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This paper aims at contributing to the modeling and control of a variable speed Wind Energy Conversion System (WEC-System) based on a Squirrel Cage Induction Generator (SCI-Generator). The connection between the SCI-Generator and the main utility grid is achieved by back-to-back three phase power converters (Generator and Grid Side Converters). A new control strategy named the Active Disturbance Rejection Control (ADRC) is proposed and utilized to control the Wind Energy Conversion (WEC) system based on the SCI-Generator. The objective is to control both the generator and the grid side converters in order to operate the system and to ensure the connection with the power grid. The first converter is used to control the SCI-Generator speed and field to extract the available maximum power from the wind turbine by using a Maximum Power Point Tracking (MPPT) technique and, also, to ensure that the extracted power does not exceed its rated value in case of strong wind speeds; in this case a pitch actuator system is used to control the blades pitch angle of the wind turbine. The second converter is used to control the active and reactive powers injected into the utility grid as well as to regulate the DC-Link Voltage. This control takes into account the rejection of internal disturbances as the variation of electrical parameters (the resistance, the inductance…) and the external disturbances as voltage dips and frequency droops in the main grid. To test and validate the performances of the proposed controller, a series of simulations were developed under MATLAB/Simulink environment, and the results have demonstrated the effectiveness of the proposed control under different case of simulations.

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The Wind Energy Conversion System (WECS) based Doubly Fed Induction Generator (DFIG) has experienced a rapid development in the world, which leads to an increasing insertion of this source of energy in the electrical grids. The sudden and temporary drop of voltage at the network can affect the operation of the DFIG; the voltage dips produce high peak currents on the stator and rotor circuits, without protection, the rotor side converter (RSC) will suffer also from over-current limit, consequently, the RSC may even be destroyed and the generator be damaged. In this paper a new Direct Power Control (DPC) method was developed, in order to control the stator powers and help the operation of the aero-generator during the faults grid; by injecting the reactive power into the network to contribute to the return of voltage, and set the active power to the optimum value to suppress the high peak currents. The DPC method was designed using the nonlinear Backstepping (BS) controller associated with the Lyapunov function to ensure the stability and robustness of the system. A comparison study was undertaken to verify the robustness and effectiveness of the DPC-BS to that of the classical vector control (VC) using Proportional-Integral (PI) correctors. All were simulated under the Simulink® software.

In this paper we present a contribution for the modeling and control of wind energy conversion system based on a Doubly Fed Induction Generator (DFIG). Since the wind speed is random the system has to produce an optimal electrical power to the Network and ensures important strength and stability. In this work, the Backstepping controller is used to control the generator via two converter witch placed a DC bus capacitor and connected to the grid by a Filter R-L, in order to optimize capture wind energy. All is simulated and presented under MATLAB/Simulink Software to show performance and robustness of the proposed controller.

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<p>This paper presents a robust coordinated control of a flywheel energy storage system (FESS) and a doubly fed induction generator (DFIG) based wind energy conversion system (WECS), used to smooth the wind induced output power fluctuations. The overall system control combines field oriented control schemes and nonlinear backstepping approach applied first, to the machine side converter (MSC) to regulate the DFIG active and reactive power in order to ensure maximum power point tracking (MPPT) operation and a unity power factor at the point of common coupling (PCC). Then, to the grid side converter (GSC) to maintain a constant DC bus voltage. Finally, to the flywheel side converter (FSC) in way that allows the storage unit to serve as a buffer that stores energy in the case of excess power and retrieves it back into the output in the case of power deficiency. A numerical simulation using Matlab/Simulink software validates the effectiveness of the proposed control strategies in terms of dynamic response, improvement of generated power quality and robustness against parametric variation.</p>

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