Comparison of Robust Control Methods Performance in the UPFC Controllers Design

The Unified Power Flow Controller (UPFC) integrates properties of shunt and series compensations and can effectively alters power system parameters in a way that increases power transfer capability and stabilizes system. Simple Proportional-Integral (PI) controllers are applied to UPFC as usual controllers, but parameters of PI controllers are usually tuned based on the trial-and-error approaches and they are incapable to obtain a good dynamic performance under a wide range of operating conditions. To solve this problem, robust control methods are proposed to design UPFC controllers. Also a supplementary damping controller to increase damping of power system oscillations is developed. A Single-Machine Infinite Bus (SMIB) power system installed with a UPFC with system parametric uncertainties is considered as case study. The system parametric uncertainties are obtained by 40% changing parameters from their typical values. Proposed methods are compared with each other to show their effectiveness and robustness. The objectives are to study and comparison robust control methods performance for UPFC control problem.