Patent ID: 8536835

Claim:
A supply and demand control apparatus for an electric power system to which generators and a secondary battery are connected, the apparatus comprising: a data detector that detects a frequency variation and an interconnection line power flow variation in the electric power system; a frequency controller that calculates local requirements of the generators and the secondary battery based on the frequency variation and interconnection line power flow variation detected by the data detector; an economical load dispatcher that calculates an output allocation of each of the generators and secondary battery; and target command value creation units that create target command values of the generators and secondary battery based on the local requirements calculated by the frequency controller and the output allocations calculated by the economical load dispatcher and output the created target command values to the corresponding generators and secondary battery, wherein the economical load dispatcher calculates a discharging threshold value and a charging threshold value based on a discharging unit price of and a charging and discharging efficiency of the secondary battery and further calculates output allocations of the generators and secondary battery such that the secondary battery is discharged when incremental fuel costs of the generators are higher than the discharging threshold value, whereas the secondary battery is charged when incremental fuel costs of the generators are lower than the charging threshold value.