Design, Modeling and Evaluation of Protective Relays for Power Systems (eBook)

Dr. Mladen Kezunovic is Eugene E. Webb Professor of Electrical and Computer Engineering at Texas A&M University, as well as Director of their Smart Grid Center. He is also Site Director of the National Science Foundation's Power System Engineering Research Center. Dr. Jinfeng Ren is currently Power System Engineer at Alstom Grid in Pullman, Washington. He has authored numerous articles in scholarly journals focusing on Power System Frequency Estimation and Synchrophasors. Dr. Saeed Lotfifard is currently Assistant Professor in the School of Electrical Engineering and Computer Science at Washington State University. His research interests include Power Systems Protection and Control, Cyber-physical Energy Systems, Smart Grid Modeling, Distribution Automation and Signal Processing in Power Systems.

Preface 5
Acknowledgments 6
Contents 7
List of Figures 11
List of Tables 19
Chapter 1: Introduction 20
1.1 Scope 20
1.2 Basics of Protection Relaying 21
1.3 Modeling and Simulation Methodology and Tools 22
1.3.1 Relay Elements Library 22
1.3.2 Signal Source Library and Analysis Tools 22
1.3.3 Relay Models and Power Network Elements Library 23
References 27
Chapter 2: Power System Fault Analysis and Short-Circuit Computations 28
2.1 Introduction 28
2.2 Symmetrical Components 29
2.2.1 Module 1: Analysis of a System with an Unbalanced Source Using Symmetrical Components 32
2.2.2 Module 2: Analysis of a System with Single Line-Ground Fault Using Symmetrical Components 36
2.2.2.1 Fault Connections Represented Using Symmetrical Components 37
2.2.2.2 Positive Sequence Network 38
2.2.2.3 Negative Sequence Network 40
2.2.2.4 Zero Sequence Network 40
2.2.2.5 Connected Sequence Networks 41
2.3 Short-Circuit Analysis 41
2.4 Sequence Networks 45
2.4.1 Transmission Line 45
2.4.1.1 Transposed and Rotated Lines 45
2.4.1.2 Parallel Lines 48
2.4.1.3 Symmetrical Line with Tap Loads 53
2.4.2 Load Model 54
2.4.3 Two-Winding Transformer 55
2.4.4 Synchronous Machine 56
2.4.5 Positive Sequence Network Model 56
2.4.6 Negative Sequence Network 58
2.4.7 Sequence Networks in Steady State 58
2.4.8 Induction Motor 59
2.5 Matrix Method for Short-Circuit Calculation 61
2.5.1 Matrix Computation Approach 61
2.5.2 Admittance and Impedance Approaches 63
2.6 Summary 63
Reference 63
Chapter 3: Basics of Protective Relaying and Design Principles 64
3.1 Introduction 64
3.2 Overcurrent Relaying 65
3.2.1 Introduction 65
3.2.2 Relaying Basics 65
3.2.2.1 Analysis of Load and Fault Conditions 68
3.2.2.2 Selecting the CTs and CBs 68
3.2.2.3 Selecting and Setting the Relays 69
Pick-up Current 69
Time Delay 69
3.2.2.4 Sensitivity Check 70
3.2.3 Software Models 70
3.2.3.1 Model Activation 73
3.2.3.2 Numerical Example 74
Load Flow Calculations 74
Selecting the CTs 75
Short-Circuit Calculations 75
Setting the Relays 75
Sensitivity Check 76
Prediction of the Average Clearing Times 76
3.3 Impedance Relaying 76
3.3.1 Introduction 76
3.3.2 Relaying Basics 77
3.3.2.1 Analysis of the Load and Fault Conditions 81
3.3.2.2 Selecting the CTs and VTs 81
3.3.2.3 Selecting the CBs 81
3.3.2.4 Selecting and Setting the Relays 81
First Zone Reach 82
First Zone Time Delay 82
Second Zone Reach 82
Second Zone Time Delay 82
3.3.3 Software Models 83
3.3.3.1 Model Activation 85
3.3.3.2 Numerical Examples 85
Load Flow Calculations 85
Selecting the CTs and VTs 85
Short-Circuit Calculations 85
Setting the Relays 86
3.4 Differential Relaying 87
3.4.1 Introduction 87
3.4.2 Relaying Basics 87
3.4.2.1 Analysis of the Load and Fault Conditions 89
3.4.2.2 Selecting the CTs and CBs 90
3.4.2.3 Selecting and Setting the Relays 90
Matching Ratio 90
Pick-Up Current 91
Bias 91
3.4.2.4 Software Models 91
3.4.2.5 Model Activation 93
3.4.2.6 Simulation Examples 94
Load Flow Calculations 94
Selecting the CTs 94
Short-Circuit Calculations 94
Setting the Relays 94
3.5 Summary 94
References 95
Chapter 4: Modeling of Digital Relay and Power System Signals 96
4.1 Introduction 96
4.2 Major Elements of a Digital Relay 96
4.2.1 Data Acquisition Block 97
4.2.1.1 Sampling 98
4.2.1.2 Sampling Frequency 98
4.2.1.3 Aliasing 99
4.2.1.4 Analog Filter 100
4.2.1.5 Word Length of an A/D Converter 100
4.2.1.6 Conclusions 101
4.2.2 Phasor Estimation 102
4.2.2.1 Definition 102
4.2.2.2 Application 102
4.2.2.3 Requirements 102
4.2.2.4 Orthogonal Components 103
Sample Orthogonal Filters 104
Data Window 104
Fourier Algorithm 105
Frequency Response 105
4.2.2.5 Conclusions 105
4.3 Library of Modeling Elements 106
4.3.1 Bias Characteristic 106
4.3.1.1 Purpose 106
4.3.1.2 Input 106
4.3.1.3 Dialog Box 107
4.3.1.4 Description 107
4.3.1.5 Parameters 108
4.3.1.6 Recommended Solver 108
4.3.1.7 Example 108
4.3.2 Basic Measurements 110
4.3.2.1 Purpose 110
4.3.2.2 Dialog Box 110
4.3.2.3 Description 110
Basic Processing 111
Post-processing Filter 111
Mean Filter 111
Median Filter 111
4.3.2.4 Parameters 112
4.3.2.5 Recommended Solver 112
4.3.2.6 Example 112
4.3.3 Data Acquisition Board 113
4.3.3.1 Purpose 113
4.3.3.2 Inputs 113
4.3.3.3 Outputs 113
4.3.3.4 Dialog Box 113
4.3.3.5 Description 114
Analog Filter 114
Signal Conditioner 115
A/D Converter 115
Buffer 116
4.3.3.6 Parameters 116
4.3.3.7 Recommended Solver 117
4.3.3.8 Example 117
4.3.4 Directional Element 118
4.3.4.1 Purpose 118
4.3.4.2 Inputs 118
4.3.4.3 Outputs 118
4.3.4.4 Dialog Box 119
4.3.4.5 Description 119
4.3.4.6 Parameters 119
4.3.4.7 Recommended Solver 120
4.3.4.8 Example 120
4.3.5 Differential Equation-Based Impedance Measurement 121
4.3.5.1 Purpose 121
4.3.5.2 Inputs 121
4.3.5.3 Outputs 121
4.3.5.4 Description 121
Pre-processing 122
Fourier Filter 123
Walsh Filter 123
Solution Methods Combined with Numerical Integration/Differentiation Methods 123
Numerical Integration/Differentiation Methods 123
Two Points in Time Dislocated by m Samples Method 124
Least Square Method Over a Data Window of d Samples 124
Post-Processing Methods 125
4.3.5.5 Parameters 125
4.3.5.6 Recommended Solver 126
4.3.5.7 Example 126
4.3.6 Digital Filter 126
4.3.6.1 Purpose 126
4.3.6.2 Inputs 126
4.3.6.3 Outputs 126
4.3.6.4 Dialog Box 128
4.3.6.5 Description 128
Sine Data Window Band-Pass Filters 128
First-Order Walsh Filters 129
Second-Order Walsh Filters 130
Third-Order Walsh Filters 130
Fourth-Order Walsh Filters 130
4.3.6.6 Parameters 131
4.3.6.7 Recommended Solver 131
4.3.6.8 Example 131
4.3.7 Digital Fourier Transform 131
4.3.7.1 Purpose 131
4.3.7.2 Input 133
4.3.7.3 Output 133
4.3.7.4 Dialog Box 133
4.3.7.5 Description 133
4.3.7.6 Parameters 134
4.3.7.7 Recommended Solver 135
4.3.7.8 Example 135
4.3.8 Orthogonal Components 135
4.3.8.1 Purpose 135
4.3.8.2 Inputs 136
4.3.8.3 Outputs 136
4.3.8.4 Dialog Box 136
4.3.8.5 Description 136
Fourier-Based Orthogonal Components Filter 137
Walsh-Based Orthogonal Components Filter 138
4.3.8.6 Parameters 140
4.3.8.7 Recommended Solver 140
4.3.8.8 Example 140
4.3.9 Symmetrical Components 141
4.3.9.1 Purpose 141
4.3.9.2 Inputs 142
4.3.9.3 Outputs 142
4.3.9.4 Dialog Box 142
4.3.9.5 Description 142
4.3.9.6 Parameters 144
4.3.9.7 Recommended Solver 144
4.3.9.8 Example 144
4.3.10 Triggering Element 144
4.3.10.1 Purpose 144
4.3.10.2 Input 146
4.3.10.3 Output 146
4.3.10.4 Dialog Box 146
4.3.10.5 Description 147
Value 147
Sample to Sample 147
Cycle to Cycle 147
Activating and Deactivating Counters 147
4.3.10.6 Parameters 147
4.3.10.7 Recommended Solver 148
4.3.10.8 Example 148
4.3.11 Universal Comparator 148
4.3.11.1 Purpose 148
4.3.11.2 Inputs 149
4.3.11.3 Output 150
4.3.11.4 Dialog Box 150
4.3.11.5 Description 150
Signal-to-Threshold Comparison 151
Signal-to-Signal Comparison 151
Signal-to-Time Comparison 151
I-t Emulation Method 152
4.3.11.6 Parameters 155
4.3.11.7 Recommended Solver 155
4.3.11.8 Examples 155
4.3.12 Phase Selection 158
4.3.12.1 Purpose 158
4.3.12.2 Inputs 158
4.3.12.3 Outputs 158
4.3.12.4 Dialog Box 158
4.3.12.5 Description 158
4.3.12.6 Parameters 160
4.3.12.7 Recommended Solver 160
4.3.12.8 Example 160
4.3.13 Vector Group Compensator for 2-Winding Transformers 160
4.3.13.1 Purpose 160
4.3.13.2 Inputs 162
4.3.13.3 Outputs 162
4.3.13.4 Dialog Box 162
4.3.13.5 Description 163
4.3.13.6 Parameters 164
4.3.13.7 Recommended Solver 164
4.3.13.8 Example 164
4.3.14 Zone Comparator 166
4.3.14.1 Purpose 166
4.3.14.2 Inputs 166
4.3.14.3 Outputs 166
4.3.14.4 Dialog Box 166
4.3.14.5 Description 167
4.3.14.6 Parameters 168
4.3.14.7 Recommended Solver 168
4.3.14.8 Example 168
4.4 Interfacing Power System and Relay Models 169
4.4.1 Analytical Generator 169
4.4.1.1 Purpose 169
4.4.1.2 Output 169
4.4.1.3 Dialog Box 169
4.4.1.4 Description 170
4.4.1.5 Parameters 170
4.4.1.6 Recommended Solver 170
4.4.1.7 Example 170
4.4.2 Fault Signal Generator 171
4.4.2.1 Purpose 171
4.4.2.2 Outputs 171
4.4.2.3 Dialog Box 172
Description 172
4.4.2.4 Parameters 173
4.4.2.5 Recommended Solver 173
4.4.3 Example 174
4.4.4 Phasor Generator 175
4.4.4.1 Purpose 175
4.4.4.2 Outputs 175
4.4.4.3 Dialog Box 175
4.4.4.4 Description 175
4.4.4.5 Parameters 176
4.4.4.6 Recommended Solver 176
4.4.4.7 Example 177
4.4.5 Spectrum Generator 177
4.4.5.1 Purpose 177
4.4.5.2 Outputs 177
4.4.5.3 Dialog Box 177
4.4.5.4 Description 179
4.4.5.5 Parameters 179
4.4.5.6 Recommended Solver 179
4.4.5.7 Example 180
4.4.6 Three-Phase Phasor Generator 180
4.4.6.1 Purpose 180
4.4.6.2 Outputs 181
4.4.6.3 Dialog Box 181
4.4.6.4 Description 181
4.4.7 Parameters 183
4.4.7.1 Recommended Solver 183
4.4.7.2 Example 183
4.5 GUI and Analysis Tools 185
4.5.1 Phasor Display 185
4.5.1.1 Purpose 185
4.5.1.2 Inputs 185
4.5.1.3 Output 185
4.5.1.4 Dialog Box 185
4.5.1.5 Description 186
4.5.1.6 Parameters 187
4.5.1.7 Recommended Solver 187
4.5.1.8 Example 187
4.6 Summary 188
Chapter 5: Design and Implementation of Relay Communication Schemes and Trip Logic 189
5.1 Introduction 189
5.2 Communication Schemes 189
5.2.1 Introduction 189
5.2.2 Working with Software 189
5.2.2.1 Transmission Line Model 190
5.2.2.2 Measuring System 191
Measuring System for PUTT Logic (Figs.5.4 and 5.5) 193
Measuring System for PUTT+OZ Logic (Figs.5.6 and 5.7) 193
Measuring System for BLOV+TB Logic (Figs.5.8 and 5.9) 194
Measuring System for BLOV+UZ+TB Logic (Figs.5.10 and 5.11) 194
Measuring System for BLUN Logic (Figs.5.12 and 5.13) 195
Measuring System for POTT+WEI+TB Logic (Figs.5.14 and 5.15) 197
5.2.2.3 Trip Logic 198
PUTT Logic 198
PUTT+OZ Logic 201
BLOV+TB Logic 201
BLOV+UZ+TB Logic 202
BLUN Logic 202
POTT+WEI+TB Logic 203
5.2.2.4 Communication Channel 204
5.3 Summary 206
Chapter 6: Design and Implementation of Overcurrent, Pilot, and Distance Protection 207
6.1 Introduction 207
6.2 Line Protection System: Overcurrent Relaying 207
6.2.1 Introduction 207
6.2.2 Theoretical Background 208
6.2.2.1 Importance of Transmission Lines 208
6.2.2.2 Backup Protection 208
6.2.2.3 Directional Overcurrent Relays 209
6.2.2.4 Principle of Operation 209
6.2.2.5 Phase-Fault Directional Sensing 210
6.2.2.6 The 90-60 Connection 211
6.2.2.7 Time Overcurrent Relays 212
6.2.2.8 Residual Time Overcurrent Relay 214
6.2.3 Simulation Models 214
6.2.3.1 Description of the System 214
6.2.3.2 Three-Phase Voltage Source 215
6.2.3.3 Current Transformer Block 215
6.2.3.4 Voltage Transformer Block 216
6.2.3.5 Breakers 216
6.2.3.6 Line Model 217
6.2.3.7 Faults 219
6.2.3.8 Signal Processing 221
6.2.3.9 Description of Protection Schemes 223
6.2.3.10 Implementation of Directional Overcurrent Relay 224
6.2.3.11 Implementation of Time Overcurrent Relay 225
6.2.3.12 Implementation of Residual Overcurrent Relay 225
6.2.4 Minimizing the False Trip in the Directional Relay 226
6.3 Line Protection System: Differential Relaying 229
6.3.1 Introduction 229
6.3.2 Theoretical Background 229
6.3.2.1 Power System Model 229
6.3.2.2 Differential Protection Scheme 230
6.3.2.3 Distance Protection Scheme 232
6.3.3 Simulation Models 234
6.3.3.1 Differential Relay 234
6.3.3.2 Current Differential Protection 235
6.3.3.3 Distance Protection 236
6.4 Line Protection System: Zone Protection 236
6.4.1 Introduction 236
6.4.2 Simulation Models 239
6.4.2.1 Relay Design 239
6.4.2.2 Measurement Block 239
6.4.2.3 Relay Logic 240
6.4.2.4 Six-Element Five-Zone Distance Relay 241
6.4.2.5 Five-Zone Distance Block 241
6.4.2.6 Directional Element 243
6.4.2.7 Power Swing Block 245
6.4.2.8 Directional Overcurrent Blocks 247
6.5 Line Protection System: Pilot Protection 247
6.5.1 Introduction 247
6.5.2 Relay Design 248
6.5.2.1 Scheme Structure 250
6.5.2.2 Preprocessing and Data Acquisition Block 250
6.5.2.3 Voltage and Current Combination Block 251
6.5.2.4 Impedance Measurement and Zone Comparison Blocks 251
6.5.2.5 Logic Matrix Block 254
6.5.2.6 Undervoltage Element 254
6.5.2.7 Pilot Logic 255
PUTT 255
BLOVTB 256
6.6 Summary 256
Reference 257
Chapter 7: Design and Implementation of Transformer and Busbar Differential Protection 258
7.1 Introduction 258
7.2 Transformer Protection Systems 258
7.2.1 Introduction 258
7.2.2 Theoretical Background 259
7.2.3 Simulation Models 260
7.2.3.1 Overall Design 260
7.2.3.2 Measurements 260
7.2.3.3 Signal Processing 262
7.2.3.4 Differential Relay 263
7.2.3.5 Restricted Earth Protection for the Wye-Connected Winding 263
7.2.3.6 Three-Phase Inverse-Time Overcurrent Relay 266
7.2.3.7 Six-Element Three-Zone Impedance Relay 269
7.3 Busbar Protection Systems 272
7.3.1 Introduction 272
7.3.2 Theoretical Background 272
7.3.2.1 Typical Bus Arrangements 272
7.3.2.2 Busbar Protection 273
7.3.2.3 Time-Overcurrent Differential 273
7.3.2.4 High-Impedance Voltage Differential 273
7.3.2.5 Air-Core Transformers Differential 274
7.3.2.6 Low-Impedance Differential 274
7.3.2.7 Directional Comparison Differential 274
7.3.2.8 Partial Differential 275
7.3.2.9 Zero-Sequence Current/Voltage 275
7.3.3 Simulation Models 275
7.3.3.1 Overall Relay Design 275
7.3.3.2 Data Acquisition System 276
7.3.3.3 Differential Relay Measuring/Tripping Logic (with Harmonic Restraint) 277
7.4 Summary 278
Chapter 8: Testing of Digital Protective Relays 279
8.1 Introduction 279
8.2 Modeling and Testing Digital Relays 280
8.2.1 Modeling and Testing Overcurrent Relay 280
8.2.1.1 Overcurrent Relay Model 281
8.2.1.2 Transmission Line Model 282
8.2.1.3 Generator Model 283
8.2.1.4 CT and VT Model 284
8.2.1.5 Breaker Model 284
8.2.1.6 Load Model 286
8.2.1.7 Voltage and Current Scopes (Measurement Elements) 286
8.2.1.8 Trip and Logic Scopes (Measurement Elements) 287
8.2.1.9 Fault Type Display 287
8.2.1.10 Default System Data 288
8.2.1.11 Model Activation 291
8.2.2 Modeling and Testing Impedance Relay 291
8.2.2.1 Impedance Relay Model 294
8.2.2.2 Fault Zone Display 294
8.2.2.3 Default System Data 295
8.2.2.4 Model Activation 297
8.3 Test Using Digital Simulator 297
8.3.1 Digital Simulator-Based Relay Test System 298
8.3.1.1 Test System Overview 298
8.3.1.2 Digital Simulator 299
8.3.1.3 Protective Relays 300
8.3.1.4 Default System Data 301
8.3.1.5 Relay Assistant Software 301
8.3.2 System Modeling and Simulation Programs 306
8.3.2.1 Overcurrent Relay 306
8.3.2.2 To File Block 306
8.3.2.3 Default System Data 306
8.3.2.4 Model Activation 308
8.3.2.5 Impedance Relay 309
8.3.2.6 To File Block 309
8.3.2.7 Default System Data 309
8.3.2.8 Model Activation 311
8.4 Closed-Loop and Open-Loop Analysis 312
8.4.1 General Procedures for Performing Tests 312
8.5 Summary 313
Reference 313