Abstract
The current research of wind turbine drivetrain is mainly concentrated in dynamic characteristics of gearbox with a specific suspension of main shaft, such as one-point and two-point suspension. However, little attention is paid to the effects of these suspension configurations on the dynamic responses of wind turbine gearbox. This paper investigates the influences of suspension configurations of main shaft on the dynamic characteristics of drivetrain. For evaluating the dynamic behaviors of drivetrain with multi-stage transmission system more realistically, a dynamic modeling approach of drivetrain is proposed based on Timoshenko beam theory and Lagrange’s equation. Considering the flexibility and different suspension configurations of main shaft, time-varying mesh stiffness excitation, time-varying transmission error excitation and gravity excitation, etc., a three-dimensional dynamic model of drivetrain is developed, and the dynamic responses of drivetrain are investigated. Results show that with the one-point suspension of main shaft, the resonance frequencies in gearbox, especially at the low-speed stage, obviously shift to the higher frequency range compared to the gearbox without main shaft, but this trend could be inversed by increasing main shaft length. Meanwhile, the loads in main shaft, main shaft bearing and carrier bearing are greatly sensitive to the main shaft length. Hence, the load sharing is further disrupted by main shaft, but this effect could be alleviated by larger load torque. Comparing to the one-point suspension of main shaft, there occurs the obvious load reduction at the low-speed stage with two-point suspension of main shaft. However, those advantages greatly depend on the distance between two main bearings, and come at the expense of increased load in upwind main shaft unit and the corresponding main bearing. Finally, a wind field test is conducted to verify the proposed drivetrain model. This study develops a numerical model of drivetrain which is able to evaluate the effects of different suspension configurations of main shaft on gearbox.
Highlights
Wind turbine drivetrain is a typical example of mechanical transmission system, which has complicated structure connection and kinematic relation
For two-point suspension of main shaft as shown in Figures 11b and 12b, the bending force of main shaft unit (S2) and bearing force of main shaft, which are closer to gearbox, are obviously smaller than the loads in main shaft unit (S1) and main shaft bearing, respectively
It needs to notice that this suspension configuration would cause severely unbalanced loads in main shaft, leading to greater load concentrated in upwind part of main shaft
Summary
Wind turbine drivetrain is a typical example of mechanical transmission system, which has complicated structure connection and kinematic relation. Zhang et al [11] built a multibody dynamic model considering three-point suspension for wind turbine drivetrain and analyzed the potential resonance which agreed well with the experiment. Little investigation was carried out to compare the effects of suspension configuration of main shaft on the dynamic responses of drivetrain for further structure optimization. Zhu et al [18, 19] built a coupled nonlinear dynamic model to investigate the dynamic responses of wind turbine gearbox considering the flexible pin. Guo et al [1, 2, 21] indicated that the flexibility and suspension configuration of main shaft could greatly affect the gearbox’s internal response, and their models considered six DOFs for each component. The experiment is carried out to verify the proposed model
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