Adaptive second order sliding mode control of doubly fed induction generator in wind energy conversion system

A dynamic synchronous d-q reference frame based modeling and a novel adaptive higher order sliding mode control theory for doubly fed induction generator (DFIG) based wind energy conversion system (WECS) have been proposed in this paper. As depicted from the literature, the sliding mode control strategy involving computation of converter currents introduces some inaccuracies for optimal extraction of the power references of the DFIG. On the contrary, the proposed method contributes with some important features such as chatter-free performance and heftiness in terms of transient response of the non-linear systems subjected to dynamic conditions such as lower and higher wind speeds. Consequently, a higher order sliding mode controller using the active and reactive power of the DFIG as controller inputs has been proposed in this paper. As compared with the other two methods, the proposed higher order sliding mode power control souvenirs a significantly improved as well as stable performance of the DFIG based WECS in terms of reduced settling time as well as quickly damping out the oscillations exhibited by the system. The robustness and stability of the proposed control strategy has been validated in MATLAB environment, in terms of the comparison of its performance with traditional proportional-integral and existing first-order sliding mode controller (employing converter current as input) subjected to a wide range of disturbances for sub and super synchronous mode of operation of the DFIG subjected to lower and higher wind speeds along with the available practical wind speed data, as depicted in the simulation and result section.