Design of Adjustable Blade Wind

Turbine for Constant Generated Power

6th IEEE POWER INDIA ,INTERNATIONAL CONFERENCE -2014

Presented by-

Rajeev Kumar

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.

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

WIND TURBINES & GENERATION

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.

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

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.

CONCEPT IDEA & DESIGNING

Concept of Designing

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.

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.

Contd…

At TSR Value= 5 At TSR Value= 9

CALCULATIONS & PERFORMANCE

CHARACTERISTICS

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

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

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 45.250

5

10

15

20

25

30

35

40

45

50

8 10 12 14 16 18 20

Wind Speed (m/sec)

Area (m2)

Generated Power at Different Wind Speed

0

500

1000

1500

2000

2500

3000

3500

4000

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

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.

Thank You