Fuzzy logic based sensorless MPPT algorithm for wind turbine system driven DFIG

Abstract

This paper offers an improved Tip speed ratio (TSR) technique for variable speed operating mode of grid connected doubly-fed induction generator (DFIG) system. As we know from the literature, the TSR is the fastest MPPT (maximum power point tracking) technique because it uses directly the wind velocity signal to compute the optimal rotational speed of the wind turbine, However, the significant wind speed variations at different points over the blades swept area makes difficult any direct measurement of effective wind velocity, our objective is to increase the system's reliability by reducing the cost of both equipment and maintenance by means of a rotor speed observer, and wind speed estimator. Firstly, a MRAS (model reference adaptive system) based on fuzzy logic control is used to estimate the generator's rotational speed. Then, the wind velocity is approximated from the estimated generator speed, the electromagnetic torque of reference and the estimated mechanical power of the wind turbine. The proposed control method has been applied to a WTS (wind turbine system) driving a 1.5MW DFIG, and has been tested in MATLAB/ SimPowerSystem environment.