Optimal Coordination of Distance Relays in Interconnected Power Systems

This paper presents a new method for optimal coordination of distance relays for the sake of global stability and local optimization when the characteristics of distance relays coordination principles and engineering practices are taken into consideration in China. Active constraints and passive constraints are proposed to determine whether the region in which the relays will be reset should be expanded. The method to determine the optimal coordination state is proposed to minimize the number of the relays which need to be reset. The comparison between the proposed method and the conventional method is made and it shows that the proposed method makes the settings of distance relays global stable and local optimal.