Relationships between vibrations of main device and mechanical network in a classical vibration control system

Abstract

For a classical vibration control system consisting of a main device, an auxiliary device and a mechanical network, two major results are obtained. The first major result is analyzing the effect of adjusting the main device vibration on the vibration of the mechanical network. The second major result is establishing the upper and lower bounds of the amplitude–frequency curve of the mechanical network when the amplitude–frequency curve of the main device is fixed. For theoretical research, the first conclusion can be used to predict the variation trend of the vibration of the mechanical network when the vibration of the main device is further suppressed. For engineering applications, the second conclusion can be used to evaluate whether the vibration suppression performance indicators can be achieved. Then, to demonstrate the effectiveness, these two major results are applied to wind turbine load mitigation. A 7-DOF onshore wind turbine model including nacelle relative displacement is established. By replacing the rigid connection between the nacelle and the tower top with a mechanical network, the tower top relative displacement is reduced under both wind loads and seismic waves. Finally, a theoretical explanation of the simulation results is provided using the two major results above.