Remote monitoring and nondestructive evaluation of wind turbine towers

Abstract

Wind turbine towers are in need of condition monitoring so as to lower the cost of unexpected maintenance. Wind loading from turbulence and gusts can cause damage in horizontal axis wind turbines even the supporting towers. Monitoring of wind turbines in service using embedded data sensor arrays usually is not targeted at the turbine-tower interaction from the perspective of structural dynamics. In this study the remote monitoring of the tower supporting a horizontal-axis wind turbine was attempted using a microwave interferometer. The dominant frequency of one tower was found to be decreased by more than 20% in 16 months. Numerical modeling using spectral finite elements is in progress and should provide further information regarding frequency shift due to stiffness variation and added mass. Expected outcome will contribute to remote monitoring procedures and nondestructive evaluation techniques for local wind turbine structures during operation.

Dynamic survey of wind turbine vibrations

“…The current study is part of a multiple-year research that investigates various aspects in the changes of dynamic characteristics of wind turbine-tower systems. Transient lateral displacements of the supporting towers have been measured in various operating conditions using a radar-based microwave interferometer, or IBIS [2]. The vibration of rotor blades was also monitored when the wind turbines were secured for maintenance.…”