CHAPTER 1

INTRODUCTION TO SMART GRID

1.1 Introduction

1.1.1 Definition:

The smart grid system is vast collection of technologies to provide an electricity network having the ability to solve the major issues related to reliability, cost effectiveness of electric power and decentralization or grid dependency

The smart grid technology using renewable energy sources transferred electricity towards user side with the concept of integration of renewable energy sources.

1.1.2 Why Smart Grid Technology Adopted

The demand of electricity is increased so much by the passage of time, which creates some major problems related to conventional electricity network. By 2020 energy demand will be doubled from the present demand [1]. Smart grid is the result of such efforts which are performed to make availability of electricity more reliable, economical and user friendly with the concept of decentralized network due to two way communication of electricity through network[2].

The Architectural model of a 21st century power system that interconnects everyone to affordable, abundant, clean, reliable, and efficient electricity anytime, anywhere. The purpose of Smart Grid is also to integrate several renewable resources with our national Grid and enhances the efficiency; reliability and thus providing a hassle free Transmission of electric power. It also contributes to reduce carbon emissions and providing a pollution free environment.

1.2 Back Ground

1.2.1 The European Development in the Area of Smart Grid

In the next three decades European member state will expend about 750 billion in power infrastructure. This amount will expend on generation and networks. The European Technology plate form was developed in 2005 to solve the problems of Network Owners, operators and users[3].

1.2.2 Smart Grid Development in USA

In USA the Smart grid developments initiated during first Bush Administration[4]. In 2002 a DOE study describes the hundred of million of Dollar spent In US power systems on transmission practices and results a proposal of construction of transformed national electricity grid upto2030 providing the best and secure transmission of electricity[5].

1.2.3 Smart Grid Development in Australia

Under the Energy Transformed Flagship the Intelligent Grid Program was launched on 19 Aug, 2008. This Program researched in the fields of Control methodologies and economic modeling for distributed generation, Social impact of Intelligent grid, New housing developments and micro grids[6].

1.3 Design Description

1.3.1 Features of Smart Grid

The most important features of Smart Grid Technology are:

  • Integration of Renewable Sources
  • Battery Storage option
  • Provide electric power to both AC and DC loads
  • Advance Monitoring

1.3.2 Proposed Methodology

Above figure shows prototype modeling of smart grid system at micro level along with the integration of several renewable energy resources such as small wind plant and solar panels. The charge controllers are special devices used for the purpose to control the abrupt change in voltage and stop the reverse flow of current towards PV or wind turbine systems, and also control the charging and discharging of batteries.

An integrator is also one of the most important components of our project. The function of this device to integrate powers from both energy sources in a way that during operating time of the sources loads will directly get power from these sources and at night or the time when these sources are not operating loads are facilitated through battery banks.

1.4 Advantages of Smart Grid

A. Motivates and Includes the Consumer

Smart Grid is a end user device it motivates the consumer to generate a free source of electricity and to utilize it in household appliances when electricity from Grid is not available.

B. Provides Power Quality for 21st Century Needs

It provides power free of disturbance, sags, interruptions and spikes.

C. Markets Opportunities

Smart grid supports energy markets that encourage both investment and innovation.

D. Operates Efficiently and Optimizes Assets

Smart grid is easy to install infrastructure, transmit more power through existing systems and optimizes easily with present grid.

E. Reduction in cost of power infrastructure

When renewable energy sources are infused into the power grid, end-use demands can be adjusted to available power supplies. The ability to manage and reduce peak demands demolishes the need for costly peaking and “just-in-case” power infrastructure.

F. Reduced use of polluting plants

Some existing powerplants are not environment friendly which is adversely affecting the environment around us. Smart grid can produce pollution free generation of electricity.

G. Clean power market

During serious air pollution alerts, power plants and heavy industries sometimes shut down. Smart Grid ensures you clean power options.

H. Energy storage

Smart Grid is also equipped with battery backup options which not only stores energy also used as grid shock absorbers as well.

I. Integrate able with Energy Resources and Storage Options

The system also enables "plug-and-play" interconnection to multiple energy resources and storage devices (e.g. solar, wind, battery storage, etc.)

1.5 Brief Introduction to chapters

Chapter 2

This chapter is a survey report about renewable energy sources. Also wind and solar characteristics of Pakistan are given in this chapter. Supply and Demand gap also discussed in this chapter.

Chapter 3

This chapter is about PV system. Complete introduction and types of PV system are discussed also given here the architecture model of PV system with design description. And the experimental values also mentioned in this chapter.

Chapter 4

This chapter defines the wind turbine specifications. Chapter starts from introduction then history discussed and after that design description is completely described. The experimental values also given in this chapter with advantages and drawbacks of wind turbine technology.

Chapter 5

This chapter covers the remaining portion of smart grid technology. First of all integrator is discussed with design after that charge controller and power inverters also discussed with there design and circuitry.

CHAPTER 2

LITERATURE SURVEY

Contents:

  • World Wide Survey of Renewable Energy
  • Demand Supply Gap in Pakistan
  • Depletion in Oil and Gas
  • Energy Sources in Pakistan
  • Wind Energy
  • Solar Energy

2.1 World Wide Survey of Renewable Energy

Renewable energy has an essential contribution in world energy generation. So many projects are under consideration regarding to renewable energy.

2.1.1 Global Status Report

This report describes the market condition, investment and targets as well as policies. The report doesn't describe analysis or conclusions, though it reveals some extra ordinary facts regarding the renewable energy . By the end of 2005 only 45 countries were included in the achievement of renewable energy targets which are increased up to 76 in 2009. According to this report last year was the best era for renewable energy. Capacity in developing countries grew to 119GW, or 43% of the total.

Including Pakistan and magnolia less or more than 8-0 countries has started plantation of wind power plants at commercial measures[7]. Some achievements of the year 2008 are:

  • In just 1 year the capacity of solar photovoltaic plants tripled to 3 GW from 200 KW.
  • Wind power by 29% and solar hot water increased by 15%.
  • Grid connected photovoltaic systems increased up to 13GW, wind energy grew up to 250%, 121GW and total power generation capacity from renewable energy boost up to 75%.
  • Spain becomes the super power in the field of grid connected PV systems with inclusion of 2.6GW. Germany also takes some handy steps and added 1,5GW in their system.
  • Some other developed countries also provide large contributions like USA(3ooMW), Italy ( 300MW) , South Korea ( 270MW) and Japan (240MW) respectively . in total 16GW is the generation of solar including off-grid by 2009 worldwide.

POWER GENERATION (GW)

RENEWABLE ENERGY RESOURCES IN 2009-2010

RENWABLE ENERGY EXSISTING IN 2009-2010

Large Hydro Power

25-30

860

Small Hydro Power

6-8

85

Wind Energy

27

121

Tidal Energy

0

0.3

Solar Systems

5.4

13

Biomass

2

52

Geo Thermal

2

3

Table2.1 Energy Added and Exists in 2009-2010

2.2 Demand Supply gap in Pakistan

If we give a look at demand supply graph then we will come to know that the difference between demand and supply is becoming wider and wider by the passage of time .the scenario in 3rd world countries is totally discriminated e.g. Pakistan. Needs are increasing exponentially but we are desperately lacking in finding out a good solution. if we have an eye view we may find 3 reasons of demand supply gap.

Increase in prices of oil and gas , increase in population and increase in cost of energy .

2.2.1 Energy Demand

With the increase in population energy requirements are also increasing. All the industry and the production of our daily need in dependent upon electricity .

2.2.2 Energy Supply

Current era's total production of energy does not meet the current requirement of energy , though the end results are critical in the sense of increase in demand supply gap . Serious steps are needed to be

2.2.3 Energy cost

If we have eye view on last few decades we will come to see the highlighted reduction in the reserves of oil and natural gas, which causes the increase in the cost of per unit production of electricity. This is also the reason of widening the demand supply gap.

2.2.4 Sustainability level

The systems which are to be used for the generation of electricity must be stable, but unfortunately we have not surety of sustainability level of present system and the graph is gradually decreasing according to our present and future demands . This decrease in sustainability may overcome by using alternative techniques.

2.3 Depletion in oil and gas

A large amount of electricity is being produced by fossil fuels and the present value of electricity generated by fossil fuels is increasing. According to the European energy commission and International energy the present reservoirs of oil and gas are not sufficient enough to meet the future requirements. so as the result after 10-12 years we have the depletion in the percentage of Oil using for the generation of electricity as shown in fig 2.2.

As from the above it is obvious that from 1930 to one word till 2010 there is continuous growth in both oil and gas reserves but after 2010 there is deep declined. If the above graph follows the same pattern there is near future we will be totally dependent upon alternates of energy generation.

2.4 ENERGY SOURCES IN PAKISTAN

The primary energy supplies today are not enough to meet even the present demand. More, a very large part of rural area does not have the electricity facilities because they are too expensive to be connected to the national grid. So, Pakistan like other developing countries in the region is facing a severe challenge in energy deficit. The development of renewable energy sources can play an important role in meeting such challenge.

If we see around yourself Pakistan best suits for Solar (PV, thermal), water, wind and Wastes. These are the best renewable sources and Pakistan doesn't lack these. Pakistan can b benefited from these as substitute energy in areas where these renewable sources exist.

  • Renewable energy
  • Fossil fuels
  • Nuclear power

2.4.1 Renewable energy

It is energy which is produced by natural sources such as wind rain solar and geothermal heat.

2.4.1.1 Types of renewable Energy

  • Wind
  • Biomass
  • Solar
  • Wave and tidal
  • Geothermal

These all sources are best placed in Pakistan and we are not lacking in any at all , thus we can produce great amount of energy using these renewable sources , Capturing renewable energy by animals , plants and humans does not permanently deplete the resource. Fossil fuels are renewable but on a very long time-scale, are exploited at rates that may deplete these resources in the near future.

2.4.2 Fossil Fuels

It includes natural gas, oil and coal . fossil fuels are lacking in Pakistan as well the world therefore renewable sources are needed to meet th essential needs

2.5 Wind Energy

Wind energy is one of the best of renewable sources and probably suits Pakistan atmosphere at peak. As our project is related to wind energy as well. In Pakistan wind energy projects are working under the Pakistan Meteorological Dept with the financial collaboration of Ministry of Science and Technology which are accomplishing many such projects in Pakistan.

About 3% of the total Pakistan's land area is termed as good to excellent for utility scale production of electricity. Fig2.3. shows the variations of wind speeds in different areas of Pakistan

Average wind speed in Lahore is 3m/s as shown in Fig.2.4 . Therefore for the prototype smart Grid system, average wind speed must exceeds the theoretical values as given in[10].

2.6 Solar energy

Its one of the types of renewable energies, as in our project we are working on solar energy, in photovoltaic system solar cells covert sun radiation to DC electricity. The provinces of Sindh , Punjab and Baluchistan and the Thar desert are specially suited for the utilization of solar energy.

The solar statistics in Pakistan is highly favourable for energy generation. According to Fig2.5. the South western province offers perfect condition for utilization of solar energy. Since Pakistan locates near the equator so it has relatively high UV index as compared to other regions of the World.

The solar characteristics graph in the Lahore region is shown in Fig. 2.6. Lahore city also offers suitable condition for harnessing solar energy The average sunlight hours lies between 7 to 8 hours per day which is approximately 2700 hours per annually. Graph in Fig. 3 shows the UV index of Lahore during a day time in the month of April. Usually the radiation intensity has its maximum value at noon .And value of solar radiation reaches its maximum value during the mid of summers.

Chapter No 3

PHOTOVOLTAIC SYSTEM

Contents:

  • Introduction to solar panels
  • History of PV system
  • Photovoltaic Cell Architecture
  • Implementation of PV system
  • Battery

3.1 Introduction:

Solar cell or photovoltaic cell is the device use to convert sunlight into electricity. It works on the basic principle of photovoltaic effect.

3.1.1 Photovoltaic effect

When the photons of light falls on the semiconductor material. The photons try to knockout the electrons from the conduction bands. As the energy gap between valence and conduction band increases and when a sufficient amount of energy is projected by the light photons .the electrons knocked out from their respective atom and started to move freely. These free electrons moves towards n-side and holes created due to the deficiency of electrons in this region moves towards p-side to recombine themselves .This difference of potential allows the flow of current.

The PV cell absorbs incoming light photons in p-type. This p-type layer should be synchronized in such a way that it can absorb as many as photons possible and set free as many as electrons possible, to make a radiant flow of current.

In order to make and efficient flow solar cell , the surface of the cell should be kept rough to maximize the absorption of photons while reflection should be minimized in this way maximum conduction can be achieved

3.2 History

The photovoltaic cell was developed in 1954 at Bell Laboratories. The first highly efficient solar cell was developed by Daryl Chapin, Calvin Souther Fuller and Gerald Pearson in year 1954 using a diffused silicon p-n junction. Firstly, cells were developed for toys and other minor uses, as the cost of their production was very high.

Design of solar cells is improved day by day to utilize it for more applications. The applications for that solar panels are used are different and there are three levels of generation

3.2.1 First Generation:

First generation cells are single junction devices and they have large area also having high quality with reduction in production cost

3.2.2 Second Generation:

These materials are developed to address energy requirements and production cost. They reduce high temperature processing as vapour deposition, electroplating and Ultrasonic nozzles.

3.2.3 Third Generation:

The aimof these technologies is to improve poor electrical performance of second generation technologies with low production cost.

3.3 Photovoltaic cell architecture

A PV module consists of a silicon cell .These cell are connected in series or parallel manner in order to produce desired voltage and current .Inside a PV cell a circuit is present that is sealed from the envoi metal protective lamination .A PV panel consists of one or more modules joined together. Finally these panels are combined to make a single PV array which is a complete electricity producing unit.

The performance of a PV array or its modules is rated by its maximum throughput power under S.T.C (Standard Test Condition).STC is defined as when a PV module\cell is operated under 25 °C (77F), with an incident solar irradiation of 1000 W/m2 with the spectral distribution of 1.5 air mass. These are the perfect condition for a PV module to operate in , but in actual the performance of a PV module is almost 80 to 90 percent of its STC rating.

The operating lifetime of a PV module is between 20 to 30 years .Most of the manufactures offers warranty of 20 or more years of its DC output power to a sustainable amount .PV modules are also lice censed under (UL) qualification test for its reliability checks.

3.3.1 Types of Solar Cell

Now a days there are various types of cell materials are developed. Multi junction PV cells

are made in order to increase the cell efficiency while decreasing its volume and weight. But they are far more expensive then an ordinary silicon cells.

The maximum efficiency of a PV cell is achieved almost to 30 percent by doping different intrinsic material together .Example of the exotic materials are Gallium arsenide and Indium serenade etc. However silicon cells are the most common and widely used PV cells.

There are three major types of Silicon cell:

  • Amorphous silicon solar Cell or Thin Film Cell
  • Mono-crystalline Wafers
  • Poly crystalline Cell

Amorphous Silicon Solar Cell

Amorphous technology is often seen in small devices, such as those in garden lamps or calculators, although amorphous panels are also increasingly used in other larger applications. They are formed by depositing a thin film of silicon onto a sheet of different material such as steel. The panel formed as one piece and each cell is not as visible as in other types.

Efficiency of an amorphous solar cell is between 6 and 8%. The Lifetime of an amorphous cell is however shorter than that of crystalline cell. Amorphous cells have current density of about 15 mA/cm2,and the voltage of the cell without any connected load is 0.8 V, which is more as compared to crystalline cells. The efficiency of amorphous solar panels is low as those made from individual solar cells, although improvement has been made over recent years to a point where they can be use as a practical alternative to panels made with crystalline cells.

Crystalline silicon solar cell

The maximum efficiency of silicon solar cell is around 23 %, by adding some other semi-conductor materials it can increase up to 30 %, it depends on wavelength and semiconductor material being used. Crystalline solar cells are made up of wafers like stuff, which has about 0.3 mm thick and diameter of 10 to 15 cm. They can generate approximately 35 mA of current per cm2 of area at voltage of about 550 mV at full illumination.

Crystalline solar cells can be wired in series or parallel to produce a solar panel. As each cell produces a voltage of between 0.5 and 0.6 Volts, 36 cells equipped in series are needed to produce an open-circuit voltage of about 20 Volts. This is enough to charge a 12 Volt battery under certain conditions. Although the efficiency of mono-crystalline cells is slightly higher as compared to that of a polycrystalline cells, but there are some practical difference in their performance. Crystalline cells have longer lifetime than that of amorphous solar cells.

In our project we have used crystalline silicon cell because they are more efficient yet lesser in volume as compared to other types of solar cell, easily available in market and it is more economical.

Polycrystalline Cell

Polycrystalline silicon, also called poly silicon , consists of small silicon crystals of Polycrystalline cells which can be recognized by a visible grain, a “metal flake effect”. Semiconductor grade (solar grade) polycrystalline silicon then form to "single crystal" silicon, that is randomly associated crystallites of silicon in "polycrystalline silicon" are converted to a large "single" crystal[11]. Single crystal silicon is used in manufacture most of Si-based microelectronic devices. Polycrystalline silicon can be available up to 99.9999% pure.

3.4 Implementation of PV system:

3.4.1 Types of PV system

There are three types of PV system being implemented around the world depending upon its function and integration with other energy resources.

  • Standalone PV system
  • Grid Connected PV system
  • Hybrid Systems

Stand alone PV system

This type of system is usually present in our wrist watches, calculators and in space crafts also. These are dependent totally on its self generated power through solar panels and are directly used by DC loads or AC loads through inverter.

In some system battery bank is also available to store the unused power to facilitate loads during night or under low light conditions.

Further more a charge controller is also required in order to avoid battery from over charging and deep discharging. An inverter is also employed to provide power to AC loads.

Grid Connected PV system

In grid connected type the PV module has also backed up with WAPDA line or Grid connection. In this way if load is not getting enough power from the PV module or its battery, it will switch to the WAPDA line. This type of system is most commonly used around the World. Its applications are found mostly in small industries and homes.

Hybrid System

In this type the PV system is also integrated with two or more type of energy resources which may or may not be renewable resources .For example a wind turbine, steam engine or a small hydro plant etc. Other energy sources can also be integrated depending upon climate, geographical location of the place and several other perspectives. These systems are more appropriate for remote applications such as military installation, communication stations and rural villages.

3.4.2 Design Methodology

Our project is based on a Hybrid System Consisting of a PV module and a windmill as two renewable energy resources, we have chosen these sources keeping in mind the climate and terrain of Lahore.

3.4.2.1 Components of Photovoltaic system:

  • Solar cell Panel
  • Inverter
  • Charge Controller
  • Batteries
  • Integrator

The major component of our system is the integrator .The function of this device is to integrate powers from both energy sources in a way that during operating time of the sources loads will directly get power from these sources and at night or the time when these sources are not operating loads are facilitated through battery banks. A controller is placed in the integrator circuit that is continuously monitoring the voltage level being provided by the sources. If the load can operate single handed by either of the sources the rely will build its connection from load with that source while the energy generated by the second source is being stored in the batteries .If both sources are required to derive a certain load rely opens up its connection of both sources with the load.

When both sources are not providing a sufficient amount of power to the loads the controller will check whether batteries could provide sufficient amount of voltage so, it will start delivering power to load from the battery bank otherwise an LED blinks indicating that system cannot provide sufficient amount of power and will shutdown eventually.

3.4.2.2 Solar Panel Characteristics

I/p rating

1kw/m2

DC input

45W

Normal Volts

12V

Vpp

1 volt at SOC

Length

0.685m

Width

0.584m

Area

0.4004m2

No. of cells

36

Length of each cell

0.15m

Width of each cell

0.0513m

Area of each cell

0.0077m2

Area of total no. of cell

0.278m2

o/p per m2

45/0.278=161.6 W/m2

100 Watts

0.6176m2

Area Required

0.6176m2

Table 3.1. Solar Panel Characteristics

3.4.2.3 Experimental Values

This table shows the experimental results of output voltage and output current with respect to different timings and temperature variations in a day.

Sr.#

Time

Temp °C/K

UV Index watt/m2

DC O/P Voltage

(V)

DC O/P Current

(A)

DC O/P Power

(W)

solar

solar

solar

1

08am

22/295

16

12.2

3.27

40

2

09am

23/296

16

12.17

3.32

40.5

3

10am

24/297

18

12.32

3.32

41

4

11am

25/298

19

12.58

3.25

41

5

12pm

24/297

18

12.41

3.22

40

6

01pm

23/296

17

12.33

3.21

39.7

7

02pm

21/294

15

12.14

3.16

38.4

8

03pm

21/294

15

12.17

3.21

39

9

03pm

20/293

14

11.91

3.27

39

10

04pm

18/291

11

11.42

3.23

37

Table 3.2. Solar Panel Throughput

3.4.2.4 Factors Affecting Output Power

STC(Standard Test Condition)

The electricity produce by solar cell is in DC, the DC output of solar panel is Tested under the STC that is

Cell Temperature= 25°C

Solar Radiation Intensity= 1000 W/m2..

Air Mass= 1.5

These are the standard test condition at which Solar cell gives its Maximum Efficiency, in other conditions there is almost 10 to 15 percent of decrease in the efficiency of cell with respect to its STC rating.

Temperature

Output power of the solar cell is inversely proportion to the increase in temperature of the cell. For a crystalline module , a typical temperature reduction factor proposed by CEC is 89 percent which means ”95 watts” module will typically provide 85 Watts (95watts*0.89=85watts) under sunlight conditions during summer seasons.

Mismatch and wiring Losses

The performance of the system can be affected due to mismatch of module connections. The loss in power also depends upon the increase in length of wire between source and load. As the distance between source and load increases losses also increases. Therefore the distance should be kept minimal to get maximum power throughput.

DC To AC conversion Losses

Since our system produces DC power and to facilitate AC load an inverter is also employed. Inverter converts DC power to AC and it may also cause losses due to this convergence. This results in Loss of generated power.

3.5 Batteries

The energy used produced by the system remains unused is saved in the batteries. This saved energy can be utilized when the system is not providing direct power from the sources under low light or during night.

Since the batteries used in our system is often charged/discharged this is the reason we haven't preferred car batteries for our system also they takes lots of space and maintenance is also required for these type batteries. We are looking for a less or maintenance free batteries for our system yet it can be easily carried to different places and also it should be long lasted[12].

3.5.1 Types of Batteries

§ Sealed Gel Cell Lead Acid Battery:

In sealed gel cell or VRLA battery fumed silica is an additive to the electrolyte, which hardens the liquid to form a gel. This ingredient dries the gel until fissures develop between the anode and the cathode. These cracks provide the path for conduction. This type of battery is used for PV system. It is durable, maintenance free and has long life.

Charging

Pb+2H2 SO4+PbO2=======èPbSO4+2H2 O+PbSO4

ç========

Discharging

§ Dry Cell Battery

This battery is used with the windmill. It is a common zinc-carbon battery. It consists of a paste which has enough moisture in it to function. Since it does not have electrolyte in liquid form so, it doesn't leak or drip out when handled roughly. It is economical and is suitable for portable devices.

3.5.2 Charging and Discharging Time of Battery

SOLAR:

Since P=vi => I = P/v = 45/12 = 3.75 A

Battery is 40 Amp-hours, 12v

Energy stored in Battery= C=iT

Where T is mean time to charge the Battery

T= C1/i =40AH/3.75A = 10.66 hours

Therefore C1 = 40*0.8 = 32AH

We can only discharge up to 80% of battery

CHAPTER 4

WIND TURBINE

Contents:

  • Introduction to wind turbines
  • History of wind turbines
  • Design Description
  • Experimental Values
  • Battery Charging Time
  • Advantages and Disadvantages
  • Economical View

4.1 Introduction

4.1.1 Definition

The machine which transforms the kinetic energy in the wind to mechanical energy in the shaft and finally into electrical energy in a generator is known as wind turbine.

Due to sun heat air is heated and rises leaving a vacuum and cooler air from surrounding rushes in to fill it up. This movement of rushing air is known as wind. And wind energy is the energy contained in the force of wind blowing across the earth surface.

4.1.2 Types

There are two types of wind turbine

  • Vertical axis wind turbine
  • Horizontal Axis wind Turbine

Vertical Axis Wind Turbine

There is vertically aligned shaft in this type of wind turbine. The most important advantage of this type of turbine is that there is no need for the turbine to be pointed into the wind for effectiveness. These Wind turbines Are used on sites that exhibits variable wind direction. A wind force from any direction can be used by this device.

Horizontal Axis Wind Turbine

This type of machine houses an electric generator and the main rotor shaft at the top of the tower. To produce electricity, both need to be pointed in the wind. A wind vane for small motors and a servo motor for large turbines is used. The rotation of blades controlled by gear box which increases the rotational speed of wind blades.

4.1.2.1 Why Horizontal Axis wind turbine is better than Vertical Axis?

The most frequently used design in wind farms and for home turbines is horizontal axis wind turbine. In this design blades are perpendicular to the direction of the wind and receiving more power for the purpose of rotation. The problem with the Vertical axis wind turbine is that the torque created by its shape added some stress on the tower that making it unreliable. The maintenance and installation of horizontal axis wind turbines is easy.

4.2 History

4.2.1 Early History Up to 1875

First wind turbine is used in Persia for grain grinding or water pumping and of the type of Vertical axis turbine. According to the first documentation of wind mill grain grinding is the wind mill application. About 2000years ago grain grinding is also the wind mill application in China but there Vertical axis wind turbine is used.

4.2.2 Role of Smaller Systems

At the subsistence level the most important application of the wind mill is the mechanical water pumping using relatively smaller systems having rotor Diameter from one to several meters. During the 19th Century these systems are perfected in the United States. The Aermeter and Dumpster Designs are still using now a days in United States.

4.3 Design Description

Wind is the important factor for designing a wind turbine. Wind strikes on he blades and they convert wind energy into rotor rotational energy. The block Diagram of wind turbine is shown as;

4.3.1 Wind Speed

4.3.1.1 Wind Varies With Height

First of all speed of wind is very important. At ground level wind speed is no more but as height increases wind speed also increases because the obstacles such as buildings vanished as move upward.

This is the important relationship of wind speed and height. The standard height is 10m for meteorological observations. At a very low speed it is very difficult for turbine to rotate and at high speeds there may be faced damages

At sea level density of air is 1.23kg/m3. This density will decline as the altitude increases. The graph below showing the density variation with altitudes.

4.3.1.2 Wind Speed Output Power

Power Generated by the wind is determined by following equation.

3

Where,

Density of Air=3

Swept Area= 2

Wind Velocity=

4.3.2 Wind Blades

4.3.2.1 Number of Blades

In this project horizontal axis wind turbine has 3 blades to extract energy from wind. Reason is that stability of wind turbine. A rotor having an even number of blades facing stability problems. Because when the uppermost blade bends backward due to the reason it gets maximum power from wind, the lowermost blade passes in front of tower and in the wind shade. If wind speed and tip speed ratio is constant the two bladed turbine has high RPMs, but low power output and cost than three bladed turbine. Another disadvantage of two bladed wind turbine is that it will receive higher wind at the top than bottom. This causes a vibration problem caused by couple different reasons. And vibration in wind turbine is undesirable[15].

The three bladed turbine solve all problems. Any thing more than 3 blades add drag force. When moving in the air blades are efficient that move at least here times faster than the wind speed.

4.3.2.2 Material of blades

Wind turbine have blades of different materials. Blades may be made by wood, PVC, Aluminium alloy, fiber glass. Each material has its own characteristics. Wooden blades are easy to make and easy to destroy. Wooden blades are used in simple and small wind turbines. PVC blades have light weight and easy to install but used only for small wind turbines. Aluminium alloy blades not unusual blades material for small wind turbines. And mostly used for 1kw-5kw rated wind turbines. Fiber glass is the popular material. It is difficult to use it for home or small industry turbines because it is expensive.

In this project horizontal axis wind turbine has 3 blades made by PVC. Because PVC material is used for small wind turbines due to the reason it is light weight and cheap material.

4.3.2.3 Design of Blades

Wind turbine blades are working by generating lift due to their shapes. Wind blades have one side more curved that is generating low air pressure. While on the other side of blades high pressure air pushes. In the result a force acting perpendicular to the direction of flow of air.

As the blade is turned to present it self at a greater angle to the wind the lift force increases. This angle is called “Angle of Attack”. But at very large angle of attack blades “stalls” and Lift force decreases. So there is optimum angle of attack to generate maximum lift[16]. A drag force also acting parallel to the wind flow and increases as angle of attack increases. If airfoil shape is good the lift force is greater than drag force. And at an angle slightly less than maximum lift angle the blade is at its maximum lift to drag ratio.

4.3.2.4 Length of Blades

The length of blades determine by following equations;

3

2

3

Where;

P is the rated output power

A is the Swept Area

R is the Radius of wind blades

Wind speed is the most important constrain nature put for the wind turbine. We not have any control on it. Second constrain is tip speed ratio (TSR), set by designers. TSR number for the given wind speed is always set high as possibly so that more power extract due to high rotation. TSR value is not set as high as it causes wind turbine damages.

TSR and other parameters are closely related by the following equations;

Where;

Nis the revolutions per minute

Ris the Radius of wind blades

Number of Blades

3

Material of Blades

PVC

TSR

5

Blades Efficiency

0.4

Blade Radius(ft)

2

Wind Speed(m/s)

5

Power(watt)

35.6

Rotational Speed(RPM)

392

Torque(Nm)

0.87

Table 4.1. Wind Blade Design Description

Radius(ft)

Chord(inch)

0.2

21.084

0.4

10.536

0.6

7.032

0.8

5.268

1.0

4.212

1.2

3.516

1.4

3.012

1.6

2.64

1.8

2.34

2.0

2.112

Table4.2 Wind Blade Calculations

4.3.3 Wind Turbine Generator

4.3.3.1 Types

  • AC Generator
  • DC Generator

In this project DC Generator is used and output power of DC generator is converted into AC by using single phase 220V AC inverter.

DC Generator

4.3.3.1.1 Introduction

The energy conversion from mechanical to electrical is called generator action.

Electromagnetic Induction

When the conductor cuts the magnetic field of lines, as a result a voltage induced in it. This is the basic principle of electrical generators.

4.3.3.1.2 Motional Voltage

In the magnetic field when the conductor moves from initial position to final position , the motional voltage can be expressed as;

Where;

e induced voltage in V

B magnetic flux density in Wb/m2

L active length of conductor in m

V speed of conductor in m/s

angle between conductor and magnetic field

4.3.3.2 DC Generator Construction

DC generator is made by the following components;

  • Stator
  • Rotor
  • Armature Windings
  • Commutator
  • Brushes

Induced emf of a DC Generator

According to Faraday's Law of electromagnetic induction;

The product of emf per conductor and the number of conductors in series per parallel path is equal to the net emf induced.

The electromagnetic torque will be;

Where;

Ec induced emf per conductor inV

Eg induced emf in V

P number of polls of generator

flux per pole in Wb

N speed in rpm

Z total number of armature conductors

A number of parallel paths

4.3.3.3 Theory of communication

During the operation of generator the coils or conductors moves from one pole to another. The direction of current in the coils reverses by the combined action of commutator and brushes. The brushes are fixed on commutators segments. When the coils rotate in clockwise direction the brushes move from one segment to another.

4.3.3.4 Voltage regulation of a DC Generator

As the generator load increases it is used to identify the change in terminal voltage. It is also defined as change in voltage no load to full load and expressed in mathematical form As;

4.3.3.5 Types of DC Generator

DC generators are of two types.

  • Separately excited DC Generators
  • Self Excited DC Generators

Self excited DC Generators are further categorized as;

  • Series Generators
  • Shunt Generators

4.3.3.6 Losses of DC Generators

DC Generators has some power losses as;

  • Copper Losses
  • Iron Losses
  • Mechanical Losses
  • Eddy current Losses
  • Hysteresis Losses

4.3.3.7 Efficiency of a DC Generator

Efficiency is the ratio of output power and input power. Efficiency of generator has dependency on load.

Generator Output

Variable loss

Constant loss

Input Power

Generator Efficiency

Efficiency will be maximum when he constant loss will be equal to variable loss.

4.3.3.8 Design Description

  • Wind Turbine Startup Wind speed 1.5-2m/s
  • Generating Power 200W
  • Generator Weight 5kg
  • Out put voltage is variable so it is synchronous
  • Permanent Magnet motor

Rated Power(Watt)

24.92

Rated Voltage(V)

12

Startup wind speed(m/s)

1.5-2

Rated rotating speed(RPM)

358

Rated wind speed(m/s)

5

Security wind speed(m/s)

35

Rotor Diameter(inch)

1.3

Generator material

Casted Iron

Generator type

Synchronous

Table 4.3 Wind Turbine generator specifications

The efficiency of our generator must be 0.7* Rotor net output power.

So, if Rotor output power is 35.6 Watt. Then Generator efficiency will be 24.92 Watt.

4.3.4 Tower

Wind turbines are mounted on tall towers to capture more energy. Towers are made by tubular steel or steel lattice because wind speed is higher and less turbulent on 30m or more above ground.

Wind speed is faster at high altitudes than low altitudes. From 10m to 120m wind speed is easily observed so towers are mounted in this range. At high altitudes wind density is less than at sea level but this is negligible because in the equation power is proportional to square of velocity but proportional only to density[17].

In this project tower has 48mm diameter and length of tower is kept at 4ft. Because tower must be minimum two times greater than the radius of wind blades.

4.4 Experimental Values

These values of wind turbine are taken on different timings in a day of 13May,2011.

These values shows that variations of wind speed on effected on output power of wind turbine.

By using 12V-3A battery as a load the experimental values are given below;

Timing

Output Voltage(V)

Output Current(A)

Rotational Speed(RPM)

08AM

9.61

0.12

257

09PM

12.84

0.48

358

10AM

14.25

0.61

478

11AM

17.32

1.14

635

12PM

13.8

0.54

427

01PM

9.5

0.1

248

04PM

11.9

0.35

311

Table 4.4 Experimental values taken on different timings on 13May,2011

4.5 Battery Charging And Discharging Time For Wind Turbine :

Battery is 80 Amp-hours, 12v

Since P=vi => I = P/v = 200/12 = 16.67 A

Where T is mean time to charge the Battery

Energy stored in Battery= C=iT

T= C2/i = 80AH/16.67A = 4.799 hours

we can only discharge up to 80% of battery

Therefore C2 = 80*0.8 = 64AH

After integrating both energies stored in the batteries

C = C1+C2 = 32AH+64AH = 98AH

Output load = 200W (AC)

Time to utilize the total batteries power = T = C/i =

Since P=vi => i= P/v =200/12 = 16.67A

98AH/16.67A = 5.88 hours

4.6 Advantages and Disadvantages

4.6.1 Advantages

  • Wind blows day and night which allows wind mill to produce electricity throughout a day.
  • As wind speed varies energy output from wind turbine also varies.
  • Wind energy is domestic and this renewable energy has a little environmental impact. Land used for wind farms can also be used for other profitable activities such as farming and forestry.
  • The decreasing cost of wind power ensure that it will become a viable energy source in U.S and worldwide also.
  • Compared to solar panels wind generators do not take up that much space.
  • Wind turbine is the alternative energy source and prove to be a great resource to supply energy to rural areas[18].

4.6.2 Disadvantages

  • Wind turbine depends on wind, if there is no wind there is no output power.
  • Some blades have a span of 100ft or more. If they are moving with high speed just like a propeller it is difficult to see them. So with such height and high speed birds fly into the blade path and get killed.
  • Sounds from wind speed

Increasing tip speed causes less sound

The closest neighbour should be at 300m almost experiences no sound.

4.7 Economical View

  • The cost of typical wind turbine rated 600kw is $450,000.
  • Installations costs are approximately $125,000.
  • There fore total cost will be $575,000.
  • The average cost for large, modern wind farms is about $1000 per kilowatt electrical power installed.
  • Modern wind turbines are designed to work for 120,000 hours of operation throughout there design life time of 20 years.
  • Maintenance costs are 1.5-2 percent per years.

CHAPTER 5

IMPLEMENTATION

Contents:

  • Integrator
  • Charge Controller
  • Power Inverter
  • Results
  • Conclusion and Future Work

5.1 Integrator

5.1.1 Introduction

5.1.1.1 Definition

An integrator is a circuit which is bringing together subsystems into a whole and ensuring that those subsystem work together, the practical known as System Integration.

The integrator (hybrid) system is combine two or more than two subsystems and give continues and reliable power. And store the power by using the battery bank.

5.1.2 Back ground history

As we know the renewable energy in the form of wind turbine and solar panel has been around for over 100 years. But first it use apart with each other. But the integrator(hybrid) system are introduce after 1990 AD.

In Dec 1992, this involved the German Agency for Technical Operations(GTZ) in co-operation with the Indian institute of technology in new Delhi. The follow-through has been the implementation of a plan to introduce a wind-solar hybrid system for application in rural households throughout in India.

Aug 2001- UNTRON was selected by IT Power for electrification of an ”island” of coast of Pondicherry through use of wind-solar hybrid system. This project was completed in Aug 2001 and till dated has proved 100% availability.

Aug 1, 2006- In Texas, the Bush land team designed wind-solar and biodiesel hybrid system.

July 10, 2008- Sea party Technology Co Ltd was incorporated on 10 July, 2008 in Taiwan as a private limited company. Company will integrate wind-solar power supply system.

June 2009, Hunan University signed an agreement into another technology research on wind -solar hybrid power control system.

5.1.3 Design Description

5.1.3.1 Feature

Integrator is heart of Smart Grid. Our integrator deliver the uninterruptable power and provide regulated 12.3v DC voltage to load and 14.3v dc to battery bank. Automatic switch the sources. one source give power to load and at the same time second charge the battery bank. The voltage are regulated at 12.3v at load terminal. So, when load increase the voltage drop occur across the terminal of load. The system not damage so by sensing the voltage load switch at other source. Because the sources are variable so, If the load more than the capacity of wind turbine the load automatic switch on solar panel and orange led on and vice versa. If load does not drive from both sources than load switch at battery bank and green led is on. If both power sources and battery bank not provide the power than the system auto shutdown and red LED is on. Our integrator give above 80% efficiency.

5.1.3.2 Components

We use 1N4001 blocking diode, which block the reverse current that in night the when solar panel is off and generator of wind turbine not rotate as load. For automatic switching we use DC 12v relays with the help of pic16f877A and BC338 transistor. we use LM7805 provide fix 5v input to microcontroller And using internal ADC of pic16f877A microcontroller and programmed as such that it sense the voltage level and switch the relays. for voltage regulation we use 1N5243 13v zener diode and D1047 power transistor which pass max 12A current. At load terminal we use 6800uf capacitor because when relay switch the load do not off. For voltage sensing we use potentiometer.

5.2 Charge controller

5.2.1 Introduction

Charge controller is a circuit which control the charging and discharging of battery.

5.2.1.1 Preventing Overcharge

We use the led Acid battery. When terminal voltage of our battery goes up to 13v it supposed to b battery full charge. We use internal ADC of pic16f877A microcontroller which sense the voltage. When voltage goes up to 13v the controller switch off relay which is at the input of charge controller. And no more current flow and charging also stop and orange led is on. And switch on the relay which is at the the output side which indicate that the battery available for use.

5.2.1.2 Preventing Discharging

And at the same method when battery voltage is 11.7v supposed to b that the battery is half empty. And relay1 switch on. And relay2 also switch on for battery availability. At this time the led green is on. But if battery voltage below to 11v it suppose that battery empty than relay2 is switch off, that the battery not available for further use. And the Red led is on.

5.2.1.3 Design of charge controller using pic16f877A

By using internal ADC of pic16f877A microcontroller we sense the voltage from potentiometer. And fix the level of voltage 13v for stop charging and 11v for stop discharging. We use two relays, pic16f877A and LM7805 for fix 5v for input voltage of pic16f877A microcontroller.

5.3 Power Inverter

5.3.  Introduction

5.3.1.1 Definition

An inverter is a electronic circuit that convert DC(direct current) into AC(alternating current). The converted required voltage and frequency with the use of transformer, oscillator and power transistors.

5.3.1.2 Types

There are three types of inverter as follow,

  • Square wave inverter
  • Modified sine wave inverter
  • Pure sine wave inverter

We use square wave inverter because it has more efficiency and low power consumption and low costly than others.

5.3.2 Components

We use LM7809 for fix 9v at which IC CD4047 operate and a square wave produce. the square wave input to c1061 NPN power transistor and the output of c1061 is the input of 2N3055 NPN power transistor. We use four c1061 and six 2N3055. We use a center tap transformer which step up the voltage from 12v Ac to 220v Ac. Our circuit is of 500w power, but the transformer of our circuit is very small which give only 1A current at 220v. so the power of our circuit is 220w maximum.

5.3.3 Drawbacks

The main difference or drawback of this type of inverter is that it only use for non-inductive load such as bulb etc. It is not used for inductive load such as household fan, motor etc.

5.4 Results

Sr.#

Time

Temp °C/K

Turbine

RPM

UV Index watt/m2

DC O/P Voltage

(V)

DC O/P Current

(A)

DC O/P Power

(W)

DC O/P Power

(W)

AC O/P

V

(V)

AC O/P

I

(A)

AC O/P Power

(W)

Efficiency

Wind

Solar

Wind

Solar

total

Wind

Solar

Total

Whole system

%

1

08am

22/295

257

16

9.61

12.2

0.12

3.27

3.39

1.15

40

41.15

37.45

219

1.02

225

90

2

09am

23/296

358

16

12.84

12.17

0.48

3.32

3.80

6.16

40.5

46.66

41.2

219

1.02

225

88

3

10am

24/297

478

18

14.25

12.32

0.61

3.32

3.93

8.7

41

49.7

42.3

219

1.01

223

85

4

11am

25/298

635

19

17.32

12.58

1.14

3.25

4.39

19.75

41

60.75

58.6

219.1

1.04

229

93

5

12pm

24/297

427

18

13.8

12.41

0.54

3.22

3.76

7.45

40

47.45

42.3

219.2

1.05

232

89

6

01pm

23/296

248

17

9.5

12.33

0.1

3.21

3.31

0.95

39.7

40.65

35.47

219.3

1.06

237

87

7

02pm

21/294

101

15

5

12.14

0.02

3.16

3.18

0.1

38.4

38.5

33.43

219.5

1.08

239

88

8

03pm

21/294

291

15

10.4

12.17

0.17

3.21

3.38

1.8

39

40.8

35.6

219.5

1.08

240

89

9

04pm

20/293

311

14

11.9

11.91

0.35

3.27

3.62

4.16

39

43.16

38.1

219.4

1.08

239

89

10

05pm

20/293

730

11

19.16

11.42

1.25

3.23

4.48

23.95

37

60.95

56.75

219.5

1.07

237

93

11

06pm

25/298

845

20

20

11.6

1.31

3.2

4.51

26.2

37

63.2

59.1

219.5

1.07

237

93

5.5 Conclusion and Future Work

5.5.1 Summery

At the end of this project , there is an integrated system of wind turbine and solar panel at COMSATS Lahore campus. The wind turbine vary the voltage from 0v to 24v and the solar is maximum 16v. the integrator automatic switch with respect to load. If there is no load the system will store the energy into battery bank. And for storing energy we use charge controller for stop overcharging And discharging of battery bank. when we required more power we use battery bank. Because the both power sources provide DC power and most house and office appliances are AC. So we use a power inverter to convert DC power into AC power. We use a square wave inverter. Which have better efficiency than others. But the drawback is that we not use inductive load such as motors etc. We use only non-inductive load such as bulb etc.

5.5.3 Future work

There is a integrated method which we use. By this method we expand the whole system such for an small village. Because the solar-wind hybrid system more efficient in rural area rather than urban area. This method we integrate more than two systems such as biomass, diesel, solar, wind at micro level which is called smart grid. And further we integrate at macro level such as with conventional grid. By using these renewable sources we make some small smart grid stations at micro level and destroy the present energy crisis particularly in Pakistan.