Mathematical basis for modal-transformation based improved digital distance relaying algorithm

An improved algorithm for calculating the fault distance has been proposed for power transmission lines. The proposed algorithm uses modal transformation for deriving performance equations. The proposed algorithm assumes that prior estimation of the fundamental frequency component of the phasor of voltage and current signals and fault classification have been performed using established methods. The mathematical basis of the proposed algorithm is discussed. The proposed algorithm has computational advantage over the previously suggested algorithms. The proposed algorithm was tested using a numerical example and fault data. Some results are reported