Power flow considerations in multi-cellular, multi-level converters

This paper considers arrangements for multi-level, multi-cellular power-converters with emphasis on applications in the field of transmission and distribution. A classification system for such converter structures is proposed which allows the many possible topological variations to be individually identified, introducing the concept of multi-cellular converters. A description of the model used to analyse power-flow within multi-cellular converter structures is given. Particular attention is given to line-frequency switching strategies and the implications if doing so in terms of the specific bridge-circuit implemented within the converter. Finally the extension of the principles to three-phase converters is considered.