First and High Order Sliding Mode Control of a DFIG-Based Wind Turbine

Abstract

Wind energy has many advantages, because it does not pollute and is an inexhaustible source of energy. In this paper, we study the dynamical behavior of the Horizontal Axis Wind Turbine (HAWT) with MPPT (Maximum Power Point Tracking) algorithm and a pitch control, using a Doubly Fed Induction Generator (DFIG). The DFIG stator is directly linked to the grid; the rotor is connected via a back-to-back converter. To ensure a maximal power extraction, we use the MPPT algorithm combined with a PI controller to generate the maximum power and to force the system to work at the maximum operation point. The pitch control is used to protect the Wind Turbine (WT) against high wind speed. Field Oriented Control (FOC) based on a Sliding Mode (SM) first order and high order (super-twisting) are compared. These schemes control the stator active and reactive powers as well as the stator power factor and improve the power quality injected in the grid. Simulations illustrate the active and reactive power control of the HAWT by adjusting the rotor voltages of the DFIG. We choose the two rotor currents to define the sliding surfaces, in order to avoid the measurement of the electromagnetic torque and stator active and reactive powers. Adequate simulations results with Matlab-Simulink of the whole system including the MPPT algorithm, pitch control and SM controllers are presented and discussed.