PURPOSE: To prevent the reverse flow of electric power to a commercial power supply system side even though the electric power of a load decreases when a separately provided power supply system is operated at the maximum power in parallel with the commercial power supply system.
CONSTITUTION: When the electric power detecting value W of an electric power detector 11 connected between a commercial power supply system 2 and load 4 becomes lower than the set value of a suppression commanding value setter 13, a comparator 12 outputs a suppression commanding signal P to an output control circuit 14. Upon inputting the signal P, the circuit 14 changes the output of a charging control circuit 8 so as to maintain the detecting value W at a prescribed level even when the electric power of the load 4 fluctuates by outputting a current commanding value C to the circuit 8. The circuit 14 is constituted in such a way that, when a suppression control relay is actuated by the signal P, an adder calculates the difference between the set value of an electric power setter and the detecting value W and a proportional-plus- integration adjuster inputs the calculated result of the adder and outputs a current command value C for adjusting the inputted difference to zero.
MARUYAMA KAZUHIKO
YAMAMOTO SHUNICHI
