Analytical Formulation for Sizing and Estimating the Dimensions and Weight of Wind Turbine Hub and Drivetrain Components

Abstract

This report summarizes the theory, verification, and validation of a new sizing tool for wind turbine drivetrain com ponents, the Drivetrain Systems Engineering (DriveSE) tool. DriveSE calculates the dimensions and mass properties of the hub, main shaft, main bearing(s), gearbox, bedplate, transformer if up-tower, and yaw system. The level of fi delity for each component varies depending on whether semiempirical parametric or physics-based models are used. The physics-based models have internal iteration schemes based on system constraints and design criteria. Every model is validated against available industry data or finite-element analysis. The verification and validation results show that the models reasonably capture primary drivers for the sizing and design of major drivetrain components. iii This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications-continued from previous page Nomenclature Meaning GB Gearbox gbx Gearbox gc Gear coupling GE Generator gen Generator hb Hub hs High-speed shaft/coupling mb1, mb2 Upwind and downwind main bearing for four-point suspension mb Main bearing for three-point suspension ms Main shaft ms, i Inner main shaft norm Normal stress range p Planet r Rotor ra Radial rb Rotor-main bearing RNA Rotor-nacelle assembly s Sun rg Ring t Transformer T F Transformer TW Tower Superscript Meaning x, y, z Coordinates de, mean, ult, max Load type (deterministic, mean, ultimate, maximum) st stochastic vi This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications

A systems engineering analysis of three‐point and four‐point wind turbine drivetrain configurations

“…The system outputs are the cumulative weight, moment of inertia and center of gravity of the entire hub and nacelle assemblies, which are used as inputs at the tower design level as well as inputs to plant cost models where those system attributes impact installation costs. The individual drivetrain component models in WISDEM were compared with known component specifications as well as higher‐order finite element analysis . Results from different models agree reasonably well.…”

“…Drive Systems Engineering consists of a series of interacting mathematical models of drivetrain subcomponents as shown in Figure and described in detail in the DriveSE theory manual . At this time, DriveSE contains physical loads‐based models for the low‐speed shaft, main bearings, gearbox, bedplate and yaw system.…”

“…Other general assumptions include homogeneously distributed component masses for calculating moments of inertia and center of mass (CM). For more information on the DriveSE model formulation, validation and other documentation, refer to the DriveSE model report .…”

“…Because the WISDEM drivetrain module, DriveSE, sizes drivetrain components using rotor loading from an upstream model, model outputs such as component geometry, mass and cost properties can be more closely linked to rotor loads of a given blade design and even site selection (e.g. a land‐based or offshore location) . This integrated analysis aids in evaluating design choices such as main bearing configurations that may strongly affect overall turbine capital costs.…”

Integrated design of downwind land‐based wind turbines using analytic gradients

“…A new drivetrain model was developed to replace the former scaling model. 24 Some of the simpler drivetrain components used updated scaling relationships (bearings, yaw system and generator), while others used bottom-up physics models (bedplate, gearbox and low-speed shaft). For the purposes of facilitating gradient-based optimization in this study, each of the models was modified slightly in order to produce output that was continuously differentiable.…”