System integration and demonstration of a 4.5 MVA STATCOM based on emitter turn-off (ETO) thyristor and cascade multilevel converter

Static synchronous compensator (STATCOM), providing quick and robust voltage support, is an "enabling infrastructure technology" for power engineering today. The emitter turn-off (ETO) thyristor, as an emerging kilohertz power semiconductor device, provides significant advantages over other competing power switch technologies and will result in a fast response STATCOM system with reduced overall cost per kVA. Meanwhile, the cascade-multilevel converter (CMC) is the most feasible topology for STATCOM because of its compact structure, fast response, clean power quality, easy modularity and scalability. Combining advanced switch technology, modular converter technology and control technology, a 4.5 MVA STATCOM system is developed. This paper discusses system integration of the STATCOM with emphasis on power stage design and verification, digital controller design and verification. Finally, the grid tie system demonstration of STATCOM is presented.