Page 8 - Wind Energy Handbook

viii CONTENTS

4.2 Constant Rotational Speed Operation 177
4.2.1 The K P 1=º curve 177
4.2.2 Stall regulation 178
4.2.3 Effect of rotational speed change 179
4.2.4 Effect of blade pitch angle change 180
4.2.5 Pitch regulation 180
4.2.6 Pitching to stall 181
4.2.7 Pitching to feather 181
4.3 Comparison of Measured with Theoretical Performance 182
4.4 Variable-speed Operation 184
4.5 Estimation of Energy Capture 185
4.6 Wind-turbine Field Testing 190
4.6.1 Introduction 190
4.6.2 Information sources for wind-turbine testing 190
4.7 Wind-turbine Performance Measurement 191
4.7.1 Field testing methodology 192
4.7.2 Wind-speed measurement 193
4.7.3 Wind-direction measurement 194
4.7.4 Air temperature and pressure measurement 194
4.7.5 Power measurement 196
4.7.6 Wind-turbine status 196
4.7.7 Data acquisition system 196
4.7.8 Data acquisition rate 197
4.8 Analysis of Test Data 197
4.9 Turbulence Effects 198
4.10 Aerodynamic Performance Assessment 200
4.11 Errors and Uncertainty 204
4.11.1 Evaluation of uncertainty 204
4.11.2 Sensitivity factors 205
4.11.3 Estimating uncertainties 206
4.11.4 Combining uncertainties 206
References 207

5 Design Loads for Horizontal-axis Wind Turbines 209
5.1 National and International Standards 209
5.1.1 Historical development 209
5.1.2 IEC 61400-1 209
5.1.3 Germanisher Lloyd rules for certification 210
5.1.4 Danish Standard DS 472 211
5.2 Basis for Design Loads 211
5.2.1 Sources of loading 211
5.2.2 Ultimate loads 211
5.2.3 Fatigue loads 212
5.2.4 Partial safety factors for loads 212
5.2.5 Functions of the control and safety systems 213
5.3 Turbulence and Wakes 213