A discrete-time numerical equation of frequency-dependent parameters is established by adopting projection transform and algebraic approximation of differential function. And z transform is used to convert the numerical equation into a traveling wave propagation equation in z domain. The recursive discrete sequences of propagation function and wave impedance are obtained through Poisson summation formula. Considering that the propagation function’s frequency response is equivalent to a IIR low-pass filter

the parameters are fitted as the form of a zero pole via Prony algorithm to decrease the number of discrete sequences

and eventually to convert the calculation of traveling wave propagation into the recursive calculation with less coefficients. In the condition of lower sampling frequency suitable for the existing protection devices

the fast algorithm for calculating contralateral traveling wave by making use of head traveling wave is realized on the basis of the frequency-dependent model. Simulation with PSCAD show that the proposed algorithm is more accurate and precise.