Nine-level SHE-PWM VSC based STATCOM for VAR compensation

The paper presents a nine-level selective harmonic elimination pulse width modulation (SHE-PWM) cascaded voltage source converter based STATCOM system. The structure allows direct connection to the grid without the need of any step-up transformers. The converter is controlled with the SHE-PWM technique which provides an elimination to lower order harmonics to improve output waveforms and furthermore, allowing the use of smaller filters. The control methods used for voltage, stress balance and dc voltage regulation are also described in the paper. The operations and the performance of the STATCOM for reactive power (VAR) compensation are validated by simulation studies using SIMULINK/MATLAB software which confirm the theoretical predictions.