Superconducting magnetic energy storage（SMES） system has the characteristics of high power density and zero impedance;therefore

there is an inevitable trend for SMES to be applied in power system. In order to suppress the fluctuation of wind power more effectively

a hybrid energy storage system（HESS） based on SMES and battery energy storage system（BESS） is selected as the research object

and a hierarchical control strategy consisting of device level and system level is designed. At the device level

a PI with power feed-forward controller for SMES is proposed to maintain the stability of DC-side voltage; At the system level

a multilevel power allocation strategy for HESS based on empirical mode decomposition

fuzzy control and optimized control is proposed to achieve efficient grid connections for the wind farm

which can smooth the power fluctuation of the wind farm maximally when the state of charge of HESS is within a limit.The simulation results verify the effectiveness of the proposed hierarchical control strategies

which provide a new method to take advantage of the complementary nature of the different power and energy characteristics of the SMES system and BESS.