TITLE:
Dynamic Stability Analysis of the National Power Grid of the Republic of the Congo: STATCOM-PSS Interactions on Voltage Regulation and Electromechanical Oscillations
AUTHORS:
Mavie Grâce Mimiesse, Rostand Martialy Davy Souamy Loembe, Smaël Magloire Elombo Motoula, Désiré Lilonga-Boynga
KEYWORDS:
Voltage Stability, Electromechanical Oscillations, STATCOM, Power System Stabilizer, Republic of the Congo
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.16 No.10,
October
30,
2026
ABSTRACT: This article investigates the interactions between Power System Stabilizers (PSS), used to mitigate power oscillations, and STATCOM-type FACTS devices, employed for voltage support, in order to enhance the dynamic stability of the transmission network of the Republic of the Congo. The study is performed using the Power System Analysis Toolbox (PSAT) in MATLAB. Without control devices, several nodes show significant voltage drops, notably 10.97 kV at Tsielampo (node 20) and 14.55 kV at Djiri (node 30) for a nominal voltage of 30 kV, while an unstable mode emerges at the Moukoukoulou generator (node 19). The addition of PSS at nodes 1, 6, and 34 improves the damping of power oscillations, with voltages stabilizing around 242 kV and 211 kV and damping ratios of 0.256 at Djéno and 0.187 at Moukoukoulou. The combined integration of PSS and two STATCOM units installed at nodes 25 and 29 further enhances system stability: voltages in Brazzaville remain within the acceptable ±10% range around 30 kV, and generator voltages stabilize around 231.13 kV (CEC), 224.46 kV (Imboulou), 213.51 kV (Djéno), and 112.26 kV (Moukoukoulou). The unstable mode (λ19 = 3.2115) only appears after the joint addition of the PSS and STATCOM, suggesting that it arises from their interaction.