It is widely accepted that the coordination between multi-type power sources is one effective measure to smooth stochastic fluctuations in wind power and improve wind power utilization. In this paper

two indices called upward-regulation flexibility margin and downward-regulation flexibility margin are put forward from the viewpoint of balance between operational flexibility supply and demand

which are used to allocate the limited flexible resources to deal with the adverse effects of large-scale wind power. On this basis

we formulate a wind-hydro-gas-thermal coordinated optimal dispatching model

in which the minimized total pollutant emission is taken as the objective. Based on the hierarchic optimization strategy

this model is decomposed into 4 operation layers according to the type of power sources to reduce the complexity of the large-scale optimization problem. Then a solving framework integrating mutative-scale optimization method

improved daily start-stop peak regulation method and improved particle swarm optimization(IPSO)coupling a heuristic unit commitment method is proposed to implement the optimal coordination between multi-type power sources. Simulation based on actual data of short-term optimal dispatching in a provincial power grid is performed to validate the proposed algorithm. The results show that this method can ensure the integration and accommodation of wind power

and it can reduce system reserve redundancy and pollutant emission at the same time.