Six-phase PMSG wind energy conversion system based on medium-voltage multilevel converter

A new power converter interface for permanent magnet synchronous generator (PMSG) based wind energy conversion systems (WECS) is presented in this paper. The converter stage is capable to step-up the low-voltage side of standard six-phase PMSG used in today´s WECS to a medium-voltage grid side. The proposed converter is an hybrid back-to-back topology composed of two series connected three-phase voltage source converters (VSC) at the generator side, and a 3-level neutral point clamped converter (NPC) at the grid side. Operating with a multilevel converter at medium voltage at the grid side has several advantages like improved power quality, increased efficiency, easier grid code compliance and smaller cables to name a few. Compared to a back-to-back NPC configuration at both ends, the proposed topology does not require a medium voltage generator. The feasibility of the proposed configuration is verified by simulation analysis.