Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in terms of power density and reliability, which can be considered as two of the most important criteria for the converters placed in wind turbine nacelles. Given the grid connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs.