Research on Typical Vibration Accelerations of Wind Wheel Changing with Yaw Angle

Abstract

Dynamic and static frequency of the rotor about diameter of 1.4m small horizontal axis wind turbine was tested by using PULSE16.1 structural vibration analysis system., through combining the data of static frequency to identify rotor Dynamic frequency using spectrum analysis method. The conclusions found that, at a yaw condition of constant rotor speed, vibration acceleration of axial movement, disc effect and first order vibration of rotor increased with the increase of the yaw angle. The reason was that yaw exciting force which generated by the yaw behavior increased with the increase of yaw angle. At a constant load yaw, vibration acceleration of axial float, disc effect increased with the increase of the yaw angle. At the yaw condition of constant load R=82Ω、R=118Ω and the yaw angle 25°,30°,the acceleration value sharp increased and occurred the machine resonance phenomenon due to the tower instability. First order symmetric and anti symmetric vibration acceleration of rotor decreased with the increase of the yaw angle. The reason was that after the wind turbine yaw, the speed decreased of rotor caused the centrifugal force of the blades decreased, the impact of the centrifugal load changed was far greater than yaw exciting force for the first order vibration acceleration. The study also found that vibration acceleration values of rotor first order anti symmetric was ​​greater than axial movement, disc effect and first order symmetric vibration acceleration values, which shows that stress concentration in root of blade was large and the blade fatigue damage was more serious. This paper related research results can provided a new analytical thinking for rotor fatigue damage or breakage occurred frequently in wind turbine operation process, and may provide a reference for the vibration characteristics of rotor in the process of yaw.