Field testing of an in-service wind turbine tower using a laser based remote sensing method

As a special slender structure,a wind turbine tower with a turbine on the top of the structure is sensitive to dynamic loading. Therefore,it is critical to accurately assess the vibrational behaviors of the wind turbine tower. To facilitate field testing of wind turbine towers,a laser Doppler vibrometer was proposed in the ambient vibration testing. Comparisons between the conventional contact accelerometer method and the laser based remote sensing method were made in the aspects of testing efficiency and result validity. Based on a series of vibration signals collected from a 1.5 MW wind turbine tower,the natural frequencies of this tower were obtained by using different vibration analysis methods.