DC capacitor voltage balance control of H-bridge cascaded STATCOM

The DC capacitor voltage fluctuation of H-bridge cascaded STATCOM will induce the DC voltage imbalance and influence the reliable system operation, aiming at which, the PR(Proportional Resonant) controller based on the three-level balance control strategy of DC capacitor voltage is adopted to improve the average global DC voltage control;the ADRC(Active Disturbance Rejection Controller) is applied to realize the inter-phase DC voltage balance control and the dynamic compensation for outside disturbance; the modulation wave of each power unit is translated to realize the in-phase DC voltage balance control and, combined with the CPS-PWM(Carrier Phase Shifting PWM), to facilitate the FPGA digital realization. Experimental results show that, being effective, the proposed control method has good dynamic performance and strong robustness.