THE UNIFIED POWER-FLOW CONTROLLER - A NEW APPROACH TO POWER TRANSMISSION CONTROL

This paper shows that the Unified Power Flow Controller (UPFC) is able to control both the transmitted real power and, independently, the re active power flows at the sending- and the receiving-end of the transm ission line. The unique capabilities of the UPFC in multiple line comp ensation are integrated into a generalized power now controller that i s able to maintain prescribed, and independently controllable, real po wer and reactive power flow in the line. The paper describes the basic concepts of the proposed generalized P and Q controller and compares it to the more conventional, but related power flow controllers, such as the Thyristor-Controlled Series Capacitor and Thyristor-Controlled Phase Angle Regulator. The paper also presents results of computer sim ulations showing the performance of the UPFC under different system co nditions.