Bus Voltage Control Through 5 and 11 Level Voltage-Sourced Inverter Statcom

This paper describes and analyses methods of controlling bus voltage through 5 and 11 level voltage-sourced inverter STATCOM. The performance analysis is based on the level of voltage support, harmonics, and degree of dc-link voltage balancing of the inverter in constraining the bus voltage within acceptable limits, whereas the performance comparison relates cost and efficiency. An attempt is also made to describe the basic concept of VSI-STATCOM from the first principle. Superiority of the 11 level in controlling the bus voltage due to a faster response and greater voltage support is also documented. Furthermore the paper describes the switching methods mathematically and demonstrates the merits and drawbacks of inverters experimentally