METHOD FOR CONTROLLING SODIUM-SULFUR BATTERY

A method for controlling a plurality of sodium-sulfur batteries that, in an interconnected system in which a power generation device that fluctuates in output and an electric power storage-compensation device are combined to supply power to an electric power system, are each included in the electric power storage-compensation device and compensate for output fluctuations of the power generation device, is provided. When one sodium-sulfur battery of the plurality of sodium-sulfur batteries reaches a discharge end, the sodium-sulfur battery reaching the discharge end is charged from a sodium-sulfur battery other than the sodium-sulfur battery reaching the discharge end. When one sodium-sulfur battery of the plurality of sodium-sulfur batteries reaches a charge end, the sodium-sulfur battery reaching the charge end is discharged to charge a sodium-sulfur battery other than the sodium-sulfur battery reaching the charge end. Thus, control is performed so that all of the plurality of sodium-sulfur batteries are in a state of not reaching any of the charge end and the discharge end. This sodium-sulfur battery control method enables fluctuations of natural energy to be compensated over a wide range.