This study proposes a real-time sliding mode field oriented control for a doubly-fed induction generator (DFIG)-based wind turbine prototype connected to the grid. The proposed controller is used to track the desired direct current (DC) voltage reference at the output of the DC link, to maintain constant the grid power factor at the step-up transformer terminals controlled by the grid side converter, and to force independently the stator active and reactive power to track desired values through the rotor currents controlled by the rotor side converter. This control scheme is based on a recurrent high-order neural network (RHONN) identifier trained on-line by an extended Kalman filter. The RHONN is used to approximate the DC link and the DFIG mathematical models. The adequate approximation helps to calculate the exact equivalent control part of the sliding mode controller and to eliminate the effects of disturbances and unknown dynamics appearing in the grid, which improves the robustness of the control scheme. This controller is experimentally validated on a 1/4 HP DFIG prototype and tested for variable wind speed to track a time-varying power reference and to extract the maximum power from the wind, under both balanced and unbalanced grid conditions.

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Summary Wind energy has many advantages because it does not pollute and is an endless source of energy. The most used electric machines for horizontal axis wind turbine is the doubly fed induction generator (DFIG). In this paper, the authors propose a real‐time field‐oriented control based on sliding mode (FOC‐SM) for a DFIG prototype connected to the grid via a 3‐phase transmission line. To track the desired DC voltage reference at the output of the DC link and to maintain constant the electric power factor at the step‐up transformer terminals controlled by grid‐side converter, a vector‐oriented control combined with sliding mode is introduced; and to force independently the rotor currents to track a specified reference defined from the required stator active and reactive powers, controlled by rotor‐side converter, an FOC‐SM control scheme is proposed. The DFIG rotor is coupled to the grid via a back to back power electronic converter, whereas the stator is directly linked to the grid. The proposed control scheme is experimentally validated on a 1/4 HP DFIG prototype and tested under constant and variable wind speed, maximum power extraction, and fault grid conditions. The real‐time results show that the proposed controllers achieve a high performance under ideal and no‐ideal grid conditions. Moreover, the proposed scheme is robust in presence of uncertainties, which usually exist in the real system.

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In this paper, we propose different linearization control algorithms to solve the stabilization problem of the quadrotor. First we introduce the nonlinear model of the quadrotor. Then using tangent linearization method, a linear model is generated of the system where decentralized and centralized LQR control methods are applied. The second strategy is based on exact feedback linearization of the nonlinear model of the quadrotor. The comparison between these methods is highlighted by simulations to show effectiveness of the proposed methods.