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Urban micro wind turbinesKent Hogan
Onslow College
Fellowship goals:
1. Investigate micro wind turbines to determine the practicality of their use for domestic energy production.
2. Investigate the current uses, engineering, effects & possible future directions of micro wind turbines.
3. Learn computing skills such as Java programming and webpage design.
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What is micro-wind?
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Why micro-wind?
• Cheaper than other alternatives (solar, larger scale wind)
• Less intrusive
• Smaller rotational inertia means faster response to wind gusts & more power
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Why Wellington?
• Lots of wind (obviously)
• Urban environment
• Strong gusts on top of high average wind speed
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Warning: Statistics content
Real data (histogram) and simulated Weibull distribution (black line) for Kelburn wind speeds 2004-2008
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Available Power
Rotor swept areaA
v1 v2
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Warning: Calculus content
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Wellington Wind Energy Distribution
Model Weibull distribution of wind speed and available energy for Wellington wind distribution
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Continuous power extraction
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.2 0.4 0.6 0.8 1
Pe
xtra
cte
d /
P in
V2 / V1
Power ratio extracted
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Optimum speed ratio
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Optimum speed ratio
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Vertical Axis Wind Turbine (VAWT)
• Wind direction− No wind seeking mechanism needed
• Tower loading− Generator, etc can all be placed near the ground, placing less stress on tower
• Not self-starting− Darrieus need a ‘push’ at start-up
• Efficiency− Generally not as efficient as horizontal axis turbines
Darrieus VAWT
Savonius VAWT
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Horizontal Axis Wind Turbine (HAWT)
• Upwind / downwind rotor− Wind shadowing by tower− Wind tracking mechanism− Blade flex
• Fixed tip speed / tip speed ratio− Stresses on blades− Output frequency− Power at varying wind speeds
• Number of blades− Size of aerodynamic surface− Turbulence in rotor plane− Torque on rotor hub
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Typical uses
• Typically used off-grid to charge battery banks (yachts, isolated cabins).
• Batteries need ‘continuous’ charging, so turbines are optimised for average wind speeds.
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Batteries vs grid-tied
Battery charging:Optimised for average wind speed, low total energy
Grid tied:Free to optimise for high wind speeds to maximise total energy
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Grid tied turbines
3 phase rectifier
Turbine
Wild A.C. –variable voltage
variable frequency
D.C.–D.C. voltage
converterInverter
240 V 50 Hz synchronous A.C.
To Grid
Feedback loop
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Measurement & Control
3 phaserectifier
Dump load
MeasurementControl
AnemometerWind vane
Turbine
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Measurement & Control
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Teething problems
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Burnout (the turbine, not me)
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Data mining
0
0.05
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0.15
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0.9
1.5
2.1
2.8
3.4
4.0
4.6
5.2
5.9
6.5
7.1
7.7
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9.0
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.4
Re
lati
ve F
req
ue
ncy
Wind Speed (m/s)
Wind Speed Distribution
N
NW
E
SE
S
SW
W
NW
Wind Direction - Relative Frequency
0
100
200
300
400
0.0 2.0 4.0 6.0 8.0 10.0 12.0
Po
we
r (W
)
Wind Speed (m/s)
Average & Peak Power
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Data mining
N
NE
E
SE
S
SW
W
NW
Relative wind power - direction
N
NE
E
SE
S
SW
W
NW
Relative turbine power - direction
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Load matchingP
ow
er
Voltage
Power at varied wind speed
6 m/s
8 m/s
10 m/s
12 m/s
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Constant Voltage LoadP
ow
er
Voltage
Power at varied wind speed
6 m/s
8 m/s
10 m/s
12 m/s
Constant load
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Smart LoadP
ow
er
Voltage
Power at varied wind speed
6 m/s
8 m/s
10 m/s
12 m/s
Smart load
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Where to from here?• Second horizontal axis turbine
• Vertical axis turbine
• Smart load
• Cheaper inverter
• Immersion water heater
• Gusting hysteresis
• Data live to the web
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Data live to web (well, liveish)
csv data file saved every 15 min
Labview measurement software Graph images produced & saved by Java program
Latest saved images uploaded by website
ABSURDLY TRICKY
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Micro-wind – is it worth it?
PROS• Wind is free
• Wind is renewable
• Can harness increased power in wind gusts
• Excess power buy-back
• Wind turbines look cool
• Great conversation topic at cocktail parties
• ‘Feel-good’ / Green factor
CONS• Local council by-laws vary
• Currently downstream electronics required for grid-tying are expensive
• …this & low power produced make micro turbines economically iffy
• May annoy the neighbours
• May annoy the neighboursDepends on the
neighbours I guess
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What I’ve gained…
Evaluating the potential of the wind resource at the King
of Tonga’s house
Time to learn new skills
Opportunities:Working with RPNYC to plan education centre
Time to get my head around stuff
Played with lots of fun toys
Flexibility to see what goes on in other parts of the
education sector
Sorry, what?
The ability to ask the important questions
‘Achieved’… What does that mean?
Experience what its like from the other side of the fence
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Huge thanks to:
Chris Bumby, John Hannah, Tim Exley, Howard Lukefahr, Alan Rennie,
Manu Pouajen-Blakiston, David Stead, Peter ‘Pondy’ Andreae…
James Capper & Roy Godkin
Joseph Lawrence
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Thanks Especially to Gill & Miki
The New Zealand Science, Mathematics and Technology Teacher Fellowship Scheme is funded by the New Zealand Government
and administered by the Royal Society of New Zealand
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www.kenthogan.blogspot.com