DRIVE TRAIN MECHANICAL EQUIPMENT FOR A 4 MW VERTICAL AXIS WIND TURBINE GENERATOR

Abstract

This paper describes the optimization, design philosophy and final arrangement of the mechanical drive train connecting a 4000 m2 swept area Darrieus type vertical axis wind turbine rotor to a 4 MW rated electric generator. The components covered are: (1) the pivot mechanism which caters for angular displacement of the rotor column which is secured in position by guywires. In addition it transfers the torque generated by the rotor to the shaft of the bottom support bearing assembly; (2) the bottom rotor support bearing assembly. This is located in an opening in the roof of the concrete support structure with its shaft protruding into the building enclosure. It carries the loads imposed by the rotor and its tie-down system and transmits the driving torque generated by the rotor; (3) the mechanical brake discs which are directly connected to the bottom end of the bearing Shaft. The brake modules are spring to close, air to open caliper type and are used in conjunction with generator and aerodynamic braking to bring the machine to a stop from any rotational speed within the operating range; (4) a resilient type flexible coupling which is interposed between the brake and the generator shaft to dampen torsional vibrations, particularly those produced at the air gap of the generator. It also accommodates some misalignment between the drive shaft and generator shaft.