PURPOSE: To enable stability when controlling load to be improved by adding a prediction load fluctuation signal to a total load command signal and by eliminating load fluctuation due to frequency fluctuation which appears in a total load deviation signal.

CONSTITUTION: A system frequency is fed to a function generator 20 through a frequency detector 3. The function generator 20 obtains an individual governor-free prediction load fluctuation corresponding to fluctuation in frequency with a speed regulation as a reference. That prediction load fluctuation signal leads to a special change rate limiter 21 with a setting velocity of a synchronous setting equipment 7 and a change rate corresponding to it, takes out a differential deviation signal within a change rate limiter 12, adds it with an adder ADb corresponding to each individual load, and then adds the calculation result to a total load command signal in an adder ADc, thus preventing load change due to frequency fluctuation from appearing at the total load deviation signal.