lidar observation of surface wind profiles in changhua...
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Lidar observation of surface wind profiles in Changhua Coastal
Industrial Park
蔡原祥, 林博雄, 楊雅兆, 陳景林 2015.9.16
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Outline of contents Introduction Site descriptions Principle of wind Lidar Observation results Conclusions
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Aim of this study • To observe seasonal variations • Characteristics of wind profiles - wind
speed and turbulence intensity, directional difference, and inclination
• Micro-meteorology • Engineering and wind energy application
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• Changhua Coastal Industrial Park
Observation site
• Wind turbines surrounded
• Lay out of instruments
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Principle of Lidar • Windcube v2
Short range: 40-200(290) m
Observation 12 range gates simultaneously
Wave length 1543 nm
Aerosols
fo fo+2π∆f
φ
Radial velocity
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VrZ
VrW
VrE
VrS
VrN
• Lidar scanning
Velocity retrieving
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Data processing
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• Wind direction selected inconsideration the influence of the turbine wakes
• Bin averaged (day) (day)
(day)
(night)
UR=2-4, 4-6, 6-8……, 22-24 m/s
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Time series (I) • Spring, 3/24-3/31, 2014
• Summer, 6/23-6/30 • Weak wind in
summer
• Mixed with northerly and southerly wind direction
temperature
temperature
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• Autumn, 9/22-9/29
• Winter, 12/15-12/22
Time series (II)
• Strong wind and steady wind direction
temperature
temperature
• Diurnal cycle
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Profile of wind speed • Power law
• 0.02~0.28, increase with the wind speed
NE (day) SSW (day)
SE (night) NW (day)
α: power exponent
• Negative value for onshore wind
• Thermal effect for the weak wind
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Profile of turbulence intensity NE (day) SSW (day)
SE (night) NW (day)
• Turbulence intensity decreases with the increase of height
• Stabilize at night
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Profile of directional difference NE (day) SSW (day)
SE (night) NW (day)
• Significantly directional difference for the weak wind
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Profile of inclination NE (day) SSW (day)
SE (night) NW (day)
• Insignificant inclination
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Conclusions
• Significantly seasonal variations in wind speed and direction and affected by daily thermal effect
• Power law described for the rage below 120 m in all the wind conditions
• Different shape of wind profiles for the weak wind as well as sea-land breeze
• Long-term observation is required for the wind energy industry using Lidar or a mast
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Thank you for your attention!