Coordinated DFIG-STATCOM and PSS control for transient stability enhancement of wind-integrated power systems under varying load conditions

The large-scale integration of wind power reduces overall system inertia, leading to increased vulnerability in transient stability. This paper presents a coordinated control strategy combining a DFIG-based wind turbine, a midpoint Static Synchronous Compensator (STATCOM), and a Power System Stabilizer (PSS) to enhance transient stability in wind-integrated power systems. Detailed nonlinear time-domain simulations are conducted in MATLAB/Simulink for both two-machine and multi-machine test systems under light (1000 MW), rated (2000 MW), and heavy (5000 MW) loading conditions. A severe three-phase-to-ground fault is applied at t = 3 s and cleared after 0.1 s. System performance is evaluated using key indices including maximum rotor angle deviation, settling time, damping ratio of electromechanical modes, and post-fault voltage recovery. Results demonstrate that the coordinated wind-STATCOM-PSS scheme maintains terminal voltage and rotor speed close to their nominal values (1.0 p.u.) after fault clearance, while providing improved damping of rotor angle oscillations and faster voltage recovery compared with the STATCOM-only configuration, particularly under rated loading conditions. However, under heavy loading in the multi-machine system, inter-area oscillations become dominant, limiting the effectiveness of the single midpoint device. The study systematically addresses the research gap in extending two-machine analyses to realistic multi-machine networks and highlights practical limitations, offering valuable insights for future adaptive and wide-area control strategies.