Load transfer and islanding analysis of active distribution network

When fault occurs in distribution network, the loads of faulty line are transferred to adjacent lines to restore the power supply. The interconnection of distributed generator (DG) and energy storage system (ESS) poses challenge to traditional load transfer, and loads that are not restored by the load transfer can be islanded with DG and ESS to further reduce the outage. To address this issue, model of power supply capacity of autonomous local control region and active distribution network line are established, considering the power restrictions of DG and ESS, and this model is effective to simplify the network of load transfer. Constraints for practical islanded operation, including the restriction of backup capacity against the power fluctuation are proposed, and a practical stepwise optimal algorithm is put forward for load transfer and islanding based on the radial characteristic of distribution network. In contrast to traditional intelligence algorithm, the computation amount of load transfer and islanding has been reduced by the proposed stepwise optimal algorithm, and the islanding is also well considered that further reduces the outage. The case study shows that the computation amount is reduced by about 70% comparing with genetic algorithm, and the restored load is increased by about 40%. Copyright (c) 2014 John Wiley & Sons, Ltd.