NOVELTY - The apparatus (14) has a total output judging part (18) determining whether total output is more than total output of a natural fluctuation power supply, which calculates allowable total output by an allowable total output calculation part (17) and a total output calculation part (16). A maximum output command value calculation part (19) calculates maximum output command value of the natural fluctuation power supply, where total output of the natural fluctuation power supply fills allowable total output based on determination result of the total output judging part.    USE - Operating apparatus for natural fluctuation power supply e.g. wind power generation installation and photovoltaic power generation installation, connected to an electric power system.    ADVANTAGE - The apparatus ensures that maximum output command value allocated difference with respect to the natural fluctuation power supply and moderated output suppression is calculated, so that interconnection of the natural fluctuation power supply of electric power generation introduction amount is obtained by the electric power system, thus maintaining supply and demand adjustment force of the electric power system in an easy manner and utilizing output of a natural fluctuation power supply in an easy manner. The apparatus can calculate maximum output command value of the natural fluctuation power supply, so that output suppression can be proportionally distributed by utilizing a rated output, thus allocating amount of suppression and suppression relief quantity in an easy manner.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for operating a natural fluctuation power supply.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of an operating apparatus. '(Drawing includes non-English language text)'    Electric power system (11)    Wind power generation installation (12)    Thermal power station (13)    Operating apparatus (14)    Total output calculation part (16)    Allowable total output Calculation part (17)    Total output judging part (18)    Maximum output command value calculation part (19)