State-Space Dynamic Model of Unified MMC Structure for Hybrid AC/DC Grids

The state-space modelling process and validation of a generalized DC/DC/AC MMC structure is presented. This structure can be used to represent two different MMC topologies that are capable of performing simultaneous AC/DC and DC/DC conversions. The DC/DC/AC models enable controlled power exchanges between two DC systems and an AC system. The time-averaged model is developed in the $\alpha\beta0-$frame, and includes all dynamics in the converter structure, barring switching harmonics. The resulting model is validated against a switched converter model implemented in PLECS. The model can be used to perform time-domain studies of the multiport converters, at a much reduced simulation time than its switched model counterpart.