Characterizing the structural dynamic response of a horizontal axis wind turbine in a yawed flow field using rotor- and nacelle-mounted inertial sensors
Abstract
It has been shown that even a small decrease in the accuracy of a turbine’s yaw control due to hysteresis of the yaw drive and other factors results in considerable loss in energy capture by the rotor. As a cost-effective means of characterizing the turbine’s dynamic response when such losses are experienced, it is proposed that rotor-mounted inertial sensors can be used to measure static and dynamic variables that are correlated with swept wind loads on the blades. Based on this type of measurement, it is shown that the yaw set point can be tuned to shape the loads on the rotor to maximize energy capture. Improved maintenance schedules for individual turbines can also be realized using these measurements to reduce turbine down time and increase turbine component life. For example, cyclic loading that is observed in the blade’s lead-lag direction is known to cause torsional oscillations that result in accelerated gear and bearing wear. In this thesis, free and forced dynamic response measurements on a 2.1 meter horizontal axis wind turbine are used to characterize the rotor-dynamics of a turbine operating in yawed wind flow to demonstrate that rotor-mounted inertial sensors provide an effective means for characterizing the wind loads on the rotor disk. It is shown that operational modal analysis of the flap degree of freedom (DOF) exhibits a 1.5% change at 1 rot-1 in the order domain per degree change in yaw error when the yaw misalignment occurs between +/-5°. Furthermore, the lead-lag and span measurements are shown to be more sensitive to changes in yaw error than the flap DOF at yaw errors near 20° with a change of 0.78% per degree change in yaw error, again at 1 rot-1.
Degree
M.S.M.E.
Advisors
Fleeter, Purdue University.
Subject Area
Mechanical engineering
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