This research presents a transmission line model aimed for the fault location in power systems using a method based on the Electromagnetic Time-Reversal (EMTR). The discrete-time model simulates the waves travelling in the line by means of many unit delays implemented with digital Nb hits shift registers. The flexibility and robustness of this fully digital realization are discussed and compared to previous analog implementations and evaluated in the frame of the fault location. The impact of the signal quantization on the fault location accuracy is therefore discussed. An extension of the line model for the simulation of more complex network topologies, such as interconnected or multi-conductor networks is also presented. It is then shown that a fault on a three-conductor line can he located within few tens of milliseconds with a resolution of 1%, considering the model implemented in a TSNIC 0.18 mu m process. Through this is speed improvement, about a hundred limes faster than classical digital solvers, this promising approach makes real-time implementation realistic.