Urban micro wind turbines
Kent 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.
What is micro-wind?
Why micro-wind?
• Cheaper than other
alternatives (solar, larger
scale wind)
• Less intrusive
• Smaller rotational inertia
means faster response to
wind gusts & more power
Why Wellington?
• Lots of wind
(obviously)
• Urban
environment
• Strong gusts on
top of high average
wind speed
Warning: Statistics content
Real data (histogram) and simulated Weibull distribution
(black line) for Kelburn wind speeds 2004-2008
Available Power
Rotor swept area
A
v1
v2
Warning: Calculus content
Wellington Wind Energy Distribution
Model Weibull distribution of wind speed and available
energy for Wellington wind distribution
Continuous power extraction
Power ratio extracted
0.7
0.6
P extracted / P in
0.5
0.4
0.3
0.2
0.1
0
0
0.2
0.4
0.6
V2 / V1
0.8
1
Optimum speed ratio
Optimum speed ratio
Betz Limit
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
Darrieus VAWT
• Not self-starting
− Darrieus need a ‘push’ at start-up
• Efficiency
− Generally not as efficient as horizontal
axis turbines
Savonius VAWT
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
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.
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
Grid tied turbines
Turbine
Feedback loop
3 phase
rectifier
Wild A.C. –
variable voltage
variable frequency
D.C.–D.C.
voltage
converter
Inverter
To Grid
240 V 50 Hz
synchronous A.C.
Measurement & Control
Wind vane
Anemometer
Turbine
3 phase
rectifier
Control
Dump
load
Measurement
Measurement & Control
Teething problems
Burnout (the turbine, not me)
Data mining
Data mining
Wind Direction - Relative
Frequency
0.2
0.15
N
0.1
0.05
0
NW
NW
0.3
0.9
1.5
2.1
2.8
3.4
4.0
4.6
5.2
5.9
6.5
7.1
7.7
8.3
9.0
9.6
10.2
10.8
11.4
Relative Frequency
Wind Speed Distribution
Wind Speed (m/s)
Average & Peak Power
E
W
Power (W)
400
300
200
100
SE
SW
0
0.0
2.0
4.0
6.0
8.0
Wind Speed (m/s)
10.0
12.0
S
Data mining
Relative wind power - direction
Relative turbine power - direction
N
N
NE
NW
E
W
SE
SW
S
NE
NW
E
W
SE
SW
S
Load matching
Power
Power at varied wind speed
6 m/s
8 m/s
10 m/s
12 m/s
Voltage
Constant Voltage Load
Power at varied wind speed
Power
6 m/s
8 m/s
10 m/s
12 m/s
Constant load
Voltage
Smart Load
Power at varied wind speed
Power
6 m/s
8 m/s
10 m/s
12 m/s
Smart load
Voltage
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
Data live to web (well, liveish)
Labview measurement software
Graph images produced & saved by Java program
ABSURDLY TRICKY
csv data file saved
every 15 min
Latest saved images uploaded by website
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
• May annoy the neighbours
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
Depends on the
neighbours I guess
What I’ve gained…
Sorry, what?
The ability to ask the
important questions
Evaluating the potential of
the wind resource at the King
of Tonga’s house
Time to get my head
around stuff
Opportunities:
Working with RPNYC to
plan education centre
Played with lots
of fun toys
Time to learn new skills
Flexibility to see what goes
on in other parts of the
education sector
‘Achieved’…
What does that mean?
Experience what its like from the
other side of the fence
Huge thanks to:
James Capper & Roy Godkin
Joseph Lawrence
Chris Bumby, John Hannah, Tim Exley,
Howard Lukefahr, Alan Rennie,
Manu Pouajen-Blakiston, David Stead,
Peter ‘Pondy’ Andreae…
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
Thanks Especially to
Gill & Miki
www.kenthogan.blogspot.com