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CDR 4914

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					Grid Connected Wind
   Turbine System
         Group 10

       Wade Overturf
      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


Advantages :                      Disadvantages :
• 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



Advantages :                             Disadvantages :
• 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
                             reducing your power bill.
             Blade Design
               Materials
Material     Advantages         Disadvantages

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
                Blade Design
                  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
                    Blade Design
                   Number of Blades
Number of Blades    Advantages               Disadvantages


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
                                             blade, more blades
                                             cause more drag
             Blade Design
            Number of Blades
   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.
                  Blade Design
                      Lift



   To incorporate lift into our blades we will
    round the leading edge of the blade to create
    a low pressure on the top of the blade.

   This will help extract more power from the
    wind.
                  Blade Design
                      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.
                     Blade Design
                      Pitch Angle




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

Mechanism     Advantages   Disadvantages

Variable      Exact        Hydraulics
Electronic    control of   design is not
Pitch         RPM          cost effective
Fixed pitch   Cost         No control of
              Effective    RPM
            Blade Design
           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.
           Blade Design
       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
         Blade Design




Source:
http://www.otherpower.com/blades.html
        Blade Design




               Source:
http://www.otherpower.com/blades.html
                 Yaw Mechanism
   The Yaw mechanism is a tail
    fin on the end of the
    generator.
   This is used to turn the
    blades into the wind
    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
    than the blade radius
   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
 Readily available.
                                       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


                                                  2 .4A F use Link
                    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
      Faraday' s law :
                        
                   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
  Breadboard            RadioShack          $ 0.00
  RPM meter                eBay             $ 0.00
Wire, Capacitor,        RadioShack          $ 16.13
   Inductor



   Gearbox
  Generator
                      Work Distribution
                         Wade    Ketul    Hiten
Board Prototyping         X

RPM Circuit design        X

Blade Design                      X
Switching P.S                     X
Part Acquisition                  X

PCB Board design                           X

Magnetic Sensor                            X

Circuit Integration       X       X        X

Mechanical Blade          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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