DFIG wind power generation systems during unbalanced network fault: Analysis and operation

This paper presents the analysis and operation of doubly fed induction generator (DFIG)-based wind power generation system under unbalanced network voltage conditions. The limited voltage and current ratings, the control capabilities of both the grid-side and the rotor-side converter (GSC & RSC) for unbalanced network voltage compensation are investigated in detail. A new current control scheme, consisting of a proportional integral (PI) controller plus a resonant (R) compensator, is presented which is implemented in a positive synchronously rotating reference frame and capable of providing precise current control for both GSC and RSC without involving the decomposition of positive and negative sequence currents. By taking into account the both converterspsila current rating, the proposed coordinated control strategy between GSC and GSC is adjusted. Finally, simulation studies are carried out on a 1.5 MW wind-turbine driven DFIG generation system and the validity and feasibility of the proposed coordinated control scheme are confirmed by the simulated results during transient network voltage unbalance.