STATCOM-Active power filter improved hysteresis current control for power quality management under unbalanced and distorted grid voltage

• STATCOM-Active power filter improved hysteresis current control. • Grid power quality management under unbalanced and distorted grid voltage. • Integrated control strategy for combined STATCOM and active power filter functionalities within a unified algorithm. Power quality degradation caused by voltage unbalance, waveform distortion, and nonlinear loads remains a significant challenge in modern electrical networks. This paper presents an enhanced current hysteresis control strategy for a static power converter connected to the electrical grid. The primary objective is to improve power quality under such disturbed conditions by developing a unified control algorithm that integrates static compensator (STATCOM) and active power filter (APF) functionalities within a single converter. The approach employs a synchronous reference frame phase-locked loop (SRF_PLL) to achieve accurate phase tracking even during severe grid disturbances. This enables simultaneous reactive power compensation and harmonic suppression, while reducing system complexity and hardware requirements. Simulation and experimental results validate the effectiveness of the proposed method, demonstrating stable operation during voltage sags up to 60 % and reducing the total harmonic distortion (THD) of grid currents below 5 % ensuring compliance with international power quality standards. The strategy thus offers a robust, high-performance solution for enhancing power quality in challenging environments.