The nacelle of the wind turbine is the external housing that contains the main mechanical components of the system. As shown in Fig. 18.7, these components include the rotor shaft and bearings, a gearbox assembly (if necessary), a lubricant filtration system, a mechanical braking system, a generator, and power electronics. The gearbox transmits power from the main shaft to a high-speed shaft, which, in turn, drives the generator. The drivetrain components and nacelle cover are mounted onto a bedplate, which in turn, is positioned on top of a yaw system that is designed to actively orient the rotor into the wind.
Although a variety of wind turbine drivetrain designs are currently in use, all utility-scale designs generally fall within three main categories . The first
concept (Fig. 18.8) involves the support of the main shaft using two bearings. The bearing nearest the rotor carries both axial and radial loads while the bearing near the gearbox carries radial loads. As a result, the main shaft transfers only torque into the gearbox. Because the gearbox may carry reaction torque towards the bed plate, the gearbox assembly may be fitted with torque arms to transfer the reaction torque to the bedplate. The second concept (Fig. 18.9), known as a
Fig. 18.10 Drivetrain layout with all main bearings integrated in the gearbox, from 
''three-point-suspension'' design, involves the use of one axial bearing to support the main shaft near the rotor, while a radial bearing supports the opposing end of the shaft from inside the gearbox. The gearbox itself is mounted on the bed plate and is supported by two torque arms. The third category of drivetrain (Fig. 18.10) involves the use of direct integration of the gearbox into the nacelle. In this design, all loads from the rotor enter the gearbox, with all of the rotor support bearings integrated into the gearbox as well. This design can be considered advantageous for the purposes of weight reduction of the nacelle; however, incompatibilities between the gearbox and the remaining components in the nacelle can lead to early failure .
Was this article helpful?