TOWER DEFLECTION MONITORING OF A WIND TURBINE USING AN ARRAY OF FIBER BRAGG GRATING SENSORS

This paper introduces a fiber Bragg grating(FBG)-based sensing system for the multi-MW scale wind turbine health monitoring, and describes the results of field tests of dynamic strain monitoring and the deformed shape estimation of the wind turbine tower structure. An FBG interrogator was developed with a spectrometer-type demodulator based on a linear photo detector. Real-time shape estimation of the wind turbine tower was accomplished using strain data gathered by surface mounted fiber Bragg grating sensors. The finite element model of the wind turbine tower was created and the displacement-strain transformation (DST) on the basis of the modal approach was obtained. The time histories of the strain were gathered for the cases of blade stop and start using the FBG sensors located at the upwind side of the tower. Finally, the full deflection shapes of the tower were successfully estimated using arrayed FBG sensors.