Abstract:Large-scale wind power equipment such as offshore wind turbines have long blades, which bear a large aerodynamic load and are prone to deformation, which affects aerodynamic performance and operational stability. In response to this problem, the 5 MW large-scale wind turbine blade of the NREL laboratory in the United States of America was taken as an example. A three-dimensional optimization of high efficiency and low load was carried out with the airfoil profile of each section, the installation angle and the pitch angle at rated power as the design variables. The maximum wind energy utilization rate and the minimum blade root bending moment were taken as the optimization goals. The optimization design based on the blade element momentum theory and the multi-island genetic algorithm, and the aerodynamic performance of the optimized blade under variable pitch and variable wind conditions was compared with the original blade. The optimization results showed that, compared with the original blade, under the design conditions, the optimized blade reduced the root bending moment by 5% while ensuring high aerodynamic efficiency. Under variable wind conditions, the wind energy utilization rate of the optimized blades before the pitch change was increased by an average of 1%, and the root bending moment of the blade was reduced by an average of 5.8%. After the pitching, the blade root bending moment of the optimized blade was reduced by an average of 4%.