Switchgear and Protection

Introduction

1.1 General Background

1.2 Sub-station Equipment

1.3 Faults and Abnormal Conditions

1.4 Fault Calculations

1.5 Fault Clearing Process

1.6 Protective Relaying

1.7 Neutral Grounding (Earthing) and Equipment Grounding

1.8 Overvoltages and Insulation Co-ordination

1.9 Some Terms in the Text

1.10 Standard Specifications

1.11 Electromechanical Relays and Static Relays

1.12 Applications of On-line Digital Computers, Microprocessors and Static Protective/Con- trol devices in Power System

1.13 Interconnected Power System

1.14 Load-Frequency Control, Load Shedding

1.15 Voltage Levels in Network and Sub-stations

1.16 Voltage Control of AC Network

1.17 Static VAr Sources (SVS)

1.18 Power System Stability

1.19 HVDC Option

1.20 Testing, Commissioning and Project Execu- tion

1.21 Functional Responsibilities of Power Engi- neers

1.22 Scope of the Subject

SECTION I

Switchgear and Sub-Station Apparatus

2. High Voltage A.C. Circuit-Breakers

2.1 Introduction

2.2 The Fault Clearing Process

2.3 The Trip-Circuit

2.4 The Historical Review

2.5 Classification Based on Arc Quenching Medium

2.6 Technical Particulars of a Circuit-breaker

2.7 Assembly of Outdoor Circuit-breakers

2.8 Structural Form of Circuit-breakers

2.9 Operating Mechanisms

2.9.1 Closing Operation (C)

2.9.2 Opening Operation (O)

2.9.3 Closing Followed by Opening Oper ation (CO)

2.9.4 Types of Mechanisms

2.10 Interlocks, Indication, Auxiliary Switch

2.11 Circuit-Breaker Time (Total Break Time)

2.12 Auto-Reclosure

2.13 Auto-Reclosure of EHV Circuit-breakers For Transmission Lines

2.14 Auto-Reclosure For Distribution Lines

2.15 Weight Operated Reclosing Pole Mounted Circuit-breakers

2.16 Trip Free Feature

2.17 Materials and Some Design Aspects

2.18 Design and Development

3. Fundamentals of Fault-Clearing, Switching Phe- nomena and Circuit-Breaker Ratings

3.1 Introduction

3.2 Network Parameters, R.L.C.

3.3 Voltage Equation of R.L.C. Series Circuit

3.4 Sudden Short-Circuit of R.L. Circuit

3.5 Sub-transient, Transient and Steady-state

3.6 Current Interruption in A.C. Circuit-Breakers

3.7 Transient Recovery Voltage (TRV)

3.7.1 Effect of Natural Frequency of TRV

3.7.2 Effect of Power Factor on TRV

3.7.3 Effect of Reactance Drop on Power Frequency Recovery Voltage

3.7.4 Effect of Armature Reaction on Recovery Voltage

3.7.5 Effect of First-Pole-to-Clear

3.7.6 First-pole-to-Clear Factor

3.8 Single Frequency Transient

3.9 Double Frequency Transient

3.10 Rate of Rise of TRV, Analysis

3.11 Resistance Switching, Damping of TRV, Opening Resistors

3.12 Interruption of Low Magnetizing Current, Current Chopping

3.13 Use of Opening Resistors

3.14. Switching of Capacitor Banks

3.14.1. Switching of unloaded Transmission lines and unloaded Cables

3.15 Interrupting the Terminal Faults 3.16 Interruption of Short-line Faults (Kilometric

Fault) 3.17 Phase Opposition Switching

3.18 Specifying the TRV Wave

3.19 Rated Characteristics of Circuit-Breakers

3.19.1 Rated Voltage

3.19.2 Rated Insulation Level

3.19.3 Rated Frequency

3.19.4 Rated Normal Current (Rated Cur- rent)

3.19.5 Rated Short-Circuit Breaking Cur- rent

3.19.6 Rated Short-Circuit Making Current

3.19.7 Rated Duration of Short-Circuit

3.19.8 Rated Operating Sequence (Duty cycle)

3.19.9 Rated Transient Recovery Voltage for Terminal Faults

3.19.10 Representation of TRV Waveform by Four-parameter method

3.19.11 Representation of TRV Waveform by Two-parameter method

3.19.12 Rated Peak withstand Current

3.19.13 Rated Quantities for Auxiliary Cir- cuits and Operating Mechanisms for opening and closing

3.19.14 Rated Pressure of supply for Pneu- matic and Hydraulic Operating devices

3.19.15 Rated Pressure of Interrupting Medium and Insulating Medium

3.19.16 Summary of Rated Characteristics of H.V. (G.C) Circuit-Breakers

3.19.17 Rated out -of-phase Breaking Cur- rent

3.19.18 Rated Cable-charging Breaking Current

3.19.19 Rated Single Capacitor Bank Breaking Current

3.19.20 Permissible Maximum Switching Over Voltages When Interrupting Line – Charging, Cable Charging and Single Capacitor Bank Breaking Current

3.19.21 Rated Capacitor Bank Inrush Mak- ing Current

Questions Rated Time Quantities

3.19.22 Rated Small Inductive Breaking Current

4. The Arc-Extinction

4.1 Introduction

4.2 The Matter and Plasma

4.3 Ionization of Gases

4.4 Deionization

4.5 Electric Arc

4.6 Arc Formation in A.C. Circuit-Breakers

4.7 Modes of Arc Extinction

4.7.1 High Resistance Interruption

4.7.2 Low Resistance of Zero Point Extinction

4.8 Arc Interruption Theories

4.9 Arc Extinction in Oil

4.10 Arc Extinction in Vacuum

4.11 Arc Extinction in Air-blast

4.12 Arc Extinction in SF, Gas

4.13 Arc Time Constant

5. Air-Break Circuit-Breaker

5.1 Introduction

5.2 Construction of an Air-Break Circuit-Breaker

5.3 Arc Extinction in A.C. Air Break C.B.

5.4 Lengthening of Arc by Means of Magnetic Fields

5.5 Some Technical Aspects

5.6. Description of a Low Voltage Air-Break Circuit Breaker

5.7 Operating Mechanism for Air Break Circuit Breaker

5.8 Series-connected Over-load Trip Coil Arrangement

5.9 Air-Break D.C. Circuit-breakers for Medium Voltages

5.10 Other Air-break Switching Devices

5.11 Miniature Circuit-Breakers, Moulded Case Circuit Breakers

6. Air Blast Circuit-Breaker

6.1 Introduction

6.2 Construction of an Air-Blast Circuit-Breaker

6.3 Principle of Arc Quenching in ABCBs

6.4 Circuit-Breakers with External Extinguishing Energy

6.5 Resistance Switching in ABCB

6.6 Voltage Distribution in Multi-Break Circuit-Breakers (ABCB, MOCB, SF)

6.7 Merits of Air-Blast Circuit-breakers and Air

6.8 Design Features of Ultra High Voltage Air- Blast Circuit-Breakers

6.9 Technical Data of 245 kV Air-Blast Circuit- Breaker

6.10 Reducing Switching Over-Voltages by Pre- closing Resistors

6.11 ABCB with Cross Air Jets and Blast with Isomater Switch

6.12 Generator Circuit-Breakers

6.13

ABCB for Arc Furnace Duty

6.14 Compressed Air System for ABCB

6.15 Maintenance Aspects

7. Sulphur Hexafluoride (SF) Circuit-Breaker and SF, Gas Insulated Metalclad Switchgear

7.1 Introduction

Part I – Properties of SF, Gaso

7.2 Physical Properties of SF, Gas

7.3 Chemical Properties of SF, Gas

7.4 Dielectric Properties of SF, Gas

7.5 Arc Extinction in SF6 Circuit-Breakers

7.5.1 Single Pressure Puffer Type Circuit- breaker with Single Flow of Quenching Medium

7.5.2 Double Flow of Quenching Medium

Part II – Outdoor SF, Circuit-Breakers

7.6 Types of Design

7.7 Single-Pressure Puffer Type SF, Circuit- Breaker

7.7.1 Configuration of a Single Pressure Puffer Type EHV Circuit-Breaker

7.8 Double-pressure, Dead Tank type SF Circuit-Breaker

7.9 Merits of Sf. Circuit-Breakers

7.10 Some Demerits of SF, Circuit-Breaker

7.11 SF, Filled Load Break Switches

7.12 Gas Monitoring and Gas Handling Systems

Part III – Sf Insulated Metalclad Switchgear

7.13 Introduction to SF, Switchgear (GIS)

7.14 Advantages of SF, Switchgear

7.15 Demerits of SF, Switchgear

7.16 Design Aspects

7.17 Busbar Modules

7.18 Transportation and Handling of SF, Gas

7.19 Gas Transfer Units

7.20 SF Insulated EHV Transmission Cables (GIC)

8. Minimum-Oil Circuit-Breakers

8.1 Introduction

8.2 Tank Type or Bulk Oil Circuit-Breaker

8.3 Minimum Oil Circuit-Breaker

8.4 Principle of Arc-Extinction on Oil Circuit- Breakers

8.5 Pre-arcing Phenomenon

8.6 Sensitivity of TRV

8.7 Circuit-Breakers with Internal Source of Extinguishing Energy – Critical Current

8.8 Disadvantage of Oil

8.9 Contact Assembly

8.10 Description of 145 kV Minimum Oil Circuit-Breaker

8.11 Minimum Oil Circuit-Breaker with Modular Construction

9. Vacuum Interrupter and Vacuum Circuit- Breaker

9.1 Introduction

9.2 Electrical Breakdown in High Vacuum

9.3 Arc Extinction Vacuum Interrupters

9.4 Construction of Vacuum Interrupter

9.5 EHV Vacuum Circuit-Breaker with Modular Construction

9.6 Arc Interruption in High Vacuum

9.7 Degree of Vacuum in Interrupters

9.7.1 Construction of a Vacuum Interrupter

9.7.2 Construction of V.C.В.

9.8 Interruption of Short-Circuit Currents in Vacuum Interrupters

9.9 Design Aspects of Vacuum Interrupters

9.9.1 Length of Interrupter

9.9.2 Contact Travel (Contact Gap)

9.9.3 Contact Stape

9.9.4 Contact Size and Shape for Required Short-circuit Breaking Current

9.9.5 Contact Material

9.10 Time/Travel Characteristics

9.11 Contact Pressure

9.12 Contact Acceleration During Opening

9.13 Contact Erosion

9.14 Vacuum Level and Shelf Life of Interrupters

9.15 Checking of Vacuum

9.16 Range of Vacuum Switchgear, Vacuum Controlgear and Vacuum Circuit-Breakers

9.17 Merits of VCB’s

9.18 Demerits of VCB’s

9.19 Switching Phenomena with VCB

9.19.1 Reignition in Vacuum C.B.

9.19.2 Single Capacitor Bank Switching

9.19.3 Parallel Capacitor Bank Switching

9.19.4 Interruption of Small Inductive Cur- rents by VCB

9.19.5 Capabilities of Modern Vacuum C.B. for Medium Voltages

9.19.6 Switching Over-voltage Problem with VCB for Motor Switching Duty

10. Testing of High Voltage A.C. Circuit Breaker and Selection of Circuit-Breakers for Service

10.1 Classification of the Tests

10.2 Type Tests

10.2.1 Mechanical Endurance Tests

10.2.2 Temperature Rise Tests

10.2.3 Measurements of D.C. Resistance

10.2.4 Millivolt Drop Tests

10.2.5 No-Load Operation Test and Oscil- lographic and other Records

10.2.6 Dielectric Tests

10.2.7 Basic Short-Circuit Test Duties V

10.3 Routine Tests

10.4 Development Tests

10.5 Reliability Tests

10.7 Insulation Resistance Measurement at Site

10.6 Commissioning Tests

10.8. High Voltage Power Frequency with Stand Test

10.9 Routine Tests on Circuit-Breakers

10.9.1 Mechanical Operating tests Questions

11. Short-Circuit Testing of Circuit Breakers

11.1 Introduction

11.2 Stresses on Circuit-Breakers During Short- circuit Tests

Part A – Short-Circuit Test Plants

11.3 Short-Circuit Testing Plants

Part B – Direct Testing

11.4 Direct Testing

11.5 Rules for Type Tests

11.6 Short Time Current Tests on Circuit- Breakers, Isolators, Bus-bars, CTs etc.

11.7 Basic Short-Circuit Test Duties

11.8 Critical Current Tests

11.9 Short-line Fault Tests

11.10 Line-charging Breaking Current Tests

11.11 Out-of Phase Switching Tests

11.12 Capacitive Current Switching Tests

11.12.1 Single Capacitor-Bank Current- Breaking Test

11.13 Cable Charging Breaking Current Test

11.13.1 Small Inductive Current Breaking Tests

11.13.2 Recommendations for Small Induc- tive Current Switching Tests

11.14 Reactor Switching Test

Part C – Indirect Testing

11.15 Unit Testing or Element Testing

11.16 Synthetic Testing

11.17 Substitution Test

11.18 Capacitance Test

11.19 Compensation Test

11.20 Development Testing of Circuit-Breakers

12. Insulation Requirement and High Voltage Testing of Circuit-Breakers

12.1 Introduction

12.2 Overvoltages

12.3 Design Aspects

12.4 Causes of Failure of Insulation

12.5 Purpose of HV Testing of Circuit-Breakers

12.6 Tests on a High Voltage Circuit-Breakers

12.7 Some Terms and Definitions

12.8 Impulse Voltage Tests and Standard Impulse Waves

12.9 Impulse Generator

12.10 Test Plant for Power Frequency Tests

12.11 H.V. Testing Transformer

12.12 H.V. Testing Transformer

12.13 Sphere Gaps Questions

13. Installation and Maintenance

13.1 Introduction

13.2 Breakdown Maintenance Versus Preventive Maintenance

13.3 Inspection, Servicing, Examination and Overhaul

13.4 Guidelines for Maintenance of switchgear

13.5 Maintenance of Schedule Check List

13.6 Maintenance of Circuit Breakers

13.7 Measurement of Contact Resistance

13.8 Typical Maintenance Record Card

13.9 Maintenance of Air Break Circuit Breaker, Fusegear for Low and Medium Voltages

13.10 Maintenance of Old Circuit Breakers (BOСВ, MOCB)

13.11 Dielectric Oil (Transformer Oil)

13.12 Maintenance of Air-Blast Circuit Breakers

13.13 Maintenance of Compressed Air Plant

13.14 Maintenance of Vacuum Circuit-Breaker

13.15 Maintenance of SF, Circuit-Breaker

13.16 Insulation Resistance-Measurement

13.17 Installation of Outdoor Circuit Breakers

14. HRC Fuses and Their Applications

14.1 Introduction

14.2 Types of Devices with Fuse

14.3 Definitions

14.4 Construction

14.4 Substitution Test

14.5 Fuse Link of HRC Fuse

14.6 Action of HRC Fuse

14.7 Shape of Fuse Element

14.8 Specification of a Fuse Link

14.9 Characteristic of a Fuse

14.10 Cut Off

14.11 Classification and Categories

14.12 Selection of Fuse Links

14.13 Protection of Motor

14.14 Discrimination

14.15 Protection of Radial Liner

14.16 Protection of Meshed Feeders with Steady Load by HRC Fuses

14.17 Equipment Incorporating Fuses

14.18 High Voltage Current Limiting Fuses

14.19 Expulsion Type High-Voltage Fuse

14.20 Drop-out Fuse

14.21 Test on Fuse

14.22 Current Limiters

15A. Metal-Enclosed Switchgear, Controlgear, and Controlgear

15.1 Introduction

15.2 Types of Switchgear

Part A – High Voltage Indoor Metal enclosed Switchgear

15.3 General Features of Indoor Metal Enclosed Switchgear

15.4 Draw-out type Metal-enclosed Switchgear

15.5 Switchgear with Vacuum Interrupters

Part B – Low-Voltage Metalclad Switchgear and Low Voltage Circuit-Breakers

15.6 Unit-Type Metalclad, Low Voltage Switch- gear and Motor Control Centres

15.7 Low Voltage Circuit Breakers

15.7.1 Classification

15.7.2 Rated Quantities

15.7.3 Tests on low Voltage Circuit Breaker

15.8 ‘Explosion Proof’ or ‘Flame Proof’ Switch- gear

Part C – Low Voltage Controlgear and Contractors

15.9 Low Voltage Controlgear

15.10 Contactors

15.11 Some Terms and Definitions

15.12 Contractor Starters for Motors

15.13 Rated Characteristics of Contractors

15.14 Tests on Contactors

15.15 Low Voltage Load Control Centre

Part D-Control Boards

15.16 Control Boards or Control Panels

15.17 Construction and Types

15.18 Control Room Layouts Questions

15B. Medium Voltage Metal Enclosed Switchgear with SF, CB and VCB

Part I – Applications and Range

15.19 Type and Range

15.20 IEC and CIRED Classification

Part II – Constructional Aspects

15.21 Configuration and Variants

Part III – Switching Phenomens Associated with Medium Voltage Switchgear with SF,CB with VCB

15.22 General Assessment Criteria

15.23 Interruption of Inductive Currents and Small Inductive Currents

15.24 Switching-ON of a Motor, Voltage Surge due to Multiple Reignition

15.25 Motor Switching with Puffer Type SF, Circuit Breakers

15.26 Capacitor Switching

15.27 Advantages of SF, CB for Medium Voltage Switchgear

15.28 Advantages of VCB for Medium Voltage Switchgear

15C. Low Voltage Control Gear and Switchgear

15.29 Applications and Basic Requirements

15.30 Components and Modular Structural Con- figuration

15.31 Switching Devices

15.32 Mechanical Rated life of a Switching Device

15.33 Design Aspects for Long Mechanical Life

15.34 Main Electrical Circuit and Components in a Switching Device

15.35 Main Circuit Components Associated with Contactor Starters of LV

15.36 Protection Aspects

15.37 Contact Travel Characteristics of LV Switching Device during Operating and Closing Operations, Switching Time Defini- tions

15.38 Connection and Cross Sectional area of Cables

15.39 Contact Configuration and Design Aspects

15.40 Contact Materials

15.41 Contact Speed During Opening Operation

15.42 Auxiliary Switches

15.43 Tripping Device and Relays

15.44 Operating Mechanism (Drive Mechanism)

15.45 Degree of Protection, IP Code

15.46 Medium Voltage Vacuum Contactors for 3.6 to 12 kV

16A. HVDC Circuit-Breaker – I

16.1 Introduction

16.2 Merits of HVDC Transmission

16.2.1 Limitations

16.3 Energy Consideration in Breaking Direct Current in HVDC Circuit-Breakers

16.4 HVDC Switching System

16.4.1 Communication Principle of HVDC Circuit Breaker

16.4.2 Control of dl/dt and dV/dt

16.4.3 Triggered Vacuum Gaps (TRG)

16.4.4 Surge Suppression

16.4.5 Complete Circuit of HVDC Switch- ing System

16.5 Main Circuit-Breaker for HVDC Switching

16.6 HVDC System Layout Questions

16B. HVDC Circuit Breaker – II (Applications and Ratings)

16.7 Introduction of HVDC Circuit Breaker Applications

16.8 Configuration of Present 2 TDC and MTDC Systems and HVDC Circuit Breaker Appli- cations for Earth Return to Metallic Return Transfer

16.9 HVDC Systems Requiring

16.10 Types of HVDC Circuit Breakers

16.10.1 Two Extreme cases of HVDC Circuit-Breaker applications

16.10.2 Practical HVDC Circuit-breakers

16.11 HVDC Circuit-Breaker Capabilities and Characteristics

16.12 Definitions of Switching Time for HVDC Circuit-Breaker

16.13 Short-Circuit Ratio (SCR) of HVDC line

16.14 Parallel Tapping of Bipolar 2 -Terminal HVDC Transmission System

16.15 HVDC Circuit-Breaker Requirements for Parallel Tap

16.16 Conclusions

17E. Electrical Layouts, Isolators and Busbar Design and Sub-stations

17.1 Introduction

17.2 Layout and Schematic Diagrams

17.3 Isolators and Earthing Switch

17.3.1 Requirement and Definitions

17.3.2 Types of Construction of Isolators

17.3.3 Pantograph Isolator

17.3.4 Ratings of Isolators and Tests

17.4 Bus-bar Arrangements

17.4.1 Busbar System Recommended for Large Important Sub Stations

17.4.2 Maintenance Zoning

17.5 Use of Load-Break Switches

17.6 Switchgear in Generating-Stations

17.6.1 Main Switchgear Schemes

17.6.2 Circuit-Breakers for Main Switch- gear

17.7 Auxiliary Switchgear in Power Stations –

17.8 Isolated Phase Bus Systems

17.9 Switching Sub-stations

17.10 Layout of Switchyard Equipment

17.11 Location of Current Transformers

17.12 Typical Sub-station in Distribution System

17.13 Switchgear for Medium Size Industrial Work

17.14 Bus-Bars

17.15 Some Terms and Definitions

17.16 Materials for Bus-bars

17.17 Busbar Design

17.18 Electro-dynamic Forces on Busbars during Short-Circuits

17.19 Busbar Design

17.20 Sub-stations

17.21 Classification of Sub-stations

17.22 Specifications of a Sub-stations

17.23 Essential Features of a Sub-station

17.24 Sub-station Structures

18. Transient Over Voltages, Insulation Co- ordination and Neutral Earthing

18.1 Introduction

18.1.1 Choice of Insulation levels of Sub-1 station Equipment

18.1.2 Protective Ratio, Protective Margin

Part I-Lightning Over-voltages

18.2 Lightning

18.3 Surge Arresters (Lightning Arresters)

18.3 A Gap Type Sic Arrester

18.4 Surge Arrester Specifications and Terms

18.5 Selection of Surge Arresters

18.5B Zinc Oxide Gapless Surge Arresters

Part II – Switching Over-voltages

18.6 Switching Overvoltages Surges

18.7 Preclosing Resistors with Circuit Breakers

18.8 Combined Opening and Closing Resistors

18.9 Travelling Waves

18.10 Surge Modifiers, Absorbers/Suppressors

18.11 Protection of Rotating Machines Against Over-voltage Surges

Part III-Insulation Co-ordination

18.12 Insulation Co-ordination

Part IV-Neutral Earthing (Grounding and Equipmeng)

18.13 Introduction to Neutral Earthings

18.14 Terms and Definitions

18.15 Disadvantages of Unground Systems

18.16 Advantages of Neutral Grounding

18.17 Types of Grounding

18.18 Reactance in Netural Connection

18.19 Connection of the Arc Suppression Coil

18.20 Neutral Point Earthing of Transformer L.V. Circuits

18.21 Neutral Grounding Practice

18.22 Earthing Transformer

18.23 Sub-Station Earthing System

SECTION II-Fault Calculations

19. Introduction to Fault Calculations

19.1 Introduction

19.2 Procedure of Fault Calculations

19.3 Representation of Power Systems

19.4 Per Unit Method

19.5 Advantages of per Unit System

19.6 Selection of Bases

19.7 Single Phase Circuits: Determination of Base-Impedance

19.8 Change of Base

19.9 Circuits Connected by Transformer

19.10 Reactance of Circuit Elements

19.11 Induction Motors

19.12 Synchronous Motors

19.13 Thevenin’s Theorem

19.14 Some Terms

19.15 Star-Delta Transformation

19.16 Notation-j

20. Symmetrical Faults and Current Limiting Reac- tors

20.1 Fault MVA and Fault Current (Steady State)

20.2 Solved Examples 20.1 to 20.15

20.3 Procedure Recommended by Standards for Short-Circuit Calculations

20.4 Reactors in Power Systems

20.5 Principle of Current Limiting Reactors

20.6 Design Features of Current Limiting Reactors

20.7 Dry, Air Cored Series Reactor

20.8 Oil Immersed Non-Magnetically Shielded Reactor

20.9 Oil Immersed Shielded Reactors

20.10 Terms and Definitions

20.11 Physical Arrangement of Series Reactors

20.12 Section of Reactors

20.13 Location of Series Reactors

20.14 Solved Examples 20.16 to 20.21

20.15 Saturated Reactors

21. Symmetrical Component

21.1 Introduction

21.2 Symmetrical Components of 3-Phase Sys- tems

21.3 Operator a

21.4 Some Trigonometric Relations

21.5 Zero Sequence Currents

21.6 Phase Displacement in Star-Delta Trans- formers Questions

22. Unsymmetrical Faults on an Unloaded Generator

22.1 Sequence Impedance

22.2 Sequence Networks of Alternator

22.3 Voltage Equations

22.4 Single Line to Ground Fault on an Unloaded Three-phase Alternator at Rated Terminal- Voltage

22.5 Double Line to Ground Fault on an Unloaded Generator

22.6 Lide of Line Fault on Unloaded Alternator (Generator) Questions

23. Faults on Power Systems

23.1 Sequence Networks Examples 23.1 to 23.9 Questions

24. Use of A.C. Network Analyser and Digital Com- puter in Fault Calculations

24.1 Introduction

24.2 A.C. Network Analyzer (A.C. Calculating Board)

24.3 Digital Computers

24.4 Organization of Digital Computers

24.5 Process of Solving Engineering Problems on Digital Computers

24.6

(I) Short circuit Studies on Digital Computer

(II) Nodal Interative Method

SECTION IIF-Power System Protection

25. Introduction to Protective Relaying

25.1 About Protective Relaying

25.2 Faults, Causes and Effects

25.3 Importance of Protective Relaying

25.4 Protective Zones

25.5 Primary and Back-up Protection

25.6 Back-up Protection by Time Grading Prin- ciple

25.6.1 Back-up Protection by Duplication Principle

25.6.2 Monitoring

25.7 Desirable Qualities of Protective Relaying

25.7.1 Selectivity and Discrimination

25.7.2 Relay Time and Fault Clearing Time

25.7.3 Sensitivity

25.7.4 Stability

25.7.5 Reliability

25.7.6 Adequateness

25.8 Some Terms in Protective Relaying

25.9 Distinction Between Relay Unit, Protective Scheme and Protective System

25.10 Protective Current Transformers and Voltage Transformers

25.11 Actuating Quantities

25.12 Electromechanical Relays and Static Relays

25.13 Power Line Carrier Channel (PLC)

25.14 Programmable Relay

25.15 System Security

25.16 Role of Engineers

26. Electromagnetic Relays

26.1 Introduction

26.2 Basic Connections of Trip Circuit

26.3 Auxiliary Switch, Sealing, Auxiliary Relays –

26.3.1 Auxiliary Switch

26.3.2 ‘Sealing’, ‘Holding’, Operations’ ‘Repeat

26.4 Measurement in Relays

26.4.1 Magnitude Measurement

26.4.2 Product Measurement

26.4.3 Ratio Measurement

26.4.4 Vector Difference

26.5 Type of Relay units

26.6 Pick-up

26.7 Reset or Drop-off

26.8 Drop-off/Pick-up Ratio

26.9 Attracted Armature Relay

26.10 Balanced Beam Relay

26.11 Induction Disc Relay

26.11.1 Plug Setting and Time Setting in Induction Disc Relays

26.11.2 Effect of Time Setting

26.12 Induction Cup Relay

26.13 Permanent Magnet Moving Coil Relay

26.14 Rectifier Relay Systems

26.14.1 Relays for One Quantity

26.14.2 Relays for Two Quantities

26.15 Thermal Relays, Bimetal Relays, Thermo-couples

26.16 Directional Relays

26.16.1 Principle of Measurement

26.16.2 Directional Relays

26.16.3 Directional Element

26.17 Polarized Moving Iron Relay

26.18 Frequency Relays

26.19 Under-voltage Relays

26.20 D.C. Relays 26.21 All-or-nothing Relays

26.22 Plug Setting

26.23 Time Setting

26.24 Test Facility Questions

27. Overcurrent Protection and Earth Fault Protec- tion

27.1 Introduction

27.2 Applications of Overcurrent Protection

27.3 Relays Used in Overcurrent Protection

27.4 Characteristics of Relay units for over- Current Protection

27.5 Methods of CT Connections in Over Current Protection of 3-Phase Circuits

27.5.1 Connection scheme with Three Over current Relays

27.6 Earth Fault Protection

27.7 Connections of CT’s for Earth-fault Protec- tion

27.7.1 Residually connected Earth-fault Relay

27.7.2 Earth-fault Relay connected in Neu- tral to Earth Circuit

27.8 Combined Phase/Earth-Fault Protection

27.9 Earth-fault Protection with Core-balance CT’S

27.10 Frame Leakage Protection

27.11 Directional Overcurrent Protection

27.12 Directional Earth-Fault Protection

28. Differential Protection

28.1 Differential Protection

28.2 Applications of Differential Protection

28.3 Principle of Circulating Current Differential Protection

28.4 Difficulties in Differential Protection

28.5 Differential Protection of 3-phase Circuits

28.6 Biased or Per Cent Differential Relay

28.7 Settings of Differential Relays

28.8 Balanced Voltage Differential Protection Questions

29. Distance Protection

29.1 Introduction to Distance Protection

29.2 Principle of R-X Diagram

29.3 Theory of Impedance Measurement

29.3.1 R-X Diagram of Plain Impedance Relay

29.3.2 Plain Impedance Characteristics

29.3.3 Disadvantages of Plain Impedance Relay

29.3.4 Time Characteristic of High Speed Impedance Relay

29.4 Method of Analysis

29.5 Directional Impedance Relay

29.6 Torque Equation of Directional Impedance Relay

29.7 Modified (shifted) Characteristic

29.8 Reactance type Distance Relay

29.9 Mho-type Distance Relay

29.10 Application of Distance Protection

29.10.1 R-X Diagram

29.10.2 Line Characteristics

29.10.3 Condition for Relay Operation

29.10.4 Operating Time

29.10.5 Stages of Relay Time Characteris- tics

29.10.6

Co-ordinated Characteristics of Distance Relays in Three Stations

29.10.7 Significance of R-X Diagram and Method of Analysis

29.10.8 Load Impedance

29.10.9 Line Impedance

29.10.10 Power Swings

29.10.11 Choice of Characteristic Mho/Reactance Mho/Static

30. Protection of Transmission Lines

30.1 Introduction

Part A-Overcurrent Protection of Transmission Lines

30.2 Non-Directional Time Graded System of Feeder Protection

30.3 Directional Time and Current Graded System

30.3.1 Setting of Directional over-current Relays of a Ring Main

30.4Current Graded Systems

30.5 Definite Time Over-current Protection of Lines

30.6 Earth Fault Protection of Lines

30.7 Summary of Overcurrent Protection of Lines

Part B-Distance Protection of Transmission Lines

30.8 Introduction to Distance Protection of H.V. and E.H.V. Lines

30.8.1 Plain Impedance Protection

30.8.2 Directional Impedance Relay

30.8.3 Reactance Relay

30.8.4 Mho Relay Admittance Relays

30.8.5 Offset Mho Characteristic

30.9 Distance Schemes

30.10 Starting Element

30.11 Stepped Characteristics

30.12 Three Step Distance Time Characteristic

30.13 Power Swings

30.14 Carrier Assisted Distance Protection

30.14.1 Carrier Transfer

30.14.2 Carrier Blocking Scheme

30.14.3 Carrier Acceleration

30.15 Distance Schemes for Single Pole and Triple-pole Auto-reclosing

30.16 Connections of Distance Relays

Part C-Protection of Based on Unit Principle Lines

30.17 Pilot Wire Protection Using Circulating Current Differential Relaying

Part D-Carrier Current Protection of Transmission Lines

30.18 Carrier Current Protection

30.19 Phase Compression Carrier Current Protec- tion

30.20 Applications of Carrier Current Relaying

30.21 Radio Links of Microwave Link

31. Protection of Induction Motors of Failures in Induction Motors

31.1 Introduction

31.2 Abnormal Operating Conditions and Cause

31.3 Protection Requirements

31.4.1 Scheme of Starting Circuit

31.4.2 Bimetal Overload Devices

31.4.3 Short Circuit Protection by HRC Fuses

31.4 Protection of Low Voltage Intuction Motors

31.5 Protection of Large Motors

31.6 Overload Protection of Induction Motors

31.7 Protection against Unbalance

31.8 Protection against Single Phasing

31.9 Phase Reversal Relay

31.10 Phase to Phase Fault Protection

31.11 Stator Earth-Fault Protection

31.12 Faults in Rooter Winding

32. Protection of Transformers

32.1 Protection Requirements

32.2 Safety Devices with Power Transformer

32.3 Low Oil Level-Fluid Level Gauge

32.4 Gas Actuated Devices

32.4.1 Pressure Relief and Pressure Relay

32.4.2 Rate of Rise Pressure Relay

32.4.3 Buchholz Relay (Gas Actuated Relay)

32.5 Biased Differential Protection, Percentage Differential Protection of Power Transformer

32.6 Problems Arising in Differential Protection Applied to Transformers

32.7 Harmonic Restraint and Harmonic Blocking

32.8 Differential Protection of Three Winding Transformer

32.9 Differential Protection of Auto-transformers

32.10 Earth Fault Protection

32.11 Restricted Earth Fault Protection

32.12 Protection of Transformers in Parallel

32.13 Over Current Protection of Power Trans- formers

32.13.1 Overload Protection

32.14 Thermal Overheating Protection of Large Transformers

32.15 Overfluxing Protection

32.16 Protection of Arc Furnace Transformers

32.16.1 Power Supply Requirements of Arc Furnace Plants

32.17 Protection of Rectifier Transformer

32.18 Protection of Grounding Transformer Questions

33. Protection of Generators

33.1 Introduction

33.2 Abnormal Conditions and Protection Sys- tems

33.2.1 External Faults

33.2.2 Thermal Overloading

33.2.3 Unbalanced Loading

33.2.4 Stator Winding Faults

33.2.5 Field Winding Faults

33.2.6 Overvoltages

33.2.7 Other Abnormal Conditions

33.3 Percentage Differential Protection of Alter- nator Stator Windings

33.4 Restricted Earth Fault Protection by Differ- ential System

33.5 Overcurrent and Earth Fault Protection for Generator Back up

33.6

(a) Sensitive Stator Earth-Fault Protection

(b) 100% Stator Earth-fault Protection

33.7 Protection against turn-to-turn fault on Stator Winding

33.8 Rotor Earth Faults Protection

33.9 Rotor Temperature Alarm

33.10 Negative Sequence Protection of Generators Against Unbalanced Loads

33.11 Negative Phase Sequence Circuit

33.12 Stator Heating Protection

33.13 Loss of Field Protection

33.14 Reverse Power Protection

33.15 Over-speed Protection

33.16 Field Suppression

33.17 Other Protections

33.18 Protection of Small, Standby Generators

33.19 Generator-Transformer Unit Protection

33.19.1 Combined Differential Protection for Generator Main Transformer

33.20 Static Protection of Large Turbogenerators and Main Transformer

34. Station Bus-Zone Protection

34.1 Introduction

34.2 Bus Protection by Overcurrent Relays of Connected Circuits

34.3 Bus Protection by Distance Protection of Incoming Line as a Remote Back-up

34.4 Bus-Zone Protection by Directional Interlock

34.5 Bus-Zone Protection by Differential Principle

34.6 Problems in Bus-zone Differential Protection

34.7 Selection of CT’s Bus-Zone Protection

34.8 Biased Differential Bus-zone Protection

34.9 High Impedance Circulating Current Differ- ential Bus-zone Protection

34.10 High Impedance Differential Protection based on Voltage Drop

34.11 High Impedance Voltage Differential System

34.12 Check Feature in Bus Protection

34.13 Location of CT’s

34.14 Monitoring of Secondary Circuits

34.15 Interlocked Overcurrent Protection for Bus Zone and Generator Unit Zone

34.16 Non-autoreclosure and Simultaneous Three Pole Operation

34.17 Bus Transfer Schemes for Auxiliary Switchgear and Industrial Switchgear

35. Current Transformers and Their Applications

35.1 Introduction

35.2 Terms and Definitions

35.3 Accuracy Class

35.4 Burden on CT

35.5 Vector Diagram of CT

35.6 Magnetisation Curve of CT

35.7 Open-circuited Secondary of CT

35.8 Polarity of CT and Connections

35.9 Selection of CT’s for Protection Rating

35.10 CT’s For Circulating Current Differential Protection

35.10.1 CT’s for Overcurrent Phase Fault Protection

35.11 CT’s for other Protection System

35.12 Types of Construction of CT’s

35.13 Core shapes For Multiturn-Wound Primary Type CT

35.14 CT’s for HV Installations

35.15 Intermediate CT

35.16 Testing of CT’s

35.17 Transient Behaviour of CT’s Questions

36. Voltage Transformers and Their Applications

36.1 Introduction

36.2 Theory of Voltage Transformers

36.3 Specifications of VT’s

36.4 Terms and Definitions

36.5 Accuracy Classes and Uses

36.6 Burdens on VT’s

36.7 Connections of VT’s

36.8 Residually Connected VT

36.9 Electromagnetic Voltage Transformers

36.10 Capacitor Voltage Transformers (CVT)

36.10.1 CVT with Stepped Output

36.10.2 Protection of Voltage Transformers

36.11 CVT as Coupling Capacitor for Carrier Cur- rent Applications

36.12 Choice of Capacitance Values for CVT

36.13 Transient Behaviour of CVT

36.14 Ferro Resonance (FR) in CVT

36.15 Testing of Voltage Transformer

36.16 Applications of CVT for Protective Relaying Questions

37. Testing and Maintenance of Protective Relays

37.1 Importance of Maintenance and Setting

37.2 Tests on Relays

37.3 Test Equipment

37.4 Routine Maintenance Tests

37.5 Inspection and Testing for Acceptance

37.6 Some Tests on CT’s

37.7 Some Test on PT’s

37.8 Some Tests Circuits and Procedure for Sec- ondary Injection Tests

37.9 Manufacturer’s Tests

37.10 Commissioning Tests Questions

SECTION IV

Static Relays and Static Protection Schemes

38.A. Introduction to Static Relays and Micropro- cessor – based Integrated Programmable Pro- tection, Monitoring and Control Systems

38.1 Introduction and Definition

38.2 Static Electromagnetic Relays

38.3 Limitation of Static Relays

38.4 Reliability and Security of Static Relays

38.5 Historical Review in Brief

38.6 Recent Developments of Static Relays

38.7 Present trends in Protection and Control Technology

38.8 Modular Concept, Building-block Principal used in Predominantly Static Protection Systems

38.9 Static Relay Functional Circuits and Index of Functions

38.10 Types of Measuring and All-or-nothing Relay units

38.11 Analogue and Digital Sub-systems in Pro- tective Relaying

38.12 Analogue Protection Systems

38.13 Limitations of Analogue Systems

38.14 Digital and Programmable Electronic Static Relays

38.15 Hard Wired Digital Systems

38.16 Programmable Digital Protective and Control Systems

38.17 Forms of Digital Electronic Circuits

38.18 Integration of Control and Protection for High voltage AC Sub-stations

38.B. Introduction to Analogue and Digital Static Relays

SECTION I – SOLID STATE DEVICES

38.6 Semiconducting Materials

38.7 Solid-state Devices

38.8 Printed Circuit Boards with Discrete Com- ponents

38.9 Static Relays with Integrated Circuits

38.9.1 Reed Relays

38.10 Static Directional Units

SECTION II – DIGITAL CIRCUITS AND THEIR APPLICA IN PROTECTIVE RELAYING

38.11 Logic Circuits

38.12 AMD Functions

38.13 OR Functions

38.14 NOT Functions

38.15 Combined Functions

38.16 Memory Function

38.17 Families of Logic Circuits

38.18 Applications of Logic Circuits in Protective Relaying

SECTION III – OP AMP. AND ANALOGUE CIRCUIT

38.19 Definitions and Applications

38.20 Symbol of Op. Amp

38.21 Characteristics of Ideal Op. Amp

38.22 Applications of Op.Amp’s

38.23 Analogue Level Detector or Comparator

38.24 Analogue/Digital Conversion

38.25 Digital Multiplexers

SECTION – IV ELECTRONIC CIRCUITS COMMONLY USED IN STATIC RELAYS

38.26 Auxiliary Voltage Supply for Static Relays

38.27 Full-wave Rectifier

38.28 Smoothing Circuits

38.29 Voltage Stabilization (Regulation) by Zener Diodes

38.30 Time – Delay Circuits

38.31 Frequency Filters

38.32 Symmertrical Component Filters

39. Comparators and Level Detectors

39.1 Static Relay Functional Circuits

39.2 Comparators

39.3 Amplitude Comparators

39.4 Phase Comparators

39.5 Phase Comparators Based on Rectangular (or Sequared) Pulses

39.6 Phase Comparators Based on Vector Product Devices

39.7 Direct (Instantaneous) and Integrating Type Comparators

39.8 Integrating Amplitude Comparator

39.9 Operating Time

39.10 Coincidence Techniques in Phase Compara- tors

39.11 Spike and Block Coincidence Technique in Phase Comparators

39.12 Phase Comparator with Phase Splitting Techniques

39.13 Hybrid Comparators

39.14 Level Detector

39.15 Level Detector by PNP Transistors

39.16 NPN Transistor as Level Detector

39.17 Schmitt Trigger with Operational Amplifier

39.18 Schmitt Trigger with two NPN Transistors

40. Static Overcurrent Relay

40.1 Introduction to Static Over Current Relays

40.2 Single Actuating Quantity Relays

40.3 Double Actuating Quantity Relays

40.4 Basic Principle of Static Over Current Relays

40.5 Time Characteristics

40.6 Timing Circuit

40.7 Directional Overcurrent Relay

40.8 Static Instantaneous AC Measuring Relays

40.9 Static Time-lag Overcurrent Relays

40.10 Static Directional Relays 

41. Static Differential Protection of Power Trans- formers

41.1 Introduction

41.2 Differential Protection of Two Winding Transformer

41.3 Differential Protection of Three Winding Transformer

41.4 Inrush-proof Qualities

41.5 Requirements to be Fulfilled by the Main CT

41.6 Auxiliary CT Questions

42. Static Distance Relays and Distance Protection of EV Lines

42.1 Introduction

42.2 Voltage Comparator and Current Compara- tion

42.3 Three Input Amplitude Comparator

42.4 Hybrid Comparator

42.5 Four Input Phase Comparator with Qua- drangular Characteristic

42.6 Error Distance Measurement

42.7 Influence of Power Swings on Distance Pro- tection

42.7.1 Power Swings what are they

42.7.2 Effect of Power Swing on the Start- ing Elements of Distance Schemes

42.7.3 Effect of Power Swing on the Mea- suring Elements in Distance Schemes

42.7.4 Representation of Power Swing on R-X Diagram

42.8 Protection of Teed Lines by Distance Relays

42.9 Back-up Protection with Intermediate Infeed

42.10 Compensation or Compounding in Distance Relays

42.11 Setting of Distance Relays

42.12 Solved Examples on Distance Relay Setting

42.13 Multifarious Functions of a Complete Mod- ular Distance Relays

42.14 Static Distance Protection Scheme Questions

43.A Imported Assorted Topics and Static Protection Schemes

Section I: Installation, Reliability and Testing of Static Relays

43.1 Combating Electrical Noise and Interferences

43.2 Transient Overvoltages in Static Relays

43.3 Protection of Static Relay Circuit

43.4 Recommended Protection Practices for Static Relaying Equipment

43.5 Testing of Static Relays with Regard to Over-voltage Transients

43.6 Reliability, Dependability and Security

43.7 Static Relays for Motor Protection

Section II: Static Protection Schemes

43.8 Static Busbar Protection Based on Directional Comparison

43.9 Disconnection of Main Supply from Inplant

Auxiliary Supply During System Faults

Section III: Back-up Protection, Centrally Co-ordinated Back-up and Protection Signalling

43.10 Breaker Back-up, Local Back-up

43.11 Use of Microprocessors for Local Back-up

43.12 Computer Based Centrally Co-ordinated Back-up

43.13 Programmable Equipment for Protective Relaying (PPRMC) Measurement and Control

43.14 Principle of Centralized Back-up Protection (CBP)

43.15 Post Fault Control (PFC) by Digital Com- puters

43.16 Communication Links for Protection Sig-nalling

43.17 Fibre Optic-Data Transmission

43.18 Local Breaker Back-up Protection Breaker Fail Protection; Stuck-breaker Protection

43.19 Uninterrupted Power Supply (UPS)

43.20 Directional Wave Relays for Fault Detection and Protection of Overhead Lines Questions

43.B Digital Relays Microprocessors Based Relays Fault Recorders and Fault Locators

43.21 Enter Microprocessors in Protection Tech- nology

43.22 Block Diagram and Components of a Digital Relay

43.23 Basic Principles of Digital Relays

43.24 Microprocessors Based Relays

43.25 Description of a Microprocessor Based Pro- tective Relay for Motor Protection

43.26 Advantages and Special features of Micro- processor Based Protective Relays

43.27 Block Diagram of a Microprocessor Based Distance Relay for Protection of Transmis- sion Line

43.28 Architecture of Microprocessor

43.29 Programming of Microprocessors based Relays

43.30 Self checking/self Monitoring in Micropro- cessor Based Relay

43.31 On line Microprocessor Based Fault Moni- toring

43.32 Microprocessor Based Fault Locators

43.33 Principle of Fault Detection in On line Digital Relays, Fault Locators and Fault Recorders 

43.32 Microprocessor Based Fault Locators

43.33 Principle of Fault Detection in On line Digital Relays, Fault Locators and Fault Recorders 

43.C Microprocessor Based Sub-station Protection Control and Monitoring

43.34 Introduction

43.35 Equipment to Automatic Control Sub- stations

43.36 Two Subsystems in Sub-stations

43.37 Two Hierarchical Levels in a Sub-station

43.38 Sub-station Level

43.39 Functions Performed by Protection and Control Equipment

43.40 Protection and Control Configuration

Section V: Power System Analysis, Interconnection System Control SCADA Systems

44. Power System Stability, Auto-reclosing Schemes Methods of Analysis and Improve- ment of Transient Stability

Part A – Concept of Power System

44.1 Power System Stability

44.2 Concept of Power System Stability

44.3 Single Machine Against Infinite Bus

Part B – Swing Curves and Swing Equation, E

Area Criterion

44.4 Dynamics or Synchronous Machines, Kinetic Energy, Inertia Constant and Stored Energy

44.4.1 Kinetic Energy of a Rotating Mass

44.4.2 Inertia Constant H

44.4.3 Stored Energy in Rotor of a Syn- chronous Machine

44.4.4 Quantities Related with Kinetic Energy of a Rotating Mass

44.5 Swing Curve

44.6 Derivation of Swing Equation from Funda- mentals

44.7 Equal Area Criterion of Transient Stability

44.8 Critical Clearing Angle

44.9 Methods of Improving Transient Stability Limit

Part C – High Speed Protection and Circuit Brea

44.10 High Speed Circuit-breakers and Fast Pro- tective Relaying and Improved Transient Stability

44.11 Auto-reclosure Improves Transient Stability

44.12 Single Pole Reclosing of Circuit-breakers

44.13 Independent Pole Mechanism

44.14 Single Pole Tripping

44.15 Selective Pole Tripping

44.16 Segregated Phase Comparison Relaying (SPCR)

44.17 Influence of Power Swings on Transmission Line Protection

Part D – Autoreclosing

44.18 Autoreclosing Schemes

44.19 Terms and Definitions Regarding Autore- closing

44.20 Rapid Autoreclosing Scheme

44.21 Delayed Autoreclosing Scheme

44.22 Synchronism Check

44.23 Control Schemes of Autoreclosing

Part E – Modern Definitions of Power System Disturbance, Stability

44.24 Terms and Definitions in Power System Stability Studies

44.25 Operational Limits with Reference to Steady State Stability Limit and Transient Stability Limit

Part F – Improvement in Steady State Trasient Stability Limits

44.26 Methods of Improving Transient Stability Limit Questions

45-A Load Frequency Control, Load Shedding and Static Frequency Relay

45.1 Introduction of System Frequency Control

45.2 Load Frequency Characteristics of Rotating Machines

45.3 Primary Load-Frequency Control

45.4 Secondary Load-Frequency Control

45.5 Load Frequency Control of a Grid

45.6 Load Shedding

45.7 Use of Frequency Relays for Load-Shedding

45.8 State Frequency Relay

45.8.1 Turbine Frequency Capability and under Frequency Limits

45.9 Network Islanding

45.10 Other Application of Frequency Relay

45.11 Load Dispatching and Network Controller Questions

45-B Voltage Control and Compensation of Reactive Power

45.12 Voltage Control in Network

45.13 Permissible Voltage Variation

45.14 Methods of Voltage Control

45.15 Compensation of Reactive Power

45.16 Effect of Reactive Power Flow on Voltages at Sending-end and Receiving end of Trans- mission Line

45.17 Series Capacitors

45.18 Applications of Power Capacitors in Electric Power Systems

45.19 Installation of Shunt Capacitors

45.20 Reactive Power of Requirements and Voltage Regulation of EHV/UHV A.C. Lines Surge Impedance Loading Questions

46-A Digital Computers Aided Protection and Automation

46.1 Introduction to Power System Control and Operation

46.2 Terms Related with Computers and Micro- processors

46.3 Supervisory Control and Data Aquisition System for Power System Operation and Control

46.4 Data Collection Equipment, Data Loggers

46.5 Data Transmission Equipment (Telemetry)

45.6 Applications of Power Line Carrier (PLC)

45.7 Man-Machine Interface

45.8 Application of Computer in Network Auto- mation

45.9 Microprocessors

45.10 Microprocessors Based Microcomputer

45.11 Applications of Digital Computers and Micro-processors in Power System Protec- tion

45.12 Microprocessor Based Inverse Time Over- Current Relay

45.13 Digital Computers for Power System Oper- ation

45.14 On Line Digital Computer for Protection of Line Questions

46-B Economic Operation of Power System and Automatic Economic Load Dispatch

46.15 Classical Method of Loading the Units in a Plant

46.16 Economic Load Distribution within a Gen- erating Station by Modern Method

45.17 Modern Method of Economic Load Distri- bution between Various Generating Stations in a Region

46.18 Distribution of Local between Generating Stations by taking into account the Trans- mission Losses: Penalty factor

46.19 Automatic Local Dispach Incorporating Local Frequency Control and Economic Local Dispach

46.20 Transmission Loss as a Function of Output Power of Generating Station

47. HVDC Transmission Systems

47.1 Introduction, Choice of HVDC Transmission

47.2 HVDC Transmission Systems

47.2.1 Applications of HVDC Transmission Systems

47.2.2 Choice of HVDC Transmission Sys- tem

47.2.3 Types of HVDC Systems and Brief Description

47.2.4 Long Distance, High Power Bipolar HVDC Transmission System

47.2.5 Power Rating of Long Bipole HVDC Transmission System

47.2.6 Configuration and Description of a Bipolar Scheme

47.2.7 Economic Comparison of Bipolar HVDC Transmission System with EHV-AC System

47.2.8 EHV-AC Versus HVDC

47.2.9 HVDC Cable Transmission

47.2.10 HVDC System Interconnection

47.2.11 HVDC Coupling System

47.2.12 EHV-AC versus HVDC Transmis- sion

47.2.13 Limitations of HVDC Transmission

47.2.14 Terms and Definitions Regarding HVDC

Control of HVDC Link

47.3.1 Steady-state Ud/Id Characteristic of Converters

47.3.2 Interesting Characteristics of Recti- fier and Inverter under Normal Operating Mode

47.3.3 Interesting Characteristic Under Steady Condition with Current Mar- gin Control

47.3.4 Power Transmission Characteristic with Constant Current Regulation of Rectifier and Constant extinction

Angle Regulation of Inverter 47.3.5 Reversal of Power Through an HVDC Link: Necessity of Reversal of Power

47.3.6 Alternatives of HVDC Control

47.4 Circuit Arrangements

47.5 Thyristor Values for HVDC Convertor

47.6 Reversal of Power

47.7 Typical Layout of HVDC Conversion of Sub-station

47.8 Over Voltage Protection

47.9 D.C. Surge Arrestors

47.10 Line Protection System

47.11 A.C. Harmonics

47.12 Harmonic Filters

47.13 HVDC Simulator

47.14 Protection System in HVDC Sub-station

47.14.1 Protection of HVDC Transmission System

47.15 Line Insulation

47.16 Maintenance of HVDC Links

47.17 D.C. Breakers and Load Switches

47.18 Control and Protective Equipment

48. EHV-AC Transmission Systems and Static VAR Sources

48.1 General Background of EHV-AC Transmis- sion

48.2 Voltage Levels for Transmission Lines

48.3 Hierarchial Levels of Transmission and Dis- tribution

48.4 Tasks of Transmission Systems

48.5 Functional Requirements of Transmission Systems and Design Aspects

48.6 Configuration of EHV-AC Transmission Systems and Bipolar HVDC Transmission System

48.7 Power Transferability of AC Line

48.8 Line Losses

48.9 Conductor Cost

48.10 Transient Stability Limit of AC Line

48.11 Control of Power Flow Through Line

48.12 Short Circuit Levels

48.13 Voltage Control of AC Lines and Compen- sation of Reactive Power

48.14 Insulation Co-ordination and Surge Arrestor Protection

48.15 Line Insulation, Clearance and Creepage Distances

48.16 Right-of-Way (Row)

48.17 Corona

48.18 Towers (Supports)

48.19 Bundle Conductors

48.20 Switching Phenomena Associated with EHV-AC Line Switching

48.21 Audible Noise (AN)

48.22 Biological Effect of Electric Field and Lim- iting Value of Electric Field Strength

48.23 Radio Interference and Television Interfer- ence

48.24 Rapid-Auto Reclosing and Delayed Auto- reclosing of Circuit-Breakers

48.25 Surge Impedance Loading of AC Transmis- sion Lines

48.26 Sub-Synchronous Resonance in Series Compensated AC Lines

48.27 Static VAR System (SVS)

48.28 Applications

49. Interconnected Power Systems

49.1 Introduction

49.2 System Configuration and Principle of Interconnection

49.2.1 Individual System

49.2.2 Total Generation in Interconnected Systems

49.3 Merits of Interconnected Power Systems

49.4 Limitations of Interconnected Power System

49.5 Obligations of Each Interconnected Systems

49.6 Objectives of Automatic Generation Control and Tie-Line Power Flow Control

49.7 Overall Objective and Co-relation between Real Power and Reactive Power Control and Tie-line Power Flow

49.8 Tie-Line Power Flow Control in 2-Area System

49.9 Tie-Line Power Flow in 3-Area System

49.10 Alternative Principles of Control and Tie-line Bias Control

49.11 Equations of Tie-line Power Flow Control Reviewed

49.12 Actions by the Control Room Operators to Change Tie-line Power

49.13 Actions by Control Room Operators for Voltage Control

49.14 Controlling Tie-Line Power by Means of Phase Shifting Transformer

49.15 Phase Shifting Transformer

49.16 Types of Interchange in Interconnected Sys- tem

49.17 National Grid and Growth of Power System in India

50. Operation and Control of Interconnected Power Systems, AGC and SCADA

50.1 Introduction

50.2 Main Tasks in Power System Operation

50.2.1 Planning of Operations

50.2.2 Operational Tasks

50.2.3 Operating Accounting and Financial Control

50.3 Automatic Generation Control (MW)

50.4 Supervisory Control and Data Aquisition (SCADA) System

50.4.1 Division of Tasks between Various Control Centres

50.4.2 Functions of SCADA Systems

50.4.3 Common Features of all SCADA Systems

50.4.4 Alarm Functions

50.4.5 Integration of Measurement Control and Protection Functions by SCADA System

50.5 Automatic Sub-station Control

50.6 SCADA Configurations

50.7

Energy Managment Systems (EMS)

50.8 System Operating Systems

50.8.1 Normal States

50.8.2 Alert State

50.8.3 Emergency State

Islanding (In Extermis) State

50.8.4 50.8.5

Restoration State

50.9 System Security

50.9.1 Security Control

50.10 State Estimation

50.11 Expert Systems using Artifical Intelligence for Power System Operation

50.11.1 What is an Expert System?

50.11.2 Components of Expert System

50.11.3 Example of an Expert System’s Working

50.11.4 Applications in Power Systems

50.12 Centralised Diagnostic Expert System using Artifical Intelligence

51-A Power System Planning

51.1 Scope of Power System Planning and Design

51.2 Significance of System Planning and Design

51.3 Computer Programmes for Planning

51-B Project Planning, Installation, Commissioning and Maintenance of Sub-stations

51.4 Project Planning

51.5 Civil Activities

51.6 Despatch to Site

51.7 Inspection on Arrival at Site

51.8 Storage

51.9 Foundations

51.10 Civil Works of Control Room and Other Buildings

51.11 Erection of Structures

51.12 Erection of Yard Equipment

51.13 Drying Out

51.14 Measurement of Insulation Resistance and Polarisation of Index of Transformers

51.15 Commissioning Tests

51.16 Tests on Protection Systems

51.17 On Load Test

51.18 Handing- Over to the Customers Operating Staff

51.19 Preventive Maintenance of Sub-station Equipment

52 Improving Dynamic Stability by Flexible AC Transmission System (FACT) and HVDC Systems

52.1 Inter-relationship between Voltage, Active Power, Reactive Power, Power Angle, Ocil- lations and Various Types of Stabilities

52.1.1 Review of Concepts of Power System Stability and Basic Equations

52.2 Parameters for Dynamic Control

52.3 Fundamental Requirements of AC Trans- mission System

52.4 Time Ranges of Abnormal Conditions and Disturbances

52.5 Enter Thyristor Control

52.6 First Swing Period and Oscillatory Period

52.7 Review of Power System Problems and Methods for Improvements

52.8 Flexible AC Transmission (FACT)

52.9 Damping of Oscillators in AC Networks by Means of HVDC Damping Control Asynchronous HVDC Link for Improving Stability of AC System

52.10 Stabilisation of Adjucent A.C. Lines Syn- chronous HVDC Link for Improving Stability of AC Systems

52.11 DAmping of AC Network Oscillation with different Conditions of DC Control for Syn- chronous HVDC Link

53. Computer Aided Power System Studies

53.1 Computer Aided Engineering (CAE) for Power System Studies

53.2 Purpose and Need of System Studies

53.3 Basic Power System Studies

53.4 Preparation for System Studies

53.5 Software Programmes on Power System Engineering

53.6 Tools for Power System Studies

54. Power System Reliability Studies

54.1 Introduction

54.2 Terms and Definitions

54.3 Reliability Indexes

54.4 Procedure of System Reliability Evalution

54.5 Service Interruption

54.6 Failure Mode and Effect Analysis

54.7 Availability

54.8 Scheduled Outage

54.9 Forced Outage

55. Power System Security and Optimum Load Flow

55.1 Power System Security

55.2 Purpose of Security Analysis

55.3 EMS Configuration and Security Analysis

55.4 Power System Monitoring as Essential part of Security Improvement

55.5 Softwares in Energy Management System

55.6 Optimal Load Flow

56. Energy and Power Plants

56.1. Energy Resources and Forms of Energy

56.2. Units of Electrical Energy

56.3. Electrical Load and Demand

56.4. Load and Curves and Peak Load

56.5. Base Load, Intermediate Load and Peak Load

56.6. Load Duration Curve

56.7. Types of Generating Units for Base Load, Intermediate Load and Peaking Load

56.8. Plant Factors and Reserves

56.9. Power Plant with Conventional Energy Resources

56.10. Coal Fired Steam-Turbine Power Plants

56.10.1. Fluidised Bed Combustion Chamber Boilers

56.11. Integrated Coal Gasification Combined Cycle Power Plant (ICGCC)

56.12. Hydro Electric Power Plant

56.13. Nuclear Fission Reactor Power Plants

56.14. Gas Turbine Power Plant

56.15. Combined Cycle Power Plants

56.15.1. Integrated Coal Gasification Combined Cycle Plant

56.16. Diesel Electric Power Plants

56.17. Age of Renewables and Alternatives

56.18. Energy Storage Plants

56.19. Power Quality

56.20. Interconnected Power System

56.21. Projected Growth of Energy Supply System India

56.22. Significance of Switchgear Protection and Power System Automation