Comparison of DFIG and SEF-DFIG operation in wind turbine systems

Recently, the idea of a variable speed wind turbine equipped with doubly fed induction generator (DFIG) has obtained great regard because of its considerable superiority over other wind turbine generators. New configuration of DFIG is single external feeding of DFIG (SEF-DFIG) where a rotor side converter (RSC) is set instead of the back to back variable frequency converter (VFC) in the conventional DFIG. In this paper, the vector control method for the SEF-DFIG is defined, then DFIG and SEF-DFIG operation in wind turbine system (WTS) during normal condition and grid fault, is compared. Also a static synchronous compensator (STATCOM) is employed to supply the reactive power and voltage support to a wind turbine equipped with conventional DFIG and SEF-DFIG and power system during normal grid condition and grid faults. Simulation has been done using PSCAD/EMTDC software.