Sliding mode control of a Brushless doubly fed induction generator

This paper presents a sliding mode control (SMC) associated to the field oriented control (FOC) of a Brushless doubly fed induction generator (BDFIG) based wind energy conversion systems (WECSs). The stator of this machine incorporates two sets of three phase windings with different number of poles. The study of operation of the wind turbine leads us to two essential cases: optimization of the power for wind speeds lower than the nominal speed of the turbine and limitation of the power for higher speeds. Conventional electrical grid connected WECS present interesting control demands, due to the intrinsic nonlinear characteristic of wind mills and electric generators. The SMC is a robust nonlinear algorithm which uses discontinuous control to force the system states trajectories to join some specified sliding surface, it has been widely used for its robustness to model parameter uncertainties and external disturbances, is studied. In order to verify the validity of the proposed method, a dynamic model of the proposed system has been simulated, to demonstrate its performance.