WIND ENERGY SYSTEMS - Cd3wd

More documents

Recommendations

Info

Chapter 6—Asynchronous Generators 6–39 Figure 23: Simplified schematic of field-modulated generator. balanced conditions as far as the generator is concerned. The field modulated generator can also be used to generate three-phase power. This requires three separate rotor windings spaced along a single rotor, each with its own set of three stator windings. Each rotor winding is excited separately. Each set of three stator windings has the same electronics circuit as was shown in Fig. 23. The outputs of these three single-phase systems are then tied together to form a three-phase output. Measured efficiency of a 60 kW field modulated generator tested at Oklahoma State University[1] was approximately 90 percent, quite competitive with other types of generators of similar size. The major disadvantage would be the cost and complexity of the power electronics circuit. It appears that this extra cost will be difficult to justify except in stand alone applications where precisely 60 Hz is required. Whenever frequency deviations of up to 10 percent are acceptable, induction generators or ac generators would appear to be less expensive and probably more reliable. 8 ROESEL GENERATOR Another type of electrical generator which delivers fixed frequency power over a range of shaft speeds is the Roesel generator, named after its inventor, J. F. Roesel, Jr.[12, 9, 4]. To understand this generator we need to recall that the output frequency of all electrical generators is given by Wind Energy Systems by Dr. Gary L. Johnson November 21, 2001
Chapter 6—Asynchronous Generators 6–40 f = np (28) 120 where n is the rotational speed in revolutions per minute and p is the number of poles. All the electrical generators we have considered thus far have an even number of poles determined by physical windings on the generator rotor. This forces the output frequency to vary with the rotational speed. The Roesel generator is different in that the number of poles can be changed continuously and inversely proportional to n so that f can be maintained at a constant value. The basic diagram of the Roesel generator is shown in Fig. 24. The stator, with its windings connected to an external load, is located on the inside of the generator. The rotor, which contains the field poles, rotates on the outside of the stator. The stator contains an excitation coil wrapped around the excitor head in addition to the usual output windings. The rotor is built in two layers, with the outer layer being high permeability laminated generator steel and the inner layer being a hard magnetizable material such as barium ferrite. Ferrites typically do not have the mechanical strength characteristics of steel, so this design helps to maintain mechanical integrity by having the steel carry the centrifugal forces. The ferrite would have to be much stronger if the rotor were inside the stator. Figure 24: Basic diagram of Roesel generator. A precise sinusoidal frequency is applied to the excitation coil and magnetizes a pole on Wind Energy Systems by Dr. Gary L. Johnson November 21, 2001
Page 1 and 2:
WIND ENERGY SYSTEMS Electronic Edit
Page 3 and 4:
ii 4 Wind Turbine Power, Energy, an
Page 5 and 6:
iv 9.9 Wind farm Costs.............
Page 7 and 8:
vi and Chapter 8, so we can give a
Page 9 and 10:
Chapter 1—Introduction 1-1 INTROD
Page 11 and 12:
Chapter 1—Introduction 1-3 same w
Page 13 and 14:
Chapter 1—Introduction 1-5 Thomas
Page 15 and 16:
Chapter 1—Introduction 1-7 Figure
Page 17 and 18:
Chapter 1—Introduction 1-9 power
Page 19 and 20:
Chapter 1—Introduction 1-11 servi
Page 21 and 22:
Chapter 1—Introduction 1-13 incre
Page 23 and 24:
Chapter 1—Introduction 1-15 Figur
Page 25 and 26:
Chapter 1—Introduction 1-17 three
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Chapter 1—Introduction 1-23 [9] R
Page 33 and 34:
Chapter 2—Wind Characteristics 2-
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Chapter 3—Wind Measurements 3-2 g
Page 103 and 104:
Chapter 3—Wind Measurements 3-4 F
Page 105 and 106:
Chapter 3—Wind Measurements 3-6 i
Page 107 and 108:
Chapter 3—Wind Measurements 3-8 F
Page 109 and 110:
Chapter 3—Wind Measurements 3-10
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Chapter 4—Wind Turbine Power 4-1
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Chapter 5—Electrical Network 5-1
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240: Chapter 5—Electrical Network 5-49
Page 253 and 254: Chapter 6—Asynchronous Generators
Page 289: Chapter 6—Asynchronous Generators
Page 297 and 298: Chapter 7—Asynchronous Loads 7-2
Page 341 and 342:
Chapter 7—Asynchronous Loads 7-46
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Chapter 8—Economics 8-2 are the t
Page 349 and 350:
Chapter 8—Economics 8-4 Table 8.1
Page 351 and 352:
Chapter 8—Economics 8-6 by the di
Page 353 and 354:
Chapter 8—Economics 8-8 understan
Page 355 and 356:
Chapter 8—Economics 8-10 bank at
Page 357 and 358:
Chapter 8—Economics 8-12 i a = 1+
Page 359 and 360:
Chapter 8—Economics 8-14 ( ) 20 1
Page 361 and 362:
Chapter 8—Economics 8-16 and the
Page 363 and 364:
Chapter 8—Economics 8-18 The unit
Page 365 and 366:
Chapter 8—Economics 8-20 L ′ fu
Page 367 and 368:
Chapter 8—Economics 8-22 L ′ vo
Page 369 and 370:
Chapter 8—Economics 8-24 conventi
Page 371 and 372:
Chapter 8—Economics 8-26 7 PROBLE
Page 373 and 374:
Chapter 8—Economics 8-28 [2] Boll
Page 375 and 376:
Chapter 9—Wind Power Plants 9-2 6
Page 377 and 378:
Chapter 9—Wind Power Plants 9-4 w
Page 379 and 380:
Chapter 9—Wind Power Plants 9-6 t
Page 381 and 382:
Chapter 9—Wind Power Plants 9-8 s
Page 383 and 384:
Chapter 9—Wind Power Plants 9-10
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
Page 393 and 394:
Page 395 and 396:
Page 397 and 398:
Page 399 and 400:
Page 401 and 402:
Page 403 and 404:
Page 405 and 406:
Page 407 and 408:
Page 409 and 410:
Page 411 and 412:
Page 413 and 414:
Page 415 and 416:
Page 417 and 418:
Page 419:
show all

WIND ENERGY SYSTEMS - Cd3wd

Create successful ePaper yourself

Delete template?

Save as template?