NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Introducing WISDEMTM:

An Integrated System Model of Wind 

Turbines and Plants

Katherine Dykes, Peter Graf, George Scott, Andrew Ning, Ryan King, Yi 

Guo, Taylor Parsons, Rick Damiani, Fort Felker, and Paul Veers

National Renewable Energy Laboratory/National Wind Technology 

Center

January 14, 2015

Third Wind Energy Systems Engineering Workshop, Boulder, Colorado

PR-5000-63564
2

Outline

• Wind energy systems engineering 

program and software by the National 

Renewable Energy Laboratory (NREL) 

o Integrated wind turbine and plant 

modeling

o Software platform

o Summary and future work.
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Integrated Wind Turbine and Plant 

Modeling
4

Wind Energy System Cost of Energy

Often use simplified cost of energy (COE) representation 

as a global system objective:

CCCCCC =

FF ∗ CCCCCCCCCC +

Where COE is the cost of energy, 

F is the financing rate to 

annualize investment costs, 

CAPEX is the sum of all capital 

expenditures, OPEX are the 

annual operating expenses, and 

AEP is the net annual energy 

production.

Graphic by Al Hicks, NREL
5

• The NREL cost and scaling 

model uses parameterized 

functional relationships 

calibrated to historical trends

o Originated with detailed design 

studies in early 2000s 

(WindPACT)

o Abstraction to simple parametric 

relationships

o Useful for two primary types of 

analyses on system costs:

– Changing input factor prices 

over time 

– Scaling of conventional 

technology within a limited 

range.

o Publicly available model.

Structure of NREL cost and scaling model

Determining Wind Cost of Energy

Fingersh, L.; Hand, M.; Laxson, A. (2006). Wind Turbine Design Cost and Scaling Model. 43 pp.; NREL Report No. TP-500-40566.
6

NREL Wind Energy Systems Engineering

• The key focus of a wind energy systems 

engineering effort includes:

o Integrating wind plant engineering performance and cost software 

modeling to enable full system analysis

o Applying a variety of advanced analysis methods in 

multidisciplinary design analysis and optimization (MDAO) and 

related fields

o Developing a common platform and toolset to promote 

collaborative research and analysis among national laboratories, 

industry, and academia.
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Software Platform
8

Systems Engineering Software Framework
9

Systems Engineering Software Framework

OpenMDAO: 

• Work flows integrate models together in 

structured ways (use of National 

Aeronautics and Space Administration’s 

[NASA]’s OpenMDAO software)

• Easily reconfigured (model selection and 

analysis structure).

FUSED-Wind: 

• Developed in collaboration with the 

Danish Technical University Wind 

Energy Department

• Support software for structured 

interface of wind turbine and plant 

modeling tools into OpenMDAO

• Allows interchange of models, and 

sharing of common turbine and 

plant input descriptions.

NREL WISDEMTM: 

• Collection of NREL engineering and 

cost turbine and plant analysis tools 

integrated into FUSED-Wind and 

OpenMDAO

• Full wind turbine and plant model set 

planned for release.
10

RotorSE (with CCBlade, PreComp, and pBEAM)

AIRFOIL

• Radial location, chord, twist

• Profile shape

• Lift curves and drag polars 

(parameterized by Re and t/c)

• Web locations

ATMOSPHERE

• Density

• Viscosity

• Shear exponent

• Wind speed distribution

LAMINATE STACK

• Sequence of lamina

• Number of plies

• Ply thickness

• Ply orientation

• Ply material

TURBINE INPUTS

• Hub height

• Cut-in and cut-out speed

• Min/max rotation speed

• Rated power

• Machine type 

(Fixed/variable speed/pitch)

• Drivetrain efficiency

ROTOR INPUTS

• Number of blades

• Precone, tilt ROTOR STRUCTURE AND 

PERFORMANCE

• Blade mass and moments of 

inertia

• Cost

• Power curve

• Turbine AEP

• Hub loads

• Sound power level

• Natural frequencies

• Blade displacements

• Panel buckling loads

• Axial and shear stress

<<< INPUTS 

OUTPUTS >>>

• Rotor model 

includes 

submodels for 

aerodynamics 

and structure 

• Either aero or 

structural 

models can 

be tied to 

optimizer (or 

both 

together).
11

Turbine Assembly and Turbine_CostsSE

• Model integrates components and passes loads from the rotor to the drivetrain to the tower

• System-level optimization of turbine possible for a number of different configurations

• Costs calculated based on component mass-to-cost relationships.

•Rotor speed

•Max thrust

•Torque

•Moment

•Mass/modal 

properties

•RNA forces and moments

•RNA mass/modal 

properties

Turbine model

COMPONENT COSTS 

AND PROPERTIES:

• Mass

• Cost

• Natural 

frequencies

• Deflection

• Critical buckling 

load

• Axial stress

TURBINE CAPITAL 

COSTS AND 

PROPERTIES:

• Mass

• Cost

TURBINE MODEL 

INPUT DESIGN 

PARAMETERS:

• Wind, water, and 

soil statistics

• Rotor diameter

• Rotor airfoil class

• Rotor geometry

• Drivetrain 

gearbox/generator 

configuration

• Machine rating

• Hub height

• Tower geometry

<<< INPUTS OUTPUTS >>>

Drivetrain CST

LSS

• Length

• Outer Diameter

• Inner Diameter

• Weight

Bearing Positions

Main bearings

• Weight

• Housing Weight

Gearbox Configuration

• Gear Number

• Gear Type(s)

• Overall Stage Ratio

Gearbox

• Weight

• Stage Weights

• Stage Ratios

HSS & 

Coupling

• Brake 

Weight

• HSS 

Weight

Generator Rating

Generator

• Weight

Bedplate

• Length

• Area

• Weight

Yaw

• Weight

ROTOR Outputs

• Diameter

• Mass

• Max Thrust

• Speed at Rated

• Torque at Rated

<<< INPUTS 

OUTPUTS >>>

Drivetrain Configuration

Tower Outputs

• Top Diameter

Rotor cost and sizing 

tool (CST) Rotor TEAM

<<< INPUTS 

ROTOR INPUT DESIGN 

VARIABLES:

• Geometry

• Lamina

• Airfoils

OBJECTIVE:

• For example, Mass 

minimization, cost 

minimization

CONSTRAINTS:

• Based on sets of 

Climate Conditions 

for specific load 

cases

• For example, 

ultimate strength, 

buckling strength

OUTPUTS >>>

ROTOR STRUCTURE & 

PERFORMANCE

• Blade mass and 

moments of inertia

• Cost

• Power curve

• Turbine AEP

• Hub loads

• Sound power level

• Natural frequencies

• Blade 

displacements

• Panel buckling 

loads

• Axial and shear 

stress

AIRFOIL

• Radial location, chord, twist

• Profile shape

• Lift curves and drag polars

(Parameterized by Re and t/c)

• Web locations

ATMOSPHERE

• Density

• Viscosity

• Shear exponent

• Wind speed distribution LAMINATE STACK

• Sequence of lamina

• Number of plies

• Ply thickness

• Ply orientation

• Ply material

TURBINE INPUTS

• Hub Height

• Cut-in and cut-out speed

• Min/max rotation speed

• Rated power

• Machine type 

(Fixed/Variable Speed/Pitch)

• Drivetrain Efficiency

ROTOR INPUTS

• Number of blades

• Precone, tilt ROTOR STRUCTURE & 

PERFORMANCE

• Blade mass and moments of 

inertia

• Cost

• Power curve

• (AEP)

• Hub loads

• Sound power level

• Natural frequencies

• Blade displacements

• Panel buckling loads

• Axial and shear stress

<<< INPUTS 

OUTPUTS >>>

Tower/monopile CST

Tower/Monopile TEAM

<<< INPUTS 

TOWER/MONOPILE 

INPUT DESIGN 

VARIABLES:

• Geometry

OBJECTIVE:

• For example, Mass 

minimization, cost 

minimization

CONSTRAINTS:

• Based on sets of 

Climate Conditions, 

Rotor / Drivetrain

Outputs (one for each 

relevant load case)

• For example, 

maximum 

displacement, 

allowable frequency 

range

TOWER

• Mass

• Cost

TRANSITION

• Mass

• Cost

OUTPUTS >>>

INTEGRATED TOWER/ 

MONOPILE

• Mass (optimized)

• Cost (optimized)

• natural frequencies

• Deflection

• critical buckling 

load

• axial stress

PILE

• Mass

• Cost

TOWER

• Mass

• Cost

SOIL

• Shear Modulus

• Depth of Soil

• Poisson’s Ratio

WATER & CURRENT

• Depth

• Current Speed & Direction

• Density & Viscosity

WAVE

• Significant Wave Height

• Period

Pile 

Embedment

PILE

• Mass

• Cost

Mean Water Line

Seafloor

Water Depth

Hub Height

TRANSITION

• Mass

• Cost

ROTOR & DRIVETRAIN 

CST OUTPUTS

• Mass Properties

• Moments of Inertia

• Forces & Moments

<<< INPUTS 

OUTPUTS >>>

TOWER, TRANSITION & 

PILE INPUTS

• Geometry: Thickness 

& Diameter by Height

• Positions: Hub, 

Freeboard, Pile

• Material: Elasticity & 

Shear Moduli, Density

INTEGRATED TOWER 

& MONOPILE

• Mass

• Natural 

frequencies

• Displacements

• Von mises stress

• Shell buckling

• Cost

WIND

• Speed & Direction

• Density & Viscosity

Freeboard

Rotor nacelle 

assembly (RNA)
12

Plant_EnergySE (With openWind)

• Basic energy production model based on wind resource statistics and loss inputs

• Wrapper for AWS Truepower openWind allows for flow model with wake effects

o Updated wrapper for current openWind Enterprise version to be released in 2014.

Annual energy production model

ENERGY 

PRODUCTION:

• AEP

• Plant capacity 

factor

ROTOR MODEL 

INPUT DESIGN 

PARAMETERS 

• Wind statistics

• Rotor diameter

• Rotor airfoil class

• Rotor geometry

• Drivetrain gearbox 

/generator 

configuration

• Machine rating

• Hub height

• Drivetrain 

efficiency

<<< INPUTS OUTPUTS >>>

Energy production model

•Power curve

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

0

200

400

600

800

1000

1200

1400

1600

1800

0.0 5.0 10.0 15.0 20.0

Wind Speed Distribution [%]

Power Rating [kW]

Wind Speed [m/s]

Turbine Power Curve and Site Hub Height Wind Speed Annual PDF

Turbine Power Curve Site Hub Height Wind Speed Annual PDF

x Availability

 x Plant losses

Rotor CST

Rotor TEAM

<<< INPUTS 

ROTOR INPUT DESIGN 

VARIABLES:

• Geometry

• Lamina

• Airfoils

OBJECTIVE:

• For example, Mass 

minimization, cost 

minimization

CONSTRAINTS:

• Based on sets of 

Climate Conditions 

for specific load 

cases

• For example, 

ultimate strength, 

buckling strength

OUTPUTS >>>

ROTOR STRUCTURE & 

PERFORMANCE

• Blade mass and 

moments of inertia

• Cost

• Power curve

• Turbine AEP

• Hub loads

• Sound power level

• Natural frequencies

• Blade 

displacements

• Panel buckling 

loads

• Axial and shear 

stress

AIRFOIL

• Radial location, chord, twist

• Profile shape

• Lift curves and drag polars

(Parameterized by Re and t/c)

• Web locations

ATMOSPHERE

• Density

• Viscosity

• Shear exponent

• Wind speed distribution LAMINATE STACK

• Sequence of lamina

• Number of plies

• Ply thickness

• Ply orientation

• Ply material

TURBINE INPUTS

• Hub Height

• Cut-in and cut-out speed

• Min/max rotation speed

• Rated power

• Machine type 

(Fixed/Variable Speed/Pitch)

• Drivetrain Efficiency

ROTOR INPUTS

• Number of blades

• Precone, tilt ROTOR STRUCTURE & 

PERFORMANCE

• Blade mass and moments of 

inertia

• Cost

• Power curve

• (AEP)

• Hub loads

• Sound power level

• Natural frequencies

• Blade displacements

• Panel buckling loads

• Axial and shear stress

<<< INPUTS 

OUTPUTS >>>

O&M model

•Availability
13

Rotor aero Rotor

structure

Nacelle

structure

Tower and 

support 

structure

Turbine 

costs

Plant 

balance of 

station 

(BOS)

Plant OPEX Plant

energy 

production

Plant 

finance

NREL cost and sizing models (CSM) NREL CSM NREL CSM NREL CSM NREL CSM NREL CSM

RotorSE RotorSE NacelleSE 

(with 

DriveSE 

option)

TowerSE/ 

JacketSE

Turbine_ 

CostsSE

NREL 

onshore/

offshore 

BOS

NREL

OPEX/

ECN 

Offshore 

O&M 

model

AWS 

Truepower 

openWind

NREL

System 

Advisor 

Model 

(SAM)

Systems Engineering Software Framework

• Integration of models into FUSED-Wind-based 

WISDEM (http://nwtc.nrel.gov/WISDEM) includes 

several areas:

1. Turbine component structure and cost models

2. Plant energy production and cost models

• For each area, multiple levels of fidelity are 

possible.
14

Ongoing/Future WISDEM Model Development

• Planned model fidelity build-out over time with 

coordinated efforts through FUSED-Wind activities

• Current model development

o Updated turbine cost models

o Support structure design

– Floating platform design

o Plant energy production

– FLORIS_SE

– WindSE

o Plant costs

– NREL BOS models

– NREL OPEX models

o Plant finance

– SAM wrapper.
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Summary and Future Work
16

• WISDEM is a toolset for modeling integrated wind plant 

systems for performance and cost that has the ability to select 

different model fidelities for different parts of a system

• WISDEM provides a collaborative platform via FUSED-Wind so 

that models can be mixed and matched among users for many 

different applications

• The first version includes a relatively simple model set to span 

the full system. Additional models of higher levels of fidelity 

will be included over time (or can be contributed from the 

larger wind model development community).

Summary
17

Discussion/Q&A

http://www.nrel.gov/wind/systems_engineering

http://nwtc.nrel.gov/WISDEM

Contact: systems.engineering@nrel.gov
18

Acknowledgments

This work was supported by the U.S. 

Department of Energy under Contract No. DEAC36-08GO28308 with the National Renewable 

Energy Laboratory. Funding for the work was 

provided by the DOE Office of Energy Efficiency 

and Renewable Energy, Wind and Water Power 

Technologies Office.