Acknowledgment
The book of this nature on emerging technologies, such as the wind and photovoltaic power systems, cannot possibly be written without the help from many sources. I have been extremely fortunate to receive full support from many organizations and individuals in the field. They not only encouraged me to write the book on this timely subject, but also provided valuable suggestions and comments during the development of the book.
Dr. Nazmi Shehadeh, head of the Electrical and Computer Engineering Department at the University of Minnesota, Duluth, gave me the opportunity to develop and teach this subject to his students who were enthusiastic about learning new technologies. Dr. Elliott Bayly, president of the World Power Technologies in Duluth, shared with me and my students his long experience in the field. He helped me develop the course outline, which later became the book outline. Dr. Jean Posbic of Solarex Corporation in Frederick, Maryland and Mr. Carl-Erik Olsen of Nordtank Energy Group/NEG Micon, Denmark, kindly reviewed the draft and provided valuable suggestions for improvement. Mr. Bernard Chabot of ADEME, Valbonne, France, provided the profitability charts for screening the wind and photovoltaic power sites. Mr. Ian Baring-Gould of the National Renewable Energy Laboratory, Golden, Colorado, 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 Society, the European Wind Energy Association, the Risø National Laboratory, Denmark, the Tata Energy Research Institute, India, and many corporations engaged in the wind and solar power technologies. Many individuals at these organizations gladly provided help I requested.
I gratefully acknowledge the generous support from all of you.
Mukund Patel
Yardley, Pennsylvania
© 1999 by CRC Press LLC
Contents
1.Introduction
1.1Industry Overview
1.2Incentives for Renewables
1.3Utility Perspective
1.3.1Modularity
1.3.2Emission-Free
References
2.Wind Power
2.1Wind in the World
2.2The U.S.A.
2.3Europe
2.4India
2.5Mexico
2.6Ongoing Research and Development References
3.Photovoltaic Power
3.1Present Status
3.2Building Integrated pv Systems
3.3pv Cell Technologies
3.3.1Single-Crystalline Silicon
3.3.2Polycrystalline and Semicrystalline
3.3.3Thin Films
3.3.4Amorphous Silicon
3.3.5Spheral
3.3.6Concentrated Cells
3.4pv Energy Maps
References
4.Wind Speed and Energy Distributions
4.1Speed and Power Relations
4.2Power Extracted from the Wind
4.3Rotor Swept Area
4.4Air Density
4.5Global Wind Patterns
4.6Wind Speed Distribution
4.6.1Weibull Probability Distribution
4.6.2Mode and Mean Speeds
©1999 by CRC Press LLC
4.6.3Root Mean Cube Speed
4.6.4Mode, Mean, and rmc Speeds Compared
4.6.5Energy Distribution
4.6.6Digital Data Loggers
4.6.7Effect of Height
4.6.8Importance of Reliable Data
4.7Wind Speed Prediction
4.8Wind Resource Maps
4.8.1The U.S.A.
4.8.2Minnesota
4.8.3The United Kingdom
4.8.4Europe
4.8.5Mexico
4.8.6India
References
5.Wind Power System
5.1System Components
5.1.1Tower
5.1.2Turbine Blades
5.1.3Yaw Control
5.1.4Speed Control
5.2Turbine Rating
5.3Electrical Load Matching
5.4Variable-Speed Operation
5.5System Design Features
5.5.1Number of Blades
5.5.2Rotor Upwind or Downwind
5.5.3Horizontal Axis Versus Vertical Axis
5.5.4Spacing of the Towers
5.6Maximum Power Operation
5.6.1Constant Tip-Speed Ratio Scheme
5.6.2Peak Power Tracking Scheme
5.7System Control Requirements
5.7.1Speed Control
5.7.2Rate Control
5.8Environmental Aspects
5.8.1Audible Noise
5.8.2Electromagnetic Interference (EMI)
References
6.Electrical Generator
6.1Electromechanical Energy Conversion
6.1.1DC Machine
6.1.2Synchronous Machine
6.1.3Induction Machine
©1999 by CRC Press LLC
6.2Induction Generator
6.2.1Construction
6.2.2Working Principle
6.2.3Rotor Speed and Slip
6.2.4Equivalent Circuit for Performance Calculations
6.2.5Efficiency and Cooling
6.2.6Self-Excitation Capacitance
6.2.7Torque-Speed Characteristic
6.2.8Transients
References
7.Generator Drives
7.1Speed Control Regions
7.2Generator Drives
7.2.1One Fixed-Speed Drive
7.2.2Two Fixed-Speeds Drive
7.2.3Variable-Speed Using Gear Drive
7.2.4Variable-Speed Using Power Electronics
7.2.5Scherbius Variable-Speed Drive
7.2.6Variable-Speed Direct Drive
7.3Drive Selection
7.4Cut-Out Speed Selection
References
8.Solar Photovoltaic Power System
8.1The pv Cell
8.2Module and Array
8.3Equivalent Electrical Circuit
8.4Open Circuit Voltage and Short Circuit Current
8.5i-v and p-v Curves
8.6Array Design
8.6.1Sun Intensity
8.6.2Sun Angle
8.6.3Shadow Effect
8.6.4Temperature Effect
8.6.5Effect of Climate
8.6.6Electrical Load Matching
8.6.7Sun Tracking
8.7Peak Power Point Operation
8.8pv System Components
References
9.Solar Thermal System
9.1Energy Collection
9.1.1Parabolic Trough
9.1.2Central Receiver
9.1.3Parabolic Dish
© 1999 by CRC Press LLC
9.2Solar II Power Plant
9.3Synchronous Generator
9.3.1Equivalent Electrical Circuit
9.3.2Excitation Methods
9.3.3Electrical Power Output
9.3.4Transient Stability Limit
9.4Commercial Power Plants References
10.Energy Storage
10.1Battery
10.2Types of Batteries
10.2.1Lead-Acid
10.2.2Nickel Cadmium
10.2.3Nickel-Metal Hydride
10.2.4Lithium-Ion
10.2.5Lithium-Polymer
10.2.6Zinc-Air
10.3Equivalent Electrical Circuit
10.4Performance Characteristics
10.4.1Charge/Discharge Voltages
10.4.2Charge/Discharge Ratio
10.4.3Energy Efficiency
10.4.4Internal Resistance
10.4.5Charge Efficiency
10.4.6Self-Discharge and Trickle Charge
10.4.7Memory Effect
10.4.8Effects of Temperature
10.4.9Internal Loss and Temperature Rise
10.4.10Random Failure
10.4.11Wear-Out Failure
10.4.12Various Batteries Compared
10.5More on Lead-Acid Battery
10.6Battery Design
10.7Battery Charging
10.8Charge Regulators
10.8.1Multiple Charge Rates
10.8.2Single Charge Rate
10.8.3Unregulated Charging
10.9Battery Management
10.9.1Monitoring and Controls
10.9.2Safety
10.10Flywheel
10.10.1Energy Relations
10.10.2Flywheel System Components
10.10.3Flywheel Benefits Over Battery
©1999 by CRC Press LLC
10.11Compressed Air
10.12Superconducting Coil References
11.Power Electronics
11.1Basic Switching Devices
11.2AC to DC Rectifier
11.3DC to AC Inverter
11.4Grid Interface Controls
11.4.1Voltage Control
11.4.2Frequency Control
11.5Battery Charge/Discharge Converters
11.5.1Battery Charge Converter
11.5.2Battery Discharge Converter
11.6Power Shunts
References
12.Stand-Alone System
12.1pv Stand-Alone
12.2Electric Vehicle
12.3Wind Stand-Alone
12.4Hybrid System
12.4.1Hybrid with Diesel
12.4.2Hybrid with Fuel Cell
12.4.3Mode Controller
12.4.4Load Sharing
12.5System Sizing
12.5.1Power and Energy Estimates
12.5.2Battery Sizing
12.5.3pv Array Sizing
12.6Wind Farm Sizing
References
13.Grid-Connected System
13.1Interface Requirements
13.2Synchronizing with Grid
13.2.1Inrush Current
13.2.2Synchronous Operation
13.2.3Load Transient
13.2.4Safety
13.3Operating Limit
13.3.1Voltage Regulation
13.3.2Stability Limit
13.4Energy Storage and Load Scheduling
13.5Utility Resource Planning Tool References
©1999 by CRC Press LLC
14.Electrical Performance
14.1Voltage Current and Power Relations
14.2Component Design for Maximum Efficiency
14.3Electrical System Model
14.4Static Bus Impedance and Voltage Regulation
14.5Dynamic Bus Impedance and Ripple
14.6Harmonics
14.7Quality of Power
14.7.1Harmonic Distortion
14.7.2Voltage Transients and Sags
14.7.3Voltage Flickers
14.8Renewable Capacity Limit
14.8.1Systems Stiffness
14.8.2Interfacing Standards
14.9Lightning Protection
14.10National Electrical Code® on Renewable Power Systems References
15.Plant Economy
15.1Energy Delivery Factor
15.2Initial Capital Cost
15.3Availability and Maintenance
15.4Energy Cost Estimates
15.5Sensitivity Analysis
15.5.1Effect of Wind Speed Variations
15.5.2Effect of Tower Height
15.6Profitability Index
15.6.1Wind Farm Screening Chart
15.6.2pv Park Screening Chart
15.6.3Stand-Alone pv Versus Grid Line
15.7Hybrid Economics
References
16.The Future
16.1World Electricity Demand to 2015
16.2Wind Future
16.3pv Future
16.4Declining Production Costs
16.5Market Penetration
16.6Effect of Utility Restructuring
16.6.1Energy Policy Act of 1992
16.6.2Impact on Renewable Power Producers
References
Further Reading
Appendix 1
© 1999 by CRC Press LLC
Appendix 2
Acronyms
Conversion of Units
© 1999 by CRC Press LLC