For the fast fault repair and power supply recovery from multi-fault in the distribution network with distributed generators(DGs)

a phased and hierarchical coordination strategy of the repair and recovery optimization model is proposed based on the dynamic programming principle. In the emergency repair and recovery stage

the maximum load recovery value and minimum comprehensive economic loss are taken as the inner and outer optimization objective

respectively in the stages of emergency recovery; in the repair and recovery network structure stage

the minimum network loss and shortest repair time are taken as the inner and outer optimization objective

respectively in the stages of network reconfiguration to solve the optimal repair and recovery strategy. According to the different characteristics of the inner and outer optimization models

the improved ant colony algorithm and improved bacterial chemotaxis(DBCC)algorithm are used respectively to solve the inner and outer optimization models. Meanwhile

DG islanding

controllable load alliance and dynamic scheduling of emergency generators are used to restore the important load

and the methods of feeder equivalence to virtual DG and fault equivalence model are adopted to simplify the optimization process. The feasibility and validity of the method proposed are verified by modeling and simulation of the improved IEEE 69-bus system. This work is supported by National Natural Science Foundation of China(No. 61573302)and Hebei Provincial Natural Science Foundation of China(No. E2014203254).