Abstract: The distributed energy storage has flexible energy regulation characteristics,and the controllability of its interface converter can be used to control steady-state disturbances such as reactive power and three-phase imbalance,as well as transient disturbances such as voltage sags and power supply interruptions,which thus can reduce power grid disturbances and improve the quality of load power supply in a multifunctional manner,and help to improve the application efficiency of distributed energy storage systems. To facilitate this goal,this paper a multifunctional three-level hybrid energy storage converter,which uses a two-stage threelevel topology as the carrier to improve the efficiency of system energy conversion,achieves comprehensive optimization of transient/steady-state performance by means of the hybrid connection of supercapacitors and energy storage batteries,and realizes efficient governance of steady-state and transient power quality problems by designing the multifunctional control and smooth switching strategy. The Simulation and experiments have verified the feasibility and effectiveness of the proposed methods.