Frequency Response and Fault Ride Through of a Novel MMC Based Hybrid Energy Storage System

Energy storage is seen as a solution to the problem of inertia and fault ride through in high penetration power system. Comparing to single energy storage system, hybrid energy storage system has some advantages and has drown much attention. A novel hybrid energy storage topology based on multilevel modular converter(MMC) has been proposed. The MMC-based topology has better reliability, and simplified control. This paper focus on the operation of the MMC-based hybrid energy storage system under dynamic and grid fault conditions. The frequency response and power allocation method for the MMC-based hybrid energy storage under dynamic conditions is presented, and unbalance current compensation and low voltage ride through strategy is proposed. A low voltage ride through recover method is proposed to fasten the recover process. All the control method is verified by PLECS-based simulation. With proposed control in this paper, the MMC-based hybrid energy storage can deal with several dynamic and grid fault conditions.