BG Fernandes Department of Electrical Engineering II T - Power ...

More documents

Recommendations

Info

⇒ Tap changing : Slow ( 5-6 sec/step) ⇒ Gate control is used for initial rapid control action ⇒ Followed by tap changing to restore the converter quantities ( ‘α’ of rectifier & ‘γ’ for inverter) to their normal ranges Application of Power Electronics in Power Systems B. G. Fernandes 372/454
Basis for selection of control : Following considerations influences the selection of control characteristics • Prevention of large fluctuations of DC current due to variation in AC system • Maintaining DC voltage near rated value • Maintaining power factor at the sending & receiving end that are as high as possible • Prevention of commutation failure in inverter Application of Power Electronics in Power Systems B. G. Fernandes 373/454
Page 1 and 2:
EE 660 Application of Power Electro
Page 3 and 4:
Books for Reference • T. J. E. Mi
Page 5 and 6:
• Consumption of Electricity are
Page 7 and 8:
• Thermal limit (depends on ambie
Page 9 and 10:
• Voltage profile along the line
Page 11 and 12:
• To control V R & ↑ power tran
Page 13 and 14:
• High ‘V’ & high KVar source
Page 15 and 16:
• What sort of PWM technique to u
Page 17 and 18:
V = V = V = m S R V It can be shown
Page 19 and 20:
Provide • Series capacitive compe
Page 21 and 22:
• Is it possible to change the ph
Page 23 and 24:
• Injecting V in series with line
Page 25 and 26:
• Definite amount of power that s
Page 27 and 28:
• To control the power flow & to
Page 29 and 30:
• Most of the loads are Non-linea
Page 31 and 32:
Current drawn by the load fed from
Page 33 and 34:
Effect of harmonics: A. In the Rota
Page 35 and 36:
Conclusions • Load compensator +
Page 37 and 38:
Notation of quality of supply • H
Page 39 and 40:
Ideal compensator • Correct the p
Page 41 and 42:
Voltage regulation • Which is the
Page 43 and 44:
I L = P L − V jQ L ΔV = ( R + jX
Page 45 and 46:
Vary Q S => ΔV rotates till E = V
Page 47 and 48:
• Approximate relationship for vo
Page 49 and 50:
• If short circuit resistance of
Page 51 and 52:
I a = V R ab Vca − jX VL∠0 V∠
Page 53 and 54:
I b = I c ∠120 ⎛ ⎜ ⎝ 3 2X
Page 55 and 56:
Contd.. • Using passive reactive
Page 57 and 58:
Comments • Branch currents of Δ
Page 59 and 60:
Application of Power Electronics in
Page 61 and 62:
• May not be possible • Most of
Page 63 and 64:
• Can be shown that if V < C1 V S
Page 65 and 66:
• M => Magnitude of sine wave (no
Page 67 and 68:
Review • Linear lagging load can
Page 69 and 70:
Contd.. • If space vector PWM is
Page 71 and 72:
⇒ (n-1) harmonics are eliminated
Page 73 and 74:
• Assume that there are 5 switchi
Page 75 and 76:
• Non-linear transcendental equat
Page 77 and 78:
How to calculate Ref. Var ? i = I m
Page 79 and 80:
Controlled current SLCVC • Compen
Page 81 and 82:
Control strategy -I Application of
Page 83 and 84:
Review • In harmonic elimination
Page 85 and 86:
Contd.. Controlled current SLCVC
Page 87 and 88:
• i S * is in phase with v S •
Page 89 and 90:
• If Inverter i S * is changed in
Page 91 and 92:
• Use two compensators & connect
Page 93 and 94:
• Main compensator ⇒ Voltage co
Page 95 and 96:
i Cm1 = V S −VCm 1∠ −δ Z∠
Page 97 and 98:
• Var calculator determines V * d
Page 99 and 100:
Contd.. • For high power applicat
Page 101 and 102:
[A] [v'] = [z] [A] [i'] [v'] = [A]
Page 103 and 104:
Vector representation of instantane
Page 105 and 106:
[ C] t = ⎡ ⎢ ⎢− ⎢ ⎣−
Page 107 and 108:
⎡v ⎢ ⎢ v ⎢⎣ v a b c ⎤
Page 109 and 110:
e e i i α β α β = = V V S S cos
Page 111 and 112:
Page 113 and 114:
e . q i * = β α C 3 2 + ( 2 2 ) e
Page 115 and 116:
• Frequency of e α , i α , e β
Page 117 and 118:
Review Instantaneous real power P =
Page 119 and 120:
Contd.. Application of Power Electr
Page 121 and 122:
Change of reference frame q S d S d
Page 123 and 124:
• Let us assume that v S is along
Page 125 and 126:
• AC filtering ⇒ phase shift
Page 127 and 128:
• Information about system freque
Page 129 and 130:
* x ∫ ω xt () x y n + 1 − Δ t
Page 131 and 132:
e α = e a − 1 2 e b − 1 2 e c
Page 133 and 134:
e d e d = = = e e s e s α cos( θ
Page 135 and 136:
Review • In synchronous rotating
Page 137 and 138:
To change MI using harmonic elimina
Page 139 and 140:
Page 141 and 142:
• 3φ sinusoids which are in phas
Page 143 and 144:
• This voltage waveform can be us
Page 145 and 146:
1 1 • = = Switching frequency T T
Page 147 and 148:
• Assume that over one cycle V re
Page 149 and 150:
Rule to be followed • A term in t
Page 151 and 152:
S 4 , S 3 ON for DT S : di L = V s
Page 153 and 154:
Aim • i s and V s should be in ph
Page 155 and 156:
Contd.. • Generate reset pulse at
Page 157 and 158:
1φ AC-DC Control technique (1 −
Page 159 and 160:
Alternate Approach DC-DC Converter
Page 161 and 162:
• Information regarding V s shoul
Page 163 and 164:
Page 165 and 166:
Inverter topology for high power ap
Page 167 and 168:
• Number of pulse should be high
Page 169 and 170:
Switches ON V AX S1, S2 V dc S2, S3
Page 171 and 172:
Page 173 and 174:
Review • In one cycle control ‘
Page 175 and 176:
Contd.. • At any time 2-devices (
Page 177 and 178:
4-level inverter • Number of swit
Page 179 and 180:
S2, S3, S4 ON : ⇒ V AX = 2V dc /3
Page 181 and 182:
• ‘V’ rating of D B = 2V dc /
Page 183 and 184:
Voltage space vectors for 3 level i
Page 185 and 186:
( NNP ) ⇒ ( 001 ) ⇒ ( PPN ) ⇒
Page 187 and 188:
C B A O O N O N O N O O C B A O N N
Page 189 and 190:
V q ∴V S = = 3 2 V 2 dC ⎡V ⎢
Page 191 and 192:
OOP : V AO = V dC /2, V BO = V CO =
Page 193 and 194:
OPO : V AO = V CO = 0, V BO = V dC
Page 195 and 196:
Medium voltage vectors ONP : V AO =
Page 197 and 198:
NPO : V AO = 0, V BO = V dC /2 , V
Page 199 and 200:
Page 201 and 202:
Contd.. • No. of medium voltage v
Page 203 and 204:
Voltage control • Space vector PW
Page 205 and 206:
• Unbalances has no effect on loa
Page 207 and 208:
• Passive elements Load compensat
Page 209 and 210:
Shunt Compensation : • Inject cur
Page 211 and 212:
Mid point voltage regulator • Two
Page 213 and 214:
Page 215 and 216:
• Reactive power supplied by the
Page 217 and 218:
• Shunt compensator can increase
Page 219 and 220:
Review Mid-point shunt compensation
Page 221 and 222:
Summary • Compensator must remain
Page 223 and 224:
Variable impedance type S.V.C 1. Th
Page 225 and 226:
• ‘i’ is continuous when α =
Page 227 and 228:
2. Thyristor switched capacitor (TS
Page 229 and 230:
3. Fixed Capacitor, Thyristor contr
Page 231 and 232:
• At α = π/2, Q L = Q L(max)
Page 233 and 234:
Control • ‘Q’ is controlled b
Page 235 and 236:
Operating V-I region Application of
Page 237 and 238:
Contd.. T.S.C • Thyristors are tr
Page 239 and 240:
Advantages • Since voltage profil
Page 241 and 242:
Series compensation • Injects vol
Page 243 and 244:
X eff = ( X − X ) L C = ( 1− K
Page 245 and 246:
Q Q se sh = tan ⎛ ⎜ ⎝ 2 δ ma
Page 247 and 248:
Approaches to controllable series c
Page 249 and 250:
• Amplitude of the fundamental V
Page 251 and 252:
(b). Impedance compensation mode: V
Page 253 and 254:
Review GTO controlled series capaci
Page 255 and 256:
Contd.. • Control ‘i’ in ‘L
Page 257 and 258:
Voltage compensating mode : • Rea
Page 259 and 260:
• In FCTCR continuously varying c
Page 261 and 262:
V 2 1 I1 ⎜ Sin X ⎝ π π ⎛
Page 263 and 264:
Page 265 and 266:
• If X L (α) < X C , There are t
Page 267 and 268:
• ‘V C ’ gets distorted • I
Page 269 and 270:
• If X TCR = 1.5X C ⇒ Capacitiv
Page 271 and 272:
Modes of operation By pass mode :
Page 273 and 274:
Static Synchronous Series Compensat
Page 275 and 276:
• Voltage across ‘L’ ⇒ V (
Page 277 and 278:
Contd.. • For both region X L < X
Page 279 and 280:
Control range: • Voltage compensa
Page 281 and 282:
• Compensation for both reactive
Page 283 and 284:
• If V S = V R =V Per phase power
Page 285 and 286:
⇒ Reactive VA associated with the
Page 287 and 288:
Voltage & phase angle regulators Vo
Page 289 and 290:
Power flow control : • Optimal lo
Page 291 and 292:
• Basic idea is to keep the trans
Page 293 and 294:
UPFC : • Able to control simultan
Page 295 and 296:
• Independently control the react
Page 297 and 298:
Case1 : Control capabilities ρ = 0
Page 299 and 300:
U.P.F.C : Review • Two VSI connec
Page 301 and 302:
Using UPFC • Active power flow an
Page 303 and 304:
⇒ A common DC-link voltage is reg
Page 305 and 306:
= Ve ⎧V ⎨ ⎩ ( Cosδ 2 − jSi
Page 307 and 308:
• ‘ρ’ can vary from 0 to 2π
Page 309 and 310:
⇒ Shunt current is controlled ind
Page 311 and 312:
FACTS installments in India • TSC
Page 313 and 314:
HVDC • Long distance transmission
Page 315 and 316:
Back to Back : • Chandrapur - Ram
Page 317 and 318:
• ‘P’ through link can not be
Page 319 and 320:
• If alternator-2 generates 1000
Page 321 and 322: Application of Power Electronics in
Page 323 and 324: • One conductor (generally -ve)
Page 325 and 326: • Each terminal has two converter
Page 327 and 328: Components of HVDC transmission Bi-
Page 329 and 330: Smoothing Reactor : Large value of
Page 331 and 332: Reactive power support : • Both c
Page 333 and 334: • If α 1 is trigger angle for br
Page 335 and 336: ⇒T 1 is turned off at ωt= 30+ (3
Page 337 and 338: At ωt = 210 o V a = Sin210 = −1
Page 339 and 340: At ωt = 330 o V a −1 2, V = 1 =
Page 341 and 342: At ωt = 300 o V − 3 2, V = 0 V =
Page 343 and 344: Vdc = 2.34V ph. Cosα =1.35V LL .Co
Page 345 and 346: Contd.. • As α 1 ↑ (AC-DC conv
Page 347 and 348: Phase relationship between phase V
Page 349 and 350: As α↑: • V dc ↓ • Displace
Page 351 and 352: Boundary conditions : At ωt = α,
Page 353 and 354: ∴V 0 = V pn −V mn V = − 2 cn
Page 355 and 356: Representation of inverter mode of
Page 357 and 358: Converter α ⇒ delay angle μ ⇒
Page 359 and 360: V dco = [cos + cos γ ] − − −
Page 361 and 362: 12-pulse converter • Series conne
Page 363 and 364: Application of Power Electronics in
Page 365 and 366: V d ⎛ 3 = VdoCosα − Id . B.
Page 367 and 368: • 24/36 harmonic filter ⇒ 2*80
Page 369 and 370: Direct current : • Nominal I ⇒
Page 371: Basic control : • DC voltage or I
Page 375 and 376: • Denominator is very small • A
Page 377 and 378: • P.F should be as high as possib
Page 379 and 380: • γ ⇒ necessary to maintain a
Page 381 and 382: I d = V dcor Cosα −V R + R + cr
Page 383 and 384: • Maintains adequate commutation
Page 385 and 386: • As taps are changed, CEA regula
Page 387 and 388: Basic control : • DC voltage or I
Page 389 and 390: Basis for selection of control : Fo
Page 391 and 392: • Rectifier control ⇒ To preven
Page 393 and 394: Control of HVDC system Application
Page 395 and 396: • Quantities forming the co-ordin
Page 397 and 398: • Rectifier characteristics can b
Page 399 and 400: • Constant current characteristic
Page 401 and 402: • After some time, tap changer ch
Page 403 and 404: • Therefore rectifier characteris
Page 405 and 406: • At normal voltage , characteris
Page 407 and 408: • In order to avoid the problem,
Page 409 and 410: • When inverter is on current con
Page 411 and 412: When does change over take place ?
Page 413 and 414: Review Rectifier characteristics Co
Page 415 and 416: • ‘e’ is -ve, ‘K’ is +ve
Page 417 and 418: • Due to line fault or during low
Page 419 and 420: Inverter side : • I d can be ↑
Page 421 and 422: Mode stabilization : • Intersecti
Page 423 and 424:
• ‘V’ profile is flat • Con
Page 425 and 426:
• V dcoi Cosβ remains constant
Page 427 and 428:
Current limit Maximum current limit
Page 429 and 430:
Voltage depend current-order limit
Page 431 and 432:
• VDCOL characteristics could be
Page 433 and 434:
Contd.. But I ref(R) > I ref(I) I r
Page 435 and 436:
Contd.. Mode stabilization : • In
Page 437 and 438:
Voltage depend current-order limit
Page 439 and 440:
• VDCOL characteristics could be
Page 441 and 442:
Page 443 and 444:
Significant aspects of basic contro
Page 445 and 446:
• If there is a ↓ in AC voltage
Page 447 and 448:
⇒ Achieved using by pass valve an
Page 449 and 450:
• For energization of blocked bri
Page 451 and 452:
• Instead use VSI • ‘I’ cou
Page 453 and 454:
• ‘V’ can not reverse, but
show all

BG Fernandes Department of Electrical Engineering II T - Power ...

Create successful ePaper yourself

Delete template?

Save as template?