# CDR 4914

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```					Grid Connected Wind
Turbine System
Group 10

Hiten Champaneri
Ketul Champaneri
GOAL
   Wind Turbine
 Low maintenance
 Low cost

 Scalable system

kW           System             kW    Design
Cost*                   System
1           \$2,680.00                  Cost
3           \$6800.00             2    \$800.00
* Official website of ABS Alaskan.
SPECIFICATION AND REQURMENT

   Produce 4kWh per day

   120kWh per month

   \$7 per month assuming 5.6 cents charge per
kWh.
Background

   People have used wind for centuries as an energy
source for sailing ships, pumping water etc.

   Now a days, wind has become one of the
important energy source for generating electricity.

   Wind energy doesn't require any fossil-fuel for its
operation, its environmental friendly and
inexhaustible.
Interesting Fact

   In 2006, U.S. Wind Power capacity had been
increased by 27%.

   It is expected to grow an additional 26% in 2007.

   Wind energy facilities currently installed in the U.S.
will produce an estimated 31 billion kilowatt-hours
annually or enough electricity to serve 2.9 million
American homes.
Equations
   Power in wind
P = Power
ρ = air density
R = the rotor radius in meters
V= velocity of wind speed

To   calculate ρ (air density)

R=8.314 J/K, gas constant
• pressure at sea level
P=101,325 N/m^2 (Pa);
T= Temperature
Availability of Wind in Orlando

Average speed of wind in Orlando is around 9
mph
Average Temperature

Average Temperature in Orlando is 75
Degree/Fahrenheit
Calculation

   P = (0.5) x (3.14) x (1.184kg/m^3) x (1.83 m )^2 x (4.4704 m/s)^3
P= 557 Watts continuous
   Assuming our blade design is perfect.
   According to Betz limits, maximum power that can
be extracted from the wind by blades is 59.26% of
557 Watts.
   This yields: 330.1 Watts left to be converted into
electrical energy.
Design

   Types of Wind Power Generation.

   Typical Battery Wind Power Generation.

   Typical Battery-Less Wind Power Generation.

   Our Design
Typical Battery Wind Power System
1.   Wind turbine on tower
2.   Wind turbine controller
3.   Battery bank
4.   Grid-tie inverter
5.   Utility meter to track how
much energy is fed into the
electric grid

• Un-interruptible power can be   • Power losses due to chemical storage
supplied.                         of electricity.
• Batteries are rage around \$180-\$200,
so that’s really expensive.
•Battery is only good for 2-3 years.
Typical Battery-Less Wind Power System

1.   Wind turbine on tower
2.   Wind turbine controller
3.   Grid-tie inverter
4.   Utility meter to track how
much energy is fed into the
electric grid

• Power output will be more Efficient.   • There will no Backup power.
• No chemical losses involved.
• Less Investment.
Our Custom Design

1. Wind turbine on tower
2. RPM Controlled Relay
3. Utility meter to track how
much energy is fed into the
electric grid
Net metering
   We are using the benefits of net
metering to store our energy
onto the power companies grid.

   While turbine is generating
power this will slow or reverse
the power flow coming into the
house.

Bi-directional meter        The meter will subtract the
amount of power that is
produced by the generator, thus
Materials

Steel        Cheap              Weight, rusts,
requires welding
equipment
Aluminum     Light & Strong     Expensive, Fatigue
Factors & Past
failures
Fiberglass   Cheap, Strong,     Uses chemicals that
Light & Less       damages human
fatigue            nervous system,
messy
Wood         Cheap, Strong,     Variations of
easily available   material
Materials

   For the project wooden blades will be
shaped using wood working equipment.
   Wood is readily available and easy to work
with
   2 2x10x12 feet pieces of wood cost \$23.94
to make ourselves. Typical blades this size
made from fiberglass cost \$300 or more

One                 Less weight, low         Difficult to control,
frontal area, more       requires counter
revolution               balancing weight
Two                 More energy captured     Imbalance with change
than single blade        in wind direction
system, operate at
high speeds
Three               Aerodynamically          Wind Energy per blade
efficient, more energy   reduces, more weight
captured
Four and above      none                     Added expense, very
low wind energy per
cause more drag
   We have decided to use three blades,
because it captures more energy overall.
   By using wood, the design should be
somewhat light weight and will absorb small
vibrations.
   Three blades are more aerodynamically
efficient and have proven to be affective.
Lift

   To incorporate lift into our blades we will
a low pressure on the top of the blade.

   This will help extract more power from the
wind.
Drag

   Drag force is the force which acts in the
direction of the wind on the cross section of
the rotor blade pushing them back but there
is no way to design around this.
Pitch Angle

   We have selected 6 degrees of pitch angle for blade
turning at low wind speed and it will stall at about
35 to 40 mph.
Control RPM

Variable      Exact        Hydraulics
Electronic    control of   design is not
Pitch         RPM          cost effective
Fixed pitch   Cost         No control of
Effective    RPM
Tip Speed Ratio
Tip Speed Ratio (TSR) = (Speed of the Blade’s
tip)
(Wind Speed)
 For a turbine blade similar to ours the tip
speed ratio was approximately 5. We are
using this TSP to calculate the RPM of the
rotors at any given wind speed.
Revolutions per Minute
RPM = (V * TSR * 60) / (6.28 * R)
RPM = (4.02336*5*60)/(6.28*1.8288)
= 105.096
V = Velocity of Wind (m/s)
TSR = Tip speed Ratio (For our project, it is
5)
R = Radius of the rotor

Source:

Source:
Yaw Mechanism
   The Yaw mechanism is a tail
fin on the end of the
generator.
   This is used to turn the
direction, no power can be
extracted when.
   So we will bolt on a trail fin
to help point the blades in
direction of wind.
Tower Height
   Increasing height of the tower, increases
wind speed faced by the blades
   But high towers cost more and require to be
very wide from the base to face winds.
   Also the tower height needs to be greater
   For good aesthetics and design, the tower
height for the turbine is 12 feet
Tower Height
   VB = VA*(hB/hA)^(α)
   VA = the wind speed measured at height hA.
   VB = the wind speed measured at height hB.
   α = description of terrain
Generation of Electricity
   There are many ways to generate electricity from a
rotational force (Prime mover).
   Things to keep in mind when selecting what type of
generator will be needed to meet specified goals of this
project:

   The generated power needs to feed into an AC transmission line.

   The generator needs to be low maintenance to be cost effective
to save money and have a quicker return on the initial
investment of the system.

   How fast the generator needs to turn to start producing a useful
output and at what point is the power extraction most efficient.
Direct Current Generators
   DC motors can be spun by a prime mover to generate DC
power.
   The speed of the rotor is directly proportional to the
voltage it produces.
   Almost all DC motors require brushes to supply power to
the rotor. The lifetime of brushes can be rated in hours and
will increase the maintenance interval of the system.
   All DC motors have permanent magnets which loose their
magnetizing force (Hs), therefore the power output over
time would decrease.
   Overall, using a DC motor to generate power from wind is
undesirable.
AC Generators
   Two types: Synchronous and Asynchronous
   Both types produce AC voltage which is
easier to implement in a grid connection.
   Both types are used in high power/high
voltage applications.
   Both types do not require brushes
AC Generator Comparison
Asynchronous Generator               Synchronous Generator
 Frequency of the power              Frequency of the power
produced is not related to the       produced is directly
speed of the rotor.                  proportional to the speed of the
 nsync = 120fe/P                      rotor.
fe = the frequency of the power    fe= (nmP)/120
grid                                 nm = revolutions per minute of the
P = is the number of magnetic                magnetic field
poles the motor has.                 P = the number of poles the generator
has
n = the speed of the motor in
fe = electrical frequency produced
RPMs
 Very rare to find for small
applications.
 Fairly inexpensive, are very
 Expensive, typically used by the
common for use as a motor on
power company only.
washing machines, sprinkler
pumps, and air compressors
Generator of Choice
   Asynchronous Generator
   The main reason for choosing this type of AC generator is that our prime
mover (wind energy) is not a constant source. Wind fluctuates and this
system needs to produced power when it is blowing 10mph and when it is
blowing at 35mph.

   This is done by the asynchronous characteristics of the generator. The
frequency of the power produced is going to be synchronized to the grid.
(Grid locked)

   The motor design chosen was a squirrel cage induction motor due to the
cost, reliability, and availability.

   Motor Specifications:
HP        RPM          Volts     Frame   List     Full load
price    Amps
2 HP      1800         120/240   56C     \$370     21.0A
Generation Region
   The synchronous speed of the generator is set by the
number of poles the generator has and is given by the
equation:
nsync = 120fe/P
   Figure 1 from Electric Machinery Fundamentals depicts the
different operating regions of a motor/generator.
Figure 1
Synchronizing to the Grid
   Synchronization is performed by slowly introducing the
induction machine to the power already being supplied by
the power company.
   The slow introduction is required to reduce the amount of
reactive power that will flow and will cause flicker or
voltage dips that might be noticed at the neighbor’s house.
   We will be connecting to the grid only when the machine is
in the power generation region, where the speed of the
rotor is above 1800 RPM. Therefore, we can just connect
to the grid and not worry about consuming reactive power
and causing brownouts.
   By precisely determining the point at which to grid connect
we can eliminate the need for reactive power compensation
by not having to turn the generator on from a stopped
position.
Gearbox Required to Increase

RPM gearbox is needed to reach the
From the blade analysis determination a 20:1
synchronous speed of the generator in 10mph wind.
   C-Face motor is a motor that has specific mounting brackets that are needed to
bolt a   gearbox to it.

   These are 60% more expensive for the same size motor as a non C-Face motor
but is a necessity. Otherwise, we would have to weld to the case of the motor
to bolt the gearbox to the face of it and have to worry about gear clearance
issues.
Specifications on the Gearbox
    Gearbox was chosen mainly by looking
at the price tag.
    The project was scaled down to what
was affordable. This was the most
expensive part of the project.
    The gearbox has to fit the frame size of
the motor which is 56C.

RPM     Max       Motor List Rati        Weigh
at 1750 torque    Moun Price o           t
t
88       461      56C     \$323    20:1   30 lbs
ft/lbs
Circuit Design
    This circuit takes a pulse generated by a magnet fixed to the motors shaft and is fed into
the LM2917 IC (National Semiconductor), which acts as a magnetic pickup buffer that
shapes the pulse into a square wave. The square wave coming out is twice the input
frequency and its amplitude is specified by the Zener diode’s reverse biasing point on pin
3. The pulse width of the square wave can be calculated by PW = (Vcc/2) x (C1/I2),
where I2 is the current through pin2.
 This is then fed into the next LM2917 IC configured as a frequency to voltage converter.
This chip changes the input frequency into a specified output DC level calculated by:
Vout = (fin)(Vcc)(R1)(C1).
15 VD C

M agnetic Pickup Buffer C ir cuit                             F r equency to Voltage C onver ter                           R                                     H yster esis R elay
91 kΩ                                        C ontr ol

M agnetic Inductive
D evice                                                                                                                                              V d iv
10 kΩ

8        7            6   5                                      8     7            6       5                       V d iv 2
2 .46 kΩ
LM 2917                                                           LM 2917

1        2            3       4                                      1     2        3           4
Induction M otor                                                                                                                                              1kΩ
fin                                     2fo u t                     fin                                        V R EF                    -                       G ener ator on /off
LF 351
+
C
R                              C                                              300 Ω
500 uF           Dz                                                                             C      10 KΩ                                   - 15 VD C
1 nF
5V               10 KΩ                                      R              0 .47 uF
100 kΩ

80 KΩ
Circuit Design
Power and grid connection page:

M JN2 C E-AC 120 V D PD T
Pow er R elays                                         G ener ator on / off

120 Volt w all connection

Single Phase Squir r el
M JN 2C E- AC 120                                      C age Induction M otor

1 :3 Step dow n
T r ansfor m er ( 2 .4 A m a x on                             1N 4003 D iodes F or w ar d
Secondar y w inding )                                            bias at 0.8 V

120 VAC           40VAC

1N 4003    1N 4003
18 .4VD C

1 N4003   1N 4003
1mF
0. 22 uF
Electr olytic
C apacitor
C apacitor
Circuit Design
Power supply and regulation
 Switching power supply chips from Linear                    +15VD C Switch in g Po wer Su p p ly                      L1
50uH

Technologies, used to stepdown and regulate the   18. 4VD C
V in                 V SW
15 VD C

voltage from 18.4VDC to 15VDC. Any                                                   LT 1074                                              R1
2 .8K Ω

fluctuations in power could result in poor grid                               GN D                  FB

Vc

connection.                                                     C3
R2
12 .79 kΩ         C1
D1
200 uF                                                                                 500 uF
M BR 745

The input for the LT1074 can be anywhere                                                 C2
0 .01 uF

from 4.5V to 40V and can step down from there.
It can output up to 3A at 15V.
-15VD C Switch in g Po wer Su p p ly
 Since these chips can be used to output any
range of voltages you have to calculate the                                   C1
220 uF
25 uH
5A
50 V

resistor values involved in the feedback loop.
R3
12 .63 kΩ

R1
V in                  V SW                      23 . 49kΩ
C2
R 3 = (Vout -2.37 ) kΩ

To achieve the positive 15VDC (Top) supply
LT 1074                                                        1000 uF
R2                                   R1 = (1.86)R 3Ω
10 V
46 .1kΩ                                R2 = (3.65)R 3Ω
GN D                  FB

the Vout = [2.21x(R1+R2)]/R1. This yielded                                                    Vc

R1=2.8kohm and R2 = 12.79kohm.                                                         C3                     D1
C4
R4
1 .82 kΩ
0 .01 uF
0.1 uF                M BR 745

To achieve the negative 15VDC (Bottom)                                                                                                                                 -15 VD C

supply we used the equations specified on the
manufacturer's datasheet. R3 = Vout - 2.37, R2
Circuit design
   The last part of that circuit is a schmitt trigger that
will protect the relay from toggling. The lifespan
of the relays in our project are rated to be turned
on and off 150,000 times.
   The motor will connect to grid when the motor
reaches 1825 RPM’s (3.28V) and will disconnect
when the motor is turning lees than 1775 RPM
(3.18V).

Frequency to Voltage Conversion

2500
RPM of Motor

2000

1500

1000

500

0
0         1            2              3   4
Voltage
Magnetic Sensor Design
 
 n
t
  Voltage produced
n  # of turns of wire
   magnetic flux
Magnetic Sensor Calculation
Due to the air gap we assumed slightly less than half of the induced flux will be
magnetically coupled.

  B A                        B  flux Density  (1.08 T )
  8.55 *106 T m 2             A  cross sec tion area
 (7.92 *106 m 2 )

     4 *106    4 *106
                      * RPM
t   60 RPM *       60
Number of Turns Calculation
 
 n
t
                  80mV
n              
           (4 *106 )(1750) 
             
                   

 t                  60         
n  230 turns
The minimum input to the RPM circuit is 20mV. We
decided to achieve 4 times minimum input voltage.
We had to calculate the number of turns that we should
wind our magnetic sensor (Inductor). We ended up
winding ours wire about 230 times to insure that the
amplitude would be large enough to the feed the RPM
circuit.
Budget
LT1074IT7          Linear Technology      \$ 0.00
LM2917N-8         National Semiconductor   \$ 8.50
RPM meter                eBay             \$ 0.00
Inductor

Gearbox
Generator
Work Distribution
Board Prototyping         X

RPM Circuit design        X

Switching P.S                     X
Part Acquisition                  X

PCB Board design                           X

Magnetic Sensor                            X

Circuit Integration       X       X        X

Test
Tower Design and          X       X        X
Prototyping
Final Test                X       X        X
Work Done
   Research = 100%
   Mechanical part = 25%
   Electrical part = 40%
   Testing = 10%
   Overall = 35%

```
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 views: 6 posted: 8/13/2012 language: pages: 48