Damping subsynchronous oscillation using UPFC-a FACTS device

This paper presents the results of a study on the application of the recently developed FACTS device, the unified power flow controller (UPFC), for the damping of torsional oscillations that occur in a series compensated AC system. The IEEE first benchmark system is considered for this study. In order to suppress unstable torsional mode oscillations, a UPFC is employed at the generator terminal. A compensator with two feedback signals is employed to generate two supplementary damping signals. An approach based on modal control theory is developed for the design of the compensator.