Coordination of Distance Protection Relays on Multiple Parallel Line Corridors

This paper will show the analytical analysis of multiple parallel line corridors with their mutual coupling and inter infeeding effects. Based on a generic model in symmetrical components the analytical description of the measured impedances of distance protection relays on faulty and unfaulty parallel lines will be presented. Based on that, worst case considerations will be carried out. They will show which parameter or current relations are decisive for influencing the distance measurement and producing the maximum measurement errors. Using these correlations, a protection coordination concept for the distance protection will be derived. It is including the generic distance zone settings as well as the earth impedance matching factors which can be chosen freely applying modern relay technology. The main goal of this concept is the robustness against all possible switching conditions.