Et wind

wind energy

1. Energy Technology (2170505) B.E. 7 th Semester Chemical Engineering G.H. Patel College of Engineering & Technology, Vallabh Vidyanagar Chapter: 6 Wind Energy Prepared by: bansi v kansagra Ad-hoc lecturer in Chemical Engineering Department GCET, V.V.Nagar

2. GTU QUESTIONS 1 What are criteria for site selection for wind farm? 5 times 2 Basic components of WECS OR Working of wind energy system with main components. 5 + 4 times 3 Advantages and disadvantages of wind energy. 2 times 4 Classify WECS and explain its working. 2 times 5 Basic principle of wind energy. 1 times 6 Onsite selection of wind energy farm. 1 times

3. Why wind energy? Current scenario of wind energy.

4. POWER IN WIND Three factors determine the output from a wind energy converter: Wind speed Cross section of wind swept by rotor The overall conversion efficiency of the rotor, transmission system and generator or pump No device – can extract all of the wind’s energy Power in the wind can be computed by using the concept of kinetics.

5. POWER IN WIND Wind mill works on the principle of converting kinetic energy of the wind to mechanical energy . Kinetic energy = watts Which gives us the maximum wind available. This equation also tells us that power available is proportional to air density. It may vary 10-15 percent during the year because of P and T change. Available wind power P a = π D 2 V 3  

6. Forces on the blades and thrust on turbines There are two types of forces which are acting on the blades: Circumferential force or torque - Acting in the direction of wheel rotation T= P/( ω = π DN) 2) Axial force or thrust - Acting in the direction of the wind stream = )  

7. Wind energy conversion Middle age wind energy used as Mill grain, Lift water, Land drainage, Watering cattle Main focus now used to generate electricity WECS, aero generators, wind turbine generators, wind turbines Small producers back up can take the form of Battery storage Connection with local electricity distribution system A stand by generator

8. Wind energy conversion Small producers Export power to grid Most produce direct current or AC Large producers Most produce constant electric output They operate primary fuel savers Reducing utilities of total fuel burns Choice of generators Depends on size of local distribution grid Generating capacity An induction generators generally used where there is a significant amount of other generating capacity Synchronous generator is more complex

9. Lift and drag : the basis for wind energy conversion Two primary mechanisms for producing forces : lift and drag Lift - perpendicular to the air flow Drag – parallel to the flow Airfoil – pressure difference produces a force that begins to act on high P side and moves towards low P side of the lifting surface Stalling- lift decrease, drag increases

10. Wind energy conversion Two other mechanisms for creating lift: Magnus Effect: spinning a cylinder in air stream at a high-speed of rotation Thwaits slot: is to blow the air through narrow slots in a cylinder

11. Site Selection Considerations High annual average wind speed Availability of anemometry data Availability of wind Vt curve at the proposed site Wind structure at the proposed site Altitude of the proposed site Terrain and its aerodynamics Local ecology Distance to road and railways Nearness of site to local Centre/users Nature of ground Favourable Land Cost Other Conditions like icing problem, salt spray or blowing dust

12. Classification of wec s Two broad classification: Horizontal Axis Machines Vertical Axis Machines According to size Small scale Medium size machines Large scale Two sub classes : Single Generator Multiple Generator

13. Classification of wec s Rotational speed Constant speed Nearly constant speed Variable speed with fixed pitch blades How the utilization of output is made Battery storage Direct connection to an electromagnetic energy converter Interconnection with conventional electric utility grids

14. ADVANTAGES AND DISADVANTAGES Advantages: Renewable source Non polluting Avoid fuel provision and transport Less costly power generation Disadvantages Fluctuating in nature Needs storage capacity Noisy in operation Large areas are required

15. basic components of wind energy conversion systems (WECS)

16. basic components of wind energy conversion systems (WECS) Aero turbine – convert energy in moving air to rotary mechanical energy. They require pitch control and yaw control Gearing and Coupling – transmits the rotary mechanical energy into electrical generator Controller – sense the wind speed, wind direction shafts speeds and torque at one or more points The physical embodiment for such an aero generator is shown in generalized form in fig.

17. basic components of wind energy conversion systems (WECS)

18. basic components of wind energy conversion systems (WECS) Sub components of the windmill are: Wind turbines or rotor Wind mill head Transmission and control Supporting structure

19. basic components of wind energy conversion systems (WECS) Rotors are mainly of two types: Horizontal axis rotor Vertical axis rotor One advantage of vertical axis machines is that they operate in all wind directions The portion of the wind turbine that collects energy from the wind is called the rotor.

20. basic components of wind energy conversion systems (WECS) 2) Windmill head Supports the rotor, housing the rotor bearings Also incorporated like changing the pitch of the blades for safety devices and tail vane to orient the rotor to face the wind

21. basic components of wind energy conversion systems (WECS) Transmissions: 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.

22. CONTINUE…. Some DC-type wind turbines do not use transmissions. Instead, they have a direct link between the rotor and generator. These are known as direct drive systems. Without a transmission, wind turbine complexity and maintenance requirements are reduced. But a much larger generator is required to deliver the same power output as the AC-type wind turbines.

23. basic components of wind energy conversion systems (WECS) Control: The modern large wind turbine generator requires a versatile and reliable control system to perform the following functions: Orientation of the wind in the rotor Generator output monitoring – status, data computation and storage

24. WIND ENERGY COLLECTORS Wind aero generators or wind turbines generators of WECS are generally classified as: horizontal axis type vertical axis type Single bladed multi bladed

25. REFERENCE [1] Energy Sources by G D Rai Khanna Publication New Delhi.