Direct Speed Control Scheme for Maximum Power Point Tracking of a 1.5MW DFIG Wind Turbine

In the present work, a control strategy for Maximum Power Point Tracking (MPPT) applied to a wind turbine is described. The electric machine consists of a 1.5MW Doubly Fed Induction Generator (DFIG). This strategy is developed according to the theory of Direct Speed Control (DSC), which includes a state observer. This strategy considers the Low Shaft Speed (LSS) as an input and the i_qr reference current as the output. This control mechanism allows monitoring the MPPT; thus, changing the Power Coefficient (Cp) to its optimal value during the wind turbine operation. Among its main features, the controller is configured to work with the incorporation of different wind inputs, a fact that permits evaluating the system’s response to disturbances and variations. For simulation tests, a wind turbine has been modeled in MATLAB-Simulink and Fatigue, Aerodynamics, Structures and Turbulence (FAST) software. The strategy has been compared to a PI-MPPT controller and has demonstrated improvements in terms of speed and output power extraction.