Authors : S.V. Ravi Kumar and S. Siva Nagaraju
Abstract: One of the most comprehensive FACTS devices is Unified Power Flow Controller (UPFC), which has been introduced by Gyugiy in 1991. The UPFC consists of two voltage-source converters, which are connected back-to-back though a DC link. The series voltage converter is connected to the transmission line by means of a series transformer and the shunt voltage converter by means of shunt transformer. The series voltage converter injects an AC voltage into the transmission line with controllable magnitude and phase angle. The shunt converter can exchange active and reactive powers with the system, which enables the system to do shunt compensation independently. To investigate the effect of the UPFC on the steady state condition of the system and load flow, different models have been introduced. These models are usually based on modification of traditional load flow methods. But, in this study, a mathematical model for UPFC which will be referred as UPFC injection model is derived. The UPFC injection model is easily incorporated in Newton-Raphson power flow model to study its effect for power flow control and losses minimization in the power system. A five-bus sample system i.e., Hale network has been taken as a case study and programme is written using MATLAB Software. Finally it is shown that a UPFC has the capability of regulating the power flow and minimizing the power loss simultaneously.
S.V. Ravi Kumar and S. Siva Nagaraju , 2007. Loss Minimization by Incorporation of UPFC in Load Flow Studies . International Journal of Electrical and Power Engineering, 1: 321-327.