Power control apparatus and method for realizing efficient load factor with lower contracted power limit

A power control apparatus, comprising:

• a calculation unit configured to calculate a spare power capacity for each subsystem based on a power demand and a maximum power capacity for each subsystem, and to calculate a total spare power capacity for an entire system based on a power demand for the entire system and a contracted power limit;
• a detection unit configured to detect whether a required spare capacity is short, based on the required spare capacity and each subsystem's spare power capacity and the total spare power capacity, the required spare capacity indicating an estimated power demand of an uncontrollable device is available;
• a storage unit configured to store a plurality of power control operation items which are to be applied to ensure the required spare capacity in order to prevent the required spare capacities for each subsystem and for the entire system from being short;
• a first selection unit configured to select at least one of the plurality of power control operation items if the detection unit detects that the required spare capacity for each subsystem or for the entire system is short;
• and
• an execution unit configured to execute an application operation of at least one of the power control operation items until the required spare capacity becomes available, and to execute a waiting operation of at least one of power control operation items executed the application operation if the required spare capacity is available.