Effect of Variations of Control Operating Points of UPFC on Power System Stability and Control Performance

A unified power flow controller (UPFC) regulates the amount of active power and reactive power along the transmission line as well as the level of voltage of shunt busbar where the UPFC is installed. The regulation is implemented through the setting of control reference values of active, reactive power and voltage of the UPFC that define the control operating point of the UPFC. In this paper, effect of variations of UPFC control operating points on power system stability and control performance is investigated via a simple single-machine example power system and a multi-machine example power system.