Patent ID: 7919951

Claim:
A system stabilizing control system of controlling reactive power by a reactive power compensating device being connected to a bus according to a voltage variation of an electric power system in which a capacitor is connected to the bus through a breaker, comprising a reactive power compensation control unit controlling the reactive power compensating device so as to suppress a voltage variation of the bus, and a switched capacitor control unit controlling the connection of the capacitor through the breaker so as to suppress a voltage variation of the bus, wherein the switched capacitor control unit controls the connection of the capacitor without being controlled by the reactive power compensation control unit, the switched capacitor control unit has a low voltage side threshold VL and a high voltage side threshold VH, the low voltage side threshold VL is set to a value higher than a voltage of a leading side inflection point of a voltage-reactive power characteristic of the reactive power compensating device, the high voltage side threshold VH is set to a value lower than a voltage of a lagging side inflection point of a voltage-reactive power characteristic of the reactive power compensating device and higher than the low voltage side threshold VL, when a voltage of the bus drops to the low voltage side threshold VL or lower, the capacitor is closed through the breaker to suppress a leading compensation reactive power amount caused by the reactive power compensating device, and when the voltage of the bus rises to the high voltage side threshold VH or higher, the capacitor is disconnected through the breaker to suppress a lagging compensation reactive power amount caused by the reactive power compensating device.