Optimum Coordination of Directional Overcurrent Relays Using Advanced Teaching Learning Based Optimization Algorithm

Optimum relay coordination problem has more constraints because of primary / backup relay coordination criteria. Different optimization techniques are available in the literature to get optimum relay settings. These techniques give a non optimum solution due to selection of an extensive range for the design variables. The use of short range makes difficult to find an initial solution to start optimization process. This paper presents advanced teaching learning based optimization (Advanced TLBO) algorithm to determine the optimum settings of directional overcurrent relays (DOCRs). In this context, the optimization problem is designed to find optimum settings TMS (time multiplier settings) and PS (plug settings). Initially, the population for TMS is developed using wide range to find an initial solution. The available solution is optimized in next iterations by reducing the upper bound on the range of TMS by a predefined value ATMS. A case study is with 14 - relays presented here to show the feasibility of proposed algorithm.