Transmission andDistribution

ElectricalEngineering

Third edition

Dr C. R. Bayliss CEng FIET andB. J. Hardy ACGI CEng FIET

AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD

ELSEVIER PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO

Newnes is an imprint of Elsevier

Contents

About the authorsContributorsPreface

1 System Studies

1.1 Introduction1.2 Load flow

1.2.1 Purpose1.2.2 Sample study

1.3 System stability1.3.1 Introduction1.3.2 Analytical aspects1.3.3 Steady state stability1.3.4 Transient stability1.3.5 Dynamic stability1.3.6 Effect of induction motors1.3.7 Data requirements and interpretation of transient

stability studies1.3.8 Case studies

1.4 Short circuit analysis1.4.1 Purpose1.4.2 Sample study

2 Drawings and Diagrams

2.1 Introduction2.2 Block diagrams2.3 Schematic diagrams

2.3.1 Method of representation2.3.2 Main circuits2.3.3 Control, signalling and monitoring circuits

xxixxiiixxvii

1

111288

101417282930

35

4242

50

505051515555

vi Contents

2.4 Manufacturers' drawings2.4.1 Combined wiring/cabling diagrams2.4.2 British practice2.4.3 European practice2.4.4 Other systems

2.5 Computer aided design (CAD)2.6 Case study2.7 Graphical symbolsAppendix A: Relay identification - numerical codesAppendix B: Comparison between German, British,

US/Canadian and international symbolsB1 General circuit elementsB2 Operating mechanismsB3 Switchgear

3 Substation Layouts

3.1 Introduction3.2 Substation design considerations

3.2.1 Security of supply3.2.2 Extendibility3.2.3 Maintainability3.2.4 Operational flexibility3.2.5 Protection arrangements3.2.6 Short circuit limitations3.2.7 Land area3.2.8 Cost

3.3 Alternative layouts3.3.1 Single busbar3.3.2 Transformer feeder3.3.3 Mesh3.3.4 Ring3.3.5 Double busbar3.3.6 VA Circuit breaker

3.4 Space requirements3.4.1 Introduction3.4.2 Safety clearances3.4.3 Phase-phase and phase-earth clearances

4 Substation Auxiliary Power Supplies

4.1 Introduction4.2 DC supplies

4.2.1 Battery and charger configurations4.2.2 Battery charger components4.2.3 Installation requirements4.2.4 Typical enquiry data - DC switchboard

Contents vii

4.3 Batteries 1264.3.1 Introduction 1264.3.2 Battery capacity 1264.3.3 Characteristics of batteries 1274.3.4 Battery sizing calculations 1304.3.5 Typical enquiry data 13 3

4.4 AC supplies 1354.4.1 Power sources 1354.4.2 LVAC switchboard fault level 1374.4.3 Auxiliary transformer LV connections 1374.4.4 Allowance for future extension 1394.4.5 Typical enquiry data 1394.4.6 Earthing transformer selection 1404.4.7 Uninterruptible power supplies 144

5 Current and Voltage Transformers 149

5.1 Introduction 1495.2 Current transformers 149

5.2.1 Introduction 1495.2.2 Protection CT classifications 1495.2.3 Metering CTs 1535.2.4 Design and construction considerations 1545.2.5 Terminal markings 1565.2.6 Specifications 157

5.3 Voltage transformers 1575.3.1 Introduction 1575.3.2 Electromagnetic VTs 1575.3.3 Capacitor VTs 1585.3.4 Specifications 159

5.4 Future trends 159

163

163163163164164164168168169169172173

6 Insulators

6.16.2

6.3

6.4

IntroductionInsulator materials *6.2.16.2.2

Polymeric and resin materialsGlass and porcelain

Insulator types6.3.16.3.26.3.3

Post insulatorsCap and pin insulatorsLong rod

Pollution control6.4.16.4.26.4.3

Environment/creepage distancesRemedial measuresCalculation of specific creepage path

viii Contents

6.5

6.6

Insulator specification6.5.16.5.2Tests6.6.16.6.2

7 Substation

7.17.2

7.37.4

7.5

StandardsDesign characteristics

Sample and routine testsTechnical particulars

Building Services

IntroductionLighting7.2.17.2.27.2.37.2.4

TerminologyInternal lightingExternal lightingControl

Distribution characterizationHeating, ventilation and air-conditioning7.4.17.4.27.4.3

Air circulationAir-conditioningHeating

Fire detection and suppression7.5.17.5.27.5.37.5.47.5.57.5.6

IntroductionFire extinguishersAccess, first aid and safetyFire detectionFire suppressionCables, control panels and power supplies

8 Earthing and Bonding

8.1 Introduction8.2 Design criteria

8.2.1 Touch and step voltages8.2.2 Touch and step voltage limits

8.3 Substation earthing calculations8.3.1 Environmental conditions8.3.2 Earthing materials8.3.3 Earth resistance and earth potential rise8.3.4 Hazard voltage tolerable limits

8.4 Computer simulationReferences

9 Insulation Co-ordination

9.1 Introduction9.2 System voltages

9.2.1 Power frequency voltage9.2.2 Overvoltages

Contents ix

9.3 Clearances 2459.3.1 Air 2459.3.2 SF6 248

9.4 Procedures for co-ordination 2489.4.1 The IEC standard approach 2489.4.2 Statistical approach 2499.4.3 Non-statistical approach 251

9.5 Surge protection 2519.5.1 Rod or spark gaps 2519.5.2 Surge arresters 253

References 268

10 Relay Protection 269

10.110.2

10.3

10.4

10.5

10.6

IntroductionSystem10.2.110.2.210.2.310.2.410.2.5

configurationsFaultsUnearthed systemsImpedance earthed systemsSolidly earthed systemsNetwork arrangements

Power system protection principles10.3.110.3.210.3.310.3.410.3.5

Discrimination by timeDiscrimination by current magnitudeDiscrimination by time and fault directionUnit protectionSignalling channel assistance

Current relays10.4.110.4.2

10.4.310.4.410.4.5

IntroductionInverse definite minimum time lag(IDMTL) relaysAlternative characteristic curvesPlotting relay curves on log/log graph paperCurrent relay application examples

Differential protection schemes10.5.110.5.210.5.310.5.410.5.5

Biased differential protectionHigh impedance protectionTransformer protection application examplesPilot wire unit protectionBusbar protection

Distance relays10.6.110.6.210.6.310.6.410.6.5

IntroductionBasic principlesRelay characteristicsZones of protectionSwitched relays

269270270270270271271274274275275275276277277

277280280281292292295296300303306306307307313314

x Contents

10.6.6 Typical overhead transmission line protectionschemes

10.7 Auxiliary relays10.7.1 Tripping and auxiliary10.7.2 AC auxiliary relays10.7.3 Timers10.7.4 Undervoltage10.7.5 Underfrequency

10.8 Computer assisted grading exercise10.8.1 Basic input data10.8.2 Network fault levels10.8.3 CT ratios and protection devices10.8.4 Relay settings

10.9 Practical distribution network case study10.9.1 Introduction10.9.2 Main substation protection10.9.3 Traction system protection10.9.4 21 kV distribution system and protection

philosophy10.9.5 21 kV pilot wire unit protection10.9.6 21 kV system back-up protection10.9.7 Use of earth fault indicators10.9.8 Summary

10.10 Recent advances in control, protection andmonitoring10.10.1 Background10.10.2 Developments

References

11 Fuses and Miniature Circuit Breakers

11.111.2

11.3

11.4

IntroductionFuses11.2.111.2.211.2.311.2.411.2.5

Types and standardsDefinitions and terminologyHRC fusesHigh voltage fusesCartridge fuse construction

Fuse operation11.3.111.3.211.3.311.3.411.3.5

High speed operationDiscriminationCable protectionMotor protectionSemiconductor protection

Miniature circuit breakers11.4.1 Operation

Contents xi

11.4.211.4.3

References

12 Cables

12.112.212.3

12.4

12.5

12.6

12.7

12.8

StandardsApplication

IntroductionCodes and standardsTypes of cables and materials12.3.112.3.212.3.312.3.4Cable12.4.112.4.212.4.312.4.412.4.512.4.612.4.7

General design criteriaCable constructionSubmarine cablesJoints and terminations

sizingIntroductionCables laid in airCables laid direct in groundCables laid in ductsEarthing and bondingShort circuit ratingsCalculation examples

Calculation of losses in cables12.5.112.5.2

Dielectric lossesScreen or sheath losses

Fire properties of cables12.6.112.6.212.6.312.6.412.6.512.6.612.6.7

IntroductionToxic and corrosive gasesSmoke emissionOxygen index and temperature indexFlame retardance/flammabilityFire resistanceMechanical properties

Control and communication cables12.7.112.7.212.7.3Cable12.8.112.8.212.8.3

References

Low voltage and multicore control cablesTelephone cablesFibre optic cables '

management systemsStandard cable laying arrangementsComputer aided cable installation systemsInterface definition

367368373

374

374374377377378386388389389390390395396398400410410411411411411412413413414415415415416417423423426429435

13 Switchgear 436

13.1 Introduction 43613.2 Terminology and standards 436

xii Contents

13.3 Switching13.3.1 Basic principles13.3.2 Special switching cases13.3.3 Switches and disconnectors13.3.4 Contactors

13.4 Arc quenching media13.4.1 Introduction13.4.2 Sulphur hexafluoride (SF6)13.4.3 Vacuum13.4.4 Oil13.4.5 Air

13.5 Operating mechanisms13.5.1 Closing and opening13.5.2 Interlocking13.5.3 Integral earthing

13.6 Equipment specifications13.6.1 12 kV metal-clad indoor switchboard example13.6.213.6.313.6.4

References

Open terminal 145 kV switchgear examplesDistribution system switchgear exampleDistribution ring main unit

Power Transformers

14.114.2

14.3

14.4

IntroductionStandards and principles14.2.114.2.214.2.314.2.414.2.514.2.6Voltage,14.3.114.3.214.3.314.3.414.3.514.3.614.3.714.3.814.3.9

Thermal14.4.114.4.214.4.3

Basic transformer actionTransformer equivalent circuitVoltage and current distributionTransformer impedance representationTap changersUseful standardsimpedance and power ratingGeneralVoltage dropImpedanceVoltage ratio and tappings - generalVoltage ratio with off-circuit tappingsVoltage ratio and on-load tappingsBasic insulation levels (BIL)Vector groups and neutral earthingCalculation example to determine impedanceand tap rangedesignGeneralTemperature riseLoss of life expectancy with temperature

Contents xiii

14.4.4 Ambient temperature 53414.4.5 Solar heating 53514.4.6 Transformer cooling classifications 53514.4.7 Selection of cooling classification 53814.4.8 Change of cooling classification in the field 53914.4.9 Capitalization of losses 540

14.5 Constructional aspects 54114.5.1 Cores 54114.5.2 Windings 54214.5.3 Tanks and enclosures 54414.5.4 Cooling plant 54614.5.5 Low fire risk types 54714.5.6 Neutral earthing transformers 54914.5.7 Reactors 549

14.6 Accessories 55214.6.1 General 55214.6.2 Buchholz relay 55214.6.3 Sudden pressure relay and gas analyser relay 55314.6.4 Pressure relief devices 55314.6.5 Temperature monitoring 55314.6.6 Breathers 55414.6.7 Miscellaneous 55414.6.8 Transformer ordering details 556

References 564

15 Substation and Overhead Line Foundations 565

15.1 Introduction 56515.2 Soil investigations 56515.3 Foundation types 56615.4 Foundation design 57515.5 Site works 576

15.5.1 Setting out 57615.5.2 Excavation 57715.5.3 Piling 57715.5.4 Earthworks 57915.5.5 Concrete ' 58015.5.6 Steelwork fixings 583

16 Overhead Line Routing 585

16.1 Introduction 58516.2 Routing objectives 58516.3 Preliminary routing 587

16.3.1 Survey equipment requirements 58716.3.2 Aerial survey 58716.3.3 Ground survey 58716.3.4 Ground soil conditions 587

xiv Contents

16.3.5 Wayleave, access and terrain16.3.6 Optimization

16.4 Detailed line survey and profile16.4.1 Accuracy requirements16.4.2 Profile requirements16.4.3 Computer aided techniques

17 Structures, Towers and Poles

17.1 Introduction17.2 Environmental conditions

17.2.1 Typical parameters17.2.2 Effect on tower or support design17.2.3 Conductor loads

17.3 Structure design17.3.1 Lattice steel tower design considerations17.3.2 Tower testing

17.4 Pole and tower types17.4.1 Pole structures17.4.2 Tower structures

References

18 Overhead Line Conductor and Technical Specifications

18.1 Introduction18.2 Environmental conditions18.3 Conductor selection

18.3.1 General18.3.2 Types of conductor18.3.3 Aerial bundled conductor and BLX18.3.4 Conductor breaking strengths18.3.5 Bi-metal connectors18.3.6 Corrosion

18.4 Calculated electrical ratings18.4.1 Heat balance equation18.4.2 Power carrying capacity18.4.3 Corona discharge18.4.4 Overhead line calculation example

18.5 Design spans, clearances and loadings18.5.1 Design spans18.5.2 Conductor and earth wire spacing and clearances18.5.3 Broken wire conditions18.5.4 Conductor tests/inspections

18.6 Overhead line fittings18.6.1 Fittings related to aerodynamic phenomena18.6.2 Suspension clamps

Contents xv

18.6.3 Sag adjusters 67818.6.4 Miscellaneous fittings 678

18.7 Overhead line impedance 67818.7.1 Inductive reactance 67818.7.2 Capacitive reactance 68018.7.3 Resistance 680

18.8 Substation busbar selection - case study 68118.8.1 Introduction 68118.8.2 Conductor diameter/current carrying capacity 68118.8.3 Conductor selection on weight basis 68118.8.4 Conductor short circuit current capability 68418.8.5 Conductor support arrangements 687

References 692

19 Testing and Commissioning 693

19.1 Introduction 69319.2 Quality assurance 694

19.2.1 Introduction 69419.2.2 Inspection release notice 69619.2.3 Partial acceptance testing 69619.2.4 System acceptance testing 69619.2.5 Documentation and record systems 696

19.3 Works inspections and testing 69819.3.1 Objectives 69819.3.2 Specifications and responsibilities 69919.3.3 Type tests 69919.3.4 Routine production tests 700

19.4 Site inspection and testing 70019.4.1 Pre-commissioning and testing 70019.4.2 Maintenance inspection 70119.4.3 On-line inspection and testing 701

19.5 Testing and commissioning methods 70519.5.1 Switchgear 70519.5.2 Transformers 71319.5.3 Cables t 71819.5.4 Protection 724

Appendix A: Commissioning test procedure requirements 738Appendix B: Drawings, diagrams and manuals 739

20 Electromagnetic Compatibility 741

20.1 Introduction 74120.2 Standards 74220.3 Compliance 74320.4 Testing 744

20.4.1 Introduction 744

xvi Contents

20.4.2 Magnetic field radiated emission measurements 74420.4.3 Electric field radiated emission measurements 74620.4.4 Conducted emission measurements 74820.4.5 Immunity testing 749

20.5 Screening 75020.5.1 Introduction 75020.5.2 The use of screen wire 75020.5.3 The use of screen boxes and Faraday enclosures 75020.5.4 The use of screen floors in rooms 752

20.6 Typical useful formulae 75520.6.1 Decibel reference levels 75520.6.2 Field strength calculations 75520.6.3 Mutual inductance between two long parallel 756

pairs of wires20.6.4 Attenuation factors 756

20.7 Case studies 75720.7.1 Screening power cables 75720.7.2 Measurement of field strengths 761

References 763

21 Supervisory Control and Data Acquisition 764

21.1 Introduction 76421.2 Programmable logic controllers 764

21.2.1 Functions 76421.2.2 PLC selection 76521.2.3 Application example 770

21.3 Power line carrier communication links 77621.3.1 Introduction 77621.3.2 Power line carrier communication principles 777

21.4 Supervisory control and data acquisition 78021.4.1 Introduction 78021.4.2 Typical characteristics 78321.4.3 Design issues 78521.4.4 Example (Channel Tunnel) 786

21.5 Software management 78821.5.1 Software - a special case 78921.5.2 Software life cycle ,• 79021.5.3 Software implementation practice 79321.5.4 Software project management 796

References 798

22 Project Management 799

22.1 Introduction 79922.2 Project evaluation 799

22.2.1 Introduction 799

22.3

22.4

22.5

22.6

22.7

22.2.222.2.3

Contents

Financial assessmentEconomic assessment

Financing22.3.122.3.222.3.322.3.422.3.522.3.6

Responsibilities for fundingCash flowSources of financeExport credit agenciesFunding risk reductionUse of private finance

Project phases22.4.122.4.222.4.322.4.422.4.522.4.6Terms22.5.122.5.222.5.322.5.4

The project life cycleCash flowBondsAdvance payments and retentionsInsurancesProject closeout

and conditions of contractTime, cost and qualityBasic types of contractStandard terms and conditions of contractKey clauses

Tendering22.6.122.6.222.6.3Model

Appendix A:Appendix B:

Choosing the contractorEstimatingTender evaluation

forms of contract - exerciseProject definition/questionnaireBidding checklist

xvii

800807811811811812812813814816816817819820822822822822823825829832832832834835837863

23 Distribution Planning 867

867867868869870870870871872873873878878

23.2.12 Peak responsibility factor (PRF) 880

23.1 Introduction23.2 Definitions

23.2.123.2.223.2.323.2.423.2.523.2.623.2.723.2.823.2.923.2.1023.2.11

Demand or average demandMaximum demand (MD) *Demand factorUtilization factor (UF)Load factor (LDF)Diversity factor (DF)Coincident factor (CF)Load diversityLoss factor (LSF)Load durationLoss equivalent hours

xviii Contents

23.3 Load forecasting23.3.1 Users of load forecasts23.3.2 The preparation of load forecasts23.3.3 The micro load forecast23.3.4 The macro load forecast23.3.5 Nature of the load forecast

23.4 System parameters23.4.1 Distribution feeder arrangements23.4.2 Voltage drop calculations23.4.3 Positive sequence resistance23.4.4 Inductive reactance23.4.5 Economic loading of distribution feeders

and transformers23.4.6 System losses

23.5 System reliability23.5.1 Introduction23.5.2 Reliability functions23.5.3 Predictability analysis

23.6 Drawings and materials take off

24 Power Quality - Harmonics in Power Systems

24.1 Introduction24.2 The nature of harmonics

24.2.1 Introduction24.2.2 Three phase harmonics

24.3 The generation of harmonics24.3.1 General24.3.2 Transformers24.3.3 Converters24.3.4 The thyristor bridge24.3.5 Railway and tramway traction systems24.3.6 Static VAr compensators and balancers

24.4 The effects of harmonics24.4.1 Heating effects of harmonics24.4.2 Harmonic overvoltages24.4.3 Resonances24.4.4 Interference

24.5 The limitation pf harmonics24.5.1 Harmonic filters24.5.2 Capacitor detuning

24.6 Ferroresonance and subharmonics24.6.1 Introduction24.6.2 A physical description of ferroresonance24.6.3 Subharmonics24.6.4 Interharmonics

Contents xix

24.7 Harmonic studies 92924.7.1 The requirement 92924.7.2 The studies 93024.7.3 Measurement 931

24.8 Case studies 931References 931

25 Power Quality-Voltage Fluctuations 933

25.1 Introduction 93325.2 The nature and cause of voltage disturbances in 933

power systems25.2.1 Short-term interruptions and voltage dips 933

and peaks25.2.2 Voltage fluctuations 93725.2.3 Voltage flicker 93725.2.4 Slow-voltage fluctuations 93825.2.5 Voltage unbalance 93825.2.6 Step-change events 939

25.3 Solutions 93925.3.1 Energy storage 93925.3.2 Balancing 94025.3.3 Static var compensators 94025.3.4 The STATCOM 942

25.4 Case study 942References 944

26 Fundamentals 945

26.1 Introduction 94526.2 Symbols and nomenclature 945

26.2.1 Symbols 94526.2.2 Units and conversion tables 946

26.3 Alternating quantities 95126.4 Vector representation 95426.5 Vector algebra ' 959

26.5.1 The j operator 95926.5.2 Exponential vector format 96026.5.3 Polar co-ordinate vector format 96126.5.4 Algebraic operations on vectors 96126.5.5 The h operator 962

26.6 Sequence components 96226.6.1 Theoretical background 96226.6.2 Calculation methodology and approximations 96426.6.3 Interpretation 965

26.7 Network fault analysis 966

xx Contents

26.7.1 Introduction 96626.7.2 Fundamental formulae 96626.7.3 Simplified network reduction example 971

26.8 Design optimization 97726.8.1 Introduction 97726.8.2 Technical problems 97826.8.3 Loss reduction 98226.8.4 Communication link gain or attenuation 99026.8.5 Reactive compensation 99126.8.6 Power factor correction calculation procedures 994

References 998

Index 1001