Wind turbines use the kinetic energy of the wind for generating the electricity by using ac generators. The produced energy mainly depends on the wind speed and the swept area of the turbine. As the wind speed increases accordingly the dimensions of the blades of wind turbine reduces. The blades are made auto adjustable with the help of stepper motor and control unit mounted on it. The wind turbine blades power and efficiency has been measured at different tip-speed-ratios and a maximum efficiency of 30% at 1.27 N/m3 air density. Present work gives an insight into the design aspects of a wind turbine, like turbine blade design, wind power and output power calculation. This paper presents an idea to maintain the generated power constant at variable wind speed by changing the blade dimensions

1. Design of Adjustable Blade Wind
Turbine for Constant Generated Power
6th IEEE POWER INDIA ,INTERNATIONAL CONFERENCE -2014
Presented by-
Rajeev Kumar

2. Abstract
 Wind turbines use the kinetic energy of the wind for generating the
electricity by using ac generators.
 The produced energy mainly depends on the wind speed and the swept
area of the turbine. As the wind speed increases accordingly the
dimensions of the blades of wind turbine reduces. The blades are made
auto adjustable with the help of stepper motor and control unit mounted
on it.
 The wind turbine blades power and efficiency has been measured at
different tip-speed-ratios and a maximum efficiency of 30% at 1.27 N/m3 air
density.
 Present work gives an insight into the design aspects of a wind turbine, like
turbine blade design, wind power and output power calculation. This
paper presents an idea to maintain the generated power constant at
variable wind speed by changing the blade dimensions.

3. Introduction
 Power generation from a wind turbine over hundreds of year by using
historical designs such as wind mill and anemometer.
 Power generation from wind is the function of the wind speed. Wind power
is produce by the conversion of wind energy such as using wind turbines to
generate electricity, windmills for mechanical power, and wind pumps for
water pumping. So the wind power has been proved the potential source
of generating the electrical energy.
 The total amount of economically extractable power available from the
wind is considerably more than present electrical power use from all
sources.
 Wind power, as an alternative to fossil fuels, is abundant, renewable, widely
spread, clean, and produces no greenhouse gas emissions during
operation. Wind power is the world’s rapid growing source of energy

4. WIND TURBINES & GENERATION

5. Induction Generator
 Wind turbines are connected to ac generators such as Singly Excited
Induction Generator (SEIG), Doubly Fed Induction Generator (DFIG) and
Permanent Magnet Synchronous Generator (PMSG).
 Doubly Fed Induction Generators are widely used because of the
advantageous features such as rugged construction, low cost and less
maintenance.
 The stator winding of DFIG is connected to the grid with converter. Basically
doubly fed induction motor is used for this operation.
 Induction motor may run on subsynchronous speed or supersynchronous
speed depending upon the frequency. When doubly fed induction motor
runs on above the synchronous speed then slip is negative and motor works
as a generator and start feeding power to the grid.

6. Contd..
 A wind turbine extracts kinetic energy from the swept area of the blades.
Equation (1) is used for calculation of generated power. Where P is the
power generated by wind (in watts) , ρ is the air density (1.225 kg/m3 at
15°C and normal pressure), A is the swept area in (square meter), and V is
the wind velocity without rotor interference i.e. ideally at infinite distance
from the rotor (in meter per second).
P = 0.5 r A Cp V3

7. Permanent Magnet Synchronus Generator(
PMSG)
 Efficiency of PMSG is better than DFIG
 In PMSG, excitation produced by permanent magnetic pole which has
mounted on rotor surface. With the permanent magnetic poles we do not
need any dc excitation and it requires less maintenance due to absence of
gear box.
 Armature winding consists of the set of three conductors which has phase
difference 1200 apart to each other and providing a uniform force or
torque on the generator’s rotor.

8. CONCEPT IDEA & DESIGNING

9. Concept of Designing

10. Contd..
 This paper gives a conceptual idea that how to maintain the constant
speed of wind turbine during variable wind speed.
 To get constant speed operation auto adjustable blades has used, which
automatically adjust the dimension of blades under variable wind speed.
 A schematic way of operation can be explained with block arrangement
of wind turbine, stepper motor, controlling and sensing device.
 A speed sensor has continuously observe the speed of turbine which can
be stored in control unit, if the speed of turbine suddenly start to decrease,
control unit operates the stepper motor, and the swept area of blade has
changed to maintain the rotations constant.
 Thus speed of the turbine is always maintained constant by controlling the
dimensions of blades.

11. Turbine Blade Design
 In this design blades are auto folded in the
mid span to tip by using of folded action
which is controlled by stepper motor,
assembled in the hub of rotor.
 The control unit has continuously observed
the data of speed sensor, if the speed of
turbine has disturbed from a prescribed
value, it has sends a signal to stepper motor
to operate.
 During the low wind speed condition rotor
blades are unfolded and provide the more
swept area, but in the high wind speed
condition rotor blades are folded so that
width of blade has narrow and reduce the
area.

12. Contd…
 At TSR Value= 5  At TSR Value= 9

13. CALCULATIONS & PERFORMANCE
CHARACTERISTICS

14. Calculations
 Using Online Simulator power 4.24 kw is measure at 20 m/sec wind speed
with swept area 2.89 m2. So,
 Generated power P = 4.24 kw
 Tip speed ratio "TSR" = ‘5’
 Wind speed "V" = 20 m/s
 Swept rotor area "A" = 2.11 m2
 Radius of rotor = 0.96 m
P = 0.5 r A Cp V3
Constant K, (rCp)= P/0.5AV
Constant K= 0 .366

15. Contd..
 For variable wind speed the swept area changes at constant power
generation in Table-III
 Wind speed = 18 m/sec (assume)
 Power = 4.24 kw (constant)
K=0.366
A=2P/k*V3
A= (2*4240)/ (0.366*183)
A= 3.97 m2

16. Calculation of Blades Area at Different Wind
Speed
Power
(watt)
Wind
Speed(m/sec) Area (m2)
4240 20 2.89
4240 18 3.97
4240 16 5.65
4240 14 8.44
4240 12 13.40
4240 10 23.16
4240 8 45.25
50
45
40
35
30
25
20
15
10
5
0
8 10 12 14 16 18 20
Wind Speed (m/sec)
Area (m2)

17. Generated Power at Different Wind Speed
4000
3500
3000
2500
2000
1500
1000
500
0
5 8 10 12 14 16 18 20
Wind Speed (m/sec)
Rotational speed
(rpm) at TSR 5
Rotational speed
(rpm) at TSR 7
Rotational speed
(rpm) at TSR 9
Power (Watt)
Wind Speed
(m/sec)
Rotational speed
(rpm) at
Power
(Watt)
TSR 5 TSR 7 TSR 9
5 265.3 371.4 477.5 58.2
8 424.4 594.2 763.9 234.4
10 530.5 742.7 954.9 465.7
12 636.6 891.3 1145.9 804.7
14 742.7 1039.8 1336.9 1277.8
16 848.8 1188.4 1527.9 1910
18 954.9 1336.9 1718.9 2720
20 1061 1485.4 1909.9 3720

18. Conculsion
 With the help of on line wind turbine simulator the power is generated as
4.2 kw. Various calculations have been carried out for TSR value 5,7&9.
 In the variable wind speeds such as 12m/sec & 20 m/sec rotation of turbine
has maintained constant by control unit.
 Power calculations at 20 m/sec wind speed, area of blade is 2.89 m2 or
wind speed 12 m/sec, the area of blade is13.4 m2.

19. Thank You