In order to improve the scheduling flexibility of grid connected wind power generation system, it is necessary to apply energy storage technology, and the main key technology of energy storage system is how to determine the capacity configuration of energy storage system. Using the individual advantages of superconducting magnetic energy storage (SMES), battery energy storage and hydrogen storage, the capacity is configured, which is an energy management strategy based on the principle of meeting the load power shortage rate and improving the overall economy of the energy storage system. According to the whole life cycle cost theory, the annual average cost function expression of energy storage device is established, and the optimal allocation model of energy storage capacity is proposed with the minimum value of the function as the goal and the operation indices such as load shortage rate as constraints. An example is calculated by using the improved particle swarm optimization algorithm to verify the correctness, effectiveness and stability of the optimization model and algorithm.