Fault Location on Transmission and Distribution Lines

Swagata Das, PhD, is an Application Engineer (Protection) at Schweitzer Engineering Laboratories, Texas, USA. She is an IEEE Senior Member and has published in peer-reviewed journals and presented her research on fault location and fault data analysis in transmission and distribution networks to industry professionals at several IEEE Power and Energy Society conferences.Surya Santoso, PhD, is a Professor in Electrical Engineering at The University of Texas at Austin, USA. His research interests include power systems fault analytics and protection, power systems modeling and simulation, and power quality. He is an IEEE Fellow and a Distinguished Lecturer for the IEEE Power and Energy Society. Sundaravaradan N. Ananthan, PhD, is a Project Engineer (Protection) at Schweitzer Engineering Laboratories, Texas, USA. He has a background in power system protection and fault location in transmission and distribution networks and has published his research in many international journals and conferences.

• Preface ixAbout the Companion Website xi1 Introduction 11.1 Power System Faults 11.2 What Causes Shunt Faults? 41.3 Aim and Importance of Fault Location 161.4 Types of Fault-Locating Algorithms 191.5 How are Fault-Locating Algorithms Implemented? 211.6 Evaluation of Fault-Locating Algorithms 251.7 The Best Fault-Locating Algorithm 261.8 Summary 262 Symmetrical Components 272.1 Phasors 282.2 Theory of Symmetrical Components 292.3 Interconnecting Sequence Networks 312.4 Sequence Impedances of Three-Phase Lines 362.5 Exercise Problems 412.6 Summary 463 Fault Location on Transmission Lines 493.1 One-Ended Impedance-Based Fault Location Algorithms 493.1.1 Simple Reactance Method 523.1.2 Takagi Method 543.1.3 Modified Takagi Method 563.1.4 Current Distribution Factor Method 573.2 Two-Ended Impedance-Based Fault Location Algorithms 583.2.1 Synchronized Method 593.2.2 Unsynchronized Method 603.2.3 Unsynchronized Negative-Sequence Method 613.2.4 Synchronized Line Current Differential Method 623.3 Three-Ended Impedance-Based Fault Location Algorithms 623.3.1 Synchronized Method 633.3.2 Unsynchronized Method 653.3.3 Unsynchronized Negative-Sequence Method 663.3.4 Synchronized Line Current Differential Method 673.4 Traveling-Wave Fault Location Algorithms 683.4.1 Single-Ended TravelingWave Method 693.4.2 Double-Ended Traveling-Wave Method 713.4.3 Error Sources 713.5 Exercise Problems 773.6 Summary 934 Error Sources in Impedance-Based Fault Location 954.1 Power System Model 954.2 Input Data Errors 964.2.1 DC Offset 974.2.2 CT Saturation 994.2.3 Aging CCVTs 1014.2.4 Open-Delta VTs 1014.2.5 Inaccurate Line Length 1044.2.6 Untransposed Lines 1044.2.7 Variation in Earth Resistivity 1064.2.8 Non-Homogeneous Lines 1074.2.9 Incorrect Fault Type Selection 1094.3 Application Errors 1094.3.1 Load 1094.3.2 Non-Homogeneous System 1114.3.3 Zero-Sequence Mutual Coupling 1114.3.4 Series Compensation 1184.3.5 Three-Terminal Lines 1194.3.6 Radial Tap 1204.3.7 Evolving Faults 1214.4 Exercise Problems 1224.5 Summary 1265 Fault Location on Overhead Distribution Feeders 1295.1 Impedance-Based Methods 1345.1.1 Loop Reactance Method 1355.1.2 Simple Reactance Method 1405.1.3 Takagi Method 1405.1.4 Modified Takagi Method 1415.1.5 Girgis et al. Method 1415.1.6 Santoso et al. Method 1435.1.7 Novosel et al. Method 1445.2 Challenges with Distribution Fault Location 1465.2.1 Load 1465.2.2 Non-Homogeneous Lines 1465.2.3 Inaccurate Earth Resistivity 1495.2.4 Multiple Laterals 1505.2.5 Best Data for Fault Location: Feeder or Substation Relays 1515.2.6 Distributed Generation 1525.2.7 High Impedance Faults 1565.2.8 CT Saturation 1565.2.9 Grounding 1565.2.10 Short Duration Faults 1575.2.11 Missing Voltage 1575.3 Exercise Problems 1585.4 Summary 1776 Distribution Fault Location With Current Only 1796.1 Current Phasors Only Method 1796.2 Current Magnitude Only Method 1846.3 Short-Circuit Fault Current Profile Method 1916.4 Exercise Problems 1936.5 Summary 2087 System and Operational Benefits of Fault Location 2097.1 Verify Relay Operation 2107.2 Discover Erroneous Relay Settings 2117.3 Detect Instrument Transformer Installation Errors 2177.4 Validate Zero-Sequence Line Impedance 2227.5 Calculate Fault Resistance 2257.6 Prove Short-Circuit Model 2267.7 Adapt Autoreclosing in Hybrid Lines 2277.8 Detect the Occurrence of Multiple Faults 2287.9 Identify Impending Failures and Take Corrective Action 2327.10 Exercise Problems 2327.11 Summary 239A Fault Location Suite in MATLAB 241A.1 Understanding the Fault Location Script 241References 261Index 269