Versatile power flow transformer

Real and reactive power flow in an alternating current transmission line are independently controlled by connecting, to the transmission line, a series-compensating voltage, which is variable in magnitude and at variable angle with respect to the transmission line voltage as well as the prevailing line current. The traditional technology of transformer and tap changer is used to implement this novel technique. An additional voltage regulation capability can also be implemented. The speed of tap changer operation determines the response time of this power flow controller, which is quite adequate in most utility applications. If suitable solid-state switches are available to replace the mechanical taps, the response time can be improved.