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Stability of large horizontal-axis axisymmetric wind turbines

Conference · · Alternative Energy Sources; (United States)
OSTI ID:7173667
This paper examines the stability of large horizontal axis, axi-symmetric, power producing wind turbines. The analytical model used includes the dynamic coupling of the rotor, tower and power generating system. The aerodynamic loading is derived from blade element theory. Each rotor blade is permitted two principal elastic bending degrees of freedom, one degree of freedom in torsion and controlled pitch as a rigid body. The rotor hub is mounted in a rigid nacelle which may yaw freely or in a controlled manner. The tower can bend in two principal directions and may twist. Also, the rotor speed can vary and may induce perturbation reactions within the power generating equipment. Stability is determined by the eigenvalues of a set of linearized constant coefficient differential equations. All results presented are based on a 3-bladed, 300 ft.-diameter, 2.0 megawatt wind turbine. Some of the parameters varied are; wind speed, rotor speed structural stiffness and damping, the effective stiffness and damping of the power generating system and the principal bending directions of the rotor blades. The results show that unstable or weakly stable behavior can be caused by aerodynamic forces due to motion of the rotor blades and tower in the plane of rotation or by mechanical coupling between the rotor system and the tower.
Research Organization:
NASA-Lewis Research Center Cleveland, Ohio
OSTI ID:
7173667
Report Number(s):
CONF-801210-
Conference Information:
Journal Name: Alternative Energy Sources; (United States) Journal Volume: 4
Country of Publication:
United States
Language:
English