Wind Turbines

by Hau, Erich

• ISBN13: 9783540242406
• ISBN10: 3540242406
• Edition: 2nd
• Format: Hardcover
• Copyright: 2005-11-15
• Publisher: Springer Verlag

Summary

Wind Turbines addresses all those professionally involved in research, development, manufacture and operation of wind turbines. It provides a cross-disciplinary overview of modern wind turbine technology and an orientation in the associated technical, economic and environmental fields. It is based on the author's experience gained over decades designing wind energy converters with a major industrial manufacturer and, more recently, in technical consulting and in the planning of large wind park installations, with special attention to economics. The second edition accounts for the emerging concerns over increasing numbers of installed wind turbines. In particular, an important new chapter has been added which deals with offshore wind utilisation. All advanced chapters have been extensively revised and in some cases considerably extended

Table of Contents

Frequently used Symbols	xvii
Windmills and Windwheels	1	(22)
The Origins of Windmills	1	(3)
European Windmills	4	(7)
Economic Importance of Historical Windmills	11	(2)
Scientific and Technical Development of Windmills	13	(4)
The American Wind Turbine	17	(6)
References	21	(2)
Electrical Power from the Wind -- The First Attempts	23	(44)
Poul La Cour -- A Pioneer in Denmark	23	(5)
Large Wind Power Plants -- Ambitious Projects in Germany	28	(5)
1250 kW from the Wind -- The First Large Wind Turbine in the US	33	(3)
Wind Turbines in the Fifties -- Before the ``Energy Crisis''	36	(8)
After the Energy Crisis -- A New Start toward Modern Wind Power Applications	44	(3)
The Large Experimental Turbines of the Eighties	47	(10)
First Successes with the Small Wind Turbines in Denmark	57	(2)
The Wind Farms in the United States	59	(8)
References	64	(3)
Basic Concepts of Wind Energy Converters	67	(14)
Rotors with a Vertical Axis of Rotation	68	(3)
Horizontal Axis Rotors	71	(3)
Wind Energy Concentrators	74	(5)
Terms and Expressions	79	(2)
References	80	(1)
Physical Principles of Wind Energy Conversion	81	(10)
Betz's Elementary Momentum Theory	81	(5)
Wind Energy Converters Using Aerodynamic Drag or Lift	86	(5)
References	89	(2)
Rotor Aerodynamics	91	(70)
Mathematical Models and Calculations	92	(6)
Rotor Power Characteristics	98	(4)
Aerodynamic Power Control	102	(14)
Power Control by Rotor Blade Pitching	103	(5)
Passive Stall Control with Fixed Blade Pitch	108	(4)
Active Stall Control	112	(1)
Aerodynamic Problems with Stall Control	113	(2)
Turning the Rotor out of the Wind	115	(1)
The Rotor Wake	116	(4)
Important Aerodynamic Design Features of the Rotor	120	(22)
Number of Rotor Blades	120	(2)
Optimum Shape of the Rotor Blades	122	(6)
Rotor Blade Twist	128	(2)
Rotor Blade Airfoil	130	(9)
Blade Thickness	139	(1)
Design Tip Speed Ratio of the Rotor	140	(2)
Existing Rotor Blade Designs	142	(4)
Yaw Control of the Rotor	146	(4)
Aerodynamics of Vertical-Axis Rotors	150	(4)
Experimental Rotor Aerodynamics	154	(7)
Measurements on Models in the Wind Tunnel	154	(3)
Measurements on Site	157	(1)
References	158	(3)
Loads and Structural Stresses	161	(58)
Loads on the Wind Turbine	162	(3)
Sources of Loading	165	(14)
Uniform and Steady-State Air Flow	165	(3)
Vertical Wind Shear and Cross Winds	168	(1)
Tower Interference	169	(5)
Wind Turbulence and Gusts	174	(4)
Gravity and Inertia Loads	178	(1)
Design Load Assumptions	179	(6)
Wind Turbine Classes	180	(1)
Normal Wind Conditions	181	(1)
Extreme Wind Conditions	182	(1)
Other Environmental Influences	183	(2)
Load Cases	185	(3)
Normal Operation	185	(2)
Technical Faults	187	(1)
Ultimate Loads and Fatigue Loading	188	(3)
Ultimate Loads	189	(1)
Fatigue Load Spectrum	189	(2)
Calculation of Fatigue Loads and Structural Stresses	191	(8)
Mathematical Models and Calculation Procedure	192	(4)
Dynamic Response of the Structure and Fatigue Strength	196	(3)
Influence of Conceptual Design Features on the Loading	199	(10)
Number of Rotor Blades	200	(1)
Rotor Hub Hinges in the Two-Bladed Rotor	201	(4)
Blade Pitch Control	205	(1)
Rotor Speed Slip and Variable-Speed Operation	206	(3)
Test Data and Testing Facilities	209	(4)
Test-Bed Trials	209	(1)
Data Acquisition Systems and Field Measurements	210	(3)
Standards and Certification of Wind Turbines	213	(6)
Important International and National Design Standards	213	(1)
Certification of Wind Turbines	214	(2)
References	216	(3)
Rotor Blades	219	(34)
Materials	220	(2)
Aircraft Wings as Model	222	(2)
Experimental Designs of Rotor Blades in the Past	224	(8)
Riveted Aluminium Designs	225	(1)
Steel Designs	226	(5)
Traditional Wood Construction	231	(1)
Modern Fibre-Reinforced Composite Blades	232	(9)
Fibre-Reinforced Composite Materials and Manufacturing Techniques	232	(3)
Previous Designs with Fibre-Reinforced Composites	235	(3)
Present Standard Design	238	(2)
Wood/Epoxy Composites	240	(1)
Blade Connection to the Rotor Hub	241	(3)
Comparison of Rotor Blade Designs	244	(4)
Aerodynamic Brakes on Stall-Controlled Rotors	248	(2)
Lightning Protection	250	(1)
Ice Warning and De-icing	251	(2)
References	252	(1)
Mechanical Drive Train and Nacelle	253	(66)
Fundamental Considerations of Power Transmission	254	(2)
Previous Experimental Designs	256	(3)
Generator in the Tower Base	257	(1)
Vertically Positioned Generator in the Tower Head	257	(2)
Current Standard Designs	259	(3)
Gearbox between Rotor and Generator	259	(1)
Direct Rotor-Driven Generator	260	(2)
Rotor Hub	262	(7)
Cast Steel Rotor Hubs for Three-bladed Rotors	264	(1)
Rotor Hub Concepts for Two-bladed Rotors	265	(4)
Blade Pitch Mechanism	269	(10)
Rotor Blade Bearings	271	(2)
Hydraulic Blade Pitch Systems	273	(2)
Electrical Blade Pitch Systems	275	(2)
Passive Blade Pitching	277	(1)
Redundancy and Safety Issues	278	(1)
Rotor Bearing Concepts	279	(8)
Bearing Technology and Service Life	279	(3)
Rotor Shaft with Separate Bearings	282	(1)
Three-Point Suspension of Rotor Shaft and Gearbox	283	(1)
Rotor Shaft Integrated into the Gear Box	284	(1)
Rotor Bearings Integrated into the Load-Bearing Nacelle Structure	285	(1)
Rotor Support on a Fixed Axle	286	(1)
Rotor Brake	287	(3)
Gearbox	290	(10)
Gearbox Configurations	290	(4)
Gearbox Dimensioning	294	(3)
Efficiency and Noise Emission	297	(3)
Installation of the Electric Generator	300	(3)
Torsional Compliance and Variable-Speed Transmission in the Mechanical Drive Train	303	(3)
Nacelle	306	(6)
Design and Load Carrying Concept	306	(3)
External Shape -- Aesthetic Aspects	309	(3)
Yaw System	312	(3)
Assembly and Performance Testing	315	(4)
References	317	(2)
Electrical System	319	(38)
Synchronous and Asynchronous Generator	320	(8)
Synchronous Generator	320	(4)
Induction Generator	324	(4)
Assessment Criteria for Electrical Generators in Wind Turbines	328	(3)
Fixed-Speed Generator Systems	331	(7)
Synchronous Generator Directly Coupled to the Grid	331	(2)
Induction Generator Directly Coupled to the Grid	333	(2)
Variable-Slip Induction Generator	335	(1)
Multi-Speed Generator Systems	336	(2)
Variable Speed Generator Systems with Inverter	338	(6)
Synchronous Generator with Inverter	339	(2)
Induction Generator with Oversynchronous Cascade	341	(1)
Double-Fed Induction Generators	342	(2)
Directly Rotor-Driven Variable-Speed Generators	344	(4)
Synchronous Generator with Electric Excitation	345	(2)
Generators with Permanent Magnets	347	(1)
Total Electrical System of a Wind Turbine	348	(5)
Large Turbines	349	(2)
Small Wind Turbines	351	(2)
Comparison of Electrical Concepts	353	(4)
References	355	(2)
Control Systems and Operation Sequence Control	357	(32)
Wind Measurement System	358	(3)
Locality of the Wind Measurement	359	(1)
Wind Sensors and Data Processing	360	(1)
Yaw Control	361	(2)
Power and Speed Control by Means of Rotor Blade Pitching	363	(13)
System Characteristics and Controlled Systems	365	(2)
Operation with Generators Directly Coupled to the Grid	367	(5)
Parallel-Grid Operation with Frequency Converter	372	(2)
Isolated Operation	374	(2)
Power Limiting by Aerodynamic Stall	376	(5)
Parallel-Grid Operation with Passive Stall	376	(1)
Isolated Operation with Passive Stall Rotors	377	(1)
Active Stall Control	378	(3)
Supervisory Control and Operational States	381	(3)
Operational States and Operating Cycle	381	(2)
Interaction with the Grid	383	(1)
Mathematical Simulation and Hardware of Control Systems	384	(5)
References	387	(2)
Vibration Problems	389	(32)
Aeroelastic Stability of Rotor Blades	390	(2)
Torsional Vibration of the Drive Train	392	(10)
Mathematical Model	393	(3)
Mechanical Models for the Electrical Grid Coupling	396	(1)
Natural Frequencies and Vibration Modes	397	(3)
Excitations and Resonances	400	(2)
Dynamics of the Yaw System	402	(4)
Modelling and Moments Around the Yaw Axis	403	(2)
Excitation and Resonances	405	(1)
Vibration of the Whole Wind Turbine	406	(15)
Tower Stiffness	408	(3)
Vibrational Characteristics of Existing Wind Turbines	411	(6)
Mathematical Simulation	417	(3)
References	420	(1)
The Tower	421	(30)
Tower Configurations	422	(3)
Free-Standing Steel Tubular Towers	425	(10)
Strength and Stiffness Design	425	(4)
Manufacturing Techniques and Construction	429	(3)
Climbing Aids and Internal Installation	432	(3)
Lattice Towers	435	(2)
Concrete Towers	437	(6)
Comparison of Different Tower Concepts	443	(2)
The Foundation	445	(6)
References	449	(2)
The Wind Resource	451	(34)
Causes of the Wind and Power in the Wind	451	(3)
Global Distribution of Wind Resources	454	(5)
Wind Resources in Europe	455	(2)
Wind Resources in North America	457	(2)
Characteristic Parameters	459	(11)
Mean Annual Wind Speed and Wind Speed Frequency Distribution	459	(2)
Increase in Wind Speed with Altitude	461	(3)
Steadiness of the Wind	464	(4)
Wind Turbulence	468	(2)
Topography and Local Wind Flow	470	(2)
Determining the Wind Speed	472	(13)
Measuring Techniques	472	(6)
Ascertaining the Wind Data and the Energy Yield from the European Wind Atlas	478	(2)
Numeric Models of Three-Dimensional Wind Fields	480	(3)
References	483	(2)
Power Output and Energy Yield	485	(48)
Principles of Power Optimisation	486	(9)
Operating Characteristics of the Rotor	486	(1)
Efficiencies in the Mechanical-Electrical Energy Conversion	487	(4)
Optimisation of Rotor Speed	491	(4)
Power Curve of the Wind Turbine	495	(8)
Definitions and Characteristics	495	(2)
Measuring the Power Curve	497	(6)
Calculation of the Annual Energy Yield	503	(2)
Major Influences on the Power Curve and the Energy Yield	505	(17)
Wind Regime on Site	506	(3)
Air Density	509	(2)
Turbulence	511	(1)
Rotor Diameter	512	(1)
Optimal Rotor Speed and Variable Rotor Speed Operation	513	(3)
Power Control	516	(1)
Installed Generator Power	517	(2)
Rotor Hub Height	519	(1)
Operational Wind Speed Range	520	(1)
Rotor Power Coefficient	521	(1)
Uniformity of Power Output	522	(3)
Efficiency of a Wind Turbine as Energy Converter	525	(1)
Approximate Calculation of the Energy Yield	526	(2)
Technical Availability	528	(5)
References	532	(1)
Environmental Impact	533	(30)
Hazards for the Environment	534	(3)
How Far Can a Rotor Blade Fly?	534	(2)
Safety Risks	536	(1)
Wind Turbine Noise	537	(12)
Acoustic Parameters and Permissible Noise Levels	538	(3)
Noise Sources in Wind Turbines	541	(3)
Noise Emission of Current Wind Turbines	544	(5)
Shadow Effects	549	(4)
Interference with Radio and Television Signals	553	(2)
Impact on Bird Life	555	(1)
Land Use	556	(2)
Visual Impact on the Landscape	558	(2)
Effect on the Environmental Climate	560	(3)
References	561	(2)
Commercial Applications of Wind Turbines	563	(52)
Stand-Alone Applications	564	(13)
Autonomous Power Supply and Storage Problems	565	(4)
Residential Heating	569	(3)
Pumping Water	572	(2)
Desalination of Sea Water	574	(3)
Small grids with Diesel Generators and Wind Turbines	577	(4)
Wind Turbines Interconnected with Large Utility Grids	581	(5)
Distributed Wind Turbines Operated by Private Consumers	581	(1)
Wind Park Installations	582	(4)
Technical Layout of Wind Park Installations	586	(7)
Wind Turbine Spacing	586	(4)
Electrical Cabling and Connections	590	(3)
Integrating Wind Turbines into the System of Interconnected Power Stations of the Utilities	593	(4)
Operational Strategies and Control Issues	594	(2)
Can Wind Turbines Replace Conventional Power Stations?	596	(1)
Market Development and Wind Energy Potential	597	(18)
Wind-Energy Utilisation Since the Eighties and Market Forecasts	598	(3)
The Wind Turbine Industry	601	(8)
The Wind Energy Potential	609	(4)
References	613	(2)
Offshore Wind Energy Utilisation	615	(38)
Offshore Wind Energy in the North Sea and the Baltic Sea	616	(14)
Oceanographic Conditions and Wind Resources	616	(4)
The First Offshore Wind Parks	620	(3)
Commercial Installations	623	(7)
Licensing Procedure	630	(4)
Legal Situation	631	(1)
Licensing Criteria	632	(2)
Technology of Offshore Siting	634	(19)
Technical Requirements for the Wind Turbines	634	(2)
Foundation on the Sea Floor	636	(4)
Electrical Infrastructure	640	(6)
Transportation, Installation and Maintenance	646	(5)
References	651	(2)
Wind Turbine Installation and Operation	653	(50)
Project Development	654	(1)
Planning and Building Permits	655	(2)
Transportation Problems	657	(3)
Erection on the Site	660	(13)
Small and Medium-Sized Turbines	661	(3)
Large Wind Turbines	664	(9)
Grid Connection	673	(6)
Commissioning	679	(3)
Commercial Wind Turbines	679	(1)
Experimental Turbines and Prototypes	680	(2)
Operation and Monitoring	682	(5)
Monitoring of Operation and Performance	682	(4)
Monitoring of Large Wind Farms	686	(1)
Safety Aspects	687	(8)
Structural Strength and Operational Safety	687	(3)
Environmental Effects	690	(5)
Maintenance and Repair	695	(8)
Routine Maintenance	696	(1)
Causes of Damage and Repair Risks	697	(2)
Background Experience and Long-Term Forecasting	699	(1)
References	700	(3)
Wind Turbine Costs	703	(48)
Specific Costs and Significant Reference Parameters	704	(2)
Costs of Previous Experimental Turbines and Prototypes	706	(1)
Sales Prices of Commercial Wind Turbines	707	(3)
Cost Structure and Manufacturing Costs of Wind Turbines	710	(7)
Cost Breakdown to Subsystems and Components	710	(4)
Economy of Scale in Series Production	714	(2)
Costs and Price Calculation in Production	716	(1)
Wind Turbine Weight and Manufacturing Costs	717	(11)
Development of Specific Mass with Turbine Size	718	(5)
Manufacturing Cost Calculation on the Basis of Mass-Related Cost Figures	723	(5)
Lowering Costs through Further Technical Development	728	(1)
Alternative Technical Concepts and Achievable Costs	729	(3)
On the Development Costs of Wind Turbines	732	(1)
Investment Costs for Turn-key Installations	733	(9)
Project Development	733	(1)
Foundations and Civil Works	734	(1)
Electrical Infrastructure and Grid Connection	735	(2)
Other Cost Factors	737	(2)
Total Investment Costs -- Selected Examples	739	(3)
Operating and Maintenance Costs	742	(5)
Maintenance and Repairs	743	(1)
Insurances	744	(1)
Other Operating Costs	745	(1)
Total Annual Operating Costs	746	(1)
Offshore Projects	747	(4)
References	750	(1)
Wind Turbine Economics	751	(24)
Financing	752	(2)
Estimating Electricity Costs and Repayment Period	754	(7)
Selected Examples	756	(3)
Offshore Wind Parks	759	(2)
Power Generation Costs of Wind Turbines in Competition with Conventional Energy Sources	761	(3)
Dynamic Calculation of Economic Viability	764	(6)
Present-Value or Discounted Cash-flow Analysis Method	764	(2)
Cash-Flow Projection	766	(4)
Energy Recovery of Wind Turbine Production and Operation	770	(1)
Effect of Wind Energy Utilisation on Employment	771	(1)
Macroeconomics and Renewable Energies	772	(3)
References	774	(1)
Subject Index	775