100_MOHDAFIZANBINISMAIL2008
65
A SMALL WIND ENERGY SYSTEM TO SAVE HOME ELECTRICITY MOHD AFIZAN BIN ISMAIL UNIVERSITI TEKNOLOGI MALAYSIA
Transcript of 100_MOHDAFIZANBINISMAIL2008
A SMALL WIND ENERGY SYSTEM TO SAVE HOME ELECTRICITY
MOHD AFIZAN BIN ISMAIL
UNIVERSITI TEKNOLOGI MALAYSIA
PSZ 19:16 (Pind. 1/07
DECLARATION OF THESIS / UNDERGRADUATE PROJECT PAPER AND COPYRIGHT
Author’s full name : MOHD AFIZAN BIN ISMAIL Date of birth : 15th AUGUST 1986 Title : A SMALL WIND ENERGY SYSTEM TO SAVE
HOME ELECTRICITY Academic Session : I declare that this thesis is classified as : I acknowledged that Universiti Teknologi Malaysia reserves the right as follows :
1. The thesis is the property of Universiti Teknologi Malaysia. 2. The Library of Universiti Teknologi Malaysia has the right to make copies for the
purpose of research only. 3. The Library has the right to make copies of the thesis for academic exchange.
Certified by :
SIGNATURE SIGNATURE OF SUPERVISOR 860815-46-5563 PM DR. MD PAUZI BIN ABDULLAH (NEW IC NO. /PASSPORT NO.) NAME OF SUPERVISOR
Date : 13th MAY 2008 Date : 13th MAY 2008
NOTES : * If the thesis is CONFIDENTIAL or RESTRICTED, please attach with the letter from the organisation with period and reasons for confidentiality or restriction.
UNIVERSITI TEKNOLOGI MALAYSIA
CONFIDENTIAL (Contains confidential information under the Official Secret Act 1972)*
RESTRICTED (Contains restricted information as specified by the organisation where research was done)*
OPEN ACCESS I agree that my thesis to be published as online open access (full text)
√
“I hereby declare that I have read this report, entitled “A Small Wind Energy System to
Save Home Electricity” and it fulfils the requirements of the scope and quality for the
Bachelor of Electrical Engineering (Power)”.
Signature : ………………………………….
Supervisor : PM DR. MD PAUZI BIN ABDULLAH
Date : 13 MAY 2008
A SMALL WIND ENERGY SYSTEM TO SAVE HOME ELECTRICITY
MOHD AFIZAN BIN ISMAIL
Submitted to the Faculty of Electrical Engineering
in partial fulfillment of the requirement for the degree of Bachelor in Electrical Engineering (Power)
Faculty of Electrical Engineering Universiti Teknologi Malaysia
MAY 2008
ii
“I declare that this work as the product of my own effort with the exception of excerpts
cited from other works of which the sources were duly noted”
Signature : …………………………..
Name : MOHD AFIZAN BIN ISMAIL
Date : 13 MAY 2008
iii
Dedicated, in thankful appreciation for support, encouragement and understandings
to:
My supervisor Dr Md Pauzi bin Abdullah
My beloved mother Meriam bte Jusoh and father Ismail Bin Salim;
my brother and sister Norharnida, Mohd Aideel, Mohd Amri
and Norziana;
also my beloved friend Ikram,Tord,Amir,Amin,Ridhuan, Aidil, Rushdi, Hadi, Mohd
Al-amin, Azizi, Ila, Fairuz and Ziera
and all person contribute to this project
iv
ACKNOWLEDGEMENT
I would like to express my special thanks to my supervisor, Dr. Md Pauzi bin
Abdullah for her advices, continual guidance and commitment in helping me doing the
research. He always gives the idea and knowledge in helping me to carry out the project
in a better way. His knowledge is very useful for me to do the research appropriately.
I would also want to thanks to cooperation provided by all friends same
supervisor as me. Their guidance and patience is very much appreciated.
Finally yet importantly, my project would not be carried out smoothly without
the continuing supports and encouragements given by my parents, lectures, Forecast FC
team members, and friends. I would like to express my sincere gratitude to them
especially for their helping during the time in need.
Thank you.
v
ABSTRACT
Wind is the motion of air about the earth caused by its rotation and by the
uneven heating of planet surface by the sun. The basic concept of the wind energy
generation by using the wind flows to rotate a turbine generator. Even though, wind
power is not popular in Malaysia but it is widely used in United Kingdom, United
State and France. Nowadays, our electricity bill always increases every year cause of
increasing fossil-fuel price. This project will discuss about small wind energy system
to save our home electricity. We will use small wind turbine as alternative to reduce
our electricity bill every months. This system will use UPS as battery storage, three
blades small wind turbine and wiring. If the wind speeds at our area are high to
generate enough power, we will direct supply that power to low electrical equipment
such as lighting, wireless gateway and more. This project also will discuss where
suitable place in our country have potential to practice this home small wind system
by using real wind speed data in Malaysia as input for the model. We have use MAT
LAB Simulink as the platform to model and simulate this wind energy system. This
project will focus on analyze the effect of wind turbine radius blades to output power
and also analyze the output power for different places in Malaysia. Lastly, for the
overall project, we could find out how much the output power can produce from this
small wind energy and also find which city in Malaysia suitable to practice this wind
system.
vi
ABSTRAK
Angin ialah pergerakan udara di permukaan bumi disebabkan oleh putaran
dan ketidaksamaan kepanasan permukaan bumi oleh pancaran matahari. Konsep asas
penjanaan tenaga angin adalah dengan menggunakan aliran angin untuk memutarkan
turbin penjana. Walaubagaimanapun, tenaga angin tidak popular di Malaysia tetapi
banyak digunakan di United Kingdom, Amerika Syarikat dan Perancis. Pada masa
kini, bil elektrik di rumah semakin meningkat setiap tahun disebabkan oleh kenaikan
bahan api. Projek ini akan membincangkan tentang system tenaga angin kecil bagi
mengurangkan bil elektrik di rumah. Kita akan menggunakan system tenaga angin
kecil sebagai alternatif bagi mengurangkan bil elektrik setiap bulan. Sistem ini akan
menggunakan UPS sebagai penyimpan tenaga, turbin angin tiga bilah dan
pendawaian. Jika kelajuan angin kat kawasan rumah kita mampu menghasilkan
kuasa yang mencukupi, maka ia boleh digunakan secara terus sebagai bekalan untuk
sistem lampu, dan lain-lain.Projek ini juga akan membincangkan tempat yang
mempunyai potensi bagi mempraktikkan sistem ini dengan mengambil data kelajuan
angin di Malaysia sebagai masukan Model. Kita menggunakan Mat-lab Simulink
sebagai pentas untuk menghasilkan model dan seterusnya menguji sistem angin ini.
Projek ini akan menfokuskan tentang pengaruh diameter turbin terhadap kuasa
keluaran dan juga pengaruh perbezaan tempat terhadap kuasa keluaran yang dapat
dijanakan.Secara keseluruhannya, kita akan mencari berapa kuantiti kuasa yang
dapat dijanakan oleh sistem tenaga angin kecil ini dan mencari bandar di Malaysia
yang sesuai untuk mempraktik sistem ini.
vii
TABLE OF CONTENT
CHAPTER TITLE PAGE
TITLE i
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF SIMBOL x
LIST OF TABLES xi
LIST OF FIGURES xii
1 INTRODUCTION 1
1.1 Background of the Study 1
1.1.1 Wind Energy 2
1.1.2 Wind System Basics 3
1.1.3 Wind Turbine 4
1.1.3.1. Horizontal axis 4
1.1.3.2. Vertical axis 7
1.2 Problem Statement 9
viii
1.3 Objectives Project 11
1.4 Scope of the Work 11
2 LITERATURE REVIEW 12
2.1 Small Wind Energy System for Homeowner 12
2.1.1 Is Wind Power Practical for Us? 13
2.1.2 Wind Speed and Energy Calculations 14
2.2 Small Wind System in U.S 15
2.3 Study Case of Wind System in U.K 17
2.3.1 Corrour Station - 2.5 kW battery charging wind turbine 18
2.3.2 Berwickshire Housing Association - Three 1.5 kW
rooftop turbines 19
2.3.3 Ladygrove Primary School - 2.5 kW turbines 19
2.4 Hybrid Wind Systems 20
2.5 Suitable Wind Turbine to Use in Malaysia 21
3 METHODOLOGY 22
3.1 Introduction 22
3.2 Small Wind Energy System 23
3.3 Circuit Simulation and Modeling 24
3.4 Use real wind speed data for a few cities in Malaysia 25
3.5 Data Analysis and Conclusion 26
4 MODELING 29
4.1 Introduction 29
4.2 Mat lab/Simulink (General) 30
4.3 Wind Energy System Model 32
4.4 Model Component and Function 33
ix
4.5 Summary 37
5 RESULT AND DISCUSSION 38
5.1 Introduction 38
5.2 Analysis result for variable radius blades 38
5.3 Analysis result for different city in Malaysia 44
5.4 Discussion 46
6 CONCLUSION AND RECOMMENDATION 47
6.1 Conclusion 47
6.2 Recommendation 48
REFERENCES 49
x
LIST OF SIMBOL
P - Active power
Q - Reactive power
A - Area of rotor
V - Wind velocity
D - Air density
xi
LIST OF TABLE
TABLE NO. TITLE PAGE
3.1 Kota Bharu and Senai wind speed data 26
xii
LIST OF FIGURES
FIGURE TITLE PAGE
1.1 The examples of HAWT 6
1.2 The examples of VAWT 9
1.3 The rooftop-mounted urban wind turbine 10
2.1 Small wind system in U.S 17
2.2 Hybrid wind systems 20
3.1 Small wind system diagram 23
3.2 Simulation flow 24
3.3 Outline of the Project 28
4.1 Mat lab toolbox 31
4.2 Wind system model 32
4.3 Input source block 33
4.4 wind turbine block 34
4.5 Drive train block 34
4.6 Induction machine block 35
4.7 P&Q measurement block 35
4.8 Scope block 36
4.9 Terminator block 36
5.1 Output current for 5 meter radius blades 40
5.2 Output power for 5 meter radius blades 40
5.3 Output current for 10 meter radius 41
5.4 Output power for 10 meter radius 41
xiii
5.5 Output current for 15 meter radius 42
5.6 Output power for 15 meter radius 42
5.7 Output power for R=5 m 43
5.8 Output power for R=10 m 43
5.9 Output power for R=15 m 43
5.10 Output power for Kota Bharu 45
5.11 Output Power for Senai 45
CHAPTER 1
INTRODUCTION
1.1 Background of Study
Wind power is the conversion of wind energy into more useful forms, such as
electricity, using wind turbines. Most modern wind power is generated in the form of
electricity by converting the rotation of turbine blades into electrical current by means of
an electrical generator [3]. In windmills (a much older technology), wind energy is used
to turn mechanical machinery to do physical work, such as crushing grain or pumping
water. Wind power is used in large scale wind farms for national electrical grids as well
as in small individual turbines for providing electricity to rural residences or grid-
isolated locations. Wind energy is plentiful, renewable, widely distributed, cleans, and
reduces toxic atmospheric and greenhouse gas emissions if used to replace fossil-fuel-
derived electricity. The intermittency of wind seldom creates problems when using wind
power at low to moderate penetration levels.
2
1.1.1 Wind Energy
The wind energy is converted through friction into diffuse heat throughout the
Earth's surface and the atmosphere. The origin of wind is complex. The Earth is
unevenly heated by the sun resulting in the poles receiving less energy from the sun than
the equator does. Also the dry land heats up (and cools down) more quickly than the seas
do. The differential heating powers a global atmospheric convection system reaching
from the Earth's surface to the stratosphere which acts as a virtual ceiling. There we have
the main advantages and disadvantages of wind power on the surrounding environment,
and the general reliability of wind turbines [7].
The advantages of wind energy;
1. Wind energy is extremely friendly to the surrounding environment; no fossil
fuels are burnt to generate electricity from wind power.
2. Wind turbines take up less space than the average power station. Windmills only
have to occupy a few square meters for the base; this allows the land around the
turbine to be used for many purposes, for example agriculture.
3. Newer technologies are making the extraction of wind energy much more
efficient. The wind is free, and we are able to cash in on more and more of this
free wind power.
4. Wind turbines are a great resource to generate energy in remote locations, such
as mountain communities and the countryside. The turbines can be a range of
different sizes in order to support varying population levels.
5. Another advantage of wind energy is that when combined with solar electricity,
this energy source is great for developed and developing countries to provide a
steady, reliable supply of electricity.
3
The disadvantages of wind energy;
1. The main disadvantage regarding wind power is down to the winds unreliability
factor. In many areas, the winds strength is too low to support a wind turbine or
wind farm, and this is where the use of solar power or geothermal power are
great alternatives.
2. A wind turbine can only support a specific population. Wind turbines aren't like
power stations, where you can just burn a bit more fuel to generate more energy
when you need it.
3. Wind turbine construction can last over a year, be very expensive and costly to
the surrounding nature environment during the build process.
4. The noise pollution from commercial wind turbines is on a par with a small jet
engine. This is fine if you live a mile or so away, where you will hardly notice
the noise, but what if you live within a few hundred meters of a turbine? This is a
major disadvantage.
5. Vast protests and/or petitions usually confront any proposed wind farm site.
People feel the countryside should be left in tact for everyone to enjoy it's
beauty.
1.1.2 Wind System Basics
All wind systems consist of a wind turbine, a tower, wiring, and the “balance of
system” components: controllers, inverters, and/or batteries [2]. Home wind turbines
consist of a rotor, a generator mounted on a frame, and (usually) a tail. Through the
spinning blades, the rotor captures the kinetic energy of the wind and converts it into
rotary motion to drive the generator. Rotors can have two or three blades, with three
being more common. The best indication of how much energy a turbine will produce is
4
the diameter of the rotor, which determines its “swept area,” or the quantity of wind
intercepted by the turbine. The frame is the strong central axis bar onto which the rotor,
generator, and tail are attached. The tail keeps the turbine facing into the wind.
1.1.3 Wind Turbine
A wind turbine is a machine that converts the kinetic energy in wind into
mechanical energy. If the mechanical energy is used directly by machinery, such as a
pump or grinding stones, the machine is usually called a windmill. If the mechanical
energy is then converted to electricity, the machine is called a wind generator, wind
turbine, or wind energy converter. Wind turbines can be separated into two types based
on the axis about which the turbine rotates [2]. Turbines that rotate around a horizontal
axis are more common. Vertical-axis turbines are less frequently used.
1.1.3.1 Horizontal axis
Horizontal-axis wind turbines (HAWT) have the main rotor shaft and electrical
generator at the top of a tower, and must be pointed into the wind. Small turbines are
pointed by a simple wind vane, while large turbines generally use a wind sensor coupled
with a servo motor. Most have a gearbox, which turns the slow rotation of the blades
into a quicker rotation that is more suitable for generating electricity. Since a tower
produces turbulence behind it, the turbine is usually pointed upwind of the tower.
Turbine blades are made stiff to prevent the blades from being pushed into the tower by
5
high winds. Additionally, the blades are placed a considerable distance in front of the
tower and are sometimes tilted up a small amount. Downwind machines have been built,
despite the problem of turbulence, because they don't need an additional mechanism for
keeping them in line with the wind, and because in high winds, the blades can be
allowed to bend which reduces their swept area and thus their wind resistance. Because
turbulence leads to fatigue failures and reliability is so important, most HAWTs are
upwind machines.
HAWT advantages
1. Blades are to the side of the turbine's center of gravity, helping stability.
2. Ability to wing warp, which gives the turbine blades the best angle of attack.
Allowing the angle of attack to be remotely adjusted gives greater control, so the
turbine collects the maximum amount of wind energy for the time of day and
season.
3. Ability to pitch the rotor blades in a storm, to minimize damage.
4. Tall tower allows access to stronger wind in sites with wind shear. In some wind
shear sites, every ten meters up, the wind speed can increase by 20% and the
power output by 34%.
5. Tall tower allows placement on uneven land or in offshore locations.
6. Can be sited in forests above the tree line.
7. Most are self-starting.
8. Can be cheaper because of higher production volume, larger sizes and, in general
higher capacity factors and efficiencies.
HAWT disadvantages
1. HAWTs have difficulty operating in near ground, turbulent winds because their
yaw and blade bearing need smoother, more laminar wind flows.
2. The tall towers and long blades (up to 180 feet (55 m) long) are difficult to
transport on the sea and on land. Transportation can now cost 20% of equipment
costs.
6
3. Tall HAWTs are difficult to install, needing very tall and expensive cranes and
skilled operators.
4. Supply of HAWTs is less than demand and between 2004 and 2006, turbine
prices increased up to 60%. At the end of 2006, all major manufacturers were
booked up with orders through 2008.
5. The FAA has raised concerns about tall HAWTs effects on radar in proximity to
air force bases.
6. Their height can create local opposition based on impacts to view sheds.
7. Offshore towers can be a navigation problem and must be installed in shallow
seas. HAWTs can't be floated on barges.
8. Downwind variants suffer from fatigue and structural failure caused by
turbulence.
Figure 1.1 The examples of HAWT
7
1.1.3.2 Vertical axis
Vertical-axis wind turbines (or VAWTs) have the main rotor shaft running
vertically. Key advantages of this arrangement are that the generator and/or gearbox can
be placed at the bottom, near the ground, so the tower doesn't need to support it, and that
the turbine doesn't need to be pointed into the wind. Drawbacks are usually pulsating
torque that can be produced during each revolution and drag created when the blade
rotates into the wind. It is also difficult to mount vertical-axis turbines on towers,
meaning they must operate in the often slower, more turbulent air flow near the ground,
resulting in lower energy extraction efficiency.
VAWT advantages
1. Easier to maintain because most of their moving parts are located near the
ground. This is due to the vertical wind turbine’s shape. The airfoils or rotor
blades are connected by arms to a shaft that sits on a bearing and drives a
generator below, usually by first connecting to a gearbox.
2. As the rotor blades are vertical, a yaw device is not needed, reducing the need for
this bearing and its cost.
3. Vertical wind turbines have a higher airfoil pitch angle, giving improved
aerodynamics while decreasing drag at low and high pressures.
4. Mesas, hilltops, ridgelines and passes can have higher and more powerful winds
near the ground than up high because of the speed up effect of winds moving up
a slope or funneling into a pass combining with the winds moving directly into
the site. In these places, VAWTs placed close to the ground can produce more
power than HAWTs placed higher up.
5. Low height useful where laws do not permit structures to be placed high.
6. Smaller VAWTs can be much easier to transport and install.
7. Does not need a free standing tower so is much less expensive and stronger in
high winds that are close to the ground.
8. Usually have a lower Tip-Speed ratio so less likely to break in high winds.
8
9. Does not need to be pointed into the wind, can turn regardless of the direction of
the wind.
VAWT disadvantages
1. Most VAWTs produce energy 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. This can be overcome by using structures to funnel more and align the
wind into the rotor or the "vortex" effect of placing straight bladed VAWTs
closely together.
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. However, this can be overcome by
connecting a multiple number of turbines together in a triangular pattern with
bracing across the top of the structure. Thus reducing the need for such strong
vertical support, and allowing the turbine blades to be made much longer.
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.
5. A VAWT that uses guyed wires to hold it in place puts stress on the bottom
bearing as all the weight of the rotor is on the bearing. Guyed wires attached to
the top bearing increase downward thrust in wind gusts. Solving this problem
requires a superstructure to hold a top bearing in place to eliminate the
downward thrusts of gust events in guyed wired models.
9
Figure 1.2 The examples of VAWT
1.2 Problem Statement
During this project, we are focus on how to use small wind energy to save our
home electricity. Small wind energy systems can be used in connection with an
electricity transmission and distribution system (called grid- connected systems), or in
stand-alone applications that are not connected to the utility grid. Small Wind Energy is
widely used in United Kingdom, United State and France but is not popular in Malaysia.
Every year, our electricity bills at home will increase because the price of fossil-fuel-
such as petroleum and gases always increase. So, this project will introduce us how to
save the electricity by using small wind energy system. Wind system is more costless
than other renewable energy likes solar system. Small Wind is defined as wind
generation systems with capacities of less than 100 kW and is usually used to power
homes, farms, and small businesses [3].
10
Small scale turbines for home use are available that are approximately 7 feet
(2 m) to 25 feet (8 m) in diameter and produce electricity at a rate of 900 watts to 10,000
watts at their tested wind speed. In urban locations, where it is difficult to obtain
predictable or large amounts of wind energy, smaller systems may still be used to run
low power equipment such as lighting, parking meters or wireless internet gateways. In
this project, a small wind turbine, which is installed on top of a tall tower, will collects
kinetic energy from the wind and converts it to electricity that is compatible with a
home's electrical system. A small, quiet wind turbine like this can generate around a
60W, 5A, 12V power supply cost by RM 5000-RM20000 depending on how much
power we wish to generate. When the turbine produces more power than the house
needs, the extra electricity is store in UPS. All of this is done automatically. Small
turbine also can be use as backup supply during home blackout. UPS will supply
electricity to our home but not for long time, maybe only for 24 hours depend on size of
our UPS energy storage that we use. The amount of energy that can be captured from the
wind is exponentially proportional to the speed of the wind.
Figure 1.3 The rooftop-mounted urban wind turbine
11
1.3 Objective Project
There are the objectives of this project:
1. To study how to the operation of small wind energy system model using Mat Lab
Simulink.
2. To analyze the effect of the power and current output when variable the radius of
blades.
3. Apply real wind speed data of few cities in Malaysia into simulink model.
1.4 Scope of Work
The scopes of this project are:
1. Do modeling and simulation using Mat Lab Simulink.
2. Analysis the output power using different blades radius.
3. Analysis the output power for few cities in Malaysia which is Kota Bharu and
Senai by using real wind speed data.
CHAPTER 2
LITERATURE REVIEW
2.1 Small Wind Energy System for Homeowner
In the 1920s and ‘30s, farm families throughout the Midwest used wind to
generate enough electricity to power their lights and electric motors. The use of wind
power declined with the government- subsidized construction of utility lines and fossil
fuel power plants. However, the energy crisis in the 1970s and a growing concern for the
environment generated an interest in alternative, environmentally friendly energy
resources. Today, homeowners in rural and remote locations across the nation are once
again examining the possibility of using wind power to provide electricity for their
domestic needs.
13
2.1.1 Is Wind Power Practical for Us?
Small wind energy systems can be used in connection with an electricity
transmission and distribution system (called grid- connected systems), or in stand-alone
applications that are not connected to the utility grid. A grid-connected wind turbine can
reduce your consumption of utility supplied electricity for lighting, appliances, and
electric heat. If the turbine cannot deliver the amount of energy we need, the utility
makes up the difference. When the wind system produces more electricity than the
household requires, the excess can be sold to the utility. With the interconnections
available today, switching takes place automatically. However, our project focus on
stand-alone wind energy only, stand-alone wind energy systems can be appropriate for
homes, farms, or even entire communities (a co-housing project, for example) that are
far from the nearest utility lines. Either type of system can be practical if the following
conditions exist.
Conditions for Stand-Alone Systems
1. We live in an area with average annual wind speeds of at least 9 miles per hour
(4.0 meters per second).
2. A grid connection is not available or can only be made through an expensive
extension. The cost of running a power line to a remote site to connect with the
utility grid can be prohibitive, ranging from $15,000 to more than $50,000 per
mile, depending on terrain.
3. We have an interest in gaining energy independence from the utility.
4. We would like to reduce the environmental impact of electricity production.
5. We acknowledge the intermittent nature of wind power and have a strategy for
using intermittent resources to meet your power needs.
Wind turbine manufacturers can use computer models to predict their machines’
performance at a specific location. They can also help us size a system based on our
14
electricity needs and the specifics of local wind patterns. However, we will need site-
specific data to determine the wind resource of our exact location. If we do not have on-
site data and want to obtain a clearer, more predictable picture of our wind resource, we
may wish to measure wind speeds at our site for a year. We can have varied wind
resources within the same property. If we live in complex terrain, take care in selecting
the installation site. If we site our wind turbine on the top or on the windy side of a hill,
for example, we will have more access to prevailing winds than in a gully or on the
leeward (sheltered) side of a hill on the same property. Consider existing obstacles and
plan for future obstructions, including trees and buildings, which could block the wind.
Also realize that the power available in the wind increases proportionally to its speed
(velocity) cubed (v3). This means that the amount of power we get from our generator
goes up exponentially as the wind speed increases. For example, if your site has an
annual average wind speed of about 12.6 miles per hour (5.6 meters per second), it has
twice the energy available as a site with a 10 mile per hour (4.5 meter per second)
average.
2.1.2 Wind Speed and Energy Calculations
The process by which the kinetic energy of wind is used to generate mechanical
power or electrical energy is known as wind power or wind energy. Kinetic means being
related to or produced by motion such as the blowing wind. A windmill converts the
force of the wind into turning force acting on the rotor blades. The strength of this
turning force is known as torque.
The amount of energy that can be captured from the wind is exponentially
proportional to the speed of the wind. If a windmill were perfectly efficient, the power
generated is approximately equal to:
15
P (watts) = 1/2 D (air density) x A (area of rotor) x V cubed (wind velocity)
Air density at sea level and 14 degrees C = 1.225 (2.1)
Therefore, if wind speed is doubled, the power in the wind increases by a factor of eight,
i.e. 2 x 2 x 2. In reality, because wind turbines are not perfectly efficient, changes in
wind velocity do not have such a dramatic effect on wind power. Betz' Law states that
you can only convert approximately 59 % of the wind energy to mechanical energy
using a wind turbine. However, small changes in velocity do impact on available energy,
making wind speed an important factor to consider in the placement of a wind turbine.
The chart below illustrates that a doubling of wind velocity increases power available by
a factor of eight.
2.2 Small Wind System in U.S
Small Wind System is popular in U.S. Our project is quite same as practice in
U.S but the difference is they used small wind turbine around 1kW until 10kw. In our
research, we use small wind turbine below 1kW known as micro wind turbine. This
micro wind turbine is enough to run some of the electrical equipment at home and the
system is not for grid connection but as stand-alone generator for our home. First of all,
we must understand the overall function of wind energy system in U.S in order to
commercial in Malaysia. The small wind turbine industry estimates that 60% of the
United States has enough wind resources for small turbine use. Small wind energy
systems cost from $3,000 to $5,000 for every kilowatt (kW) of generating capacity. One
kW is equal to 1,000 watts, which is the amount of electricity that can illuminate ten
100-watt light bulbs. According to the U.S. Department of Energy (DOE), a small
wind-powered electric generator can reduce a homeowner’s electric bill by 50% to 90%.
16
The small wind turbine industry is one of the few renewable industries still dominated
by the United States, according to a new study by the American Wind Energy
Association. The 2007 Global Small Wind Market Study finds that 6,807 small wind
turbines were sold in the United States in 2006, compared with an estimated 9,502 wind
turbines sold in the rest of the world [1]. Using small wind turbines, U.S. farmers,
ranchers, business owners, and homeowners are reducing their utility bills, stabilizing
their electricity supplies, displacing carbon emissions from fossil fuel sources, and
helping to reduce our dependence on foreign fuel markets. In U.S, Small wind energy
systems may be connected to the electricity distribution system, the grid. Grid-
connected, residential-scale models (1-10 kW) are the fastest growing market segment.
A grid-connected wind turbine can reduce consumption of utility-supplied electricity for
lighting, appliances, and electric heat. When the turbine cannot deliver the amount of
energy needed, the utility makes up the difference. The smallest turbines with power
ratings of less than 1 kW (micro wind turbine) are normally used to charge batteries for
sailboats and small homes. A distributed wind generator is an off-grid, stand alone
system that provides power to a non grid-connected area located near the point of use.
Isolated, rural areas where electric power transmission lines are limited or have not been
installed are ideal areas for distributed wind generators. However, because wind energy
is an intermittent, variable source of electricity, stand-alone turbines generally require
backup hybrid power systems that include another source of power to provide constant
power, such as solar photovoltaic or batteries with inverters (to convert DC electricity
from the batteries to AC for the home's electrical appliances).
17
Figure 2.1 small wind systems in U.S
2.3 Study Case of Wind System in U.K
We will discuss some cases of small wind turbine in U.K below. Most of the
small wind energy systems in U.K focus on to reduce the fossil-fuel in their daily live,
so they use wind turbine as new the generator to generate energy. Then, they use the
energy mostly likes we want which is to support electricity at home, school or small
business building. As we know, the UK has the best wind resource in Europe, an asset
that has the potential to provide a considerable proportion of the UK energy market in
years to come [4]. Together with several innovative manufacturers, the UK has a chance
of becoming a world leader in small wind energy technologies. The DTI (Department of
Trade and Industry) estimates that by 2050, up to 30-40% of UK's electricity generation
could be produced by small and micro generation technologies, including 6% from small
wind energy generation. The UK's housing sector is responsible for around 28% of the
UK's CO2 emissions; hence the 25 million homes in the UK, as well as schools,
businesses and other public and private sector buildings can have an important part to
18
play in tackling climate change by generating their own power. Small scale renewable
energy technologies such as small wind turbines generate clean and renewable energy
with no harmful emissions and can thus help reduce a significant proportion of the UK's
CO2 emissions. There is an increasing amount of interest and support for these
technologies from politicians, industry and the public alike. Below are the cases of small
wind system in U.K;
2.3.1 Corrour Station - 2.5 kW battery charging wind turbine
Corrour Station at Fort William, Inverness-shire is an unmanned railway station
and one of the most remote in the UK. The complete lack of an electricity supply and the
resulting absence of lights caused problems for passengers boarding and disembarking
from trains on dark mornings and evenings. In early 1993 First Scotrail invested in a
Proven 2.5 kW battery charging wind turbine that incorporated a sensor to measure light
levels and a timer programmed with train schedules. At dusk the sensor detects light is
required and the timer ensures that the lights switch on half an hour before a train arrives
and switch off half an hour after it departs. The planning application for the scheme
received approval without difficulty. The wind turbine itself is still running after 13
years (at the time of going to press) of continue.
19
2.3.2 Berwickshire Housing Association - Three 1.5 kW rooftop turbines
Berwickshire Housing Association (BHA) installed Renewable Devices 'Swift'
domestic wind turbines on two houses in Whitsome, and another in Ayton,
Berwickshire, Scotland. BHA recognizes that affordable housing is not just about the
cost of rent, but also the costs of heating and running a property. By installing small
scale wind on tenants' houses, BHA aims to lower tenants' fuel costs and reduce their
reliance on fossil fuel based energy sources. One aspect of our approach to addressing
fuel poverty has been to focus on the use of renewable energy systems. These
innovations provide energy saving features at a more manageable cost to tenants.
2.3.3 Ladygrove Primary School - 2.5 kW turbines
Ladygrove Primary School located in the Borough of Telford & Wrekin, West
Midlands is one of the many schools which have installed their own wind turbines. The
Proven wind turbine at Ladygrove Primary School generates electricity for use directly
in the school with any surplus going to the national grid for local use. Ladygrove
Primary School is also piloting a child-friendly web browser based monitoring system
for interpretation of wind speed and electricity generated. The system is installed on the
Borough of Telford & Wrekin's intranet and is available through the internet to other
schools in the area. Ladgrove Primary School received funding for the £12,000 project
from the Marches Energy Agency and the Government's Clear Skies funding scheme.
The Proven 2.5kW turbine at the school generates annual energy savings for the school
in the region of £400 and reduces CO2 emissions from fossil fuels by 3.5 tonnes a year.
This is equivalent to planting 17.5 trees a year.
20
2.4 Hybrid Wind Systems
Our project is similarly with hybrid wind systems but we only used a small wind
turbine as generator and we not combine with photovoltaic (PV). The hybrid wind
system have the same function as we need which is to supply energy and as backup
supply at our home. According to many renewable energy experts, a stand-alone
“hybrid” system that combines wind and photovoltaic (PV) technologies offers several
advantages over either single system. In much of the United States, wind speeds are low
in the summer when the sun shines brightest and longest. The wind is strong in the
winter when there is less sunlight available. Because the peak operating times for wind
and PV occur at different times of the day and year, hybrid systems are more likely to
produce power when we need it. For the times when neither the wind generator nor the
PV modules are producing electricity (for example, at night when the wind is not
blowing), most stand-alone systems provide power through batteries and/or an engine-
generator powered by fossil fuels. If the batteries run low, the engine- generator can be
run at full power until the batteries are charged. Adding a fossil- fuel-powered generator
makes the system more complex, but modern electronic controllers can operate these
complex systems automatically. Adding an engine-generator can also reduce the number
of PV modules and batteries in the system. Keep in mind that the storage capability must
be large enough to supply electrical needs during no charging periods. Battery banks are
typically sized for one to three days of windless operation.
Figure 2.2 Hybrid wind system
PV
21
2.5 Suitable Wind Turbine to Use in Malaysia
Wind Power not popular in Malaysia cause of low wind speed and there is no
wind turbine supplier for below cut-in speed (3m/s). There are no suppliers from oversea
that can supply small wind turbine suitable with our low average wind speed in
Malaysia. Most of their wind turbine has cut-in speed above 4 m/s. However there is
one turbine model, ‘Low Wind Speed Wind Turbine’ (LWSWT) has been design by
Prof. Ir. Dr. Abas Abd. Wahad from mechanical faculty, UTM is the practical turbine to
use in our country [6]. This project has been tried at Pulau Tioman and successful. LWSWT have cut-in-speed 1.5m/s and rated velocity around 3.0 m/s. These turbines
have 3 blades, 10 meter diameter with efficiency, 85% and the turbine can operate min
10 hour per day. With this turbine, most places in our country have potential to practice
wind energy system for home electricity. To use LWSWT at home still have one
problem which is the diameter of blades is large, so size of this wind turbine not too
practical to install on the house’s roof. We need some space around our home to install it
but still can be use to generate the power for home uses.
CHAPTER 3
METHODOLOGY
3.1 Introduction
The methodology of this project consists of several approaches and procedures.
In completing this research, many aspects had been taken into consideration. The
procedures that had been taken are referred from literature review through many journals
and articles founded about the small wind energy system. A suitable wind turbine has
been selected for this research. A simplified integrated wind system circuit model is
developed. As discussed in the literature review, there are some projects that have been
done before but they use small wind system as a energy storage only. This project will
extend the previous work by using the latest battery storage, UPS. The information from
journal and books will help to understand how this wind system operates and how much
the output energy can produce suitable with turbine size for our daily using.
23
3.2 Small Wind Energy System
Figure 3.1 Small wind system diagram
Figure 3.1 shows a small wind system diagram. A small wind system consist of turbine
generator, controller, batteries storage (UPS), inverter, and load as the main components
of the small wind energy system. This small wind turbine can charge 12 volt batteries
and run various 12 volt appliances within the building on which it is installed. However,
to simulate the circuit we have to use three blades wind turbine which is cut in speed
around 3 m/s until 4 m/s. The system needs a charge controller to keep UPS from
overcharging. Inverter has been installed to convert DC electricity from UPS to AC
output. This AC output will supply direct to our low power equipment at home likes
lighting. Lastly, anemoscope’s function is to get the value of average wind speed at
home for the whole time.
24
Literature Review
Get the Circuit of Small Wind Energy System
Do the Simulation Using Mat-lab Simulink
3.3 Circuit Simulation and Modeling
Figure 3.2 Simulation flow
After get the circuit, the next procedure is doing the modeling and simulation. At
the beginning, three software have been tried to simulate the circuit which are P spice,
National Instruments Simulink and Mat lab Simulink. P spice and National Instruments
Simulink are not suitable to made modeling of small wind system because they don’t
have some of main component that of wind system. So, the good decision is by using
Mat lab Simulink as the software to complete the model because Mat lab have all the
component that needed, user friendly and easy to get the data. Wind energy system most
easily to model by using specific toolbox from internet for wind system which is Beta
Wind Toolbox. After understand some of the example given, and then try to develop our
own model of wind energy system.
25
3.4 Use real wind speed data for a few cities in Malaysia
After done develop the model of wind energy system, to simulate the model, we
have used the real data of wind speed in Malaysia such data for Kota Bharu, Ipoh and
Senai. By using the different place of wind speed data, we can see which place can
produce more power output. From that, it can be conclude that place is suitable to
practice this small wind system. Table below show the latest wind speed data for Kota
Bharu and Senai ;
Table 3.1 Kota Bharu and Senai wind speed data
Days City
Kota Bharu Senai
1 10.7 9.6
2 10.3 10.1
3 9.9 11.7
4 9.8 11.5
5 15.5 7.6
6 13.5 5.4
7 15.6 5.8
8 14.2 9.2
9 13.4 10.2
10 15.2 9.6
11 11.2 7.6
12 6.7 5.6
13 9.0 8.6
14 11.6 6.3
15 13.0 7.0
16 10.7 8.3
26
17 11.7 10.2
18 11.0 5.0
19 10.7 10.0
20 8.9 11.4
21 6.3 8.8
22 5.4 9.4
23 7.4 7.2
24 5.7 8.1
25 6.8 8.1
26 6.7 8.9
27 5.5 7.2
28 7.1 5.8
29 5.9 7.1
30 5.2 8.8
3.5 Data Analysis and Conclusion
After done the modeling using Mat lab before, used that model to get data output
of power produce by varied the data of wind speed in Malaysia and wind turbine
blades. From this data, we can analysis whither this system can give enough energy to
supply our home low power equipment without using supply from TNB and then, at
the same time can reduce our electricity bill every month. We also will find out where
are the potential places in our country that can practice this small wind system by
using difference wind speed data for a few cities in Malaysia. Model of small wind
turbine that we have to design only to go through how the turbine works and how
many power produce from it. From this design, we can more understand the operations
of wind energy system.
27
The amount of energy that can be captured from the wind is exponentially
proportional to the speed of the wind. The power generated is approximately equal to:
P (watts) = 1/2 D (air density) x A (area of rotor) x V cubed (wind velocity)
28
Figure 3.3 Outline of the Project
Figure 3.3 show the outline of this project; firstly design the basic model of wind
energy system by using Matlab simulink software. Then, keep in the real data wind
speed in Malaysia as the input of the model. After that, do the analysis by variable radius
blades of turbine and variable wind speed data for a few cities in Malaysia. From the
output power of the model, then make some recommendation and conclusion for overall
project.
Literature review
Find the Small Wind Circuit to
Understand
Develop Wind System Model
Analysis Data
Project Conclusion
Mat lab Simulink
Other Alternative Software
End
CHAPTER 4
MODELING
4.1 Introduction
For this project, a Matlab simulink program has been used to model the wind
energy system.Matlab simulink is chosen for this project because it is user friendly and
have the entire component to design a model of wind system. By using the latest wind
beta toolbox, it becomes easier to understand the circuit. This beta wind toolbox can be
downloading from internet and then save at the simulink library. After done design the
model, set the parameter for each block with our own data. Beside that, Mat file from
Mat lab programming also must been used to save the wind speed data and then it can
recall back the data to simulink by using a source block from simulink library. The detail
information will be explained below.
30
4.2 Mat lab/Simulink
Simulink® is an environment for multidomain simulation and Model-Based
Design for dynamic and embedded systems. It provides an interactive graphical
environment and a customizable set of block libraries that let you design, simulate,
implement, and test a variety of time-varying systems, including communications,
controls, signal processing, video processing, and image processing. Add-on products
extend Simulink software to multiple modeling domains, as well as provide tools for
design, implementation, and verification and validation tasks. Simulink is integrated
with MATLAB®, providing immediate access to an extensive range of tools that let
you develop algorithms, analyze and visualize simulations, create batch processing
scripts, customize the modeling environment, and define signal, parameter, and test
data. A Mat lab/Simulink Toolbox for wind turbine applications has been developed
during the project. This toolbox contains models for the main components from a
wind turbine system. Wind Turbine Block set v2.0 is the newest toolbox for
modeling wind system [8].
31
Figure 4.1 Mat lab toolbox
The main libraries from this Toolbox are: Mechanical Components, Electrical
Machinery, Power Converters, Common Blocks, Transformations, Measurements,
Control.
The Mechanical Components library contains: wind models, aerodynamic
models of the wind turbine rotor, and different types of the drive train model (one-mass
model, two-mass model). Since one of the main components in the wind model is the
normally distributed white noise generator some investigations have been done in order
to obtain the same wind time series in all considered simulation tools. It has been found
that the built-in white noise generator from different simulation tools uses different
algorithms and thus different wind time series is obtained simulating the same condition
The Measurements library contains some special blocks like: calculation of the
period for a sinusoidal variable, calculation of the grid angle using a phase locked loop,
32
different modes of calculation for active and reactive power, a block to calculate the
average wind speed for a given time interval, etc.
The Control library contains blocks as: anti wind-up PI-Controller, a maximum
power point tracker block based on a look-up table obtained from the wind turbine
characteristics, active and reactive power control block for a doubly-fed induction
generator. This control algorithm for active and reactive power can also be used in
connection with a reduced order model of the machine.
4.3 Wind Energy System Model
Figure 4.2 Wind system model
33
To develop the above wind energy system, Mat lab Simulink Beta Wind toolbox has to
use. This toolbox has all components of wind energy system which are wind turbine,
drive train, voltage source, induction machine and P&Q measurement. Mat file block
must be use as the input source in order to recall the real data from Mat file. Each
component of the model has their own parameter by double click at each block to set
parameter as needed. After simulate the model, the output power magnitude and
waveform from can been see through the scope block.
4.4 Model Component and Function
Figure 4.3 Input source block
The input source for the system. Real data of wind speed will read from Mat file format
that have been save. The data can be recall from Mat file by fill the file name at this
block same as file name that we save at Mat file. For example, if the data at Mat file
save as kb, so the file name at this block must be kb.mat in order to read that data.
34
Figure 4.4 wind turbine block
Wind turbine component with parameter of radius blades, air density, cut in speed and
cut out speed. The output from turbine is torque.
Figure 4.5 Drive train block
Use to produce speed for generators operate. This drive train block has parameters such
as moment of inertia, shaft gearbox ration and some initial condition that already set up.
35
Figure 4.6 Induction machine block
This block is Squirrel Cage Induction Machine operates as generator or motor with delta
or star connection and the output is the current and torque. These blocks need 240Volt as
voltage input and also need generator speed from drive train to operate. The parameter
of this Induction Machine block has to set as generator with delta connection as show in
figure above.
Figure 4.7 P&Q measurement block
This P&Q block function to measure the value of active (P) and reactive power (Q) in
three phase with the input of three phase voltage and three phase current. This block
only has parameter of frequency that we set as 50Hz.
36
Figure 4.8 Scope block
Scope block can produce the waveform from every connection. By using this scope, we
can know the magnitude of output power.
Figure 4.9 Terminator block
This terminator block is use to terminate the output from any block that we didn’t use.
37
4.5 Summary
The entire component above is important in order to design a basic model of
wind energy system. Matlab Simulink has been choosing as the suitable platform to
design this system. This all block already design from complex math function. In order
to use this all model, we only need to keep in value of parameter that we need.
CHAPTER 5
RESULT AND DISCUSSION
5.1 Introduction
In this project, the power output from the model of wind system is analyzed by
variable the turbine radius blade and variable the wind speed data for different place in
Malaysia. Firstly the output power has been analyzed by variable radius blades at wind
turbine. For this project we used radius blades equal to 5 meter, 10 meter and 15 meter
to get the difference output power. Then, secondly do the analysis by using constant
radius blades which is 10 meter and variable the data of wind speed for Kota Bharu,
Ipoh and Senai.
39
5.2 Analysis Result for Variable Radius Blades
Firstly, by using constant wind speed data which is data for Kota Bharu and then
variable the value of radius blades has to analyze. In this project radius blades 5 meter,
10 meter and 15 meter have been used. The purpose of the analysis is to look the
relationship between radius blades and output power. Figure below will show the output
current and output power for each radius blades as mention above. From figure 5.1 and
figure 5.2, the output current and power are 7 amp and 2kW respectively for radius
blades 5 meters. Next, from figure 5.3 and figure 5.4 both wind turbine use the radius
blade equal to 10 meter, the output current around 15 amps and output power is 4kW can
be produced. Lastly for figure 5.5 and figure 5.6, by using radius blades equal to 15
meter, the output current we get is around 80 amp and output power about 15 kW until
20kW. All the value from the graph we take as magnitude. From this analysis, it can be
summarize that when the value of radius blades increase, the output current and power
also will increase. For the radius blades above 10 meter, the output power will increase
suddenly compare to when using radius below than 10 meter. This analysis can conclude
that by using the larges radius blades, the more output power can produce prom the
model.
40
5.2.1 Radius blades= 5 meter
Figure 5.1 Output current for 5 meter radius
Figure 5.2 Output power for 5 meter radius blades
41
5.2.2 Radius blades= 10 meter
Figure 5.3 Output current for 10 meter radius
Figure 5.4 Output power for 10 meter radius
42
5.2.3 Radius blades= 15 meter
Figure 5.5 Output current for 15 meter radius
Figure 5.6 Output power for 15 meter radius
43
5.2.4 Comparison on the output power for difference radius blades
Figure 5.7 Output power for R=5 m
Figure 5.8 Output power for R=10 m
Figure 5.9 Output power for R=15 m
44
5.3 Analysis Result for Difference City in Malaysia
Second analysis of this project is by using difference wind speed data for a few
cities in Malaysia as input of the model. For this analysis, use constant value of radius
blades which is 10 meter for the wind model and the variable wind speed data for Kota
Bharu, Ipoh and Senai to see whether difference power output can be produce or not.
Actually the output power for Kota Bharu and Ipoh is quit same cause of not much
difference wind speed everyday for both cities. Senai have low wind speed compare to
Kota Bharu, so after keep in the data for this two city, the difference output power
produce between this two cities. From the figure 5.10 and figure 5.11, Kota Bharu
produce output power around 4.2 kW compare to Senai only produce output power
around 3.7 kW. From this analysis, Kota Bharu could be most suitable place to practice
this wind system because more output power can be produce. The figure 5.10 and figure
5.11 below show comparison on the output power between Kota Bharu and Senai output
power.
45
5.3.1 Comparison on the Output Power between Kota Bharu and Senai
Figure 5.10 Output power for Kota Bharu
Figure 5.11 Output Power for Senai
46
5.4 Discussion
From the analysis of this project, it can be summarizing that the output power
will be increase when the value of radius blades increase. Small wind energy system
suitable to use at home have the radius blades between 1-5 meter which can produce
power output below 2kW.In general, by using the real wind speed data, the output from
small wind generator that can be applied in Malaysia is 1.5kW until 2kW.From the
simulation result, Kota Bharu and Ipoh have output power higher than Senai. So, it can
be concluding that Kota Bharu and Ipoh most suitable place to practice this system.
CHAPTER 6
CONCLUSION AND RECOMMENDATION
6.1 Conclusion
From overall project, small wind system which has radius blades from 1 until
5 meter can produce power around 1kW and Kota Bharu have good potential to install
this system. With power output 2kW, it stills not enough to supply all electrical
instruments at our home. So, this small wind system can be used to supply low power
equipment at home such as lighting, parking meter and wireless devices. For wind
turbine which has radius blade larges than 5 meter, it is not practical to install for every
house, maybe it more suitable to supply overall village for one wind turbine. After the
analysis by using real data in Malaysia, it can be conclude that this small wind system
have potential to practice in this country in the future.
48
6.2 Recommendation
After done this project, there are some recommendations for further work in
order to improve this project;
1. Use the detail or more complex model of wind system to get more accurate
output data.
2. Use more wind speed data from all places in Malaysia to find out which places
most suitable to practice this wind system.
3. Apply this wind system model for other country such as Indonesia, Filipina and
Jepun which have more islands with higher wind speed.
4. Use this wind system with battery storage as the backup supply for home and
also industries in Malaysia.
49
REFERENCES
[1] AWEA,“Wind Turbine Basic”[Online].Available http://www.awea.org/faq/wwt_basics.html[ Accessed August 2007] [2] G. Thomas Bellarmine and Joe Urquhart “Wind Energy for The 1990an and Beyond”, University of West Florida,USA,24 April 1997.
[3] WIKI, “Wind Turbine”[Online].Available http://en.wikipedia.org/wiki/Wind_turbine[ Accessed September 2007] [4] BWEA,”Small Wind Energy”[Online].Available. http://www.bwea.com/small/index[ Accessed November 2007]
[5] IEA, “Wind Energy”[Online].Available. www.ieawind.org[ Accessed January 2008]
[6] Mohd Fazril bin Mohamed Ramlee.”Potensi Tenaga Angin di Malaysia”, Faculty of Electric, UTM Skudai, May 5, 2006, 3-13.
[7] CEI, “Renewable Energy”[Online].Available. http://www.clean-energy-ideas.com/articles[ Accessed August 2007] [8] IET,”New Platform to Model Wind System”[Online].Available. www.iet.auc.dk/Research/research_prog/wind_turbine/Projects/SimPlatformPrj
/htm_files/MatlabSimulink.htm [ Accessed September 2007]
[9] ABSAK,”Wind Energy”[Online].Available. http://www.absak.com/alternative-energy/wind-energy.html [Accessed March
2008] [10] MATHWORKS,”Matlab Simulink”[Online Available] http://www.mathworks.com/products/simulink/description1.html [ Accessed February 2008]
