A 6.6-kV Transformerless Cascade PWM STATCOM

This paper deals with a 6.6-kV transformerless STATCOM cascading multiple single-phase H-bridge PWM converters in each phase. The ac voltage of the STATCOM is almost sinusoidal, so that it requires no harmonic filter. Each converter is equipped with a capacitor and a voltage sensor on the dc side, which are electrically isolated from each other. The STATCOM has the capability of self-starting and voltage-balancing without any external power supply or equipment. Experiment by a three-phase 200-V, 10-kVA laboratry system, along with computer simulation, is carried out to confirm the viability and effectiveness of the STATCOM.