Qblade-based design of a pitch mechanism for a 150 kW vertical axis wind turbine

Abstract

To address the problems of large loads acting on the local pitch mechanism of a 150 kW H-type vertical-axis wind turbine under above-rated wind conditions, as well as the resulting difficulty in structural design, a design and co-simulation analysis method for the pitch mechanism driven by aerodynamic loads is proposed. First, an aerodynamic model of the wind turbine employing the NACA0018 airfoil is established in QBlade, through which the power characteristics and key sectional loads under different wind speeds and pitch angles are obtained. The results show that the optimal tip-speed ratio of the wind turbine is 2.1, and the output power reaches the rated value of 150 kW at a wind speed of 17 m/s. Under turbulent conditions, when the wind speed is 45 m/s, and the pitch angle is approximately 43.6°, the pitching moment Mz about the spanwise axis at the pitch section reaches 1976.21 N·m. Accordingly, considering a safety factor of 1.65, the theoretical design torque of the mechanism is determined to be 3500 N·m. On this basis, a two-stage speed-reduction and torque-amplification transmission scheme consisting of a servo motor, a harmonic reducer, and a worm-gear set is developed, and the key component parameters are designed. Furthermore, static and modal analyses are conducted in Ansys, and the results demonstrate that the proposed mechanism has good load-carrying capacity. The present study can provide a reference for the design and analysis of local pitch systems for small- and medium-power vertical-axis wind turbines.