Research On Vibration And Stress Composite Sensing And Detection Technology Of Wind Power Tower Bolts

Wind turbine tower is the supporting component of wind turbine.During the operation,the tower may collapse caused by the break of flange bolt due to the strong vibration or excessive stress,bringing huge economic lose.The traditional scheduled maintenance and breakdown maintenance cannot meet the needs of the rapidly developing wind power industry because of its low efficiency and high costs.Aiming at this problem,the paper proposes an on-line detection scheme to develop a vibration/stress composite sensing and detecting device for the wind turbine tower’s status detection.Firstly,the paper studies the mechanism of vibration/stress detection based on the electromagnetic theory and proposes the structure of vibration/stress compositing sensor.Then,the influence on sensitivity of the sensor by the main parameters,including the size of the vibration beam/magnet/coil,remanence of the magnet and motivating current frequency,is analyzed by theory and finite element simulation.After that,the structure parameters of the sensor are determined.Next,according to the characteristics of signal to be measured,the signal detection and processing system is built using the DAQ USB6363 and Lab View software based on the virtual instrument technology.The system realizes the constant current excitation through virtual signal generator and constant current source circuit.Meanwhile,digital lock-in amplifier and spectrum analysis are used to obtain the information of stress and vibration.Finally,the vibration/stress composite sensor samples are prepared and tested by ZHT-2 vibration test equipment and WDW-100 E tensile tester.The result shows that the sensitivity of acceleration is about10.9m V/g and the sensitivity of stress is about 165 μ V/A/MPa,which can meet the requirements of wind turbine tower bolts’ vibration and stress detection.