Khederzadeh, Mojtaba, Shahid Beheshti University, Iran Islamic Republic of
Recent weather-related disasters experienced worldwide with huge damages to the power infrastructurehave highlighted the importance and urgency of enhancing the resiliency of the distribution grid. A Resilient distribution grid has the ability to withstand and recover from rare events. Resiliency against extreme events is conceptualized in three distinct stages: prior to the event, during the event and after the event. Rapid recoveryis a feature needed in after an event. In this paper, restoration strategies to restore loads as quickly as possible are investigated. The proposed approach firstly attempts to restore the critical loads by using tie-switches to reconfigure the network. In case of establishing isolated areas without the possibility to restore with the upstream utility grid, sectionalizing the distribution grid into several microgrids is proposed to improve the system resiliency.As the post-event stage is not surely stable, the formed microgrids may lose the adequacy (generation and demand balance), so networking the microgrids as the last step is applied. The proposed method is simulated on the unbalanced IEEE-123 bus distribution grid with random locations for DERs and critical loads. Asthe sample grid is unbalanced, so three-phase power flow is used to find the voltages and line flows.