Post on 28-Nov-2014
description
Ice throw studies
Gütsch and St. Brais February 8, 2012
René Cattin
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Icing in wind energy
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Icing in Switzerland
Wind map of Switzerland
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Icing in Switzerland
Icing map of Switzerland
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Gütsch
2‘300 m asl
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Gütsch
Enercon E-40
Enercon E-44
Enercon E-44
Does ice throw occur? - How often? - How far? - How heavy? - Where?
Ca. 7 days/year meteorological icing Ca. 30 days/year instrumental icing Ca. 150 days/year temperature below 0°C Wind turbines equipped with blade heating
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Alpine Test Site Gütsch COST Action 727: Atmospheric Icing on Structures 2005 to 2009
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Method
After each icing event, the area around the wind turbine is inspected for ice throw. All found ice fragments are recorded - Distance - Angle - Size - Weight - Type of ice (rime, glaze, wet snow) - Photo of ice fragment
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Method
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Method
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Methodik
• Not all events could be captured
• Inspection partly delayed
• Exact time of ice throw unknown
• No distinction between ice throw and ice fall
Inspections during 4 winters (2005 bis 2009) à 32 icing events recorded à 228 ice fragments documented à Also during summer
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Ice throw study Gütsch
Maximum distance: 92m (2.25 rotor diameter) Maximum weight: 1.8 kg
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Ice throw study Gütsch
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Ice throw study Gütsch
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Ice throw study Gütsch
Föhn
à Risky areas seem to be dependant on wind statistics under icing consitions
Icing
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Ice throw study Gütsch
Types of ice
Rime Glaze Wet snow
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Ice throw study Gütsch
Distance to wind turbine
50%
Rotor blade
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Ice throw study Gütsch
Angle relative to wind turbine
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Ice throw study Gütsch
Resultate
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Conclusions
• Ice throw occurs
• Wind conditions during icing event define risk areas
• Ice throw when blade is moving downwards?
• 50% of ice fragments found under rotor blade
• Heavy ice fragments (> 600 g) under rotor blade
• Ice throw also during summer time
à Übertragbarkeit der Resultate auf grössere WEA??
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Counter measures
• Routing of winter walkway was changes
• Warning signs were installed
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Conclusions
Further study during winter 2011/12
2 Enercon E-82 Hub height 78 m Enercon blade heating
St. Brais 1‘100 m asl
No real icing events so far
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Ice throw model SWIM
• Simple Wind turbine Icethrow Model
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Ice throw model SWIM
• Simple Wind turbine Icethrow Model
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Ice throw model SWIM
• Simple Wind turbine Icethrow Model
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Thank you…
METEOTEST Fabrikstrasse 14 CH-3012 Bern www.meteotest.ch
…for your attention