Active yaw control in a horizontal axis wind system without requiring wind direction measurement

This study presents an improved active yaw control technique for a horizontal-axis wind turbine that is driven by a full power converter system with maximum power point tracking control. The turbine is aligned to the wind direction through the error between the rotor speed determined by the optimal tip speed ratio and the real rotor speed commanded by the maximum power point tracking control. Thus, the implementation of the yaw control is not based on the measurement of the wind direction and therefore, it is not influenced by inaccuracies that may be caused by the vortex flow downstream of the blades. The proposed yaw control method is intended for large turbines, since larger increase in the generated electric energy can be attained. However, since it is cost-effective, it is affordable to be applied in low power wind systems. Selective simulation and experimental results are presented in order to demonstrate the effectiveness and the resulting improvements of the proposed control scheme. The simulation analysis is conducted in a large wind turbine with permanent magnet synchronous generator and the experimental verification in a low power real wind system with squirrel cage induction generator. However, it can also be applied to a doubly fed induction generator.