STABILIZING APPARATUS FOR AC POWER SYSTEM

PROBLEM TO BE SOLVED: To provide a stabilizing apparatus, for an AC power system, by which the overvoltage of the AC power system provided with a static power conversion device for linkage such as for frequency conversion or the like is suppressed at a high speed. SOLUTION: A stabilizing apparatus is provided with an AC excitation-type generator-motor 10 in which a primary winding 11 is connected to an AC system 1 via a transformer 5, with an AC excitation device 12 which supplies an AC current to its secondary winding 12 and with an exciting-current control system 20 which comprises a voltage controller 21, an effective-power controller 22 and a current controller 23. When a voltage Vp, at the AC system 1, detected by a voltage detector 9 is raised due to the trip or the like of a static power conversion device 2 so as to become higher than a prescribed voltage Vover, the voltage controller 21 outputs a voltage command Id which suppressed the overvoltage of the system voltage Vp, the reactive voltage of the system is absorbed by the AC excitation-type generator-motor 10, and a rise in a system voltage is suppressed at a high speed.