Investigation of a unified power flow controller

Power flow in an AC transmission system depends on three basic parameters: transmission line impedance, voltage magnitude and phase angle. Maximum utilisation of the power system can be ensured by the control of these parameters in real-time. It is shown experimentally that a unified power flow controller (UPFC) can control each of the parameters either selectively or simultaneously in appropriate combinations. It is also shown that a UPFC can control independently the real and reactive power flow in a transmission circuit. Results from computer simulations and a hardware laboratory model are presented