Abstract: In order to study the influence of hybrid energy storage system with fast frequency response on the dynamics of the new power system, and find the best control strategies for different scenarios, a generalized dynamic model of the hybrid energy storage system is proposed. On the basis of this model, the PI, H∞ and sliding mode controllers for the hybrid energy storage system consisting of battery and flywheel energy storage are designed. A case study serves to compare the different control strategies of the hybrid energy system. The results show that the combination of battery with H∞ control and flywheel with sliding mode control has the best frequency support capability.