Calculation of transient due to fault initiation on a double-circuit transmission line

In this paper, a mathematical analysis of a transient due to initiation of a single line-earth fault at any intermediate point on a double-circuit transmission line, using the modified Fourier-transform method, is presented. The double-circuit line has been modelled, taking into account the mutual coupling between the two circuits. A typical 400kV double-circuit line is considered and the fault transient is evaluated for both transposed and untransposed configurations of the line. The effect of the frequency dependence of line parameters on the fault transient has been investigated.