Effectiveness of Sliding Mode Control for a variable Speed Wind System Using DFIM

This paper, presents a study on the modeling and control of a doubly fed induction machine (DFIM) based on wind energy conversion system (WECS)With Maximum Power Point Tracking (MPPT)with the enslavement of pitch angle control. As it’s known in the literature, the control method uses a classical linear PI controller, which presents some disadvantages, such as instantaneous errors in the mechanical speed and active and reactive powers due to the stochastic nature of wind and parametric uncertainties of the machine and their variation. In order to improve the system performances by eliminating these errors while maintaining acceptable dynamic behavior, we applied in this article a non-linear robust control technique known as First-order sliding mode control (SMC). This approach is known by its precision in tracking, simplicity, stability and robustness, as for the response time it gives very low response time. The chattering phenomenon of the SMC approach that appear as fluctuations in the electromagnetic torque is the principal flaw of this technique, the outcomes simulation obtained with a 1.5 MW wind turbine substantiate the effectiveness and the performance of the suggested control approach.