A Novel Control Method for Individual DC Voltage Balancing in H-bridge Cascaded STATCOM

H-bridge cascaded static synchronous compensator (STATCOM) is often used to compensate the harmonic and reactive current derived from non-linear load. However, with the special topology structure, the voltage balancing of DC capacitors of H-bridge cascaded STATCOM is a key problem. Many papers adjust active voltage to solve this problem with the conventional PI controller which needs to regulate the complex parameters of PI and introduces the delay. Hence, this paper proposed a novel balance control method for individual DC voltage balancing based on the popular carrier phase-shifted sinusoidal PWM (CPS-SPWM) strategy. With the upper and lower translations of modulation wave in CPS-SPWM, the proposed method could more simply and flexibly balance the DC-voltages during the charging and discharging processes. Finally, the simulation and experiment results show the effectiveness of the proposed method in controlling individual capacitor voltages.