Distributed load identification for vertical wind turbine straight blade

Wind energy gains more and more attention nowadays, the size of wind turbines is increasing over the years, but the reports on failure of wind turbine blades are also growing. Therefore knowing actual wind load distribution over a blade is critical for both safety and economy. Since direct measurement of wind pressures over a large blade is impractical or uneconomic, identification methods based on measured blade responses to reconstruct distributed wind load on the blade are desirable. In this paper, three identification methods are proposed to reconstruct distributed load over a straight blade of a vertical wind turbine. The first method is based on the measured acceleration responses of the blade, the measured reaction forces at its supports, and the given load distribution. The second method uses the measured strain responses of the blade only but without load distribution assumption. The last method resorts to the measured acceleration responses, strain responses, and reaction forces but does not need any load distribution assumption. Numerical examples show that if wind load distribution acting on the straight blade is known, the first identification method is preferable because of its simplicity and accuracy. If wind load distribution is not known, the third method has to be used to ensure load identification accuracy.