To make load change rate higher so as to be able to rapidly cope with increase in demanded load on a demand side.

When the demanded load on a consumption side 2 is increased, by a switching means 6, in order to follow up the increase in the load corresponding to the rise in the demanded load on the consumption side 2, the supply of power to a load means 4 is stopped, the power consumed by the load means 4 is added to the supply power to the consumption side 2, the increase rate of the power is made higher by sending the power consumed by the load means 4 to the consumption side 2, and the load change rate is made higher so as to be able to rapidly cope with the increase in the load demand on the demand side.