Design of an Mppt based on the torque estimator for variable speed turbines

This paper presents a modeling and Maximum Power Point Tracking (MPPT) control method of DFIG-based variable-speed wind energy conversion system. The aim of the control strategy is initially to define an electromagnetic torque reference by an Mppt system based on mechanical torque estimator using backstepping control then in a second time the second order sliding mode control is applied to achieve smooth regulation of both electromagnetic torque and stator reactive power. Compared with traditional controls, the proposed strategy using robust control, allow to directly track the DFIG torque leading to maximum power extraction. This allows a large wind system performances. Simulation is carried out in SimPower toolbox of Matlab/Simulink. It's shown that the controller meets its objectives.