Patent ID: 8723359

Claim:
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 power and a plurality of electric power storage-compensation devices are combined to supply power to an electric power system, are each included in one of the plurality of the electric power storage-compensation devices and compensate for fluctuations of the output power of the power generation device, the method comprising: dividing the plurality of sodium-sulfur batteries in the plurality of power storage-compensation devices into three or more groups according to a difference in control method; setting the difference in the control method of the groups to one of a constant power control, which controls the sodium-sulfur battery by constant power without depending on output fluctuations of the power generation device, a following control, which controls the sodium-sulfur battery following output fluctuations of the power generation device, and a stop, wherein at least one group is set to the constant power control, at least one group is set to the following control and at least one group is set to the stop, wherein a control target value of a bidirectional converter of each group of power storage-compensation devices changes the control method set for the group and changes a level of power to be input to or output from a group of power storage-compensation devices; distributing power to be input or output, to or from each group based on the difference in the control method set, the power being assigned to all sodium-sulfur batteries in order to compensate for the fluctuations of the output power of the power generation device; and periodically rotating the control method of the plurality of sodium-sulfur batteries divided in the groups to achieve a uniform utilization rate of the sodium-sulfur batteries.