Design, implementation and performance evaluation of a new digital distance relaying algorithm

This paper presents the design, simulation, implementation and performance evaluation of a computationally efficient and accurate digital distance relaying algorithm. Published historical data were used in the first phase for validation purposes. Sample results illustrating highly accurate fault impedance estimates for various conditions are reported. The second phase uses voltage and current signals generated by the Alternative Transients Program (ATP) and a sample power system for various first-zone, second-zone and third-zone faults. Results of these studies, confirming the stability and computational efficiency of the algorithm, are presented and discussed. In the third phase, a prototype of the relay was developed and tested using real-time fault data generated from physical models of the transmission lines. Oscillographs for these conditions were recorded. Results of these tests indicating high speed relay operation are also discussed. The performance evaluation studies reported in this paper conclusively demonstrate that the new algorithm provides fast and accurate fault impedance estimates for the three-zone protection of transmission lines.