In this research paper we will cover the study of the modelling and the control methods of the variable speed wind turbine based on doubly-fed induction generator (DFIG). It represents the most stressed structure given its distinctive characteristics. To control the electrical powers generated by this system independently, the vector control with the stator flux orientation is founded according to two techniques: i) the control of the powers by the backstepping technique and ii) the robust control based on the active disturbances rejection control. After the synthesis of the controllers of those two methods, their performances will be tested and compared to evaluate their effectiveness. We are mainly interested in the robustness test of the two control strategies with respect to the internal parameters’ fluctuation of the generator. The computing of the different parameters regulators of these two strategies is carried out using a genetic algorithm. This computing method makes it possible to arrive at an optimal solution of the DFIG power control. The different parts are simulated using MATLAB/Simulink environment.

Many countries have focused on the study of the electrical energy production using wind generators. These studies include maintaining the production under disturbed conditions at the grid connection point of wind farms, and maintaining production during voltage dips. Electrical grid operators have established different requirements for connecting renewable energy production systems to electrical grids. In this research paper, we are interested in the study of the wind power system based on the Doubly Fed Induction Generator during a voltage dip. We are also developing a control approach based on Active Disturbance Rejection Control and Genetic Algorithms, which aims to control the stator flux variations which should be taken into account during the current controllers computing. This control strategy will allow the wind power system to remain connected to the grid under voltage dips, and to resume the normal operation after the fault disappearance. The model of the wind power system and the proposed control strategy, are tested in the MATLAB-Simulink software.

The calculation of control parameters for a system control method is based on the model of the system with assumed fixed internal parameters. However, these parameters can vary greatly due to several phenomena. This paper presents an adapted control of a doubly fed induction generator machine robust against the rotor resistance variations of the machine used as a generator in wind energy conversion systems. The adaptation is ensured by a system allowing to identify in real time the value of the resistance, the system used is mainly based on a Luenberger observer. The conversion system is divided into two parts, the first mechanical part containing the turbine and the gearbox, the second electrical one consisting of a double fed induction generator, linked on the stator side directly to the grid, and on the rotor, side linked to the grid through two power electronics converters interposed with a direct current (DC) link. The machine-side converter is used to control the active and reactive powers, and the second on the grid side is used to control the DC link voltage. The converters are controlled by the sliding mode strategy, and the validity of the methods is checked by simulation using MATLAB/Simulink.

<span lang="EN-US">Wind energy conversion system (WECS) is composed of many non-linear power electronic sub systems, which contribute significantly in harmonic emissions that is a threat for the quality of electrical power. Hence, for a better integration of WECS in the electrical grid and in order to satisfy IEEE 519 standards, WECS must inject a quality power with a rate of total harmonics distortion (THD) that is less than 5%. Multilevel Inverters are an emerging solution for having a perfect sinusoidal output voltage with minimum harmonic content and lower switching losses than the two-level inverter so that only a smaller filter size is required. Thus, in this paper we are presenting a significantly improved results of the reduction of the grid injected current THD using three types of inverters (two-levels, three-levels NPC, and five-levels H-bridge cascade) for a WECS and comparing the THD performances of using each of the studied inverter. All results of THD are verified by a Fast Fourier transform simulation using MATLAB/Simulink. </span>

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