Wind turbine drivetrain components are; low-speed shaft, high-speed shaft, rotor, gearbox, and generator.
These drivetrain configuration of a wind turbine is; rotor-low speed shaft-gearbox-high speed shaft-generator; where the low-speed shaft introduces mechanical energy from the wind turbine rotor into the gearbox which amplifies and transmits this energy through the high-speed shaft to the generator.
In this article, the components of a wind turbine drivetrain are discussed, as follows;
1). Rotor (as one of the Wind Turbine Drivetrain Components)
The rotor is the foremost component in a typical wind turbine drivetrain configuration.
It is responsible for bearing the turbine blades, which capture and convert wind kinetic energy to rotary mechanical energy.
A turbine rotor is made of materials that are mechanically resilient; like alloy steel comprising of chromium and nickel. The rotor blades are designed to be flexible, relatively light-weight and mechanically resilient, and could be made from aluminum or steel, among others.
Average rotor radius in wind turbines is about 60.96 meters or 200 ft, as of 2023.
Types of rotors used in wind turbines are; drag-based and lift-based rotors; which are categorized based on their aerodynamic interaction with wind energy.
2). Low-Speed Shaft
The low-speed shaft in a wind turbine is the component that transfers low-speed mechanical energy directly from the rotor to the gearbox, for it to be amplified and converted to high-speed mechanical energy.
It is called low-speed shaft or main shaft because the mechanical rotation that is derived directly from wind energy in the blades and rotor, is of low speed compared to that which is required to start the turbine generator and generate electricity.
A low speed wind turbine is called a direct-drive turbine, because it uses only the main shaft and has no gearbox or high-speed shaft for torque amplification. Such turbines have very poor performance and are not practically applicable for generating power.
The lowest speeds for wind turbines are generally below 10 rotations per minute (RPM). For low-speed shafts, their rotational speed ranges from 7-60 rotations per minute on average, and varies depending on factors like wind speed (km/hr), turbine size, design and working condition.
Significant energy loss usually occurs at the low-speed shaft, due to frictional forces resisting rotation . Minimizing friction through the use of lubrication-and-bearing systems is an important aspect of low-speed shaft design.
3). Gearbox (as one of the Wind Turbine Drivetrain Components)
Gearbox in a wind turbine is a component which is equipped with multiple gears that work together to convert low-speed rotation from the rotor blades to high-speed rotation that is transmitted to the generator .
In a wind turbine gearbox, there are usually about three gears with varying number of teeth, which are interconnected with each other. These gears may be distinguished based on design, relative position and relative-function into planetary, ordinary, one-stage, multistage, fixed-shaft gear, and so forth . The number of teeth per gear may also vary from over 1,000 to less than 20.
Types of gearboxes used in wind turbines include; planetary gearbox, parallel-shaft gearbox, and helical gearbox. These are distinguished based on the types of gears used, and the operational configuration (internal and external) of the gearboxes. Planetary gearbox is among the most-commonly used.
4). High-Speed Shaft
The high-speed shaft in a wind turbine is connected to the gearbox, which transmits high-speed rotational torque that has been produced by modification of the low-speed shaft rotation.
High-speed shafts play the role of driving the generator, to which they are linked as electromagnetic conductors for current induction.
To generate electricity, the high-speed shaft is usually attached to a copper coil called the armature, which provides suitable conductive surface area for the electromagnetic effect to take place as the shaft rotates at high speed.
In high-speed shafts, it is common to achieve a rotational speed of between 1200 and 1800 rotations per minute. Due to the large mechanical load to which they are subjected, high-speed shafts are highly susceptible to failure  . They must therefore be designed for both energy efficiency and mechanical resilience.
5). Generator (as one of the Wind Turbine Drivetrain Components)
Generators used in wind turbines include the permanent magnet (PM), high temperature-superconducting (HTS), switched reluctance (SR) and doubly-fed induction generator (DFIG). Among these, the induction generator is most common, due to its simplicity and reliability compared to other types.
The generator in a wind turbine works by converting rotary mechanical energy of the high-speed shaft, to electricity through the principle of electromagnetic induction.
By enabling the turbine to achieve electricity generation, this component completes the drivetrain working process. It also usually occurs last in the drivetrain configuration of wind turbines.
Wind turbine drivetrain components are;
1. Low-Speed Shaft
2. High-Speed Shaft
1). Gitano-Briggs, H. (2012). "Low Speed Wind Turbine Design." Advances in Wind Power. Available at: https://doi.org/10.5772/53141. (Accessed 15 March 2023).
2). He, G.; Ding, K.; Li, W.; Jiao, X. (2016). "A novel order tracking method for wind turbine planetary gearbox vibration analysis based on discrete spectrum correction technique." Renewable Energy 87:364-375. Available at: https://doi.org/10.1016/j.renene.2015.10.036. (Accessed 15 March 2023).
3). Li, H. (2018). "Gearbox of Wind Turbine." In: Hu, W. (eds) Advanced Wind Turbine Technology. Springer, Cham. Available at: https://doi.org/10.1007/978-3-319-78166-2_3. (Accessed 15 March 2023).
4). Saidi, L.; Ali, J. B.; Bechhoefer, E.; Benbouzid, M. (2017). "Wind turbine high-speed shaft bearings health prognosis through a spectral Kurtosis-derived indices and SVR." Applied Acoustics 120:1-8. Available at: https://doi.org/10.1016/j.apacoust.2017.01.005. (Accessed 15 March 2023).
5). Teng, W.; Wang, F.; Zhang, K.; Liu, Y.; Ding, X. (2014). "Pitting Fault Detection of a Wind Turbine Gearbox Using Empirical Mode Decomposition." Strojniski Vestnik 60(1):12-20. Available at: https://doi.org/10.5545/sv-jme.2013.1295. (Accessed 15 March 2023).
6). Wasilczuk, M.; Gawarkiewicz, R.; Bastian, B. (2018). "Analysis of Failures of High Speed Shaft Bearing System in a Wind Turbine." IOP Conference Series Materials Science and Engineering 295(1):012023. Available at: https://doi.org/10.1088/1757-899X/295/1/012023. (Accessed 15 March 2023).