The Hybrid Energy Storage System (HESS) consisting of battery and super capacitor has the advantages of fast response and high power capacity, which can well act as distributed energy storage equipment to compensate power grid frequency fluctuation. This paper puts forward a self-learning smooth energy storage control strategy based on State-of-Charge (SOC) feedback under energy storage unit system optimal matching, which automatically concludes and updates the control rule of hybrid energy storage and makes use of Virtual Synchronous Generator (VSG) to solve the problem of grid frequency offset caused by power fluctuation of renewable energy. Finally, a photovoltaic-storage- microgrid model is established in Matlab/Simulink. Simulation results show that the proposed HESS based VSG can effectively simulate the rotational inertia and the primary frequency modulation characteristics of SG, which improves the stability of the connected grid. This work is supported by National Natural Science Foundation of China (No.51307009).