Control and Performance of a Transformerless Cascade PWM STATCOM With Star Configuration

 Control and Performance of a Transformerless Cascade PWM STATCOM With Star Configuration

presents a three-phase transformer-less cascade pulsewidth-modulation (PWM) STATic synchronous COMpensator (STATCOM) intended for installation on industrial and utility power distribution systems. It proposes a control al-gorithm that devotes itself not only to meeting the demand of reactive power but also to voltage balancing of multiple galvan-ically isolated and floating dc capacitors. The control algorithm based on a phase-shifted carrier modulation strategy is prominent in having no restriction on the cascade number. Experimental waveforms verify that a 200-V 10-kVA cascade PWM STATCOM with star configuration has the capability of inductive to capacitive (or capacitive to inductive) operation at the rated reactive power of 10 kVA within 20 ms while keeping the nine dc mean voltages controlled and balanced even during the transient state.