Based on an established axial vibration model of the wind turbine tower-nacelle system, the
mechanical impedance method was applied to construct the mechanical network diagram for the axial
vibration of the tower-nacelle system. Then, the axial free vibration and forced vibration of the system
were analyzed theoretically with considering the displacement impedance or admittance as the transfer
function. The analysis shows: for free vibration, the system performs damped vibration with light
damping, the amplitude attenuates exponentially with light damping, the system returns to the
equilibrium position directly with over-damping, and the system does not generate reciprocating
vibration with critical damping; for forced vibration, the amplitude of the axial displacement response
is related to the frequency ratio of rotation rate. The resonance frequency does not occur at the
undamped natural frequency 0. The peak value of the vibration triggered by blade mass imbalance
shifts toward the high frequency direction along with the increase of damping ratio , while the peak
value of the vibration triggered by tower front spoiler and pneumatic imbalance shifts toward the low
frequency direction along with the increase of . If >
2
2 , the amplitude frequency has no peak value,
and resonance does not occur. The analysis provides a theoretical basis for the design and control of the
wind turbine tower.
關聯:
Journal of Applied Science and Engineering 19(1), pp.53-64
