Output maximization control for DFIG wind turbines without using wind and shaft speed measurements

Wind turbine generators (WTGs) are usually equipped with mechanical sensors to measure wind speed and turbine shaft rotating speed for system monitoring, control, and protection. The use of these sensors increases the cost and hardware complexity and reduces the reliability of the WTG system. This paper proposes a novel real-time speed estimation algorithm for wind turbines equipped with doubly-fed induction generators (DFIGs). In the proposed algorithm, both the wind and turbine shaft speeds are estimated from the measured DFIG output electrical power. The estimated speeds are then used to determine the maximum power point of the DFIG wind turbine. A P-Q decoupled control strategy is developed to continuously regulate the DFIG at the maximum power point without the need of using any wind or turbine shaft speed sensors.