wind turbine icing- challenges & progress

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Wind Turbine Icing- Challenges & Progress Muhammad S. Virk Institute of Industrial Technology Faculty of Engineering Science & Technology (WindCoE Project Perspective)

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PowerPoint Presentation(WindCoE Project Perspective)
Introduction
Cold regions have good resources of wind energy, but atmospheric icing is one of the major hinderence in proper utilization of these useful resources.
Wind turbine operations/performance in cold regions get effected due to accreted ice that leads to disrupted aerodynamics, increased fatigue and structural failure due to mass imbalance and damage or harm caused by the possible uncontrolled shedding of ice chunks from wind turbines.
Atmospheric icing on wind turbines mainly occurs due to collision and freezing of super cooled water droplets with the exposed surface of wind turbines. There is at present a need to develop a better understanding of atmopsheric icing physics and it’s resultant effects to improve the design and safety of wind turbines operations in cold regions.
Ice accretion on wind tubines has resulted in up to 17% loss in annual energy production (AEP) and can reduce wind turbine performance in the range of 20-50%
International Energy Agency (IEA) Annex XIX: ‘Wind energy in cold climates’, also calls for developing new methods to better predict the effects of ice accretion on energy production.
(Example of atmospheric ice accretion on wind turbines in cold regions)
[1]-Maissan, T.M., The Effects of the Black Blades on Surface Temperatures for Wind Turbines ,in W.A.T. J., Editor 2001, Université du Québec à Rimouski: Canada.
[2]- http://www.eolos.umn.edu/research.
Main effects of atmospheric ice accretion on wind turbine are:
– Disrupted blade aerodynamics.
– Human’s harm due to ice shedding.
– Instrumental measurement errors.
– Complete stop of power production.
Active anti icing and de-icing systems are installed on wind turbines to
minimize these effects.
Wind Turbine Ice Accretion Physics
Rate and shape of atmospheric ice accretion on wind turbines depends upon both geometric and atmospheric parameters, such as:
Location. Geometric dimensions. Surface material. Wind velocity. Atmospheric temperature. Droplet size (MVD). Liquid water content (LWC).
Methodologies
Extant of ice accretion can be estimated either by field measurements, lab
based experimentation or numerical methods with certain accuracy, because:
Computational fluid dynamics
Field testing
c) Enhanced Noise Propogation
Wind CoE Progress
SCADA Data Analysis-
Icing Events Assesment
velocity more than 20m/s, as well as the power
production between 600–2200 kW.
Figure shows that during three years (2013- 2015) icing events occurred 8, 9
and 11 days respectively.
Ice Accretion
Analytical Modelling
The k-factor: Background
Assumes that ice accretion on reference collector is directly correlated with ice
accretion on the blade.
The k-factor is constant and is equal to 20, meaning that wind turbine blade will
accumulate 20 times as much ice as the collector.
Represents ice accretion at 85% blade length.
Reference collector is a cylinder, 30 mm in diameter and 0.5 meter length.
Reference collector is typically mounted on the on-site met mast.
The k-factor: Inertia parameter
The main factor is the characteristic length of the object.
For cylinder, the characteristic length is the diameter, and for airfoil it is
twice the leading edge radius.
If these two are equal, their inertia parameter are equal, assuming they
are both subjected to the same icing conditions.
By extension, their collision efficiency should also be equal.
The k-factor: Assumptions
• Assumes that ice accretion on the collector and the blade can be
represented by a constant scaling factor.
• Assumes that ice accretion of the 85% of the span is representative of
the entire blade.
• Assumes that α1 = α2 = 1 for the wind turbine blade due to high true air
speed.
Case Study: Operating conditions
Air temperature (°C) –5
Icing duration (min) 30
Chord length (m) 1.2 (NACA 0012), 1 (NACA 0015)
Droplet distribution Monodisperse, Langmuir D
Case study: CFD results comparison
Airfoil
(NACA)
Droplet
distribution
Ice Detection
Remarks
Power losses due to icing on wind turbines occur not because of single reason, but through a combination of effects that may not have been thought carefully during wind park design process.
For icing on wind turbines ,’knowing something about behaviour of icing envelopes, even if there are errors around its fringes is better than not
knowing anything’.
Still Lots More To Learn…..!!!
This research work is funded by the WindCoE (Nordic Wind Energy Centre) project, funded within Interreg IVA Botnia-Atlantica, as part of European
Territorial Cooperation (ETC).