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Transient Winds and Their Effect on Drivetrain Loads
Before We Start q This webinar will be available at
www.windpowerengineering.com & via email
q Q&A at the end of the presenta:on
q Hashtag for this webinar: #WindWebinar
Moderator Presenter
Nic Abraham Windpower Engineering
& Development
Doug Herr AeroTorque
• Increasing awareness of how transient aerodynamic events affect wind turbine drivetrains.
• Introducing new research data on how to control these impacts. • Growing the understanding of the speed of these events and
how current systems cannot stop them from occurring. • Understanding how an asymmetric approach to torque control
can enhance the system.
• What are the types of wind events that can damage drivetrains? • What is the current research saying about the roles of sheer
winds and turbulence? • What are the effects to the drivetrain when the turbine is
subjected to significant wind or other operaAng events?
• AeroTorque was spun out of PT Tech Inc. in March of 2013. • PT Tech has spent the last 36 years working to reduce transient
torque loads in many different types of equipment. • Both companies are under EBO Group, an 100% employee
owned company.
Our mission is to extend the usable life of the drivetrain by proacAvely working with owners and strategic partners and to build a stronger, more sustainable financial model for the wind industry fleets.
• Extreme operaAng gust (EOG) • Extreme direcAon change (EDC) • Extreme coherent gust (ECG) • Extreme coherent gust with direcAon change (ECD) • Extreme wind shear (EWS)
per IEC 61400-‐1
Shear winds have the following characterisAcs: • Are usually caused by nearby topography, o\en cliffs or
ridges • Cause the wind to flow verAcally up the face of the turbine,
rather than through the blade sweep • Can load the blades unevenly
Turbulent winds have the following characterisAcs: • Are non-‐linear winds, flowing without a pa]ern • Can be caused by surrounding roughness and structures • Can also cause a reducAon in power producAon • Will load the blades unevenly • Can even be caused by nearby turbines
Li\ing force has an opposite effect on the wind, pushing it tangenAally, causing spin in the opposite direcAon
Source: WE Handbook-‐ 2-‐ Aerodynamics. Wind Turbine Blade Aerodynamics (2009): 1-‐10. Gurit Wind Energy Handbook. Gurit Holding AG, 14 Dec. 2009. Web. 1 Oct. 2014.
“Horn’s Rev” turbulence
Photo: Va)enfall/Christian Steiness
Texas Tech and NREL research with dual-‐doppler systems show the downwind effect at 80 meters
Schroeder, John. Improving Wind Farm Efficiency Using Advanced Doppler Radar Technologies. Lubbock, TX: Texs Tech U, 2013. Print.
Rotor inerAa
Generator inerAa
Photo courtesy: Aaron Greco/Argonne National Laboratory
Gaining producAon at lower wind speeds can improve the operaAng profits at lower wind sites.
Significantly more wind must be deflected with larger blades
The WOPR number provides a raAo of the maximum accessible wind power the blades must withstand compared to the maximum power the turbine can extract from the wind.
WOPR = (Cut-‐out Speed ÷ Rated power speed)3
Example: Cut-‐out speed = 25mps Rated power wind speed = 15mps, WOPR number is (25 ÷ 15)3 = (1.667)3 = 4.6 The blades could produce 4.6 ;mes the power, if the generator could harness it.
Reduce cut-‐in to 12mps with larger rotor = (25/12) 3 = 9 WOPR
Nine :mes the poten:al power! Generator iner:a can momentarily cause higher loading!
To improve the economics and increase producAon, rotor sizes have moved from 89 meters to 117 meters since 2005, a growth of 31%.
89.34 92.29 90.9 93.25 95.32 98.91 105.7
111.35 117.03
0
20
40
60
80
100
120
140
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
AVER
AGE SIZE
YEAR
ROTOR DIAMETER IN METERS
A control system can only react as fast as the mechanical system that it controls. Can a control system react fast to prevent a torque reversal?
Sense the Wind speed
IniAate blade pitch
Stop pitching
How quickly can it respond to a gust or an emergency stop command?
• As turbines have and conAnue to grow in size, potenAal transient loading from wind events has increased
• Current control systems cannot react fast enough to stop damage • Asymmetric torque control miAgates sudden reverse loads, as well
as higher freqency loads • The addiAon of an asymmetric torque device in exisAng turbines is
a major step in extending the life of drive components and reducing O&M costs
Questions? Nic Abraham Windpower Engineering & Development [email protected] Twitter: @WPE_Nic
Doug Herr AeroTorque [email protected] Phone: 330.590.8105 Twitter: @AeroTorque
Thank You q This webinar will be available at
www.windpowerengineering.com & email
q Tweet with hashtag #WindWebinar
q Connect with Windpower Engineering & Development
q Discuss this on the EngineeringExchange.com