Service Restoration in Balanced and Unbalanced Distribution Systems with High DG Penetration

This paper presents a simple yet efficient service restoration algorithm for balanced and unbalanced radial distribution networks including Distributed Generators DG. The proposed algorithm that is based on load flow, begins with identifying the de-energized loads group due to fault isolation. All tie switches connecting this group with the rest of the network are the candidate switches for restoration. Branch currents from meshed network (i.e. closing all tie switches) were used as switching index to determine which one of these candidate tie switches should be closed for restoration. The restoration is carried out with objectives of maximizing the restored loads and minimizing the number of switching operations under line current limits, bus voltage limits and radial topology constraints. Each out-of-service group restored by closing the candidate tie switch with highest switching index. The proposed method has been tested on one balanced and two unbalanced systems with and without distributed generation, and compared with those reported in the literature.