Electric Power Transmission & Distribution

632 Pages·2009·18.674 MB·English

by  Sivanagaraju S., Satyanarayana S

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ELECTRIC POWER
TRANSMISSION
AND DISTRIBUTION
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ELECTRIC POWER
TRANSMISSION
AND DISTRIBUTION
S. Sivanagaraju
Associate Professor
Department of Electrical Engineering
JNTU College of Engineering
Anantapur, Andhra Pradesh
S. Satyanarayana
Professor and Head
Department of Electrical Engineering
Tenali Engineering College
Tenali, Andhra Pradesh
Delhi • Chennai • Chandigarh
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Copyright © 2009 Dorling Kindersley (India) Pvt. Ltd

This book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, resold,
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ISBN: 978-81-317-0791-3

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TO MY PARENTS
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CONTENTS
Preface xvii
Acknowledgement xix
1 TRANSMISSION AND DISTRIBUTION: AN INTRODUCTION 1
1.1 OVERVIEW 1
1.2 VARIOUS LEVELS OF POWER TRANSMISSION 2
1.3 CONVENTIONAL SOURCES OF ELECTRICAL ENERGY 3
1.3.1 Hydro Power Stations 4
1.3.2 Thermal Power Stations 4
1.3.3 Nuclear Power Stations 4
1.3.4 Diesel Power Stations 5
1.4 LOAD FORECASTING 5
1.4.1 Purpose of Load Forecasting 5
1.4.2 Classification of Load Forecasting 6
1.4.3 Forecasting Procedure 6
1.4.4 Load Characteristics 8
1.5 LOAD MODELLING 9
1.5.1 Characteristics of Load Models 9
1.6 STAR-CONNECTED LOADS 10
1.6.1 Constant Power Model 11
1.6.2 Constant Current Model 12
1.6.3 Constant Impedance Model 12
1.7 DEREGULATION 12
1.7.1 Need for Restructuring 13
1.7.2 Motivation for Restructuring the Power Industry 13
1.8 DISTRIBUTION AUTOMATION 14
2 TRANSMISSION-LINE PARAMETERS 15
2.1 INTRODUCTION 15
2.2 CONDUCTOR MATERIALS 16
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viii ELECTRIC POWER TRANSMISSION AND DISTRIBUTION
2.3 TYPES OF CONDUCTORS 17
2.4 BUNDLED CONDUCTORS 18
2.5 RESISTANCE 19
2.6 CURRENT DISTORTION EFFECT 20
2.6.1 Skin Effect 20
2.6.2 Proximity Effect 21
2.6.3 Spirality Effect 22
2.7 INDUCTANCE 22
2.7.1 Inductance of a Conductor due to Internal Flux 22
2.7.2 Inductance of a Conductor due to External Flux 24
2.8 INDUCTANCE OF A SINGLE-PHASE TWO-WIRE SYSTEM 25
2.9 FLUX LINKAGES WITH ONE SUB-CONDUCTOR OF A COMPOSITE
CONDUCTOR 28
2.10 INDUCTANCE OF A SINGLE-PHASE SYSTEM (WITH COMPOSITE
CONDUCTORS) 30
2.11 INDUCTANCE OF THREE-PHASE LINES 35
2.11.1 Equivalent (Symmetrical) Spacing 35
2.11.2 Unsymmetrical Spacing (Untransposed) 37
2.11.3 Transposition of Overhead Lines 39
2.11.4 Unsymmetrical Spacing (Transposed) 40
2.12 INDUCTANCE OF THREE-PHASE DOUBLE CIRCUIT LINE 44
2.12.1 Inductance of Three-phase Double-Circuit Line with Symmetrical
Spacing (Hexagonal) 45
2.12.2 Inductance of a Three-phase Transposed Double-Circuit Line with
Unsymmetrical Spacing 46
2.13 CAPACITANCE 51
2.14 POTENTIAL DIFFERENCE BETWEEN TWO POINTS DUE TO A CHARGE 52
2.15 CAPACITANCE OF A SINGLE-PHASE LINE (TWO-WIRE LINE) 52
2.16 POTENTIAL DIFFERENCE BETWEEN TWO CONDUCTORS OF A GROUP
OF CHARGED CONDUCTORS 55
2.17 CAPACITANCE OF THREE-PHASE LINES 55
2.17.1 Equilateral Spacing 56
2.17.2 Capacitance of an Unsymmetrical Three-phase System (Transposed) 58
2.18 CAPACITANCE OF A THREE-PHASE DOUBLE-CIRCUIT LINE 62
2.18.1 Hexagonal Spacing 63
2.18.2 Flat Vertical Spacing (Unsymmetrical Spacing) 64
2.19 EFFECT OF EARTH ON TRANSMISSION LINE CAPACITANCE 68
2.19.1 Capacitance of a Single Conductor 68
2.19.2 Capacitance of a Single-phase Transmission Line 69
2.19.3 Capacitance of Three-phase Line 71
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CONTENTS ix
3 PERFORMANCE OF SHORT AND MEDIUM
TRANSMISSION LINES 87
3.1 INTRODUCTION 87
3.2 REPRESENTATION OF LINES 88
3.3 CLASSIFICATION OF TRANSMISSION LINES 89
3.4 SHORT TRANSMISSION LINE 89
3.4.1 Effect of Power Factor on Regulation and Efficiency 96
3.5 GENERALISED NETWORK CONSTANTS 98
3.6 A, B, C, DCONSTANTS FOR SHORT TRANSMISSION LINES 100
3.7 MEDIUM TRANSMISSION LINE 100
3.7.1 Load End Capacitance Method 101
3.7.2 Nominal-T Method 104
3.7.3 Nominal-πMethod 108
4 PERFORMANCE OF LONG TRANSMISSION LINES 127
4.1 INTRODUCTION 127
4.2 RIGOROUS SOLUTION 128
4.3 INTERPRETATION OF THE LONG LINE EQUATIONS 131
4.3.1 Propagation Constant 132
4.3.2 Wave Length and Velocity of Propagation 132
4.4 EVALUATION OF TRANSMISSION LINE CONSTANTS 133
4.5 REGULATION 135
4.6 EQUIVALENT CIRCUIT REPRESENTATION OF LONG LINES 139
4.6.1 Representation of a Long Line by Equivalent- πModel 139
4.6.2 Representation of a Long Line by Equivalent-T Model 141
4.7 TUNED TRANSMISSION LINES 150
4.8 CHARACTERISTIC IMPEDANCE 150
4.9 SURGE IMPEDANCE LOADING (SIL) 151
4.10 FERRANTI EFFECT 152
4.11 CONSTANT VOLTAGE TRANSMISSION 154
4.12 CHARGING CURRENT IN LINES 154
4.12.1 Power Loss Due to Charging Current (or Open-Circuited Line) 155
4.13 LINE LOADABILITY 156
4.14 POWER FLOW THROUGH A TRANSMISSION LINE 156
4.15 CIRCLE DIAGRAM 161
4.15.1 Receiving-end Phasor Diagram 161
4.15.2 Receiving-end Power Circle Diagram 162