Page 12 - Fluid Power Engineering

x Contents

9 Wind Turbine Generator (WTG) Components .... 169
Introduction .......................... 169
Rotor System ......................... 169
Blades ........................... 170
Forces and Moments .................. 172
Rotor Hub ........................ 173
Alternative Configurations of Turbines ......... 173
Pitch ............................ 177
Nacelle ........................... 178
Gearbox .......................... 178
Yaw Drive ......................... 178
Nacelle Housing and Frame ............. 179
Lifting/Lowering Mechanism ............ 180
Towers ........................... 180
Foundation ....................... 181
Spread-Footing Foundation ............. 182
Design Loads of Wind Turbines ........... 185
Design Wind Conditions ............... 186
Normal Wind Profile Model (NWP) ........ 186
Extreme Wind Speed Model (EWM) ........ 188
Turbine Certification .................. 189

10 Basics of Electricity and Generators .......... 197
Introduction .......................... 197
Basic Principles of Electromagnetism .......... 197
Faraday’s Law of Induction ............. 198
Lenz Law ......................... 198
Lorenz Law or Biot-Savart Law ........... 198
Basic Principles of Alternating Current ......... 199
Basic Principles of Electrical Machines ......... 200
Conversion of Mechanical to Electrical Power .. 202
Synchronous Generator ................... 203
Analysis of Synchronous Generator ........... 205
Variable-Speed Permanent Magnet
Synchronous Generators .............. 208
Direct-Drive Synchronous Generator (DDSG) .. 211
Asynchronous Generators ................. 212
Variable Speed ...................... 216
11 Deploying Wind Turbines in Grid ........... 221
Introduction .......................... 221
What Happens on a Grid When There Is
No Wind? .......................... 221
“Scheduling” and Dispatch of Wind
Resources .......................... 223