EBOOK - Transmission and Distribution Electrical Engineering - Second Edition (Colin Bayliss) | Cộng đồng Kỹ thuật cơ điện Việt Nam EBOOKBKMT

EBOOK - Kỹ thuật truyền tải và phân phối điện (Colin Bayliss) - 1003 Trang.

This book covers the major topics likely to be encountered by the transmission and distribution power systems engineer engaged upon international project works. Each chapter is self-contained and gives a useful practical introduction to each topic covered. The book is intended for graduate or technician level engineers and bridges the gap between learned university theoretical textbooks and detailed single topic references. It therefore provides a practical grounding in a wide range of transmission and distribution subjects. The aim of the book is to assist the project engineer in correctly specifying equipment and systems for his particular application. In this way manufacturers and contractors should receive clear and unambiguous transmission and distribution equipment or project enquiries for work and enable competitive and comparative tenders to be received. Of particular interest are the chapters on project, system and software management since these subjects are of increasing importance to power systems engineers. In particular the book should help the reader to understand the reasoning behind the different specifications and methods used by different electrical supply utilities and organizations throughout the world to achieve their specific transmission and distribution power system requirements.

The second edition includes updates and corrections, together with the addition of two extra major chapters covering distribution planning and power system harmonics.

C. R. Bayliss

CONTENTS:

1 System Studies 1
1.1 Introduction 1
1.2 Load flow 1
1.2.1 Purpose 1
1.2.2 Sample study 2
1.3 System stability 8
1.3.1 Introduction 8
1.3.2 Analytical aspects 10
1.3.3 Steady state stability 14
1.3.4 Transient stability 17
1.3.5 Dynamic stability 28
1.3.6 Effect of induction motors 28
1.3.7 Data requirements and interpretation of transient
stability studies 29
1.3.8 Case studies 34
1.4 Short circuit analysis 42
1.4.1 Purpose 42
1.4.2 Sample study 42
2 Drawings and Diagrams 50
2.1 Introduction 50
2.2 Block diagrams 50
2.3 Schematic diagrams 51
2.3.1 Method of representation 51
2.3.2 Main circuits 55
2.3.3 Control, signalling and monitoring circuits 55
2.4 Manufacturers’ drawings 55
2.4.1 Combined wiring/cabling diagrams 55
2.4.2 British practice 61
2.4.3 European practice 63
2.4.4 Other systems 68
2.5 Computer aided design (CAD) 68
2.6 Case study 69
2.7 Graphical symbols 70
Appendix A—Relay identification—numerical codes 72
Appendix B—Comparison between German, British,
US/Canadian and international symbols 82
B1 General circuit elements 83
B2 Operating mechanisms 86
B3 Switchgear 89
3 Substation Layouts 92
3.1 Introduction 92
3.2 Substation design considerations 92
3.2.1 Security of supply 92
3.2.2 Extendibility 93
3.2.3 Maintainability 93
3.2.4 Operational flexibility 94
3.2.5 Protection arrangements 94
3.2.6 Short circuit limitations 94
3.2.7 Land area 94
3.2.8 Cost 95
3.3 Alternative layouts 95
3.3.1 Single busbar 95
3.3.2 Transformer feeder 97
3.3.3 Mesh 101
3.3.4 Ring 103
3.3.5 Double busbar 104
3.3.6 1 Circuit breaker 106
3.4 Space requirements 106
3.4.1 Introduction 106
3.4.2 Safety clearances 108
3.4.3 Phase-phase and phase-earth clearances 109
4Substation Auxiliary Power Supplies 115
4.1 Introduction 115
4.2 DC supplies 115
4.2.1 Battery/battery charger configurations 115
4.2.2 Battery charger components 118
vi Contents
4.2.3 Installation requirements 121
4.2.4 Typical enquiry data—DC switchboard 124
4.3 Batteries 125
4.3.1 Introduction 125
4.3.2 Battery capacity 125
4.3.3 Characteristics of batteries 128
4.3.4 Battery sizing calculations 129
4.3.5 Typical enquiry data 132
4.4 AC supplies 134
4.4.1 Power sources 134
4.4.2 LVAC switchboard fault level 134
4.4.3 Auxiliary transformer LV connections 134
4.4.4 Allowance for future extension 136
4.4.5 Typical enquiry data 138
4.4.6 Earthing transformer selection 139
4.4.7 Uninterruptible power supplies 143
5 Current and Voltage Transformers 147
5.1 Introduction 147
5.2 Current transformers 147
5.2.1 Introduction 147
5.2.2 Protection CT classifications 147
5.2.3 Metering CTs 151
5.2.4 Design and construction considerations 152
5.2.5 Terminal markings 154
5.2.6 Specifications 155
5.3 Voltage transformers 155
5.3.1 Introduction 155
5.3.2 Electromagnetic VTs 155
5.3.3 Capacitor VTs 156
5.3.4 Specifications 157
6 Insulators 160
6.1 Introduction 160
6.2 Insulator materials 160
6.2.1 Polymeric and resin materials 160
6.2.2 Glass and porcelain 161
6.3 Insulator types 161
6.3.1 Post insulators 161
6.3.2 Cap and pin insulators 165
6.3.3 Long rod 166
6.4 Pollution control 167
6.4.1 Environment/creepage distances 167
6.4.2 Remedial measures 169
Contents vii
6.4.3 Calculation of specific creepage path 170
6.5 Insulator specification 171
6.5.1 Standards 171
6.5.2 Design characteristics 175
6.6 Tests 176
6.6.1 Sample and routine tests 176
6.6.2 Technical particulars 177
7 Substation Building Services 179
7.1 Introduction 179
7.2 Lighting 179
7.2.1 Terminology 179
7.2.2 Internal lighting 185
7.2.3 External lighting 187
7.2.4 Control 195
7.3 Distribution characterization 196
7.4 Heating, ventilation and air conditioning 199
7.4.1 Air circulation 199
7.4.2 Air conditioning 201
7.4.3 Heating 206
7.5 Fire detection and suppression 206
7.5.1 Introduction 206
7.5.2 Fire extinguishers 207
7.5.3 Access, first aid and safety 207
7.5.4 Fire detection 208
7.5.5 Fire suppression 211
7.5.6 Cables, control panels and power supplies 212
8 Earthing and Bonding 214
8.1 Introduction 214
8.2 Design criteria 215
8.2.1 Time/current zones of effects of AC currents on persons 215
8.2.2 Touch and step voltages 215
8.2.3 Comparison of touch and step potential design criteria 217
8.3 Substation earthing calculation methodology 220
8.3.1 Boundary conditions 220
8.3.2 Earthing materials 222
8.3.3 Earthing impedance and earthing voltage 225
8.3.4 Hazard voltage tolerable limits 226
8.4 Computer generated results 228
8.4.1 Introduction 228
8.4.2 Case study 231
References 232
viii Contents
9 Insulation Co-ordination 234
9.1 Introduction 234
9.2 System voltages 234
9.2.1 Power frequency voltages 234
9.2.2 Overvoltages 235
9.3 Clearances 245
9.3.1 Air 245
9.3.2 SF
9.4 Procedures for co-ordination 247
9.4.1 Statistical approach 247
9.4.2 Non-statistical approach 248
9.5 Surge protection 248
9.5.1 Rod or spark gaps 248
9.5.2 Surge arresters 250
References 265
10 Relay Protection 266
10.1 Introduction 266
10.2 System configurations 267
10.2.1 Faults 267
10.2.2 Unearthed systems 267
10.2.3 Impedance earthed systems 267
10.2.4 Solidly earthed systems 268
10.2.5 Network arrangements 268
10.3 Power system protection principles 271
10.3.1 Discrimination by time 271
10.3.2 Discrimination by current magnitude 272
10.3.3 Discrimination by time and fault direction 272
10.3.4 Unit protection 272
10.3.5 Signalling channel assistance 273
10.4 Current relays 274
10.4.1 Introduction 274
10.4.2 Inverse definite minimum time lag (IDMTL) relays 274
10.4.3 Alternative characteristic curves 277
10.4.4 Plotting relay curves on log/log graph paper 277
10.4.5 Current relay application examples 278
10.5 Differential protection schemes 289
10.5.1 Biased differential protection 289
10.5.2 High impedance protection 292
10.5.3 Transformer protection application examples 293
10.5.4 Pilot wire unit protection 297
10.5.5 Busbar protection 300
10.6 Distance relays 303
10.6.1 Introduction 303
Contents ix
10.6.2 Basic principles 304
10.6.3 Relay characteristics 305
10.6.4 Zones of protection 309
10.6.5 Switched relays 311
10.6.6 Typical overhead transmission line protection schemes 312
10.7 Auxiliary relays 316
10.7.1 Tripping and auxiliary 316
10.7.2 AC auxiliary relays 321
10.7.3 Timers 321
10.7.4 Undervoltage 321
10.7.5 Underfrequency 322
10.8 Computer assisted grading exercise 325
10.8.1 Basic input data 325
10.8.2 Network fault levels 325
10.8.3 CT ratios and protection devices 326
10.8.4 Relay settings 326
10.9 Practical distribution network case study 326
10.9.1 Introduction 326
10.9.2 Main substation protection 328
10.9.3 Traction system protection 328
10.9.4 21 kV distribution system and protection philosophy 331
10.9.5 21 kV pilot wire unit protection 332
10.9.6 21 kV system backup protection 333
10.9.7 Use of earth fault indicators 335
10.9.8 Summary 335
11 Fuses and Miniature Circuit Breakers 336
11.1 Introduction 336
11.2 Fuses 336
11.2.1 Types and standards 336
11.2.2 Definitions and terminology 339
11.2.3 HRC fuses 339
11.2.4 High voltage fuses 344
11.2.5 Cartridge fuse construction 349
11.3 Fuse operation 350
11.3.1 High speed operation 350
11.3.2 Discrimination 351
11.3.3 Cable protection 354
11.3.4 Motor protection 355
11.3.5 Semiconductor protection 357
11.4 Miniature circuit breakers 359
11.4.1 Operation 359
11.4.2 Standards 360
11.4.3 Application 361
x Contents
References 367
12 Cables 368
12.1 Introduction 368
12.2 Codes and standards 368
12.3 Types of cables and materials 371
12.3.1 General design criteria 371
12.3.2 Cable construction 371
12.3.3 Submarine cables 382
12.3.4 Terminations 382
12.4 Cable sizing 383
12.4.1 Introduction 383
12.4.2 Cables laid in air 383
12.4.3 Cables laid direct in ground 385
12.4.4 Cables laid in ducts 386
12.4.5 Earthing and bonding 387
12.4.6 Short circuit ratings 390
12.4.7 Calculation examples 392
12.5 Calculation of losses in cables 403
12.5.1 Dielectric losses 403
12.5.2 Screen or sheath losses 403
12.6 Fire properties of cables 404
12.6.1 Toxic and corrosive gases 404
12.6.2 Smoke emission 405
12.6.3 Oxygen index and temperature index 405
12.6.4 Flame retardance/flammability 406
12.6.5 Fire resistance 406
12.6.6 Mechanical properties 407
12.7 Control and communication cables 407
12.7.1 Low voltage and multicore control cables 407
12.7.2 Telephone cables 408
12.7.3 Fibre optic cables 410
12.8 Cable management systems 416
12.8.1 Standard cable laying arrangements 416
12.8.2 Computer aided cable installation systems 419
12.8.3 Interface definition 425
References 428
13 Switchgear 429
13.1 Introduction 429
13.2 Terminology and standards 429
13.3 Switching 431
13.3.1 Basic principles 431
13.3.2 Special switching cases 443
Contents xi
13.3.3 Switches and disconnectors 446
13.3.4 Contactors 447
13.4 Arc quenching media 453
13.4.1 Introduction 453
13.4.2 Sulphur hexafluoride (SF

) 454
13.4.3 Vacuum 460
13.4.4 Oil 461
13.4.5 Air 463
13.5 Operating mechanisms 465
13.5.1 Closing and opening 465
13.5.2 Interlocking 469
13.5.3 Integral earthing 471
13.6 Equipment specifications 471
13.6.1 12 kV metal-clad indoor switchboard example 471
13.6.2 Open terminal 145 kV switchgear examples 475
13.6.3 Distribution system switchgear example 481
13.6.4 Distribution ring main unit 485
14Power Transformers 490
14.1 Introduction 490
14.2 Standards and principles 490
14.2.1 Basic transformer action 490
14.2.2 Transformer equivalent circuit 492
14.2.3 Voltage and current distribution 494
14.2.4 Transformer impedance representation 494
14.2.5 Tap changers 497
14.2.6 Useful standards 507
14.3 Voltage, impedance and power rating 508
14.3.1 General 508
14.3.2 Voltage drop 509
14.3.3 Impedance 509
14.3.4 Voltage ratio and tappings — general 510
14.3.5 Voltage ratio with off-circuit tappings 510
14.3.6 Voltage ratio and on-load tappings 511
14.3.7 Basic insulation levels (BIL) 511
14.3.8 Vector groups and neutral earthing 511
14.3.9 Calculation example to determine impedance and
tap range 514
14.4 Thermal design 522
14.4.1 General 522
14.4.2 Temperature rise 523
14.4.3 Loss of life expectancy with temperature 524
14.4.4 Ambient temperature 525
14.4.5 Solar heating 526
xii Contents
14.4.6 Transformer cooling classifications 526
14.4.7 Selection of cooling classification 529
14.4.8 Change of cooling classification in the field 530
14.4.9 Capitalization of losses 531
14.5 Constructional aspects 532
14.5.1 Cores 532
14.5.2 Windings 533
14.5.3 Tanks and enclosures 535
14.5.4 Cooling plant 537
14.5.5 Low fire risk types 538
14.5.6 Neutral earthing transformers 540
14.5.7 Reactors 541
14.6 Accessories 543
14.6.1 General 543
14.6.2 Buchholz relay 543
14.6.3 Sudden pressure relay and gas analyser relay 544
14.6.4 Pressure relief devices 544
14.6.5 Temperature monitoring 544
14.6.6 Breathers 545
14.6.7 Miscellaneous 545
14.6.8 Transformer ordering details 547
References 553
15 Substation and Overhead Line Foundations 555
15.1 Introduction 555
15.2 Soil investigations 555
15.3 Foundation types 556
15.4 Foundation design 565
15.5 Site works 565
15.5.1 Setting out 565
15.5.2 Excavation 565
15.5.3 Piling 566
15.5.4 Earthworks 567
15.5.5 Concrete 568
15.5.6 Steelwork fixings 573
16 Overhead Line Routing 575
16.1 Introduction 575
16.2 Routing objectives 575
16.3 Preliminary routing 577
16.3.1 Survey equipment requirements 577
16.3.2 Aerial survey 577
16.3.3 Ground survey 577
16.3.4 Ground soil conditions 577
Contents xiii
16.3.5 Wayleave, access and terrain 577
16.3.6 Optimization 579
16.4 Detailed line survey and profile 581
16.4.1 Accuracy requirements 581
16.4.2 Profile requirements 582
16.4.3 Computer aided techniques 584
17 Structures, Towers and Poles 586
17.1 Introduction 586
17.2 Environmental conditions 587
17.2.1 Typical parameters 587
17.2.2 Effect on tower or support design 588
17.2.3 Conductor loads 592
17.2.4 Substation gantry combined loading example 598
17.3 Structure design 599
17.3.1 Lattice steel tower design considerations 599
17.3.2 Tower testing 611
17.4 Pole and tower types 611
17.4.1 Pole structures 611
17.4.2 Tower structures 613
References 618
18 Overhead Line Conductor and Technical Specifications 619
18.1 Introduction 619
18.2 Environmental conditions 619
18.3 Conductor selection 620
18.3.1 General 620
18.3.2 Types of conductor 621
18.3.3 Aerial bundled conductor 624
18.3.4 Conductor breaking strengths 625
18.3.5 Bi-metal connectors 626
18.3.6 Corrosion 626
18.4 Calculated electrical ratings 628
18.4.1 Heat balance equation 628
18.4.2 Power carrying capacity 629
18.4.3 Corona discharge 632
18.4.4 Overhead line calculation example 636
18.5 Design spans, clearances and loadings 639
18.5.1 Design spans 639
18.5.2 Conductor and earth wire spacing and clearances 650
18.5.3 Broken wire conditions 661
18.5.4 Conductor tests/inspections 661
18.6 Overhead line fittings 661
18.6.1 Fittings related to aerodynamic phenomena 661
xiv Contents
18.6.2 Suspension clamps 665
18.6.3 Sag adjusters 665
18.6.4 Miscellaneous fittings 665
18.7 Overhead line impedance 665
18.7.1 Inductive reactance 665
18.7.2 Capacitive reactance 667
18.7.3 Resistance 668
18.8 Substation busbar selection—case study 668
18.8.1 Introduction 668
18.8.2 Conductor diameter/current carrying capacity 668
18.8.3 Conductor selection of weight basis 669
18.8.4 Conductor short circuit current capability 672
18.8.5 Conductor support arrangements 673
References 677
19 Testing and Commissioning 680
19.1 Introduction 680
19.2 Quality assurance 680
19.2.1 Introduction 680
19.2.2 Inspection release notice 682
19.2.3 Partial acceptance testing 682
19.2.4 System acceptance testing 682
19.2.5 Documentation and record systems 683
19.3 Works inspections and testing 685
19.3.1 Objectives 685
19.3.2 Specifications and responsibilities 685
19.3.3 Type tests 685
19.3.4 Routine tests 686
19.4 Site inspection and testing 686
19.4.1 Pre-commissioning and testing 686
19.4.2 Maintenance inspection 687
19.4.3 On-line inspection and testing 687
19.5 Testing and commissioning methods 691
19.5.1 Switchgear 691
19.5.2 Transformers 701
19.5.3 Cables 704
19.5.4 Protection 707
Appendix A Commissioning test procedure requirements 723
Appendix B Drawings, diagrams and manuals 724
20 Electromagnetic Compatibility 726
20.1 Introduction 726
20.2 Standards 726
20.3 Testing 727
Contents xv
20.3.1 Magnetic field radiated emission measurements 728
20.3.2 Electric field radiated emission measurements 730
20.3.3 Conducted emission measurements 732
20.3.4 Immunity testing 732
20.4 Screening 734
20.4.1 The use of screen wire 734
20.4.2 The use of screen boxes and Faraday enclosures 734
20.4.3 The use of screen floors in rooms 738
20.5 Typical useful formulae 739
20.5.1 Decibel reference levels 740
20.5.2 Field strength calculations 740
20.5.3 Mutual inductance between two long parallel pairs
of wires 741
20.5.4 Attenuation factors 741
20.6 Case studies 742
20.6.1 Screening power cables 742
20.6.2 Measurement of field strengths 745
References 747
21 System Control and Data Acquisition 748
21.1 Introduction 748
21.2 Programmable logic controllers (PLCs) 748
21.2.1 Functions 748
21.2.2 PLC selection 750
21.2.3 Application example 753
21.3 Power line carrier communication links 758
21.3.1 Introduction 758
21.3.2 Power line carrier communication principles 761
21.4 Supervisory control and data acquisition (SCADA) 766
21.4.1 Introduction 766
21.4.2 Typical characteristics 767
21.4.3 Design issues 769
21.4.4 Example (Channel Tunnel) 770
21.5 Software management 772
21.5.1 Software—a special case 773
21.5.2 Software life cycle 774
21.5.3 Software implementation practice 778
21.5.4 Software project management 780
References 783
22 Project Management 784
22.1 Introduction 784
22.2 Project evaluation 784
22.2.1 Introduction 784
xvi Contents
22.2.2 Financial assessment 785
22.2.3 Economic assessment 792
22.3 Financing 796
22.3.1 Responsibilities for funding 796
22.3.2 Cash flow 796
22.3.3 Sources of finance 797
22.3.4 Export credit agencies 798
22.3.5 Funding risk reduction 798
22.4 Project phases 800
22.4.1 The project life cycle 800
22.4.2 Cash flow 803
22.4.3 Bonds 804
22.4.4 Advance payments and retentions 806
22.4.5 Insurances 806
22.4.6 Project closeout 806
22.5 Terms and conditions of contract 807
22.5.1 Time, cost and quality 807
22.5.2 Basic types of contract 808
22.5.3 Standard terms and conditions of contract 810
22.5.4 Key clauses 812
22.6 Tendering 815
22.6.1 Choosing the contractor 815
22.6.2 Estimating 816
22.6.3 Tender evaluation 817
22.7 Model forms of contract—exercise 819
Appendix A Project definition/questionnaire 821
Appendix B Bidding checklist 845
23 Distribution Planning 849
23.1 Introduction 849
23.2 Definitions 851
23.2.1 Demand or average demand 851
23.2.2 Maximum demand (MD) 851
23.2.3 Demand factor 852
23.2.4 Utilization factor (UF) 852
23.2.5 Load factor (LDF) 853
23.2.6 Diversity factor (DF) 853
23.2.7 Coincident factor (CF) 855
23.2.8 Load diversity 855
23.2.9 Loss factor (LSF) 856
23.2.10 Load duration 860
23.2.11 Loss equivalent hours 861
23.2.12 Peak responsibility factor (PRF) 862
23.3 Load forecasting 863
Contents xvii
23.3.1 Users of load forecasts 863
23.3.2 The preparation of load forecasts 864
23.3.2 The micro load forecast 865
23.3.4 The macro load forecast 867
23.3.5 Nature of the load forecast 868
23.4 System parameters 870
23.4.1 Distribution feeder arrangements 870
23.4.2 Voltage drop calculations 871
23.4.3 Positive sequence resistance 873
23.4.4 Inductive reactance 874
23.4.5 Economic loading of distribution feeders and
transformers 875
23.4.6 System losses 876
23.5 System reliability 877
23.5.1 Introduction 877
23.5.2 Reliability functions 880
23.5.3 Predictability analysis 882
23.6 Drawings and materials take off 886
24Harmonics in Power Systems 888
24.1 Introduction 888
24.2 The nature of harmonics 888
24.2.1 Introduction 888
24.2.2 Three phase harmonics 889
24.3 The generation of harmonics 889
24.3.1 Transformers 890
24.3.2 Converters 890
24.3.3 The thyristor bridge 892
24.3.4 AC railway traction systems 894
24.3.5 Static VAr compensators and balancers 894
24.4 The effects of harmonics 894
24.4.1 Heating effects of harmonics 894
24.4.2 Overvoltages 896
24.4.3 Resonances 897
24.4.4 Interference 898
24.5 The limitation of harmonics 900
24.5.1 Harmonic filters 900
24.5.2 Capacitor detuning 902
24.6 Ferroresonance and subharmonics 903
24.6.1 Introduction 903
24.6.2 A physical description of ferroresonance 905
24.6.3 Subharmonics 906
24.7 References 906
xviii Contents
25 Fundamentals 908
25.1 Introduction 908
25.2 Symbols and nomenclature 908
25.2.1 Symbols 909
25.2.2 Units and conversion tables 914
25.3 Alternating quantities 917
25.4 Vector representation 922
25.5 Vector algebra 922
25.5.1 The j operator 924
25.5.2 Exponential vector format 925
25.5.3 Polar co-ordinate vector format 925
25.5.4 Algebraic operations on vectors 925
25.5.5 The h operator 925
25.6 Sequence components 926
25.6.1 Theoretical background 926
25.6.2 Calculation methodology and approximations 927
25.6.3 Interpretation 928
25.7 Network fault analysis 932
25.7.1 Introduction 932
25.7.2 Fundamental formulae 933
25.7.3 Simplified network reduction example 938
25.8 Design optimization 944
25.8.1 Introduction 944
25.8.2 Technical problems 945
25.8.3 Loss reduction 949
25.8.4 Communication link gain or attenuation 958
25.8.5 Reactive compensation 958
25.8.6 Power factor correction calculation procedures 962
References 966

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