Optimum Power Point Tracking of Variable Speed Wind Turbine DFIG using Genetic Algorithm

This paper presents Maximum Power Point Tracking (MPPT) controller design of Doubly Fed Induction Generator (DFIG) using Genetic Algorithm (GA). Essential feature of proposed controller is that it is used to trace the maximum power when wind speed is lower than the rated wind speed. Doubly-Fed Induction Generator DFIG has stator terminals are connected directly to the grid. However, the rotor terminals of DFIG are connected to the mains via a partially rated variable frequency ac/dc/ac converter. The ac/dc/ac converter system consisting of a rotor side converter (RSC) and a grid side converter (GSC) are connected back-to-back by a DC-link capacitor. Stator voltage orientation (SVO) is the principle control for RSC controlled by hysteresis current controller. While GSC is controlled by pulse width modulation (PWM). Due to the nature of unpredicted wind speed, determining the optimal tip speed ratio (TSR) is essential to extract the maximum available wind power at any wind speed under rated wind speed. To get the maximum output power under rated wind speed the proposed method must be used. The system under study is simulated using MATLAB/Simulink package. The digital simulation results under different conditions in terms of the variations of the wind turbine generator show that the output power, rotor speed and torque response for step change in wind speed prove the effectiveness and powerful of the proposed GA controller for MPPT.