digilib@itb.ac.id +62 812 2508 8800

Inter-Area Oscillations is a challenge in the interconnection system that affects the stability of the power system. Conventional Power System Stabilizer (PSS) used to reduce small signal oscillations has limitations in Inter-Area Oscillations. Therefore, in this thesis, a Unified Power Flow Controller (UPFC) damping control scheme is introduced. The control parameters of UPFC-based PI Controllers are tuned with the Firefly Algorithm to increase the damping of InterArea Oscillations in a multi-machine system. The performance will be compared with PSS-UPFC, which is optimized using CRPSO from the literature. Firefly Algorithm is also used to present coordinated tuning between PSS-UPFC, and the results will be compared with systems that use PSS or UPFC only, in which the parameters have also been optimized. Based on load changes and three-phase fault simulation, the proposed UPFC-Based PI Controller is proven to be able to increase the eigenvalues of the system under different conditions and provides better results in time-domain analysis, by reducing overshoot, acceleration settling time, and minimizing graph area.