Probabilistic Modelling Techniques and a Robust Design Methodology for Offshore Wind Farms
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PROBABILISTIC MODELLING TECHNIQUES AND A ROBUST DESIGN METHODOLOGY FOR OFFSHORE WIND FARMS A thesis submitted to the University of Manchester for the degree of PhD in the Faculty of Engineering and Physical Sciences 2012 Muhammad Ali Electrical Energy and Power Systems Group School of Electrical and Electronic Engineering 2 Table of Contents List of Tables ............................................................................................................................ 8 List of Figures .......................................................................................................................... 9 List of Symbols and Abbreviations ................................................................................. 14 Abstract ............................................................................................................................. 24 Declaration ............................................................................................................................. 25 Copyright Statement ........................................................................................................... 26 Acknowledgement ................................................................................................................ 28 Chapter 1 Introduction ..................................................................................................... 29 1.1 The Need for Improved Modelling and Design ................................................. 32 1.2 Overview of Wind Power Generation ................................................................ 36 1.2.1 Wind farm capacities and turbine sizes in European offshore wind farms .. 36 1.2.2 Components of an offshore wind farm ............................................................. 38 1.2.2.1 Wind turbines ........................................................................................... 38 1.2.2.2 Types of foundation .................................................................................. 40 1.2.2.3 Wind turbine array .................................................................................. 41 1.2.2.4 Array configurations ................................................................................ 41 1.2.2.5 Offshore substation .................................................................................. 44 1.2.2.6 Platform interconnection ......................................................................... 45 1.2.2.7 Transmission of electricity to shore ........................................................ 46 1.2.2.8 Onshore substations ................................................................................. 47 1.3 Wind Farm Costs ................................................................................................ 47 1.4 Review of Relevant Previous Works .................................................................. 48 1.4.1 Aggregate models for transient stability studies............................................ 48 1.4.2 Energy yield estimation and cost-benefit analysis for offshore wind farms . 50 1.4.3 Wind energy curtailments ................................................................................ 52 1.5 Summary of the Past Work ................................................................................ 54 1.6 Research Objectives ............................................................................................ 55 1.7 Major Contributions of the Research ................................................................ 56 1.7.1 Vector based wake calculation program (VebWake) ...................................... 56 1.7.2 Probabilistic wake effect model ....................................................................... 56 1.7.3 Probabilistic aggregate model of a wind farm ................................................ 56 1.7.4 Advanced method for wind farm energy yield calculation ............................. 57 1.7.5 Assessment of wind energy curtailment ......................................................... 57 1.7.6 Probabilistic identification of critical wind turbines inside the wind farm .. 57 1.7.7 Methodology for cost-benefit analysis of offshore electrical network design 57 1.7.8 Industrial software for offshore wind farm design and loss evaluation........ 58 1.8 Overview of Thesis ............................................................................................. 58 Chapter 2 Wind Turbine and Power System Components Modelling ................... 61 2.1 Introduction ........................................................................................................ 61 2.2 Wind Turbine Modelling .................................................................................... 62 2.2.1 Power extraction from a wind turbine ............................................................ 62 2.2.2 Power coefficient models and look-up table .................................................... 64 3 2.2.3 Thrust coefficient .............................................................................................. 66 2.2.4 Operating range of wind turbines .................................................................... 66 2.3 Modelling of Doubly Fed Induction Generator .................................................. 67 2.3.1 Drive train ......................................................................................................... 69 2.3.2 Generator model ................................................................................................ 71 2.3.3 Rotor-side and Grid-side converter .................................................................. 73 2.3.4 Protection system .............................................................................................. 76 2.3.4.1 DC link chopper ........................................................................................ 77 2.3.5 Rotor speed controller ....................................................................................... 77 2.3.6 Pitch control ....................................................................................................... 79 2.3.7 Yaw control ........................................................................................................ 80 2.4 Power Transmission Line Modelling ................................................................. 80 2.5 Transformer Modelling ....................................................................................... 81 2.6 Summary ............................................................................................................. 84 Chapter 3 Modelling of Wake Effects ............................................................................. 85 3.1 Introduction ......................................................................................................... 85 3.2 Wake Effects ........................................................................................................ 86 3.3 Detailed Wake Effect Modelling......................................................................... 89 3.3.1 Single wakes ...................................................................................................... 90 3.3.2 Partial wakes ..................................................................................................... 90 3.3.3 Multiple wakes .................................................................................................. 91 3.4 Development of Vector Based Wake Calculation Program .............................. 92 3.5 Impact of Wind Speed and Direction on Wind Turbine Power Output ........... 94 3.6 Effect of Height on Wind Speed ......................................................................... 97 3.7 Weibull Distribution ........................................................................................... 97 3.8 Wind Measurements ........................................................................................... 98 3.9 Wind Farm Layouts ............................................................................................ 99 3.10 Capacity Factor ................................................................................................. 101 3.11 Wind and Wake Turbulence ............................................................................. 101 3.12 Probabilistic Wake Model ................................................................................. 103 3.12.1 Jensen‘s wake model (deterministic) ............................................................. 104 3.12.2 Turbulence model ............................................................................................ 104 3.13 Case Study ......................................................................................................... 105 3.14 Power Output Analysis ..................................................................................... 107 3.15 Energy Yield Analysis ....................................................................................... 109 3.16 Summary ........................................................................................................... 110 Chapter 4 Probabilistic Aggregate Dynamic Model of a Wind Farm ................... 112 4.1 Introduction ....................................................................................................... 112 4.2 Aggregation by Wind Speed ............................................................................. 114 4.3 Support Vector Clustering ...............................................................................