Sliding Mode Control of Three-Level NPC Converter-Based STATCOM for Reactive Power Compensation

The growing demand for reactive power in electrical systems underscores the need for power electronics-based solutions that support grid stability amid the current challenges of the energy transition. This study presents the application of sliding mode control (SMC), a robust and advanced nonlinear control strategy, implemented in a three-phase static synchronous compensator (STATCOM) based on a three-level voltage source converter, designed to compensate reactive power and, consequently, the load’s harmonic currents. The SMC, recognized for its robustness against parameter variations, was applied in conjunction with pulse width modulation (PWM) in a three-level neutral-point clamped (NPC) inverter, achieving precise control performance. The analysis was carried out through simulations developed in MATLAB/Simulink®. The initially high reactive power was effectively compensated and maintained oscillating around zero, improving the power factor to unity and demonstrating the effectiveness of the control strategy. The total harmonic distortion (THD) at the grid input is 1.91%, placing the system performance within internationally accepted power quality standards in accordance with IEEE 519–2022.