A New Wind Turbine Interface to MVdc Collection Grid With High-Frequency Isolation and Input Current Shaping

A new power electronic interface suitable for the integration of the next-generation offshore wind turbines with medium voltage dc collection grids is introduced in this paper. A practical design case study provides guidance for further development of the proposed interface. The detailed simulations show acceptable operation of the proposed approach from 25% to 100% rated power, including step changes in the wind turbine generator (WTG) input power. Simulation results demonstrate 0.95 displacement power factor magnitude, near-sinusoidal WTG current, continuous output current, stiff dc link voltages, and inverter zero-current switching. Preliminary hardware results from a 250 Vdc, 700-W lab-scale prototype are introduced, demonstrating an input rectifier boost characteristic with a dominant input current fundamental and 0.95 displacement power factor magnitude. The dc link current has a large peak-to-average ratio as expected, and dc link capacitor voltage balance is achieved via adjustment of relative duty cycles between high- and low-side active rectifier switches.