Wind and Solar Power Systems: Design, Analysis, and Operation, Second Edition

434 Pages·2005·39.42 MB·English

by  Mukund R. Patel

Wind and Solar
Power Systems
Design, Analysis, and Operation
Second Edition
Mukund R. Patel
U.S. Merchant Marine Academy
Kings Point, New York, U.S.A.
Boca Raton London New York Singapore
A CRC title, part of the Taylor & Francis imprint, a member of the
Taylor & Francis Group, the academic division of T&F Informa plc.
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Cover photo: Original land use continues in a wind farm in Germany. (With permission from Vestas Wind
Systems, Denmark.)
The wind and photovoltaic power technologies are rapidly evolving. Although reasonable care has been taken
in preparing this book, neither the author nor the publisher assumes responsibility for any consequences of using
the information. The diagrams disclosed herein are for illustration purposes only and may be covered by patents.
Published in 2006 by
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© 2006 by Taylor & Francis Group, LLC
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International Standard Book Number-10: 0-8493-1570-0 (Hardcover)
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Library of Congress Cataloging-in-Publication Data
Patel, Mukund R., 1942-
Wind and solar power systems : design, analysis, and operation / Mukund R. Patel.--2nd ed.
p. cm.
Includes bibliographical references and index.
ISBN 0-8493-1570-0 (alk. paper)
1. Wind power plants. 2. Solar power plants. 3. Photovoltaic power systems. I. Title.
TK1541.P38 2005
621.31'2136--dc22 2005043904
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Dedication
Dedicated to my mother, Shakariba,
who practiced ingenuity, and to my children,
Ketan, Bina, and Vijal,
who flattered me by becoming engineers.
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Preface
The phenomenal growth and new developments in wind and solar power technolo-
gies have made the second edition of this book necessary. It reflects the need for an
expanded, revised, and updated version of the well-received first edition in just 5
years. During that time, the capital and energy costs of wind power have declined
by 20%. Today, the cost of electricity from grid-connected wind farms is below 4
cents/kWh, and that from photovoltaic (PV) parks below 20 cents/kWh. The goal
of ongoing research programs funded by the U.S. Department of Energy (DOE) and
the National Renewable Energy Laboratory (NREL) is to bring wind energy cost
below 3 cents/kWh and the PV energy cost below 15 cents/kWh by 2010. In capital
and energy costs, wind now competes on its merits with the conventional power
technologies, and has become the least expensive source of electrical power —
traditional or new — in many parts of the world. It is also abundant and environ-
mentally clean, bringing many indirect social benefits not fully reflected in the market
economics. For these reasons, wind power now finds importance in the energy
planning in all countries around the world. According to the DOE, prime wind
locales of the world have the potential of supplying more than ten times the global
energy needs. In the U.S., the DOE has established 21 partnerships with public and
private bodies to develop turbines to generate economical power in low-wind-speed
regions that would open up much larger areas of the country for rapid development
of wind power. The Electric Power Research Institute (EPRI) estimates that wind
energy will grow from less than 1% at present to as much as 10% of the U.S.
electricity demand by 2020.
Around the world, the wind power generation capacity has seen an average
annual growth rate of 30% during the period from 1993 to 2003. More than 8,000
MW of new wind capacity was added globally in 2003 with an investment value of
$9 billion. This brought the total cumulative wind capacity to 40,000 MW. The most
explosive growth occurred in Germany. Offshore wind farms are bringing a new
dimension to the energy market. Many have been installed, and many more, each
exceeding 300-MW capacity, are being installed or are in the planning stage. Most
offshore farms are less than 10 km from the shore in less than 10 m depth of water.
Denmark’s plan to install 750 MW of new wind capacity by 2008, bringing its total
to 4,000 MW for supplying 25% of the country’s electricity, includes aggressive
offshore plans. U.S. wind capacity is projected to reach 12,000 MW by 2015. Utilities
and wind power developers have announced plans for more than 5,000 MW of new
capacity in 15 states by 2006. Hydro-Quebec plans 1,000 MW of new capacity to
be added between 2006 and 2012. In these new installations, 3-MW turbines are
being routinely installed in many countries, with 5-MW machines available today
for large offshore farms; 7-MW units are in prototype tests.
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On the solar PV side, the cost of PV electricity is still high: between 15 and 25
cents/kWh. With the consumer cost of utility power ranging from 10 to 15
cents/kWh, PV cannot economically compete directly with utility power as yet,
except in remote markets where utility power is not available and transmission line
cost would be prohibitive. Many developing countries have large areas falling in
this category, and that is where the most PV growth is taking place, such as in India
and China. The worldwide solar PV is about $7 billion in annual business, mainly
driven by Germany.
Worldwide, PV installations grew at an average annual rate of 25 to 30% during
the period from 2000 to 2004. By the end of 2004, the cumulative PV capacity was
2,030 MW, with 1,000 MW in the U.S. The annual production of PV modules was
530 MW in 2004 and is projected to reach 1,600 MW by 2010. The present module
prices are $6 to $7 per watt for 1-kW modules and $3 to $4 per watt for 1-MW
plants. The emerging thin-film and concentrating PV cells are expected to reduce
the module prices substantially in the near future.
After the restructuring of U.S. electrical utilities as mandated by the Energy
Policy Act (EPAct) of 1992, industry leaders expected the power generation business,
both conventional and renewable, to become more profitable in the long run. Their
reasoning is that the generation business has been stripped of regulated prices and
opened to competition among electricity producers and resellers. The transmission
and distribution business, on the other hand, is still regulated. The American expe-
rience indicates that free business generates more profits than regulated business.
Such is the experience in the U.K. and Chile, where the electrical power industry
had long been structured similarly to the U.S. EPAct of 1992. Moreover, the renew-
able power price would be falling as the technology advances, whereas the price of
the conventional power would rise with inflation, making the wind and PV even
more profitable in the future.
North America’s darkest blackout in 2003 with its estimated $10 billion in
damage is bringing a new and sharp focus to distributed power generation. Because
overloaded transmission lines caused the blackout, and it would take decades before
new lines can be planned and built, the blackout has created a window of opportunity
for distributed power generation from wind and PV. As most large-scale wind farms
are connected to the grid lines, PV systems are expected to benefit more in distributed
power generation growth.
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The Author
Mukund R. Patel, Ph.D., P.E., is a research engineer, consultant, and educator with
40 years of hands-on involvement in designing and developing state-of-the-art elec-
trical power equipment and systems. He has served as principal engineer at the
General Electric Company in Valley Forge, Pennsylvania; fellow engineer at the
Westinghouse Research & Development Center in Pittsburgh; senior staff engineer
at Lockheed Martin Corporation in Princeton, New Jersey; development manager at
Bharat Bijlee Limited, in Bombay, and as 3M Distinguished Visiting Professor at
the University of Minnesota, Duluth. Presently, he is a professor of engineering at
the U.S. Merchant Marine Academy at Kings Point, New York, and an associate
editor of Solar Energy Journal published by the International Solar Energy Society.
Dr. Patel obtained his Ph.D. degree in electric power engineering from Rensse-
laer Polytechnic Institute, Troy, New York; M.S. in engineering management from
the University of Pittsburgh; M.E. in electrical machine design from Gujarat Uni-
versity; and B.E. from Sardar Patel University, Vallabha Vidyanagar, Gujarat, India.
He is a fellow of the Institution of Mechanical Engineers (U.K.), associate fellow
of the American Institute of Aeronautics and Astronautics, a senior member of the
IEEE, a registered professional engineer in Pennsylvania, and a member of Eta
Kappa Nu, Tau Beta Pi, Sigma Xi, and Omega Rho.
Dr. Patel has presented and published about 50 papers at national and interna-
tional conferences, holds several patents, and has earned recognition from the
National Aeronautics and Space Administration for exceptional contribution to the
photovoltaic power system design for the Upper Atmosphere Research Satellite. He
is active in consulting and teaching short courses to professional engineers in the
electrical power industry.
Dr. Patel lives in Yardley, Pennsylvania, with his wife, Sarla. They have three
children, Ketan, Bina, and Vijal, and two grandchildren, Rayna and Dhruv. Dr. Patel
can be reached at [email protected].
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About This Book
The second edition of this book is an expanded, revised, and updated version, which
was prepared when I was invited to teach a course as a visiting professor in emerging
electrical power technologies at the University of Minnesota, Duluth. Teaching the
full course to inquisitive students and short courses to professional engineers
enhanced the contents in many ways. It is designed and tested to serve as textbook
for a semester course for university seniors in electrical and mechanical engineering
fields. For practicing engineers there is a detailed treatment of this rapidly growing
segment of the power industry. Government policymakers will benefit by the over-
view of the material covered in the book, which is divided into 4 parts in 19 chapters.
Part A covers wind power technologies and ongoing programs in the U.S. and
around the world. It includes engineering fundamentals, the probability distributions
of wind speed, the annual energy potential of a site, the wind speed and energy maps
of several countries, and wind power system operation and the control requirements.
As most wind plants use induction generators for converting turbine power into
electrical power, the theory of the induction machine performance and operation is
reviewed. The electrical generator speed control for capturing maximum energy
under wind fluctuations over the year is presented. The rapidly developing offshore
wind farms with their engineering, operational, and legal aspects are covered in
detail.
Part B covers solar photovoltaic (PV) technologies and current developments
around the world. It starts with the energy conversion characteristics of the photo-
voltaic cell, and then the array design, effect of the environment variables, sun-
tracking methods for maximum power generation, the controls, and emerging trends
are discussed.
Part C starts with the large-scale energy storage technologies often required to
augment nondispatchable energy sources, such as wind and PV, to improve the
availability of power to users. It covers characteristics of various batteries, their
design methods using the energy balance analysis, factors influencing their operation,
and battery management methods. Energy density and the life and operating cost
per kilowatthour delivered are presented for various batteries such as lead-acid,
nickel-cadmium, nickel-metal-hydride, and lithium-ion. The energy storage by the
flywheel, compressed air, and the superconducting coil, and their advantages over
the batteries are reviewed. Basic theory and operation of the power electronic
converters and inverters used in the wind and solar power systems are then presented.
Over two billion people in the world not yet connected to the utility grid are the
largest potential market of stand-alone power systems using wind and PV systems
in hybrid with diesel generators or fuel cells, which are discussed in detail. The grid-
connected renewable power systems are covered with voltage and frequency control
methods needed for synchronizing the generator with the grid. The theory and
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operating characteristics of the interconnecting transmission lines, voltage regula-
tion, maximum power transfer capability, and static and dynamic stability are cov-
ered.
Part C continues with overall electrical system performance, the method of
designing system components to operate at their maximum possible efficiency, static
and dynamic bus performance, harmonics, and the increasingly important quality of
power issues applicable to the renewable power systems. The total plant economy
and the costing of energy delivered to the paying customers are presented. It also
shows the importance of a sensitivity analysis to raise the confidence level of the
investors. The profitability charts are presented for preliminary screening of potential
sites. Also reviewed are past and present trends of wind and PV power, the declining-
price model based on the learning curve, and the Fisher–Pry substitution model for
predicting the future market growth of wind and PV power based on historical data
on similar technologies. The effect of utility restructuring, mandated by the Energy
Policy Act of 1992, and its benefits on the renewable power producers are discussed.
Part D covers the ancillary power system derived from the sun, the ultimate
source of energy on the earth. It starts with the utility-scale solar thermal power
plant using concentrating heliostats and molten salt steam turbine. It then covers
solar-induced wind power, marine current power, ocean wave power, and hydropi-
ezoelectric power generators. Finally, it examines in detail a novel contrarotating
wind turbine that can improve the wind-to-electricity conversion efficiency by 25 to
40% from a given wind farm area. As the available wind farm areas, on land or
offshore, are becoming constrained due to various environment reasons, this concept
holds future potential. The last chapter includes detailed prototype construction and
test methods to guide young researchers in this evolving field.
Lastly, Appendix 1 presents the National Electrical Code® as applicable to the
renewable power sources. Appendix 2 gives sources of further information (names
and addresses of government agencies, universities, and manufacturers active in
renewable power around the world, references for further reading, list of acronyms,
and conversion of units).
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Acknowledgments
Any book of this nature on emerging technologies such as wind and photovoltaic
power systems cannot possibly be written without help from many sources. I have
been extremely fortunate to receive full support from many organizations and indi-
viduals in the field. They not only encouraged me to write on this timely subject
but also provided valuable suggestions and comments during the development of
the book.
For this second edition, I am grateful to Prof. Jose Femenia, head of the engi-
neering department; Dr. Warren Mazek, Dean; and Vice Admiral Joseph Stewart,
Superintendent, of the U.S. Merchant Marine Academy, Kings Point, New York, for
supporting my research and publications, including a sabbatical leave for writing
this book. I have benefited from the midshipmen at the academy who were taking
this course and contributing to my learning as well.
A new chapter on emerging research on contrarotating wind turbines has been
added with a special contribution from Dr. Kari Appa of Appa Technology Initiatives,
Lake Forest, California.
For the first edition, Dr. Nazmi Shehadeh of the University of Minnesota, Duluth,
gave me the start-up opportunity to develop and teach this subject to his students.
Dr. Elliott Bayly of the World Power Technologies in Duluth shared with my students
and me his long experience in the field. He helped me develop the course outline,
which eventually led to the first edition of this book. Dr. Jean Posbic of Solarex
Corporation in Frederick, Maryland, and Mr. Carl-Erik Olsen of Nordtank Energy
Group/NEG Micon in Denmark kindly reviewed the draft and provided valuable
suggestions for improvement. Bernard Chabot of ADEME, Valbonne, France, gen-
erously provided the profitability charts for screening the wind and photovoltaic
power sites. Ian Baring-Gould of the National Renewable Energy Laboratory has
been a source of useful information and the hybrid power plant simulation model.
Several institutions worldwide provided current data and reports on these rather
rapidly developing technologies. They are the American Wind Energy Association,
the American Solar Energy Association, the European Wind Energy Association, the
National Renewable Energy Laboratory, the Riso National Laboratory in Denmark,
the Tata Energy Research Institute in India, the California Energy Commission, and
many corporations engaged in the wind and solar power technologies. Numerous
individuals at these organizations gladly provided all the help I requested.
I wholeheartedly acknowledge the valuable support from you all.
Mukund R. Patel
Yardley, Pennsylvania
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Contents
PART A Wind Power Systems
Chapter 1 Introduction..........................................................................................3
1.1 Industry Overview.........................................................................................3
1.2 Incentives for Renewables.............................................................................5
1.3 Utility Perspective..........................................................................................6
1.3.1 Modularity for Growth....................................................................7
1.3.2 Emission Benefits............................................................................8
1.3.3 Consumer Choice............................................................................8
References................................................................................................................10
Chapter 2 Wind Power........................................................................................11
2.1 Wind Power in the World............................................................................11
2.2 U.S. Wind Power Development...................................................................15
2.3 Europe and the U.K.....................................................................................19
2.4 India.............................................................................................................21
References................................................................................................................23
Chapter 3 Wind Speed and Energy....................................................................25
3.1 Speed and Power Relations.........................................................................25
3.2 Power Extracted from the Wind..................................................................27
3.3 Rotor-Swept Area........................................................................................30
3.4 Air Density..................................................................................................30
3.5 Global Wind Patterns...................................................................................31
3.6 Wind Speed Distribution.............................................................................33
3.6.1 Weibull Probability Distribution...................................................34
3.6.2 Mode and Mean Speeds................................................................36
3.6.3 Root Mean Cube Speed................................................................39
3.6.4 Mode, Mean, and RMC Speeds....................................................39
3.6.5 Energy Distribution.......................................................................41
3.6.6 Digital Data Processing.................................................................43
3.6.7 Effect of Hub Height.....................................................................44
3.6.8 Importance of Reliable Data.........................................................46
3.7 Wind Speed Prediction................................................................................47
© 2006 by Taylor & Francis Group, LLC