Complex Flow Research and It's Relation to Reliablity

1. 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.
Complex Flow Research and
Its Relation to Reliability
Pat Moriarty
Matt Churchfield
Sang Lee
Paul Fleming
Julie Lundquist
John Michalakes
Avi Purkayastha
Mike Sprague

2. 2
Motivation
• Development of validated simulation tools for
wind plant operation within complex flow
environment
• Complex flow affects:
o Power production
o Fatigue loads
o Both influence revenue
generated
• Current models lack
physics
Wind speed contours through the Lillgrund wind plant

3. 3
Underperformance and Uncertainty
Industry average bias ~ -9%
Uncertainty overestimated
Johnson, AWEA WRC 2012

4. 4
Structural Loads
Atmospheric state (stable vs. unstable)
Kelley, 2011

5. 5
Wind Plant Modeling Research
• Simulator fOr Wind Farm Applications (SOWFA)
• High performance computing and engineering modules
• Outcome
– Improve industry tools
– Guide experimentalists and understand physics
TurbineFarm ArrayMesoscale
Tools:
Scale:
WRF OpenFOAM FAST
SOWFA

6. 6

7. 7
Results – Power
Reasonable agreement with field data

8. 8
Results – Structural Loads
Row D
No field data

9. 9

10. 10
• SCADA data analysis
• Detailed flow measurements
o Turbine Wind and Inflow
Characterization Study (TWICS)
• Wake and inflow measurements of
2.3 MW turbine at NWTC
• Influence of complex terrain and
stability
o Crop Wind Energy Experiment
(CWEX)
• Impact of changing roughness (i.e.
corn) on wind farm performance
• Impact of wind farm on crops
• IEA Task 31: Wakebench
Complex Flow Observation Research
Figure courtesy A. Brewer
Figure courtesy J. Lundquist

11. 11
SCADA Data Analysis
Gaumond et al. (2011)
Data is often highly averaged - physics are
lost and model validation is suspect

12. 12
Complex Flow Field Campaigns
• Full scale measurements
o Higher resolution but expensive
– New instrumentation developing quickly
o Some physics only at full scale
o Smaller scale testing
o Combined observation and simulation
Banta et al. 2013

13. 13
Wake Model Validation
Higher fidelity
models often do
better, but not
always!
decreasing simulation fidelity
Simulation Type
From IEA Task 31: Sexbierum Single Wake Benchmark

14. 14
What can we do about it?
• Complex flow will continue to exist
• Improved plant layout and turbine design
using better tools and physical understanding
• Improved control systems

15. 15
Controls Research
• Reacts to existing flow
• Greedy turbines
• Modify complex flow
between turbines
• Good neighbors
Turbine Control Plant Control

16. 16
Wind Plant Control
• Heat and flux
• Wake steering – yaw, tilt, turbine motion

17. 17
Power
Best case:
Yaw: 4.6%
Tilt: 7.1%
Pos: 41%

18. 18
Structural Loading

19. 19
Conclusions
• Complex flow is complex
o Better understanding required to improve reliability
o Many flow scales interact
o Terrain and vegetation make things more complex
o Combined observation and simulation required
• Improvements possible using design and control
• Future needs
o Simulation tools now outpacing observations
o Need data for validation
– Higher fidelity flow and SCADA data
– Data mining techniques – QA/QC
– Good meteorological data on operating wind plants
– Structural loading data
o Technology transfer to industry tools