Offshore Wind Energy Technology

A COMPREHENSIVE REFERENCE TO THE MOST RECENT ADVANCEMENTS IN OFFSHORE WIND TECHNOLOGY

Offshore Wind Energy Technology offers a reference based on the research material developed by the acclaimed Norwegian Research Centre for Offshore Wind Technology (NOWITECH) and material developed by the expert authors over the last 20 years. This comprehensive text covers critical topics such as wind energy conversion systems technology, control systems, grid connection and system integration, and novel structures including bottom-fixed and floating. The text also reviews the most current operation and maintenance strategies as well as technologies and design tools for novel offshore wind energy concepts.

The text contains a wealth of mathematical derivations, tables, graphs, worked examples, and illustrative case studies. Authoritative and accessible, Offshore Wind Energy Technology:

• Contains coverage of electricity markets for offshore wind energy and then discusses the challenges posed by the cost and limited opportunities

• Discusses novel offshore wind turbine structures and floaters

• Features an analysis of the stochastic dynamics of offshore/marine structures

• Describes the logistics of planning, designing, building, and connecting an offshore wind farm

Written for students and professionals in the field, Offshore Wind Energy Technology is a definitive resource that reviews all facets of offshore wind energy technology and grid connection.

Autorentext

OLIMPO ANAYA-LARA is a Reader in the Wind Energy and Control Centre at the University of Strathclyde, Glasgow, UK. JOHN O. TANDE is a Chief Scientist with SINTEF Energy Research and Director of NOWITECH, Norway. KJETIL UHLEN is a Professor in Electrical Power Systems at the Norwegian University of Science and Technology (NTNU), Norway. KARL MERZ is a Research Scientist at SINTEF Energy Research, Norway.

Inhalt
Notes on Contributors xiii

Foreword xvii

Preface xix

Acronyms xxi

Symbols (Individual Chapters) xxv

About the Companion Website xxxi

**1 Introduction 1
**John O. Tande

1.1 Development of Offshore Wind Energy 1

1.2 Offshore Wind Technology 5

1.3 Levelized Cost of Energy 6

1.4 Future Offshore Wind Development 9

1.5 References 10

**2 Energy Conversion Systems for Offshore Wind Turbines 13
**Olimpo Anaya?]Lara

2.1 Background 13

2.2 Offshore Wind Turbine Technology Status 14

2.3 Offshore Wind Turbine Generator Technology 14

2.4 Wind Turbine Generator Architectures 17

2.4.1 Fixed?]speed Wind Turbines 17

2.4.2 Variable?]speed Wind Turbines 18

2.4.2.1 Type II Wind Turbine Generator 18

2.4.2.2 Type III DFIG Wind Turbine Generator 19

2.4.2.3 Type IV FRC Wind Turbine Generator 20

2.5 Generators for Offshore Wind Turbines 21

2.5.1 New Generator Technologies and Concepts 22

2.5.1.1 Direct?]driven DFIG 22

2.5.1.2 Conventional Direct?]driven RFPMSG 22

2.5.1.3 Direct?]driven iPMSG 23

2.5.1.4 Superconducting Generator 23

2.5.1.5 High-Voltage Variable-Capacitance Direct Current Generator 23

2.6 Power Electronic Converters for MW Wind Turbine Generators 24

2.6.1 Technical and Operational Requirements 24

2.6.2 Back?]to?]back Connected Power Converters 25

2.6.2.1 LV Converters 25

2.6.2.2 MV Converters 27

2.6.3 Passive Generator?]side Converters 28

2.6.4 Converters for Six?]phase Generators 28

2.6.5 Power Converters Without DC?]link Matrix Converters 30

2.7 Wind Generators Compared to Conventional Power Plant 30

2.7.1 Local Impacts 31

2.7.1.1 Circuit Power Flows and Busbar Voltages 31

2.7.1.2 Protection Schemes, Fault Currents and Switchgear Rating 31

2.7.1.3 Power Quality 32

2.7.2 System?]wide Impacts 32

2.7.2.1 Power System Dynamics and Stability 32

2.7.2.2 Reactive Power and Voltage Support 33

2.7.2.3 Frequency Support 33

2.8 Acknowledgements 33

2.9 References 34

**3 Modelling and Analysis of Drivetrains in Offshore Wind Turbines 37
**Amir Rasekhi Nejad

3.1 Introduction 37

3.2 Drivetrain Concepts 39

3.2.1 Gearbox Configurations, Cost and Efficiency 39

3.3 Gearbox Failures 42

3.4 State?]of?]the-art Wind Turbine Gearbox Design Codes 44

3.5 Drivetrain Modelling and Analysis 44

3.5.1 Decoupled Approach 46

3.5.2 Multibody System (MBS) Modelling 48

3.5.2.1 General 48

3.5.2.2 Gear Model in MBS 50

3.5.2.3 Bearing Model in MBS 51

3.5.3 Gear Stress Analysis 53

3.5.4 Bearings Fatigue Analysis 54

3.5.5 Effect of Geometrical Errors 55

3.5.6 Effect of Misalignments 55

3.5.7 Flexibility in the Planetary Stage 55

3.6 Limit State Design 56

3.6.1 FLS, ULS and ALS Design Check 57

3.6.2 Ultimate Limit State (ULS) Design Check 58

3.6.3 Fatigue Limit State (FLS) Design Check 60

3.6.3.1 Gears 60

3.6.4 Structural Reliability Analysis Method 63

3.6.4.1 Uncertainties 63

3.6.4.2 Model Uncertainties 64

3.6.4.3 Failure Function 66

3.6.4.4 ULS and FLS Structural Reliability Analysis 67

3.7 Drivetrains in Floating Wind Turbines 69

3.7.1 Gearbox on TLP, spar and semi?]submersible turbines versus land?]based wind turbines 69

3.8 Condition Monitoring and Inspection 77

3.8.1 Model?]based Fault Detection 78

3.8.2 Gearbox Vulnerability Map 79

3.9 Drivetrains in Fault Conditions 82

3.10 5?]MW Reference Offshore Drivetrain 88

3.11 References 94 **4 Fixed and Floati...