A review of wind turbine drivetrain loads and load effects for fixed and floating wind turbines

Drivetrain is one of the important subsystems in the wind turbine and faults and damages in the drivetrain significantly affect the wind turbine's downtime and nonavailability. Understanding the drivetrain dynamics and load effects that results in failures has been a major research area due to challenges in the drivetrain operations and maintenance. A systematic literature review of wind turbine drivetrains is presented according to key research areas of drivetrains, such as modeling and load effects on the drivetrain. Special emphasis is given for the floating wind turbine drivetrains. A review on the state-of-art modeling techniques of the drivetrain is presented. Studies concerning the aeroelastic load effects on the drivetrain components especially the gearbox and the bearings are discussed. Several key aspects such as aero-hydro-elastic interaction load effect and platform motion excitations on the floating wind turbine drivetrain dynamics are reviewed in detail. Finally, challenges related to floating wind turbine drivetrain are also discussed.