New energy power generation system output change mitigation devices

[PROBLEMS] Electric power generated by a generator for generating electric power by converting natural energy into electric energy is greatly affected by a meteorological condition and the generator of a generation facility cannot follow the power fluctuation of generated power. [MEANS FOR SOLVING PROBLEMS] Electric power generated by a generator is detected and inputted into a change ratio calculation unit. The change ratio calculation unit is supplied with a positive direction change ratio setting value and a negative direction change ratio setting value which are set to limit values as change amounts smaller than the largest power change amount which can be followed by a governor of the generator of the generation facility. The change ratio calculation unit calculates a charge/discharge instruction value according to each imputed signal.