Vibration self-synchronous features of a wind turbine blade single-point fatigue loading test system

Aiming at self-synchronous vibration phenomenon in single-point fatigue loading test process of a wind turbine blade, the dynamic model of the single-point fatigue loading system based on Lagrangian equation was established and the influence factors of the self-synchronous vibration phenomenon were obtained. Applying the phase plane method, the vibration system was converted into an autonomous system. Then the vibration system's simulation model was built with Matlab/Simulink and the basic laws of the self-synchronous vibration phenomenon with different initial phases were deduced. At last, a set of single-point fatigue loading test equipments used to test the correctness of the dynamic model and the simulation one was set up. The experimental results showed that under the premise of the load source rotary drive frequency being the same as the blade's natural frequency, the self-synchronous vibration phenomenon occurs when the initial phase difference between them is less than π/20, the amplitude of the blade is the maximum and stable; when the initial phase difference is π/8, the self-synchronous vibration phenomenon is weak, and the amplitude of the blade gradually approaches a smaller value after fluctuating for a period of time; when the initial phase difference is π, the self-synchronous vibration phenomenon does not occur and the amplitude of the blade is unstable. The above conclusions provided a theoretical basis for the control algorithm of further fatigue loading tests. ©, 2015, Chinese Vibration Engineering Society. All right reserved.