Analysis of wind turbines connected to medium-voltage DC grids

The transmission and distribution of electrical energy with direct current (dc) is a promising alternative to established alternating-current (ac) systems. Higher efficiencies, fewer lossy pulse-width modulated converters and smaller transformers reduce operation and investment costs. Moreover, dc collector grids within wind parks leads to benefits for harvesting electrical energy. In this paper, a modular dual-active bridge (DAB) dc-dc converter system for integrating renewable energy sources, especially wind turbines (WT), into medium-voltage dc (MVDC) grids is presented and analyzed. Also, the design and efficiency of the machine-side power converter of the WT for dc grids are discussed.