Energy　storage　system　can　significantly　improve　the　power　quality　and　power　supply　reliability　of　microgrid.　In　high　power　applications,　multilevel　power　converters　are　usually　used　to　reduce　the　voltage　stress　of　the　switching　devices　and　batteries.　Modular　multilevel　converter　(MMC)　has　the　advantages　of　high　power　and　voltage　level,　and　can　block　DC　fault.　It　is　very　suitable　for　the　topology　of　high　capacity　energy　storage　converter　(ESC).　However,　the　control　of　the　MMC-based　ESC　is　a　multiobjective　optimization　problem,　for　the　fast　dynamic　and　stability　of　AC　bus,　the　normal　operation　of　the　multilevel　converter,　and　the　health　of　the　batteries　must　be　considered　at　the　same　time.　To　effectively　solve　this　problem,　a　hierarchical　control　algorithm　is　proposed　in　this　paper.　The　algorithm　consists　of　three　layers.　The　system　layer　suppresses　bus　voltage/frequency　fluctuation　and　adjusts　the　operating　state　of　the　ESC.　The　converter　layer　is　responsible　for　the　normal　operation　and　state　regulation　of　the　MMC　and　the　dual　active　bridge　(DAB).　The　battery　layer　regulates　the　battery　state　of　charge　(SOC)　and　charging/discharging　current.　In　addition,　a　real-time　priority　adjusting　strategy　is　also　introduced　to　change　the　operating　mode　of　the　ESC　to　further　improve　the　overall　system　performance.　Simulation　results　of　a　five-level　MMC-based　ESC　verifies　the　effectiveness　of　the　proposed　control　algorithm.　©　2022　IEEE.