PROJECT TITLE :

Transformerless Medium-Voltage STATCOM

ABSTRACT:

To obtain improved performance as a STATCOM in a distorted and unbalanced medium-voltage large-current (MV-LC) system, a new transformerless four-leg architecture, the modular multilevel converters (MMC) based on half-bridge converters, is proposed. In addition, an extended MMC (EMMC) is proposed to handle more precise correction for high-power applications. Both suggestions can be used to regulate reactive power and imbalance compensation, voltage regulation, and harmonic cancellation, among other things. In addition, corresponding control procedures for both the MMC and the EMMC are given in order to ensure that the source-end three-phase currents are sinusoidal and balanced. The half-bridge converters' dc-link capacitors are also controlled. The increase of power quality and performance of the electrified railway traction power supply system could be one interesting application for the EMMC-based STATCOM. Both the MMC- and EMMC-based STATCOMs, as well as their recommended control techniques, were simulated, and these concepts were also implemented on a 30-kVA modular laboratory prototype to verify the suggestions. Experiments and simulations back up the predetermined goals.