ENERGY STORAGE SYSTEM AND METHOD FOR CONTROLLING ENERGY STORAGE SYSTEM

This application provides an energy storage system and a method for controlling an energy storage system. The energy storage system (210) includes a plurality of energy storage units. The energy storage unit includes a plurality of battery cells, a plurality of balancing units, a voltage conversion unit (211), a first switch, a second switch, and a control unit (2140). The plurality of balancing units are configured to control state of charge balance between the battery cells. The first switch is disposed between a positive electrode of a battery string and a positive input end of the voltage conversion unit. The second switch is disposed between a positive balancing bus and the positive input end of the voltage conversion unit. The control unit is configured to detect fault cases of the plurality of battery cells, and control open and closed states of the first switch and the second switch. According to the energy storage system and the method for controlling an energy storage system that are provided in this application, it can be ensured each energy storage unit in the energy storage system can continuously work when a battery cell is faulty when state of charge balance between battery cells is implemented. This greatly improves reliability of the energy storage system with low costs.