A brief comparision of series-connected modular topology in STATCOM application

At present, the series-connected modular converter is widely accepted in medium-voltage high-power STATCOM application because of the merits brought by the modularized circuit. The three major topologies are cascaded H-bridge with star connection, cascaded H-bridge with delta connection and modular multilevel converter. The performances of these three topologies are different when they handle the unbalanced load under the asymmetrical grid fault condition. This paper analyses the characteristics of the three topologies based on the principle of power balancing. And then, a brief comparison of their performance in STATCOM application is carried out in this paper. The theoretical results are verified by computer simulations.