To prevent service interrupts due to non-utility generation apparatus from becoming overloaded with respect to an accident in a distribution line, a commercial power line or the like, and prevent instantaneous voltage drop in a distribution line to which a critical load is connected.
A system linkage device 21 is placed between two power systems, for example, between a receiving bus 22 wherein power reception is performed through a commercial power line 25 and a non-utility generation bus 23 supplied with power from a non-utility generation apparatus 27, and is provided with a single-phase rectifying circuit which comprises thyristors TH1-TH4 and a direct-current reactor L which functions to limit current. A controller 30 makes TH1 and TH2 and diode-operates TH3 and TH4 to be switching-operated. When an accident occurs in a system and an attempt to turn off TH1 and TH2 is made, and neither TH1 nor TH2 will turn off due to element failure, the controller 30 turns on TH1 and TH2 again, to form a current feedback loop for consuming the magnetic field energy of the direct- current reactor L, and then drives off TH3 and TH4.
MATSUBARA KATSUO
TOKUDA KENSHO
