Link Foundation Fellowship Report
The last 25 years have seen dramatic maturation of the wind energy industry. Increases in wind energy production have been tied to advancements in turbine technology, reliability, and grid compatibility; wind resource assessment, and reductions in costs. Wind energy is economically competitive with, and environmentally superior to conventional fossil and nuclear fuel-based electric power plants. Wind turbine grid connection requirements have become more demanding concomitant with increasing grid penetration. Wind generation system are now required to perform many of the duties of conventional electric power plants, such as stabilization of the grid during fault events. Unfortunately the most common and economical wind turbine architecture, which employs a doubly fed induction generator (DFIG), is prone to severe damaged while supporting the grid these fault events. Conventional modifications for providing ride-through result in limited control of the wind turbine and only modest protection during fault events. A new electrical architecture for the DFIG wind turbine was envisioned that would draw on elements of a dynamic voltage restorer (DVR). Through proper configuration and control of a DC/AC power converter, a DVR allows a sensitive utility load to be protected from grid disturbances. In the proposed DFIG architecture, the DC/AC converter power converter nominally connected in parallel with the grid in the conventional DFIG architecture is now connected in series with the grid. Conceptually this modification is straightforward, but it capabilities and implications for wind turbine operation were more enigmatic.