Outline of the Control Design for a Cascaded H-Bridge STATCOM

The cascaded H-bridge converter (CHC) topology is ideal for implementation of direct connection static compensators (STATCOMs). However the topology requires significantly different control strategies as compared to conventional two level transformer connected STATCOMs and other multilevel STATCOMs. This paper outlines all aspects of a novel controller for a CHC STATCOM, from the capacitor voltage balancing, limiting strategies, through to the real and imaginary power loops. Simulation and experimental results are presented to demonstrate its viability and performance.