International Journal of Research in Engineering Technology and Management
ISSN 2347 - 7539
Axial Flux Vertical Axis Wind Turbine Prof. B. N. Patil1, Vani V2, Rahul B. Badde3, Rajshekhar Kuragund4, Honnappa Y. Hanjagi5 1
Assistant Professor, Electrical and Electronics, Angadi Institute of Technology and Management, Belgaum, Karnataka, India.
[email protected] 2 Research Scholar, Electrical and Electronics, Angadi Institute of Technology and Management, Belgaum, Karnataka, India,
[email protected] 3 Research Scholar, Electrical and Electronics, Angadi Institute of Technology and Management, Belgaum, Karnataka, India,
[email protected] 2 Research Scholar, Electrical and Electronics, Angadi Institute of Technology and Management, Belgaum, Karnataka, India,
[email protected] 3 Research Scholar, Electrical and Electronics, Angadi Institute of Technology and Management, Belgaum, Karnataka, India,
[email protected]
Abstract Electrical power has become a prime necessity for any country for economic development. As power shortage is dominant problem, being faced by the most of the countries today. On the top of this conventional fuel sources for power generation i.e. coal & oil deposits are fast getting depleted. The obvious way out, is to shift focus to renewable sources of energy. Statistics reveal that a large amount of wind energy remains untapped. Although more invention has to be carried out still in the use of non-conventional energy sources for power generation to reach to most economic point, but every little effort in this direction may provide a solution to power shortage problems. Hence the same topic was selected as a part of the curriculum. The goal of the project is to construct a small scale axial flux vertical axis wind turbine similar to savonius 3 bladed type which is capable of producing electrical power even with the low wind velocity. In this design we are using 12 neodymium magnets since itβs more powerful on rotor and total of 9 coils on stator. It can be placed on the places like highway dividers or remote places like villages those are not economical for power transmission from a power plant. Earlier conventional practice was to use horizontal axis wind turbine. But to meet the suitability of this task, the vertical axis wind turbine has been employed. The power produced by the generator can be stored in a battery and can later be used to power the street lights. These wind turbines are portable and can therefore be used on any expressways or busy highways. The turbines can be used commercially for low power applications. The implementation of such project would reduce the dependence of a company or industry on electricity board.
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1. INTRODUCTION Wind energy has been used for thousands of years for milling grain, pumping water and other mechanical power applications. Wind power is not a new concept. The first accepted establishment of the use of windmills was in the tenth century in Persia. Today, there are several hundred thousand windmills in operation around the world. Modern windmills tend to be called wind turbines partly because of their functional similarity to the steam and gas turbines and partly to distinguish them from their traditional forbears .Wind energy was the fastest growing energy technology in the 1990s, in terms of percentage of yearly growth of installed capacity per technology source. The growth of wind energy, however, is not evenly distributed around the world.
Graph - 1: Installed capacity of wind energy in India upto Jan 2014
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International Journal of Research in Engineering Technology and Management
ISSN 2347 - 7539
2. WIND TURBINE
2.3 CHARACTERISTICS & SPECIFICATIONS OF WIND TURBINES
The wind energy system transforms the kinetic energy of the wind into mechanical or electrical energy that can be harnessed for practical use. Although there are many different wind turbine designs, they are broadly grouped in two categories based on the orientation of the axis of rotation: Horizontal Axis Wind Turbines, or HAWTS, the most common type of wind turbine, and Vertical Axis Wind Turbines, or VAWTS.
Wind Speed This is very important to the productivity of a windmill. The wind turbine only generates power with the wind. The wind rotates the axis (horizontal or vertical) and causes the shaft on the generator to sweep past the magnetic coils creating an electric current.
1.
2.
Horizontal axis wind turbine (HAWT): in which the axis of rotation is horizontal with respect to the ground (and roughly parallel to the wind stream.) Vertical axis wind turbine (VAWT): in which the axis of rotation is vertical with respect to the ground (and roughly perpendicular to the wind stream)
2.1 DIFFERENCE TURBINES HORIZONTAL AXIS WIND TURBINE
BETWEEN
TWO
WIND
VERTIACAL AXIS WIND TURBINE
1. In the case of horizontal axis 1. In case of vertical axis wind turbine air strikes from turbine air strikes from both one direction only. directions. 2. In horizontal axis wind 2. In the ease of vertical axis turbine generator, gearbox wind turbine the generator, cannot be placed on the ground. gearbox etc. may be placed on the ground. 3. In horizontal axis wind 3. In the case of vertical turbine tower is essential hence axis wind turbine tower is not cost of erecting is high. essential for the machine hence reducing the cost of erecting. 4. In horizontal axis wind 4. In vertical axis wind turbine turbine we need a yaw system. we don't need yaw system. 5. On horizontal axis wind turbine control system is required.
Blade Length This is important because the length of the blade is directly proportional to the swept area. Larger blades have a greater swept area and thus catch more wind with each revolution. Because of this, they may also have more torque. Base Height The height of the base affects the windmill immensely. The higher a windmill is, the more productive it will be due to the fact that as the altitude increases so does the winds speed. Base Design Some base is stronger than others. Base is important in the construction of the windmill because not only do they have to support the windmill, but they must also be subject to their own weight and the drag of the wind. If a weak tower is subject to these elements, then it will surely collapse. Therefore, the base must be identical so as to insure a fair comparison.
3. SAVONIUS WIND TURBINE Savonius is a type of VAWT, which uses a rotor that was introduced by Finnish engineer S. J. Savonius in 1922. Savonius turbines are one of the simplest turbines. Aerodynamically, they are drag-type devices, consisting of two or three blades (vertical β half cylinders). A two blades savonius wind turbine would look like an "S" letter shape in cross section.
5. There is no requirement of control system which also reduces the overall cost and frequent maintenance. Fig - 1: Schematic drawing showing the drag forces exert on two blade Savonius.
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International Journal of Research in Engineering Technology and Management
ISSN 2347 - 7539
V*60 D*π
Where V= wind speed D= diameter of rotor π= 3.142 Next is finding Tip speed ratio of the blade given as TSR = tip speed of the blade Wind speed Next is finding efficiency of the wind turbine as Fig - 2: Schematic drawing showing the drag forces exert on three blade Savonius
Efficiency = Output power X 100 Input power
3.1 SAVONIUS TURBINE CALCULATIONS
4. CALCULATION VARIOUS STAGES
Swept area (As) As the rotor turns, its blades generate an imaginary surface whose projection on a vertical plane to wind direction is called the swept area. The swept area for Savonius wind turbine can be calculated from the dimensions of the rotor. Savonius area = The swept area = As = H * D Where: H = the rotor height (m). D = the rotor diameter (m). Power from wind Next is to calculate the available power from wind The available power, Pa from the wind is Pa=1/2 πAsV3 Where Pa = available power from wind π = Air density = 1.22Kg/m3 As =Swept area of savonius rotor V = Velocity of wind Power that rotor can extract from wind Similarly, if the S-rotor generates the electricity, the power that the rotor can extract from the wind is Pw = E* I(Watt) Power coefficient (Cp) The power coefficient (Cp) is given by: πͺπ = πππ πππππππππ
πππππ ππππ πππ ππππ
/πππ πππππππππ πππππ ππ πππ ππππ
=π·π/π·π
OF
POWER
AT
The power output of a wind generator is proportional to the area swept by the rotor - i.e. double the swept area and the power output will also double. The Power of Wind Assuming some values such as speed of wind as 6 m/s Area of turbine as 0.5x1 m2 radius as 0.5 m Cp as 0.15 Kinetic Energy = 0.5 x Mass x Velocity2 Air has a known density (around 1.23 kg/m3 at sea level), Power = 0.5 x Swept Area x Air Density x Velocity 3 P=0.5 x p x A x Cp x V3 Where: P = Power in watts p= Air density (about 1.225 kg/m3 at sea level, less higher up) A = Rotor striking area, exposed to the wind (m2) Cp = Coefficient of performance V = Wind speed (m/s) Tip Speed of blade at 60 rpm (lrps) = (27r) x (1) x (radius) Radius = 0.5m Therefore tip speed of blade = 3.14 m/s Wind speed = 6 m/s. Tsr = 3.14/6= 0.52
The RPM for any wind speed or rotor diameter can be easily calculated as follows
_______________________________________________________________________________________ Volume: 02 Issue: 03 | May-2014, Available @ http://www.ijretm.com | Paper id - IJRETM-2014-02-03-421
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International Journal of Research in Engineering Technology and Management
ISSN 2347 - 7539
Table - 1: Calculation for electrical power output at various wind velocities Wind speed Km/h
Wind speed m/s
Calculated mechanical power in watt
Electrical power =0.2 x mech. power watt
0
0
0
0
5
1.385
0.089
0.0178
10
2.770
0.715
0.143
15
4.155
2.410
0.482
20
5.540
5.720
1.144
25
6.925
11.180
2.236
30
8.310
19.320
3.864
35
9.695
30.690
6.138
40
11.080
45.810
9.162
45
12.465
65.230
13.046
50
13.850
89.470
17.894
55
15.230
119.09
23.818
Fig - 2: Indicating winding procedure starting from 1A to 1B to 1C. Then From 2A to 2B to 2C and then from 3A to 3B to 3C.
Fig - 3: Complete setup of stator plate
6. ROTOR DESIGN The rotor which is fixed to shaft of the turbine consists of 12 magnets indicating 12 magnets.The magnets used are Neodymium magnets since they are more powerful. The Setup is shown in figure below
Graph - 2: Wind speed versus power
5. STATOR DESIGN The stator part in our project consist of coils. There totally 9 coils with 800 turns per coil and 3 phase winding. The gauge of copper wire used is 25 SWG. The setup of stator plate is as shown in figure below.
Fig - 4: Complete setup of rotor plate.
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International Journal of Research in Engineering Technology and Management
7. COMPLETE DESIGN SPECIFICATIONS ο¨ Blade Design Shaft Designing ο¨ While designing the shaft of blades it should be properly fitted to the blade. The shaft should be as possible as less in thickness & light in weight for the 3 blades. Shaft diameter 25mm SHAFT DIMENSIONS ο¨ Diameter - 25mm ο¨ Length - 72 inches
BLADE DIMENSIONS ο¨ Height - 30 inches ο¨ Diameter - 18 inches ο¨ Thickness - 0.125 inches ο¨ Angle b/w blades - 120 Β° STAND DIMENSIONS ο¨ Height - 36 inches ο¨ Width (Top) - 18 inches ο¨ Width(Bottom) β 24 inches
8. BATTERY CHARGING We can use either lead acid or rechargeable Ni-Cd batteries. In the case of a wind powdered system. The best way to fully charge a battery is to use a small current for a long time. Lead acid batteries should be kept in a charged condition. In the case of a wind powered system, you may have to wait for a wind to charge the battery. But be careful not to discharge the battery too deeply, or to keep it too long in a discharged state, or it will be damaged and become useless. Stop using a battery before it is fully discharged. If there is a problem with the wind generator, then charge the battery from another source within two weeks.
9. ADVANTAGES & DISADVATGES OF VAWT Advantages of VAWT system: 1) Easier to maintain 2) As the rotor blades are vertical, a yaw device is not needed, reducing the need for this bearing and its cost.
ISSN 2347 - 7539
3) Vertical wind turbines have a higher airfoil pitch angle, giving improved aerodynamics while decreasing drag at low and high pressures. 3) Low height useful where laws do not permit structures to be placed high. 4) Smaller VAWTs can be much easier to transport and install. 5) Does not need a free standing tower so is much less expensive and stronger in high winds that are close to the ground. 6) Does not need to be pointed into the wind, can turn regardless of the direction of the wind Disadvantages of VAWT system: 1) Most VAWTs produce energy maximum at only 50% of the efficiency of HAWTs in large part because of the additional drag that they have as their blades rotate into the wind. 2) There may be a height limitation to how tall a vertical wind turbine can be built and how much sweep area it can have. 3) Most VAWTS need to be installed on a relatively flat piece of land and some sites could be too steep for them but are still usable by HAWTs. 4) Most VAWTs have low starting torque, and may require energy to start the turning. 5) A VAWT that uses guy wires to hold it in place puts stress on the bottom bearing as all the weight of the rotor is on the bearing
10. FUTURE SCOPE The actual process of blade designing is very complex and need to be more aerodynamically sound. The use of Computational fluid dynamics (CFD) software would enable a more correct design. Glass fiber Reinforced Plastic (GRP) would have been the ideal choice for the blades as it is lighter in weight and has good tensile and compressive strength. Hence the blades would not damage and will have a longer life. Another improvement could be an arrangement to channelize the wind on to the blades using a card board piece placed on either side of turbine, on the turbine. Another important change that we can incorporate is to use a power controller circuit. As the input power is not constant, the output power changes accordingly. Moreover there is a mismatch in the generator output and the power input to the
_______________________________________________________________________________________ Volume: 02 Issue: 03 | May-2014, Available @ http://www.ijretm.com | Paper id - IJRETM-2014-02-03-421
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International Journal of Research in Engineering Technology and Management
ISSN 2347 - 7539
battery. In order to rectify this problem we can use a power controller circuit.
[3]. Putnam, Palmer Cosslett. Power from the Wind. Van Nostrand Company
There lies huge amount of potential in the wind power and we need to harness maximum energy available from it by designing and using more efficient blades, generator, rectification process and storage of energy in the battery.
[4]. G. Boyle, Renewable energy, power for a sustainable future, Oxford University Press, Oxford, England, 2004
The VAWG eliminates the guessing. Wind speed, turbine output, temperature and a host of other variables are collected and monitored in real time.
[5]. T. Ackerman, Wind energy technology and current status, a review, Elsevier science, 2000 [6]. G.M. Goselin, A review of wind energy technologies, Renewable and sustainable energy reviews, Vol. 11, 2007
11. CONCLUSION [7]. http://www.windpower.orgien/core.htm The implementation of vertical axis wind turbine on road dividers would be a great asset to the ministry of Nonconventional energy Resources as it would reduce the burden on the consumption of conventional energy sources. They can be installed on any highway with the width being the only constraint. These turbines are simple in construction and require less investment. Since, turbine is in small size, it can harness a limited amount of wind. Therefore they can be used for low power application such as for street lighting on any busy road. Moreover it can also be use to light up the advertisement hoardings. Other application could be in diversions on highways and traffic lights. Furthermore, these turbines can find application in lighting up the toll plazas on highways. Since the battery is portable we can use it in some other location for any low voltage purpose. Thus there is balance between the cost and the power available. Future prospect, the addition of speed governing system and control circuit may make the model much acceptable. The emerging trends in the technology have shown a way to the use of nonconventional energy sources so efficiently and a little effort at the side may find an effective solution for the boom of the electrical energy by the society.
[8]. http://www.daviddarling.info/encyclopedia/V/AE_verti calaxis_wind_turbine.html [9]. http://www.awea.org/faq/wwt_basics.html
12. REFERENCES [1]. Terrence C. Sankar (2008) The Case for Vertical Axis Wind Turbines. Technical Proceedings of Clean Technology Conference and Trade Show, Robert Morris University, Pittsburgh Pa, [2]. P N Shankar (March 1979) Development of vertical axis wind turbines, National Aeronautical Laboratory, Bangalore, Vol. C 2
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