Long-term Research Challenges in Wind Energy - A Research Agenda by the European Academy of Wind Energy (eBook)

Preface 6
Contents 9
Acknowledgements 7
Introduction 10
Materials and Structures 20
1.1 How Will Multi-scale Modelling Improve Materials and Structures? 21
1.1.1 Missing Links in Current Damage and Failure Process Predictions? 22
1.1.2 Multi-scale Experimental Observations? 22
1.1.3 Linking (Microscopic) Damage State with Macroscopic Observations into Health-Based Strategies 23
1.2 How Can New Materials Be Developed? 23
1.2.1 Materials Science 23
1.2.2 From Material to Application 24
1.3 How Do Joints Really Work? 25
1.3.1 Connections 25
Wind and Turbulence 27
2.1 How Should We Characterise the Dynamical Inflow Conditions? 28
2.1.1 Parameters for Wind Turbulence 28
2.1.2 Pattern of Wind 29
2.1.3 Orographic Dependences 30
2.2 What Is the Importance of Open Questions on Turbulence? 30
2.2.1 Small-Scale Turbulence 30
2.2.2 Structures Within a Turbulence Situation 31
2.2.3 Turbulence Validation 32
2.3 How Can One Model Wind, as an Energy Resource, in Space and Time? 32
2.3.1 Forecasting Weather and Climate 33
2.3.2 Limits of Predictability 34
Aerodynamics 35
3.1 Is the Acceleration of CFD Codes the Main Challenge, or Do We Still Have Physical Problems to Solve in Rotor Analysis? 36
3.1.1 Improvement of Simplified and Low-Fidelity Models 37
3.1.2 Hybrid Models and Eulerian-Lagrangian Formulation 37
3.1.3 Uncertainty Quantification 38
3.1.4 Experimental Simulation and Model Validation 38
3.1.5 Unsteady Fluid-Structure-Control Interaction 39
3.2 How Can the Aerofoil Concept Be Extended Towards an Unsteady Three-Dimensional Flow? 40
3.2.1 Flow Separation and 3D Stall 40
3.2.2 Roughness, Transition and Turbulence 40
3.2.3 Flow Control Devices and 3-D Unsteady Flow 41
3.2.4 Aerofoil Aeroacoustics 41
3.3 How Do Wake and Wake-Wake Interaction Effects Depend on Near-Wake and Blade Flow Details? 41
3.3.1 Interaction of the Wind Turbine Wake with the Atmospheric Boundary Layer 42
3.3.2 Near- to Far-Wake Transition 43
3.3.3 Wake-Wake Interaction 43
3.4 Do New and Adapted Aerodynamic Concepts Require New Knowledge? 43
3.4.1 Unsteady 3D Actuator Surface 44
3.4.2 Blade-Vortex Interaction 44
Control 45
4.1 To What Extent Can Modern Control Theory and Technology Tame the Wind? 46
4.1.1 Novel Sensor Technologies 46
4.1.2 Distributed Actuation 47
4.1.3 Floating Structures 47
4.1.4 Controller Synthesis 48
4.2 How Should We Operate a Wind Plant? 49
4.2.1 Control-Oriented Modelling 49
4.2.2 Controller Synthesis 50
4.2.3 Experimental Validation 51
Electromechanical Conversion 52
5.1 What Are the Physical Limitations and Is It Possible to Shift or Avoid Them? 53
5.1.1 Mechanical Conversion Systems—Gearboxes 53
5.1.2 Electromechanical Conversion—Generators 54
5.1.3 Electrical Conversion—Power Electronics 56
5.2 What Are the Failure Mechanisms and Is It Possible to Avoid or Mitigate Them? 57
5.2.1 Mechanical Conversion Systems—Gearboxes 57
5.2.2 Electromechanical Conversion—Generators 58
5.2.3 Electrical Conversion—Power Electronics 59
5.3 How Can the Multi-scale Problem of the System Dynamics and Local Loads Be Evaluated? 59
5.4 What Are the Best System Choices? 61
5.4.1 Which Criteria Should Be Used to Evaluate Electromechanical Conversion Systems? 61
5.4.2 Drivetrain Component Selection 61
5.4.3 Availability of Materials 62
Reliability and Uncertainty Modelling 63
6.1 How Can Operation and Maintenance Data Be Made Available to Increase O& M Knowledge?
6.1.1 The Initiation and Maintenance of a Comprehensive, Representative and Publicly Accessible Turbine Upkeep and Failure Database 64
6.1.2 The Documentation of Service Visits and Maintenance Operations 65
6.2 How Are Data Selected, Collected and Analysed, and How Can They Be Used for Improved Performance? 65
6.2.1 Knowledge About External Conditions 67
6.2.2 SCADA and Condition Monitoring Signal Retrieval and Analysis 67
6.2.3 Improved Maintenance Methods 67
6.2.4 Implementing Mathematical Probabilistic Approaches to Improve Operational Performance 68
6.3 What Are the Best-Suited Stochastic Models and Parameters for Performing Adequate and Accurate Systems Reliability Assessments? 68
6.3.1 Stochastic Models for Expressing Reliability and Failure Rate Characteristics 69
6.3.2 Simulation Models for Downtime, Availability and Annual Energy Production Calculation 69
6.3.3 “External” Information About Anticipated Risk Levels and Quality Assurance and Control 69
6.4 When and Where Are Detailed Physical Models Needed to Predict Degradation and Failure? 70
6.4.1 Degradation and Failure Modelling 71
6.4.2 Tolerances in Material Properties, Manufacturing, Assembly, Components, and/or Full Installation Exchange Inaccuracies 71
Design Methods 72
7.1 How Can We Develop Truly Holistic Design Tools? 73
7.1.1 Holistic Multidisciplinary Optimisation by Physics-Based Modelling 73
7.1.2 Uncertainties, and Probability of Failures 74
7.1.3 Beyond the Single Wind Turbine 75
7.2 What Are the Validated Simulation Models that Can Support a Holistic Multidisciplinary Design Activity? 76
7.2.1 Validated Multiple-Fidelity Simulation Models 76
7.3 How Are Cost Models Formulated so as to Capture the Effects of Each Technology and Design Choice? 78
7.3.1 How Can Reliable Cost Models Be Established? 78
7.3.2 Design-Driven Technological Assessment 79
Hydrodynamics, Soil Characteristics and Floating Wind Turbines 81
8.1 How Can We Predict Hydrodynamic Effects Relevant for Offshore Wind Turbines More Efficiently and Reliably? 82
8.1.1 Life Beyond Potential Flow and Linear Wave Theory 83
8.1.2 Numerical Tools and Validation 85
8.2 How Can We Efficiently Characterise Complex Properties and Highly Nontrivial Response of Soil Characteristics? 86
8.2.1 Models for Soil-Structure-Interaction 86
8.2.2 Uncertainties in Geotechnical Design 87
8.3 How Can We Design Efficient Offshore Turbines and Install and Operate Them Safely and Economically? 87
8.3.1 Floater Design 87
8.3.2 Installation and Operational Constraints 89
8.3.3 Wave Energy and Other Issues? 90
Offshore Environmental Aspects 91
9.1 What Are the Cumulative Environmental Impacts of Increasing Numbers of OWFs and How Can Negative Effects Be Mitigated? 92
9.1.1 Impacts of an Increasing Amount of Wind Farms on Specific Animal Groups 92
9.1.2 Impact on the Ecosystem as a Whole, also in Relation to Natural Variability 93
9.1.3 How Can Wind Farms Be Designed Wind Farms with Minimal Environmental Impacts? 94
9.2 How Can Multifunctional Use of Offshore Wind Farms Be Stimulated? 94
9.2.1 Harvesting Natural Resources 95
9.2.2 Active Aquaculture 95
Wind Energy in the Electric Power System 96
10.1 How Can the Power System Be Kept Reliable and Stable? 97
10.1.1 Wind Resource and Its Random Character 98
10.1.2 Concepts of Stabilisation 99
10.1.3 Big Data and Its Information 100
10.1.4 Ancillary Services and Power Balancingwith Wind Power 100
10.2 To Which Extend Do New Grid Structures Become Necessary? 101
10.2.1 Grid Integration of Wind Energy 102
10.2.2 From Wind to Power 102
10.2.3 Connection for Bigger Offshore Wind Farms 103
Societal and Economic Aspects of Wind Energy 104
11.1 Which Support Mechanisms Are Best Suited for Promoting Wind Energy? 105
11.1.1 Support Mechanisms 106
11.1.2 Entrepreneurship and Innovation 106
11.2 How Can System Integration of Wind Energy Be Facilitated? 107
11.2.1 Integration in the Electricity Supply System 107
11.2.2 Interplay with Other Parts of the Energy System 107
11.3 How Can We Develop Socially Responsible Innovation in Wind Energy? 108
11.3.1 Onshore Wind 109
11.3.2 Offshore Wind 109
Closing Remarks 110