1. Drivetrain Model Introduction
The Drivetrain Systems Engineering (DrivertainSE) module is a set of models for sizing wind turbine drivetrain components as part of the larger WISDEM design and analysis tool. Wind turbine drivetrains physically connect the rotor to the tower and serve as a load-path from one to the other. The drivetarin is also responsible for converting the aerodynamic torque of the rotor into electrical power that can be fed to the grid. Therefore, the drivetrain model interacts with the rotor and tower designs and it is important in looking at the overall design of a wind turbine to consider the coupling that exists between these three primary subsystem. DrivetrainSE provides the capability to take in the aerodynamic loads and rotor properties and to estimate the mass properties and dimensions for all major components; the overall nacelle properties can then be used in subsequent tower design and analysis or as part of a system-level optimization of the wind turbine. In addition, the resulting mass and dimension estimates can then be used to feed into a turbine capital cost model as well as a balance of station cost model that considers cost of assembly and installation of a wind turbine so that a full wind plant system level cost analysis could be performed.
DrivetrainSE uses a slightly different approach to the prior instances of DriveSE and HubSE, although some of the component sizing remains the same. Instead of analytical derivations of the forces and moments on the various elements and closed form expressions for sizing the components, we instead rely on Frame3DD to conduct the analysis and enable the use of optimization with stress constraints to ensure a valid design. This proves to be an easier long-term approach to maintain correct code.
DrivetrainSE features the following capabilities:
Upwind or downwind rotor configuration
Direct-drive and geared
Electromagnetic design of multiple generator technologies, including synchronous and induction generators.
Up-tower or down-tower electronics
Sizing of drivetrain components via structural analysis
DrivetrainSE includes sizing for the following components:
Hub
Spinner
Pitch system
Low speed shaft
Main bearing(s)
Gearbox (geared systems only)
High speed shaft (geared systems only)
Brake
Generator
Generator cooling
Power electronics
Bedplate
Nacelle platform
Nacelle cover
Yaw system
Some of these components are sized with very simple, empirical- or regression-based approximations. Others involve more detailed structural analysis, cast as utilization constraints, that are meant to be included in an optimization.