Abstract: When a serious outage occurs in distribution system due to extreme events， some local resources such as distributed power sources and energy storage systems can be coordinated to restore critical loads and enhance resilience. In order to change the distribution system from fault state to restoration state quickly and smoothly， it is necessary to optimize the switching operation sequence. This paper proposes a restoration operation sequence decision-making method for smart distribution systems considering multiple sources coordination. The problem is modeled as a mixed-integer linear program which can be solved by the mature commercial optimization solver to determine the optimal switching operation sequence and system operating status after each operation. The objective is to serve more critical loads as fast as possible considering their priority. The unbalanced three-phase power flow constraints， operation constraints and in-process switch operation constraints are considered. The effectiveness of the proposed method is validated by numerical simulation with the modified IEEE 13-node test system and the modified IEEE 123-node test system.

Key words: distribution system, service restoration, restoration sequence, distributed generation, resilience