pat moriarty: 2013 sandia national laboratoies wind plant reliability workshop

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

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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

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Underperformance and Uncertainty

Industry average bias ~ -9%

Uncertainty overestimated

Johnson, AWEA WRC 2012

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Structural Loads

Atmospheric state (stable vs. unstable)

Kelley, 2011

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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

Turbine Farm Array Mesoscale

Tools:

Scale:

WRF OpenFOAM FAST

SOWFA

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7

Results – Power

Reasonable agreement with field data

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Results – Structural Loads

Row D

No field data

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• 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

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SCADA Data Analysis

Gaumond et al. (2011)

Data is often highly averaged - physics are lost and model validation is suspect

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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

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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

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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

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Controls Research

• Reacts to existing flow

• Greedy turbines

• Modify complex flow between turbines

• Good neighbors

Turbine Control Plant Control

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Wind Plant Control

• Heat and flux

• Wake steering – yaw, tilt, turbine motion

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Power

Best case: Yaw: 4.6% Tilt: 7.1% Pos: 41%

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Structural Loading

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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