Abstract--In the recent years, the electric power system reinforcement against natural disasters has become one of the key challengers and concerns. The natural disasters, events and cyber-attacks are the most important challenges facing distribution networks causing widespread outages and blackouts. One of the useful techniques to cope with such problems is to utilize the microgrid formation strategy. This paper applies microgrid formation for load restoration and preventing voltage collapse. The given model enhances the system resilience following events. The proposed microgrid formation is developed by utilizing the tie-line breaker switches (BS). The IEEE 33-bus network is considered as case study and both the active-reactive powers are included in the power flow equation. The mixed integer linear planning (MILP) is used and the nonlinear equations are efficiently linearized. The results are presented under three cases including (i) without formation, (ii) formation without tie-lines, and (iii) formation with tie-lines. The numerical results demonstrate that the supplied loads in cases 1 to 3 are 57%, 64% and 71%, respectively. Therefore, the load restoration under cases 2 and 3 is increased by 7% and 14%, respectively. As well, the results illustrate that the proposed model not only improves the voltage profile but also reduces the generated power by DGs resulting in less environmental pollutions and costs.
