Design of UPFC controllers for a multimachine system

This paper presents a comprehensive approach for the design of UPFC controllers (i.e. power flow controller, DC voltage regulator and damping controller) for a multimachine system. UPFC controllers have been designed in the presence of conventional PSS. The interaction between the UPFC controllers and PSS has been studied. Investigations reveal that the system damping gets adversely affected with the incorporation of DC voltage regulator. Investigations have been carried out to understand relative effectiveness of modulation of the UPFC control signals (m_B, δ_B, m_E and δ_E) on damping of the system oscillations using controllability index. Studies reveal that the UPFC based damping controller considering modulation of control parameter m_B is most effective in damping the oscillations.