A Strategy for Protection System Recovery in a Topology-Changing Network with DGs

―Distributed generators (DG) have serious impacts on Directional overcurrent relays (DORs)-based protection system. Miscoordinated operation of DORs and escalated electromagnetic stresses on equipment are major concerns. Topology variation of the power network adds complexity to the problem. This paper proposes a simultaneous resetting-fault current limiters (FCLs) approach to sustain DORs' coordination in a reconfigurable network at minimum cost. A multi-objective constrained optimization problem is formulated. It is solved by the particle swarm optimization technique to obtain the optimal FCLs sizes and the updated setting parameters of few selected DORs. The approach is applied to IEEE 30-bus system. It efficiently restores DORs coordination and eliminates extra stresses on components.