Plural power storage systems 10 are provided in a power system. The power storage systems 10 are connected to a management system 60 via a communication network CN1. The power storage systems each include a power storage device 11, 12, and a control device 100 for controlling the power storage device. The control device stores performance information about the power storage system including the control device, location information indicating a location in the power system of the power storage system including the control device, and order information indicating an order of operation allocated to the power storage system including the control device. When a disturbance occurs in the power system, the control device performs a predetermined compensation operation based on the location information and the order information, and then returns to a preset stand-by state.