Modal analysis of vibration of tower of horizontal-axis wind turbine

According to the theory of multimodal analysis,mathematical modeling and simulation of vibrational mode were conducted for the tower of horizontal-axis wind turbine.Numerical evaluation of the model was performed by using sub space iteration method and the mechanical characteristics of the tower with natural oscillation was analyzed so that its inherent frequency and inherent vibration mode were obtained.It was shown by the analysis that the first-order innate frequency of the tower was higher than blade passing frequency(BPF),meaning that the tower was a rigid one and its resonance might be caused by the stimulation of wind wheel would not take place.According to vibration theory,the energy of tower vibration was focused at the first-and second-order frequency on its the vibration mode,showing that the shimmy was the main tower vibration mode which was the main reason of tower fatigue.