The mobile emergency power source (MEPS) takes up the power supply responsibility to important customers when blackout occurs in an urban distribution grid. The conversion of an island search problem into a precedence-constrained knapsack problem (PCKP) based on the graph model of distribution grid is proposed and solved by the exact recursion algorithm. Firstly

the optimization of the connecting point during operation is studied: obtaining every restored load value corresponding to every connecting point by forming an island at every node as the connecting point in the distribution grid. With this as the objective

the optimal connecting point of a single movable emergency source is found. Then multi-constraints optimization is made use of to solve the search for the connecting points of generation on the island. Finally

based on the optimal connecting point searching method of single MEPS

a process of generating multi-MEPS joint emergency power supply scheme is proposed. The results of a case study show that the method is able to make as much use of mobile power resources as possible to minimize economic loss.