ERROR ASSESSMENT OF BLADE DEFORMATION MEASUREMENTS ON A MULTI-MEGAWATT WIND TURBINE BASED ON DIGITAL IMAGE CORRELATION

摘要

Optical full-field measurement methods such as Digital Image Correlation (DIC) provide a new opportunity for measuring deformation and vibration in wind turbine rotor blades during operation, in high spatial and temporal resolution. Recent field tests on a multi-megawatt wind turbine have demonstrated the vast potential for full scale testing, however little is known about the overall accuracy of DIC measurements on wind turbines. The present work proposes using a virtual 3D wind turbine model for estimating the error associated with the optical measurements. The entire setup is simulated a priori and accurate error estimation becomes possible. The error estimation for a 3.2 MW wind turbine suggests that relative out-of-plane bending of the rotor blades can be measured with an accuracy of ±9.1 mm, relative in-plane bending of the rotor blades can be measured with an accuracy of ±10.2 mm, and relative blade torsion can be measured with an accuracy of ±0.07 deg. This corresponds to a relative error of 0.46% for out-of-plane bending, 1.11% for in-plane bending and 5.46% for blade torsion.