Optimal Time Coordination of Definite-Time Overcurrent Relays for Adaptive Protection Systems

The increasing penetration of distributed energy resources and new types of loads such as e-mobility are challenging the protection design of distribution grids. In order to maintain the requirements for protection systems, adaptive grid protection systems can be used, which allow an event-based and automated adaptation of the protection parameters depending on the grid state. In this paper, we present a method based on optimisation modeling to address these challenges. The proposed approach can be used for different grid topologies and aims to find an optimal and feasible parameterisation of protection devices. Using a medium-voltage grid, the method was applied to different topologies resulting from switching operations. The method provided a unique protection scheme for each topology with feasible protection design and indicated topologies for which a protection design is not feasible at all.