Efficient method for wind velocity estimation and power-extraction maximization using a fourth-order Luenberger observer in a wind-energy-conversion system

This paper proposes an advanced method for estimating numerous parameters in a wind-energy-conversion system with high precision, especially in a transient state, including the rotation speed and mechanical torque of the turbine as well as wind velocity. The suggested approach is designed into two parts. First, a fourth-order Luenberger observer is proposed to take into account the significant fluctuations of the mechanical torque that can be caused by wind gusts. This observer provides an accurate estimate of speed and mechanical torque in all weather conditions and especially when the wind is gusting. At the same time, the wind velocity is calculated using the Luenberger observer outputs and a model of the mechanical power generated by the turbine. Second, these estimated parameters are exploited as input in a maximum-power-point tracking (MPPT) algorithm using the tip-speed ratio (TSR) to improve the sensorless strategy control. Simulation results were performed using MATLAB (R)/Simulink (R) for both wind gust and real wind profiles. We have verified that for wind gusts with jumps ranging from 3 to 7 m/s, the new observer manages to better follow the rotation speed and the torque of the turbine compared to a usual observer. In addition, we demonstrated that by applying the proposed estimator in the improved TSR-MPPT strategy, it is possible to extract 3.3% more energy compared to traditional approaches.