Minor Project.docx

CONTENTS DECLARATION ACKNOWLEDMENT CERTIFICATE CONTENTS LIST OF FIGURES LIST OF TABLES INTRODUCTION ABSTRACT PROJECT BACKGROUND

Chapter 1: Wind Turbines 1.1 Horizontal Axis Wind Turbines 1.2 HAWT advantages 1.3 HAWT disadvantages 1.4 Vertical Axis Wind Turbines 1.5 VAWT advantages 1.6 VAWT disadvantages 1.7 Wind turbine glossary

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Chapter 2: An Introduction to the Small Wind Turbine Project 17-22 2.1 Small Wind Turbine Market 2.2 Small Wind Turbine Project 2.3 Small Scale Wind Energy Portable Turbine (SWEPT) 2.3.1 SWEPT design specification and Construction 2.3.2 Experimental set-up 2.4 Advantages of Small Scale Turbines

Chapter 3: Conclusion

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Chapter 4: Bibliography

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LIST OF FIGURES Fig.1.1 Horizontal axis wind turbine Fig.1.2 Vertical axis wind turbine Fig.1.3 Parts of a wind turbine Fig.1.4 Power coefficient vs tip speed ratio Fig.2.1 Small wind turbine proposed concept Fig.2.2 Small scale windmill prototype Fig.2.3 Experimental setup with schematic diagram

LIST OF TABLES Table 1.Countries with installed capacity Table 2 States with strong potential: (potential MW /installed MW)

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INTRODUCTION Renewable Energy Sources are those energy sources which are not destroyed when their energy is harnessed. Human use of renewable energy requires technologies that harness natural phenomena, such as sunlight, wind, waves, water flow, and biological processes such as anaerobic digestion, biological hydrogen production and geothermal heat. Amongst the above mentioned sources of energy there has been a lot of development in the technology for harnessing energy from the wind. Wind is the motion of air masses produced by the irregular heating of the earth’s surface by sun. These differences consequently create forces that push air masses around for balancing the global temperature or, on a much smaller scale, the temperature between land and sea or between mountains. Wind energy is not a constant source of energy. It varies continuously and gives energy in sudden bursts. About 50% of the entire energy is given out in just 15% of the operating time. Wind strengths vary and thus cannot guarantee continuous power. It is best used in the context of a system that has significant reserve capacity such as hydro, or reserve load, such as a desalination plant, to mitigate the economic effects of resource variability. The total capacity of wind power on this earth that can be harnessed is about 72 TW. There are now many thousands of wind turbines operating in various parts of the world, with utility companies having a total capacity of 59,322 MW. The power generation by wind energy was about 94.1GW in 2007 4|Page

which makes up nearly 1% of the total power generated in the world. Globally, the long-term technical potential of wind energy is believed to be 5 times current global energy consumption or 40 times current electricity demand. This would require covering 12.7% of all land area with wind turbines. This land would have to be covered with 6 large wind turbines per square kilometer. Some 80 percent of the global wind power market is now centered in just four countries—which reflects the failure of most other nations to adopt supportive renewable energy policies. Future market growth will depend in large measure on whether additional countries make way for renewable energy sources as they reform their electricity industries.

Table 1.Countries with installed capacity

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India’s Market Overview of Wind Energy Overview India has a vast supply of renewable energy resources. India has one of the world’s largest programs for deployment of renewable energy products and systems 3,700 MW from renewable energy sources installed.

Table2 States with strong potential: (potential MW /installed MW)

The Project The projects are to install two 0.8 MW wind turbine in Karnataka, India. These will generate renewable electricity, to displace fossil fuel powered electricity from the grid. Each turbine will generate enough electricity each year to power the equivalent of 550 homes in the UK – saving 1,500 tonnes of CO2 each per year.

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ABSTRACT This report describes about the wind power and its potential that can be harnessed in the future to meet the current energy demand. With detailed description of the wind turbine and the wind generator focus has been given on the interconnection of the generators with the grid and the problems associated with it. The use of power electronics in the circuitry and their applications have also been emphasized. This study provides the first systematic effort towards design and development of Small Scale Wind Turbines (SSWT) targeted to operate at low wind speeds.

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PROJECT BACKGROUND Large Scale Wind Turbines (LSWTs) have been extensively examined for decades but very few studies have been conducted on the small scale wind turbines (SSWTs) especially for the applications near ground level where wind speed is of order of few meters per second. This study provides the first systematic effort towards design and development of SSWTs (rotor diameter<50 cm) targeted to operate at low wind speeds (<5 m/s). An inverse design and optimization tool based on Blade Element Momentum theory is proposed. The utility and efficacy of the tool was validated by demonstrating a 40 cm diameter small-scale wind energy portable turbine (SWEPT) operating in very low wind speed range of 1 m/s-5 m/s with extremely high power coefficient. In comparison to the published literature, SWEPT is one of the most efficient wind turbines at the small scale and very low wind speeds with the power coefficient of 32% and overall efficiency of 21% at its rated wind speed of 4.0 m/s. It has very low cut-in speed of 1.7 m/s. Wind tunnel experiments revealed that SWEPT has rated power output of 1 W at 4.0 m/s, and it is capable of producing power output up to 9.3 W at wind speed of 10 m/s. The study was further extended to develop a piezoelectric wind turbine which operates below 2.0 m/s wind speed. The piezoelectric wind turbine of overall dimension of 100mm x 78mm x 65mm is capable of producing peak electric power of about 450 microwatt at the rated wind speed of 1.9 m/s.

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WIND TURBINES A wind turbine is a rotating machine which converts the kinetic energy in wind into mechanical energy. If the mechanical energy is then converted to electricity, the machine is called a wind generator, wind turbine, wind power unit (WPU), wind energy converter (WEC), or aerogenerator. Wind turbines can be separated into two types based by the axis in which the turbine rotates. Turbines that rotate around a horizontal axis are more common. Vertical-axis turbines are less frequently used.

HORIZONTAL AXIS WIND TURBINES

Fig.1.1 Horizontal axis wind turbine

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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. Most have a gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator. 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 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. Since cyclic (that is repetitive) turbulence may lead to fatigue failures most HAWTs are upwind machines.

HAWT advantages • Variable blade pitch, which gives the turbine blades the optimum 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. • The tall tower base 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%. • High efficiency, since the blades always move perpendicularly to the wind, receiving power through the 10 | P a g e

whole rotation. In contrast, all vertical axis wind turbines, and most proposed airborne wind turbine designs, involve various types of reciprocating actions, requiring airfoil surfaces to backtrack against the wind for part of the cycle. Backtracking against the wind leads to inherently lower efficiency.

HAWT disadvantages • The tall towers and blades up to 90 meters long are difficult to transport. Transportation can now cost 20% of equipment costs. • Tall HAWTs are difficult to install, needing very tall and expensive cranes and skilled operators. • Massive tower construction is required to support the heavy blades, gearbox, and generator. • Reflections from tall HAWTs may affect side lobes of radar installations creating signal clutter, although filtering can suppress it. • HAWTs require an additional yaw control mechanism to turn the blades toward the wind.

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Vertical Axis Wind Turbines:

Fig.1.2 Vertical axis wind turbine

Vertical-axis wind turbines (or VAWTs) have the main rotor shaft arranged vertically. Key advantages of this arrangement are that the turbine does not need to be pointed into the wind to be effective. This is an advantage on sites where the wind direction is highly variable. VAWTs can utilize winds from varying directions. With a vertical axis, the generator and gearbox can be placed near the ground, so the tower doesn't need to support it, and it is more accessible for maintenance. Drawbacks are that some designs produce pulsating torque. Drag may be created when the blade rotates into the wind.

VAWT advantages • A massive tower structure is less frequently used, as VAWTs are more frequently mounted with the lower bearing mounted near the ground. 12 | P a g e

• Designs without yaw mechanisms are possible with fixed pitch rotor designs. • A VAWT can be located nearer the ground, making it easier to maintain the moving parts. • VAWTs have lower wind startup speeds than HAWTs. Typically, they start creating electricity at 6 M.P.H. (10 km/h). • VAWTs may have a lower noise signature.

VAWT disadvantages • 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. • While VAWTs' parts are located on the ground, they are also located under the weight of the structure above it, which can make changing out parts nearly impossible without dismantling the structure if not designed properly. • Having rotors located close to the ground where wind speeds are lower due to wind shear, VAWTs may not produce as much energy at a given site as a HAWT with the same footprint or height. • Because VAWTs are not commonly deployed due mainly to the serious disadvantages mentioned above, they appear novel to those not familiar with the wind industry. This has often made them the subject of wild claims and investment scams over the last 50 years.

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Wind Turbine Glossary

Fig.1.3 Parts of a wind turbine

Anemometer: Measures the wind speed and transmits wind speed data to the controller. Blades: Most turbines have either two or three blades. Wind blowing over the blades causes the blades to "lift" and rotate. Brake: A disc brake which can be applied mechanically, electrically, or hydraulically to stop the rotor in emergencies. Controller: The controller starts up the machine at wind speeds of about 8 to 16 miles per hour (mph) and shuts off the machine at about 65 mph. Turbines cannot operate at wind 14 | P a g e

speeds above about 65 mph because their generators could overheat. Gear box: Gears connect the low-speed shaft to the highspeed shaft and increase the rotational speeds from about 30 to 60 rotations per minute (rpm) to about 1200 to 1500 rpm, the rotational speed required by most generators to produce electricity. The gear box is a costly (and heavy) part of the wind turbine and engineers are exploring "directdrive" generators that operate at lower rotational speeds and don't need gear boxes. Generator: Usually an off-the-shelf induction generator that produces 60-cycle AC electricity. High-speed shaft: Drives the generator. Low-speed shaft: The rotor turns the low-speed shaft at about 30 to 60 rotations per minute. Nacelle: The rotor attaches to the nacelle, which sits atop the tower and includes the gear box, low- and high-speed shafts, generator, controller, and brake. A cover protects the components inside the nacelle. Some nacelles are large enough for a technician to stand inside while working. Pitch: Blades are turned, or pitched, out of the wind to keep the rotor from turning in winds that are too high or too low to produce electricity. Rotor: The blades and the hub together are called the rotor. Tower: Towers are made from tubular steel (shown here) or steel lattice. Because wind speed increases with height, taller towers enable turbines to capture more energy and generate more electricity. Wind direction: This is an "upwind" turbine, so-called because it operates facing into the wind. Other turbines are designed to run "downwind", facing away from the wind. 15 | P a g e

Wind vane: Measures wind direction and communicates with the yaw drive to orient the turbine properly with respect to the wind. Yaw drive: Upwind turbines face into the wind; the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. Downwind turbines don't require a yaw drive, the wind blows the rotor downwind. Yaw motor: Powers the yaw drive. The following is a graph between Power Coefficient (CP) vs Tip Speed Ratio (λ): Fig.

Fig.1.4 Power coefficient vs tip speed ratio

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CHAPTER 2 AN INTRODUCTION TO THE SMALL WIND TURBINE PROJECT Small wind turbines are typically used for the remote or rural areas of the world including villages; a farmer who wants to water his crop; or a utility company that wants to use distributed generation to help defer building new transmission lines and distribution facilities. Small wind turbines can be used for powering communities, businesses, homes, and miscellaneous equipment to support unattended operation. This report covers the Indian Department of Energy/National Renewable Energy Laboratory Small Wind Turbine project, its specifications, its applications, the subcontractors and their small wind turbine concepts.

2.1 SMALL WIND TURBINE MARKETS Small wind turbines are used throughout the developed and developing world and are primarily used in rural or remote settings in the domestic and international markets. Small wind turbines can be used to power communities, businesses, schools, clinics, single households, farms and a variety of equipment. Small wind turbines can be developed to meet the specifications suitable for the domestic and international (developed and developing) markets.

Domestic Markets: In the India most of the population lives in rural areas and a growing number live remotely. Most of those individuals have access to the grid, but there is a group of customers where the cost to connect with the utility grid is prohibitive. For those off17 | P a g e

grid individuals, diesel generation systems, renewables (solar, wind), and a storage device (batteries) used in combination as a hybrid power system could provide a solution.

International Markets: Currently, 50% of the international rural sector (not necessarily agricultural) population does not have electric power. An estimated 2 billion people do not have access to electricity. This figure is projected to increase to 3 billion by the year 2030. Within the international market, there are two market groups: the developed countries and the developing countries. In the Organisation for Economic Cooperation and Development (OECD) nations or developed countries, electric needs are met with a mature market, with developed infrastructure and a stable population. OECD nations will experience slow growth in the power market, estimated to be at 0.7%/year. OECD countries have typical needs for gridconnected technology, which makes this market similar to the domestic market. In developing countries, energy needs are driven by migration to urban areas, growth in per capita income, increased use and manufacture of energy intensive products, and poor efficiency in providing power. Worldwide growth in energy services is expected to be seven times that of the OECD countries (5.3%/year). The World Bank has estimated that within 15 years, the total energy consumption will be greater in the developing world than in the OECD countries. "At present, in some developing countries, between one-third.

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2.2 SMALL WIND TURBINE PROJECT The goal of the Small Wind Turbine project is to help india industry develop cost-effective, high reliability small wind turbine systems for both the domestic and international wind energy markets. The objective of this project is to provide tested small wind turbine systems, sized from 5 to 40 kW (maximum power), that meet a Cost/Performance Ratio. The systems are also expected to meet certain design requirements such as: high reliability, ease of transportation and installation, low maintenance, International Electrotechnical Commiss-ion (IEC) Class II requirements, and environmental considerations (desert, coastal, cold weather) based on specific markets. The scope of work emphasizes an iterative engineering development process, including formal design reviews at the end of each project stage and tests to verify the system design and analyses. SMALL WIND TURBINE PROJECT

FIGURE 2.1 - SMALL WIND TURBINE PROPOSED CONCEPT 19 | P a g e

2.3 Small-scale wind energy portable turbine This chapter presents design and characterization of the small-scale wind energy portable turbine (SWEPT) targeted to operate near ground level (wind speed: below 5 m/s). 2.3.1 SWEPT design specifications and construction

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Fig.2.2 small-scale windmill prototype “SWEPT"

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2.3.2 Experimental set-up

Fig.2.3 Experimental set-up with the schematic diagram

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2.4 Advantages of Small Scale turbines:  High Reliability and Low Maintenance: This requirement of high reliability and low maintenance is driven primarily by the need to have operating wind turbine systems in remote or developing locations throughout the world. Unlike utility grade turbines, small wind turbines are typically sold in small groups or as stand-alone installations. This adds to the maintenance costs since turbines are not co-located. Maintenance could involve a trained windsmith who would have to travel potentially significant distance to maintain a few or one wind turbine system. An alternative is to get in-country support and have detailed simple instructions for scheduled maintenance and neasy unscheduled maintenance. The sensitivity to high reliability and low maintenance increases as the remoteness of the location increases.

 Ease of Transportation and Installation: Ease of transportation is necessary for international markets that require the use of standard shipping containers for transporting the small wind turbine systems. The primary market drivers for ease of installation are the developing countries that do not have the infrastructure (roadways, lifting equipment, and transportation systems) to support small wind turbine installation and erection. Domestic customers living in remote areas may also have limited access to lifting equipment necessary for turbine erection.

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CONCLUSIONS From the report we studied that wind has a lot of potential in it and if properly harnessed then it can help solve the energy crises in the world. The study of wind turbine and its characteristics showed that how it can be properly designed and used to get the maximum output. The power electronic circuitries have helped the concept of wind power a lot. Without them this concept would have been too expensive and far fetched. This report also showed the integration of wind farms with the transmission grid and the problems associated with it and the probable solutions that can be applied to solve them and have a better performance. The wind energy is a rapidly expanding field. Extensive research activities are being conducted across the globe in this area, with the goal of improving the efficiency of wind turbines. Several configurations of wind turbines have been proposed and the modern megawatt horizontal axis wind turbines are at this juncture very efficient with the power coefficient up to 45 % to 50 %. In spite of all the efforts, as reported in chapter 1, the overall contribution of wind power in the global total electricity generation is still a small fraction. One of the main reasons for the low success rate of wind turbines is the high rated wind speed. The low wind speed small scale wind turbines (SSWTs) are generally ignored because of their poor performance that does not allow justifying their installation and operational cost. The aim of this thesis was to develop the wind energy harvesters that can operate near the ground level where wind speed is very low (< 5 m/s). 23 | P a g e

BIBLOGRAPHY 1. Yongning Chi, Yanhua Liu, Weisheng Wang, “Voltage Stability Analysis of Wind Farm integration into Transmission Network” IEEE Trans. Energy Conversion, vol. 21, issue 1, pp. 257-264, March. 2006. 2. Poller.M.A, "Doubly-fed induction machine models for stability assessment of wind farms," Power Tech Conference Proceedings, IEEE Bologna, Volume 3, 23-26 June 2003 Page(s):6 pp. 3. K. Nandigam, B. H. Chowdhury. "Power flow and stability models for induction generators used in wind turbines," IEEE Power Engineering Society General Meeting, Vol.2, 6-10 June 2004 Page(s):2012 - 2016 4. www.windpower.org 5. www.arrc.ou.edu 6. www.pdfcoke.com 7. www.davidarling.info/encyclopedia

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