Tom Hodkinson, Simon Watson & Paul Rowley
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Transcript of Tom Hodkinson, Simon Watson & Paul Rowley
Analysing the Performance of a Building-Mounted Battery Charging Wind Turbine with Particular
Emphasis on the Effect of Yaw Misalignment
Tom Hodkinson, Simon Watson & Paul RowleyCentre for Renewable Energy Systems Technology, School of Electronic,
Electrical and Systems Engineering, Loughborough University, UK
Outline
• The problem – underperformance of urban wind turbines
• The experiment• The results• The conclusions
Under-performance of urban wind turbines
Possible Reasons
• High levels of ambient turbulence intensity• Rotor inertia leading to sub-optimal Cp-λ tracking• Non-horizontal flow – steady state or due to
turbulence• Increased yaw misalignment
Loughborough University Urban WT
• Marlec Rutland Wind Charger 913
• Rated at 90W for 10m/s• Battery charging (12V)• Wind speed & direction
measurements• Novel yaw sensor• Investigation of
performance in turbulent environment
Turbine and Sensors
• Yaw sensor made from an adapted wind vane
Site Meteorological Characteristics
010203040506070
0 2 4 6 8 10 12
Turb
ulen
ce In
tens
ity (%
)
Wind Speed (m/s)
Measured original anemometer data in 0.5 m/s wind speed binsMeasured boom anemometer data in 0.5 m/s wind speed bins
1st data period – 720 hours
2nd data period – 672 hours
Wind Roses Wind Speed Distribution
Turbulence Intensity
Turbine Performance
0
10
20
30
40
50
0 1 2 3 4 5 6 7 8 9
Pow
er (W
atts
)
Wind Speed (m/s)Raw measured data Average measured power in 0.5 m/s wind speed bins Power output given by [19]
Raw data points
Bin averaged
Published power curve
Large discrepancy
Yaw Misalignment
-180-150-120 -90 -60 -30 0 30 60 90 120 150 1800
1
2
3
4
Yaw Error (Degrees)
Prob
abili
ty D
ensit
y (%
)
0 to 1 m/s 1 to 2 m/s 2 to 3 m/s 3 to 4 m/s5 to 6 m/s 6 to 7 m/s > 7 m/s
Yaw Misalignment and Rate of Change of Wind Direction
Accurate tracking <10 degrees/second
Steep rise in error 10-20
degrees/second
Yaw Error and Power Output
𝑃 𝐿=1− (cos𝜃𝑦𝑎𝑤 )3
Fractional Power Loss (PL) should be approximately related to the cube of the yaw misalignment:
From the measured yaw misalignment this gives a predicted energy loss of 19% compared to the actual loss of 41%.
Conclusions
• Capacity factor was found to be 3.6%• Yaw error:
• <2m/s, large errors• 2m/s-7m/s, the SD of yaw error decreases 32˚ 24˚• >7m/s, the yaw error starts to increase again
• Yaw response:• wind direction changes <10˚/sec, av. yaw error is zero• yaw error increases rapidly for changes >10˚/sec
• Overall energy loss (c.f. power curve) found to be 41% with 19% estimated to be due to yaw error