D-Q model of PI controller based a unified power flow controller

The unified power flow controller is the most versatile and complex power electronic equipment that has emerged as the indispensable equipment for the control and optimization of power flow in electrical power transmission system. In this thesis the control of real and reactive power flow through a transmission line with the use of UPFC at the sending end is investigated. Computer simulation using MATLAB Simulink is done and the behavior of the UPFC is studied. In the UPFC based control of transmission line parameter control systems, it is observed that whenever the SSSC sources some real power into the transmission line it is manifested as a voltage drop across the DC link. The fall of the DC link voltage is an indication of real power demand from the receiving end. PI Controllers are used in this work in the control of DC voltage, AC voltage and power transfer.