Patent ID: 7852050

Claim:
A device for control of power flow in a three-phase ac transmission line, the device comprising: a series transformer unit comprising for each of the phases of the transmission line a series transformer comprising a primary winding and a secondary winding, wherein the secondary winding is adapted for serial connection into a respective phase of the transmission line, a shunt transformer unit comprising for each of the phases of the transmission line a shunt transformer comprising a primary winding and a secondary winding, wherein the primary winding is adapted to be connected between the transmission line and ground, and a reactance unit comprising for each of the phases of the transmission line, a first and a second controllable reactance serially connected between the secondary winding of the shunt transformers and ground, wherein junction points are provided between the first and second controllable reactances, and wherein the primary winding of the series transformer of each of the phases is connected to the junction points between the controllable reactances of the other two phases of the transmission line.