Nonlinear Multi-Frequency Dynamics of Wind Turbine Components with a Single-Mesh Helical Gear Train

Nkongho Ayuketang Arreyndip,Alain Moise Dikande,Ebobenow Joseph

doi:10.3390/mca23010012

Abstract

A complex nonlinear model for a single-mesh helical gear train is developed by including a time-varying mesh stiffness, axial vibrations, torsional vibrations, shaft and bearing damping, generator back EMF (Electromotive Force) and gear backlashes. With the help of a time series and Fast Fourier Transform (FFT) frequency spectrum, the effects of these nonlinear terms on the wind turbine and generator rotational speeds are studied under different excitation conditions by numerically integrating the associated equations using the RK4 algorithm. Results show that for lightly damped oscillations, an extra harmonic is induced in the generator dynamics due to contributions from internal excitations. However, this extra vibration can be suppressed at higher damping. Big helical angles will generally induce heavy nonlinear vibrations in the turbine and generator; a smaller mesh frequency will induce extra noise in the generator; and the external excitation due to wind gust has a greater influence on the nonlinearity of the wind turbine dynamics as compared to the internal excitations due to static transmission errors, time-varying mesh stiffness and the generator back EMF.

Highlights

IntroductionA wind turbine interacting with wind speed undergoes different mechanical dynamics
We see that multiple values and an amplitude jump exist in the frequency response, which are typical characteristics of nonlinear vibrations
We have developed a complex nonlinear model for a six-degree-of-freedom (DOF) single-mesh helical gear train by including a time-varying mesh stiffness, axial vibrations, torsional vibrations, shaft and bearing damping, generator back EMF and gear backlashes

Summary

Introduction

A wind turbine interacting with wind speed undergoes different mechanical dynamics Some of these dynamics are: tower vibration, torsional dynamics, axial vibrations and a 3p effect, which is usually caused by a non-homogeneous wind speed across the turbine rotor plane and the presence of a tower [1]. The main challenge of adopting this model is that the blade breaking point is rarely provided by manufacturers [1] Researchers of this model realize that there is a greater need to consider more sophisticated models as this model fails to address the actual behavior of the wind turbine at the gear stage and only considers the entire gearbox as a gain that adds up to the speed of a high speed shaft

Methods

Results

Conclusion