Nonlinear control scheme based on a second order sliding mode: application to DFIG supplied by five-level PWM inverter

Adaptive control is a set of approaches used for the automatic adjustment of the controller parameters in order to achieve or maintain a certain level of performance when the parameters of the control process vary over time or unknown. The parameters of the controller are adapted to ensure also that there is no overestimation of the gain with real a priori unknown value of uncertainties. The proposed control approach consists in using second-order sliding mode with a dynamically adapted control gain that guarantees the stability and robustness of the control law even with the presence of uncertainties and perturbation of the system. The control is applied by simulation (Matlab-Simulink) on a doubly fed induction generator (DFIG) integrated into a variable speed wind turbine and controlled by super twisting sliding mode control. The simulations indicate the efficiency of the proposed approach especially in the case of change of the reference speed and/or the parameters variation.