A novel fault tolerant DFIG based wind energy conversion system for seamless operation during grid faults

A novel fault tolerant configuration of doubly fed induction generator (DFIG) for wind energy conversion systems (WECS) is proposed in this paper for the seamless operation during all kinds of grid faults. The proposed configuration is developed by replacing traditional six-switch grid side converter (GSC) of DFIG with a nine-switch converter. With the additional three switches, the nine-switch converter can provide six independent output terminals. One set of three output terminals are connected to the grid through interfacing inductors to realize normal GSC operation while, the other set of three output terminals are connected to neutral side of the stator windings to provide fault ride-through (FRT) capability to the DFIG. An appropriate control algorithm is developed for the proposed configuration that 1) achieves seamless fault ride-through during any kind of grid faults and 2) strictly satisfies new grid codes requirements. The effectiveness of the proposed configuration in riding through different kind of faults is evaluated through detailed simulation studies on a 1.5MW WECS.