Robust coordination of directional overcurrent relays using a matheuristic algorithm

Directional overcurrent relays are often used in the protection of electrical power transmission and distribution systems. These devices are installed along the network, and they must be coordinated to operate as fast as possible and in the adequate sequence. However, the coordination of relays is a complex problem, due to its discrete non-linear nature and its hard constraint structure. A matheuristic algorithm to provide coordination of directional overcurrent is proposed in this work. The algorithm combines a differential evolution strategy and linear programming formulations. In addition, two local search procedures are proposed to improve convergence and to handle continuous and discrete relay setups. Results for five instances show that the proposed method is able to obtain identical or better solutions than those already reported in the literature with considerably lower computational cost. Furthermore, the algorithm can directly handle robust coordination by considering possible changes in the systems conditions.