Vibration Analysis of Wind Turbine via a Multibody Dynamics Approach

In this paper, a lumped model of horizontal axis wind turbines (HAWT) is presented for modal and vibration analysis. Motion modes such as tower fore and aft, tower side to side, blade flap, blade edge, and tower axial torsion are considered. A multibody modeling approach is used to represent the structure and components of a HAWT. A continuous component in wind turbines may be divided as discrete rigid bodies linked by proper types of joints with springs and dampers for couplings. Joints are used to describe the degrees of freedom of the component’s deformation. Springs and dampers are added to accommodate the component’s elastic and plastic properties. For example the tower is modeled as discrete rigid bodies linked by universal joints, which allow three degrees of freedom (DOF) from one torsional and two bending motions of the tower, and torsional springs are added between bodies to accommodate elastic property of the tower. The potential energy of the springs equals to the potential energy of the continuous tower, which may be represented by Timoshenko-beam model. Thus the spring stiffness is calculated based on the potential energy equivalence. Equations of motion of wind turbines are derived via Kane’s dynamical method. Modal and vibration analysis are further carried out based on this lumped multibody model. As a comparison with other approaches such as finite element analysis (FEA) that requires high data storage and long simulation time, this approach may provide a low fidelity simulation model and tool, which is suitable for analysis of dynamic loads, modal, and vibration of wind turbines with respect to fixed and moving references at high computational efficiency and low simulation costs. The approach is also a good candidate for simulating dynamical behaviors of wind turbines and preventing their fatigue failures in time domain.