WIND ENERGY SYSTEMS - Electrical And Computer Engineering
WIND ENERGY SYSTEMSElectronic EditionbyGary L. JohnsonManhattan, KS
iTABLE OF CONTENTS1 Introduction.1-11.1 Historical Uses of Wind.1-21.2 History of Wind Electric Generation.1-31.3 Horizontal Axis Wind Turbine Research.1-51.4 Darrieus Wind Turbines.1-131.5 Innovative Wind Turbines.1-161.6 California Wind farms.1-212 Wind Characteristics.2-12.1 Meteorology of Wind.2-12.2 World Distribution of Wind.2-72.3 Wind Speed Distribution in the United States.2-82.4 Atmospheric Stability.2-142.5 Wind Speed Variation With Height.2-232.6 Wind Speed Statistics.2-262.7 Weibull Statistics.2-302.8 Determining the Weibull Parameters.2-382.9 Rayleigh and Normal Distributions.2-442.10 Distribution of Extreme Winds.2-552.11 Problems.2-623 Wind Measurements.3-13.1 Eolian Features.3-13.2 Biological Indicators.3-23.3 Rotational Anemometers.3-53.4 Other Anemometers.3-143.5 Wind Direction.3-173.6 Wind Measurements with Balloons.3-283.7 Problems.3-34Wind Energy Systems by Dr. Gary L. JohnsonOctober 10, 2006
ii4 Wind Turbine Power, Energy, and Torque.4-14.1 Power Output from an Ideal Turbine.4-14.2 Aerodynamics.4-44.3 Power Output from Practical Turbines.4-74.4 Transmission and Generator Efficiencies.4-134.5 Energy Production and Capacity Factor.4-214.6 Torque at Constant Speeds.4-294.7 Drive Train Oscillations.4-334.8 Starting a Darrieus Turbine.4-394.9 Turbine Shaft Power and Torque at Variable Speeds.4-434.10 Problems.4-495 Wind Turbine on the Electrical Network.5-15.1 Methods of Generating Synchronous Power.5-15.2 AC Circuits.5-45.3 The Synchronous Generator.5-145.4 Per Unit Calculations.5-225.5 The Induction Machine.5-275.6 Motor Starting.5-375.7 Capacity Credit.5-405.8 Features of the Electrical Network.5-485.9 Problems.5-586 Asynchronous Electrical Generators.6-16.1 Asynchronous Systems.6-26.2 DC Shunt Generator with Battery Load.6-56.3 Permanent Magnet Generators.6-116.4 AC Generators.6-186.5 Self-Excitation of the Induction Generator.6-206.6 Single-Phase Operation of the Induction Generator.6-32Wind Energy Systems by Dr. Gary L. JohnsonOctober 10, 2006
iii6.7 Field Modulated Generator.6-376.8 Roesel Generator.6-396.9 Problems.6-427 Asynchronous Loads.7-17.1 Piston Water Pumps.7-27.2 Centrifugal Pumps.7-107.3 Paddle Wheel Water Heaters.7-217.4 Batteries.7-237.5 Hydrogen Economy.7-337.6 Electrolysis Cells.7-407.7 Problems.7-478 Economics of Wind Systems.8-18.1 Capital Costs.8-18.2 Economic Concepts.8-98.3 Revenue Requirements.8-158.4 Value of Wind Generated Electricity.8-208.5 Hidden Costs in Industrialized Nations.8-238.6 Economic Factors in Developing Countries.8-248.7 Problems.8-269 Wind Power Plants.9-19.1 Turbine Placement.9-19.2 Site Preparation.9-29.3 Electrical Network.9-49.4 Selection of Sizes, Low Voltage Equipment.9-79.5 Selection of Sizes, Distribution Voltage Equipment.9-149.6 Voltage Drop.9-229.7 Losses.9-249.8 Protective Relays.9-28Wind Energy Systems by Dr. Gary L. JohnsonOctober 10, 2006
iv9.9 Wind farm Costs.9-309.10 Problems.9-34Appendix A: Conversion Factors.9-36Appendix B: Answers To Selected Problems.9-37Appendix C: Wire Sizes.9-39Appendix D: Streams and Waterways.9-4510 Kansas Wind Data.10-111 Comments on Wind Development.11-112 Kansas County Topographical Maps.12-1PREFACE TO FIRST EDITIONWind energy systems draw on a wide range of disciplines. Any prospective user, regardlessof his background, will feel large gaps in his knowledge, areas where he does not even knowwhat the question is, let alone where to go look for the answer. This book is written to helppeople identify the proper question to ask.There are several groups of potential users of a book on wind energy systems. There arethose with non technical backgrounds who want a readable introduction. There are graduateengineers who need a detailed treatment of some aspect of wind power systems. And there areundergraduate engineering students who need a formal course in the subject. We have chosenthe undergraduate engineering student as the primary audience, but have tried to considerthe needs of other users. Many of the key concepts should be readily understood by thosewith a good high school education. Those sections which demand a more technical treatment,however, assume a background in chemistry, physics, calculus, circuit theory, and dynamics.Rather detailed treatments of meteorology, statistics, electrical machines, and engineeringeconomics are given, but since these subjects are not studied by all engineers, no backgroundis assumed for these areas. Enough detail is included so that a technically trained personcan evaluate a given system for a proposed application and also learn enough of the specificlanguage that he can look elsewhere for more information in an efficient manner.This book will be of interest to those students who are interested in energy sources besidescoal and nuclear. Oil and natural gas are obviously not suitable long term solutions toour energy requirements, and coal and nuclear energy face severe environmental obstacles.This means that the so-called alternative energy sources may well become primary sourcesover the next few decades. At the present time wind, solar photovoltaic, and solar thermalsystems appear to be the main contenders for supplying a substantial fraction of the energyrequirements of the United States and much of the remainder of the world as well.Wind Energy Systems by Dr. Gary L. JohnsonOctober 10, 2006
vA number of books about wind power have been written in the last decade by thoseworking in the field. These books generally have no problems at the end of the chapters, andhence are difficult to use in a formal course. The author believes that significant numbers ofstudents in engineering or technology would be interested in a course on wind energy systemsif an appropriate textbook were available. It is hoped that this book will fill such a need.An attempt has been made to pull together information from many sources and presentit in a clear, consistent fashion in this text. Most of the material is available in the openliterature, but some that has been developed from research at Kansas State University hasnot been published elsewhere. This includes some wind speed data and much of the materialon induction generators.Both large and small wind turbines are discussed. The person designing a wind farm ofmulti-megawatt machines connected to the utility grid should find the necessary backgroundmaterial here, as well as the person desiring to install a small battery charging system ina remote location. Information is included on piston pumps, centrifugal pumps, batteries,electrolysis cells, and other topics that may be important in certain wind power applications.Much of this information is difficult to find in a concise form elsewhere, so this should increasethe usefulness of the book.The field is evolving rapidly, so some specific examples will become obsolete quickly. Aneffort has been made, however, to present the basic information that is not likely to change,so the book will be useful for a number of years.It has been the author’s experience that the quantity of material is ample for a threehour course. The instructor may need to be selective about sections to be covered. Chapters2,4,5, and 8 are viewed as the heart of the course, and the other chapters can be omitted, ifnecessary, with little loss of continuity. The book has been classroom tested over a five yearperiod and much of it has been rewritten to include improvements suggested by the students.SI units have been used extensively throughout the book, with English units used asnecessary to bridge the gap between present practice and the anticipated total conversion toSI units. A list of conversion factors is given at the end of the book.A good selection of problems is given at the end of each chapter. Some problems requirethe use of a programmable hand calculator or a digital computer. These can be used whereall the students have access to such equipment to give additional practice in computationaltechniques.The author wishes to express appreciation to Theresa Shipley and Teresa Gallup for typingvarious versions of the manuscript. He also wishes to thank the many students who offeredsuggestions and criticisms. Finally, he wishes to thank his wife Jolene, and his children, Kirkand Janel, for their patience during the writing of the book.Wind Energy Systems by Dr. Gary L. JohnsonOctober 10, 2006
viPREFACE TO SECOND EDITIONA ninth chapter, on wind farm layout, has been added to the second edition. This discussestopics like wire and transformer selection. We actually start the semester with this chapterand Chapter 8, so we can give a wind farm design project early in the semester. Each studentis asked to do a paper design of a wind farm, including layout, sizing of components, andeconomic analysis. This design has worked very well, helping to make the course one of themost popular elective courses in the department. There were 46 in the course Fall 1993, whichwas the largest enrollment of any elective course in the department. The chapter has enoughtables on wire sizes, wire costs, transformer sizes and costs, and other costs that the studentcan feel confident of doing a respectable design without seeking other sources of information.Each student is given a topographical map and an aerial photo of a particular square mileat one of five sites, and performance data for a particular turbine or two at that site. Onestudent may have a flat site while another may have one with hills and sharp ravines. Somesites have railroads or pipelines. Each student has a different design to do, which greatlyreduces concern about copying, but still the difficulty of each design is approximately thesame. The deadline for designs is about two-thirds of the way through the semester, so thereis ample time to grade them.Once the designs are given, we go back to the start of the book and see how far we canget. We usually skip Chapter 3, and the portions of Chapter 5 that are covered in an earlierrequired course on Energy Conversion.After Prentice-Hall let the First Edition go out of print, the copyright was returned tothe author. This Second Edition is copyrighted, however, it is planned to grant a broadauthorization to copy and/or edit any or all of this material to a school or other organizationupon the payment of a one time fee. Any reader who is not already covered by an existingauthorization should contact the author for details.Gary L. JohnsonManhattan, KSJanuary 1994PREFACE TO ELECTRONIC EDITIONThe author took early retirement in May, 1994 and spent the next two years working as aconsultant to a wind farm developer that was interested in establishing a wind farm in Kansas.A large ranch in southern Kansas was selected and three towers were instrumented, two at 40m and one at 60 m. At the end of two years it was obvious that it would be several more yearsWind Energy Systems by Dr. Gary L. JohnsonOctober 10, 2006
viibefore wind farms were established in Kansas, so the developer walked away from the lease.The rancher and the author continued to collect data until another developer was found tolease and develop the site. The 150 MW Elk River Windfarm is now producing power at thissite.A number of copies of this book were photocopied and sold since 1994, and several organizations opted to buy the permission to edit and photocopy at will, as mentioned in theprevious preface. But things have slowed down such that economically there is no point incontinuing this process. While some of the prices are outdated, the author believes there isconsiderable basic information in this book that is still quite valid. Therefore the decision wasmade to scan in some of the figures and photographs and prepare these files in PDF format.The only change made was to put references at the end of each chapter rather than at theend of the book. Except for the photographs copyrighted by others, this material should beconsidered as in the public domain. May it yet serve a role in establishing wind power as asignificant source of electrical energy throughout the world.November, 2001October, 2006Wind Energy Systems by Dr. Gary L. JohnsonOctober 10, 2006
Chapter 1—Introduction1–1INTRODUCTIONLook at the ships also:, though they are so great and are driven by strong winds, they areguided by a very small rudder wherever the will of the pilot directs. James 3:4The wind is a free, clean, and inexhaustible energy source. It has served mankind wellfor many centuries by propelling ships and driving wind turbines to grind grain and pumpwater. Interest in wind power lagged, however, when cheap and plentiful petroleum productsbecame available after World War II. The high capital costs and the uncertainty of the windplaced wind power at an economic disadvantage. Then in 1973, the Arab nations placed anembargo on petroleum. The days of cheap and plentiful petroleum were drawing to an end.People began to realize that the world’s oil supplies would not last forever and that remainingsupplies should be conserved for the petrochemical industry. The use of oil as a boiler fuel,for example, would have to be eliminated. Other energy sources besides oil and natural gasmust be developed.The two energy sources besides petroleum which have been assumed able to supply thelong term energy needs of the United States are coal and nuclear energy. Many people thinkthere is enough coal for several centuries at present rates of consumption, and likewise fornuclear energy after the breeder reactor is fully developed. These are proven resources in thesense that the technology is highly developed, and large coal and nuclear powered electricalgenerating plants are in operation and are delivering substantial blocks of energy to theconsumer. Unfortunately, both coal and nuclear present serious environmental problems.Coal requires large scale mining operations, leaving land that is difficult or impossible torestore to usefulness in many cases. The combustion of coal may upset the planet’s heatbalance. The production of carbon dioxide and sulfur dioxide may affect the atmosphere andthe ability of the planet to produce food for its people. Coal is also a valuable petrochemicalfeedstock and many consider the burning of it as a boiler fuel to be foolish.Nuclear energy has several advantages over coal in that no carbon dioxide or sulfur dioxi
students in engineering or technology would be interested in a course on wind energy systems . the use of a programmable hand calculator or a digital computer. These can be used where . PREFACE TO SECOND EDITION A ninth chapter, on wind farm layout, has been added to the second edition. This discusses
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energy conversion scheme using both wind and photovoltaic energy sources. 1.1 Wind Energy Systems Wind energy conversion systems convert the kinetic energy associated with wind speed into electrical energy for feeding power to the grid. The energy is captured by the blades of wind turbines whose rotor is connected to the shaft of electric .
Wind energy is generated by a wind turbine which converts the kinetic energy of wind into electrical energy. The system mainly depends on speed of the wind to enhance the performance the turbine in mounted on a tall tower. Wind energy conversion system has a wind turbine, permanent magnet synchronous generator and AC-AC converter. As wind .
wind energy. The office pursues opportunities across all U.S. wind sectors—land-based utility-scale wind, offshore wind, distributed wind—as well as addressing market barriers and system integration. As we usher in 2021, we'd like to share some of the most notable wind energy research and development accomplishments from 2020. Offshore Wind
3. Energy transformations in a wind turbine A wind turbine uses energy transfer and energy transformations to generate electricity. As the wind blows it's kinetic energy transfers to the blades of the turbine giving them kinetic energy. This turns a generator which transforms kinetic energy into electrical energy. Kinetic energy (wind) .
DTU Wind Energy E-0174 5 1 0BIntroduction Wind resource assessment is the process of estimating the wind resource or wind power potential at one or several sites, or over an area. One common and well-known result of the assessment could be a wind resource map, see Figure 1. Figure 1. Wind resource map for Serra Santa Luzia region in Northern .
Offshore Wind Energy October 2010 Offo re wind turbineharne the energy of ocean wind and turn it into electricity. Several European and two A an countriehave offo re wind farm which pply local, clean, renewable energy. Although land-bad wind turbine are prevalent in the United State there are no offo re wind
Wind energy is the kinetic energy of air in motion, also called wind. Total wind energy flowing through an imaginary surface with area A during the time t is: . The London Array Offshore Wind Farm, the largest offshore wind farm in the world with an installed capacity of 630MW, ranks as the world's sixth largest wind farm. .
