ENERGY STORAGE SYSTEM AND CONTROL METHOD OF ENERGY STORAGE SYSTEM

An energy storage system may comprise: a plurality of power converters configured to perform DC/DC conversion in connection with respective battery racks; a power conversion system (PCS) configured to perform power conversion between the power converters and a power grid; and a battery section controller interworking with the plurality of power converters and the power conversion system, wherein the battery section controller is configured to control a first power converter among the plurality of power converters to perform constant voltage (CV) mode control for maintaining a voltage of a DC link at a constant level, to check a state of a first battery rack to which the first power converter is connected, and to change a subject to perform the CV mode control for the DC link according to the state of the first battery rack.