Storage battery system

A storage battery system connected to a power system and operated on a basis of a charge/discharge request from an energy management system that manages electric power supply/demand of the power system, comprising:

• a first storage battery;
• a second storage battery of a shorter service life than the first storage battery;
• a first battery management unit that monitors a state of the first storage battery;
• a second battery management unit that monitors a state of the second storage battery;
• a first power conditioning system having a function of converting AC power of the power system to DC power and charging the DC power to the first storage battery, and a function of converting the DC power of the first storage battery to the AC power and discharging the AC power to the power system;
• a second power conditioning system having a function of converting the AC power of the power system to the DC power and charging the DC power to the second storage battery, and a function of converting the DC power of the second storage battery to the AC power and discharging the AC power to the power system;
• and
• a controller that receives the charge/discharge request and storage battery information supplied from the first and second battery management units, and controls the first and second power conditioning systems on the basis of the charge/discharge request and the storage battery information,
• wherein the controller includes
• an SOC correction unit that calculates SOCs (States Of Charge) of the first and second storage batteries on the basis of the storage battery information, corrects the SOC of the second storage battery upwards in the case that the charge/discharge request is a charge request, and corrects the SOC of the second storage battery downwards in the case that the charge/discharge request is a discharge request, and
• a charge/discharge command unit that determines charge/discharge commands for the first and second power conditioning systems so as to preferentially perform charge from the storage battery of a low SOC in the case that the charge/discharge request is the charge request and to preferentially perform discharge from the storage battery of a high SOC in the case that the charge/discharge request is the discharge request.