Wind based power

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Engineering can be used to turn the generators by the energy from wind in a suitable location to produce electric power.

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Wind based power

  1. 1. Wind Power Wind resources: assessment, monitoring, site selection Energy conversion: wind turbine, gear, generator, control Tower: support at 50 m height with a strong structure.
  2. 2. Electric Power from wind Let the wind turn the turbine and generator, and produce electricity! 1. Wind resources: assessment, monitoring, site selection 2. Energy conversion: wind turbine, gear, generator, control, storage 3. Tower: support at 50 m height with a strong structure. 2
  3. 3. basic questions ?  Is there enough wind ?  Are tall wind towers allowed in your area?  Do you have enough space?  How much electricity do you need or want to produce?  Do you want to connect to the utility grid or be grid-independent?  Can you afford a wind energy system? 3
  4. 4. basic questions …  What does it take to install and maintain a system? Is there enough wind where you install it?  How much electricity do you need or want to produce? 4
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  6. 6. Wind resources  Apart from having a good wind turbine, the most critical aspects for the success of investment in the wind energy sector are  having a good site and  an accurate assessment of the wind resource at the site. Wind Resource Monitoring consists of following activities:  Siting  Wind Monitoring  Wind Resource Mapping 6
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  13. 13. Wind energy basics Kinetic > Mechanical > Electric Wind is created by the unequal heating of the Earth’s surface by the sun. Wind turbines convert the kinetic energy in wind into mechanical power that runs a generator to produce clean electricity. 13
  14. 14. How Do Wind Turbines Work?  Today’s turbines are versatile modular sources of electricity.  Their blades are aerodynamically designed to capture the maximum energy from the wind. The wind turns the blades, which spin a shaft connected to a generator 14
  15. 15. Most turbines today are horizontal axis upwind machines with two or three blades, made of a composite material like fiberglass. The amount of power a turbine will produce depends primarily on the diameter of its rotor. The diameter of the rotor defines its “swept area,” or the quantity of wind intercepted by the turbine. The turbine’s frame is the structure onto which the rotor, generator, and tail are attached. The tail keeps the turbine facing into the wind. 15
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  18. 18. For Pumping Water  One- to 10-kW turbines can be used in applications such as pumping water.  Wind-electric pumping systems can be placed where the wind resource is the best and connected to the pump motor with an electric cable. 18
  19. 19. The formula for calculating the power from a wind turbine is: 19
  20. 20. Operating Characteristics All wind machines share certain operating characteristics, such as cut-in, rated and cut- out wind speeds.  Cut-in Speed Cut-in speed is the minimum wind speed at which the wind turbine will generate usable power. This wind speed is typically between 7 and 10 mph.  Rated Speed The rated speed is the minimum wind speed at which the wind turbine will generate its designated rated power. For example, a "10 kilowatt" wind turbine may not generate 10 kilowatts until wind speeds reach 25 mph. Rated speed for most machines is in the range of 25 to 35 mph. 20
  21. 21. Rated Speed…  At wind speeds between cut-in and rated, the power output from a wind turbine increases as the wind increases. The output of most machines levels off above the rated speed. Most manufacturers provide graphs, called "power curves," showing how their wind turbine output varies with wind speed. 21
  22. 22. Cut-out Speed  At very high wind speeds, typically between 45 and 80 mph, most wind turbines cease power generation and shut down. The wind speed at which shut down occurs is called the cut-out speed. Having a cut-out speed is a safety feature which protects the wind turbine from damage. Shut down may occur in one of several ways. In some machines an automatic brake is activated by a wind speed sensor. 22
  23. 23. Cut out speed…  Some machines twist or "pitch" the blades to spill the wind. Still others use "spoilers," drag flaps mounted on the blades or the hub which are automatically activated by high rotor rpm's, or mechanically activated by a spring loaded device which turns the machine sideways to the wind stream. Normal wind turbine operation usually resumes when the wind drops back to a safe level. 23
  24. 24. Tip Speed Ratio  The tip-speed is the ratio of the rotational speed of the blade to the wind speed. The larger this ratio, the faster the rotation of the wind turbine rotor at a given wind speed. Electricity generation requires high rotational speeds. Lift-type wind turbines have maximum tip-speed ratios of around 10 24
  25. 25. Number of blades  The number of rotor blades and the total area they cover affect wind turbine performance. For a lift- type rotor to function effectively, the wind must flow smoothly over the blades.  To avoid turbulence, spacing between blades should be great enough so that one blade will not encounter the disturbed, weaker air flow caused by the blade which passed before it.  It is because of this requirement that most wind turbines have only two or three blades on their rotors 25
  26. 26. Transmission  The number of revolutions per minute (rpm) of a wind turbine rotor can range between 40 rpm and 400 rpm, depending on the model and the wind speed.  Generators typically require rpm's of 1,200 to 1,800. As a result, most wind turbines require a gear-box transmission to increase the rotation of the generator to the speeds necessary for efficient electricity production. 26
  27. 27. Generators  The generator is what converts the turning motion of a wind turbine's blades into electricity. Inside this component, coils of wire are rotated in a magnetic field to produce electricity. Different generator designs produce either alternating current (AC) or direct current (DC), and they are available in a large range of output power ratings.  The generator's rating, or size, is dependent on the length of the wind turbine's blades because more energy is captured by longer blades. 27
  28. 28. Generators… It is important to select the right type of generator to match your intended use. • Most home and office appliances operate on 120 volt (or 240 volt), 60 / 50 cycle AC. • Some appliances can operate on either AC or DC, such as light bulbs and resistance heaters, and many others can be adapted to run on DC. • Storage systems using batteries store DC and usually are configured at voltages of between 12 volts and 120 volts. 28
  29. 29. Generators….. • Generators that produce AC are generally equipped with features to produce the correct voltage (120 or 240 V) and • constant frequency (60 / 50 cycles) of electricity, even when the wind speed is fluctuating. 29
  30. 30. Towers  Tower on which a wind turbine is mounted is not just a support structure. It also raises the wind turbine so that its blades safely clear the ground and so it can reach the stronger winds at higher elevations.  Maximum tower height is optional in most cases, except where zoning restrictions apply. The decision of what height tower to use will be based on the cost of taller towers versus the value of the increase in energy production resulting from their use. 30
  31. 31. The tower must be strong enough to support the wind turbine and to sustain vibration, wind loading and the overall weather elements for the lifetime of the wind turbine. Tower costs will vary widely as a function of design and height. 31
  32. 32. Towers….  Studies have shown that the added cost of increasing tower height is often justified by the added power generated from the stronger winds.  Larger wind turbines are usually mounted on towers ranging from 40 to 70 meters tall. 32

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