarity of instantaneous power frequency voltages of the phases in the case of lightning striking tower top. By contrast, the tower wave impedance parameters changing with height are considered in the distributed transmission line tower model, so the results are more precise than those of the lumped inductance or the single wave impedance models.