A method for dispatching a power grid is disclosed. The method includes: obtaining a whole power generation interval scheduled for a cluster of renewable energy stations from a power grid dispatching center; establishing a decomposition model that includes an objection function and constraint conditions; decomposing the whole power generation interval with the decomposition model to obtain each power generation interval of each renewable energy station; and controlling each renewable energy station to generate powers based on each power generation interval. The objection function minimizes a total operating cost in the power grid and includes a renewable energy randomness indicating an actual power generation amount of each renewable energy station. The constraint conditions include a constraint from an installed capacity of each renewable energy station to each power generation interval and a constraint from the whole power generation interval to a sum of power generation intervals of renewable energy stations.