C0NTR0L and AUTOMATION of ELECTRICAL POWER DISTRIBUTION SYSTEMS

James Northcote-Green ABB Power Technologies AB Vasteras, Sweden

Robert Wilson Abasis Consulting Limited Whitchurch, Shropshire, UK

@ Taylor &. Francis Taylor & Francis G r o u p

Boca Raton London New York

CRC is an imprint of the Taylor & Francis Group, an informa business

Contents

Chapter 1 Power Delivery System Control and Automation 1

1.1 Introduction 1 1.2 Why Distribution Automation? 1

1.2.1 Incremental Implementation 4 1.2.2 Acceptance of DA by the Utility Industry 5

1.3 Power Delivery Systems 7 1.4 Control Hierarchy 9 1.5 What Is Distribution Automation? 11

1.5.1 DAConcept 11 1.6 Distribution Automation System 13 1.7 Basic Architectures and Implementation Strategies for DA 17

1.7.1 Architecture 17 1.7.2 Creating the DA Solution 19 1.7.3 Distribution Network Structure 21

1.8 Definitions of Automated Device Preparedness 22 1.9 Summary 23 References 25

Chapter 2 Central Control and Management 27

2.1 Introduction 27 2.1.1 Why Power System Control? 27

2.2 Power System Operation 28 2.3 Operations Environment of Distribution Networks 29 2.4 Evolution of Distribution Management Systems 31 2.5 Basic Distribution Management System Functions 35 2.6 Basis of a Real-Time Control System (SCADA) 39

2.6.1 Data Acquisition 39 2.6.2 Monitoring and Event Processing 41 2.6.3 Control Functions 44 2.6.4 Data Storage, Archiving, and Analysis 44 2.6.5 Hardware System Configurations 45 2.6.6 SCADA System Principles 47 2.6.7 Polling Principles 48

2.7 Outage Management 50 2.7.1 Trouble Call-Based Outage Management 52 2.7.2 Advanced Application-Based Outage Management 57 2.7.3 GIS-Centric versus SCADA-Centric 60

2.8 Decision Support Applications 60 2.8.1 Operator Load Flow 61 2.8.2 Fault Calculation 63 2.8.3 Loss Minimization 66 2.8.4 VARControl 66 2.8.5 VoltControl 67 2.8.6 Data Dependency 68

2.9 Subsystems 69 2.9.1 Substation Automation 69 2.9.2 Substation Local Automation 72

2.10 Extended Control Feeder Automation 77 2.11 Performance Measures and Response Times 79

2.11.1 Scenario Defmitions 79 2.11.2 Calculation of DA Response Times 81 2.11.3 Response Times 85

2.12 Database Structures and Interfaces 86 2.12.1 Network Data Model Representations 86 2.12.2 SCADA Data Models 87 2.12.3 DMS Data Needs, Sources, and Interfaces 89 2.12.4 Data Model Standards (CIM) 93 2.12.5 Data Interface Standards 100

2.13 Summary 100 Appendix 2A — Sample Comprehensive CIM Structure 103 References 104

Chapter 3 Design, Construction, and Operation of Distribution Systems, MV Networks 105

3.1 Introduction 105 3.2 Design of Networks 107

3.2.1 Selection of Voltage 109 3.2.2 Overhead or Underground 110 3.2.3 Sizing of Distribution Substations 110 3.2.4 Connecting the MV (The Upstream Structure) 114 3.2.5 The Required Performance of the Network 116 3.2.6 The Network Complexity Factor 117 3.2.7 Voltage Control 121 3.2.8 Current Loading 128 3.2.9 LoadGrowth 129 3.2.10 Earthing (Grounding) 131 3.2.11 Lost Energy ....132 3.2.12 Comparison of U.K. and U.S. Networks 137 3.2.13 The Cost of Installation of the Selected Design 140 3.2.14 The Cost of Owning the Network after Construction 141

3.3 LV Distribution Networks 142 3.3.1 Underground LV Distribution Networks 142 3.3.2 Overhead LV Distribution Networks 143

3.4 Switchgear for Distribution Substations and LV Networks 145 3.5 Extended Control of Distribution Substations and LV Networks 146 3.6 Summary 148 References 148

Chapter 4 Hardware for Distribution Systems 149

4.1 Introduction to Switchgear 149 4.1.1 Are Interruption Methods 150

4.2 Primary Switchgear 154 4.2.1 Substation Circuit Breakers 154 4.2.2 Substation Disconnectors 158

4.3 Ground-Mounted Network Substations 158 4.3.1 Ring Main Unit 160 4.3.2 Pad-Mount Switchgear 163

4.4 Larger Distribution/Compact Substations 164 4.5 Pole-Mounted Enclosed Switches 167 4.6 Pole-Mounted Reclosers 168

4.6.1 Single-Tank Design 169 4.6.2 Individual Pole Design 169

4.7 Pole-Mounted Switch Disconnectors and Disconnectors 170 4.8 Operating Mechanisms and Actuators 171

4.8.1 Motorized Actuators 172 4.8.2 Magnetic Actuators 173

4.9 Current and Voltage Measuring Devices 175 4.9.1 Electromagnetic Current Transformers 177 4.9.2 Voltage Transformers 180

4.10 Instrument Transformers in Extended Control 181 4.11 Current and Voltage Sensors 182

4.11.1 Current Sensor 182 4.11.2 Voltage Sensor 183 4.11.3 Combi Sensor and Sensor Packaging 184

Reference 185

Chapter 5 Protection and Control 187

5.1 Introduction 187 5.2 Protection Using Relays 187

5.2.1 Discrimination by Time 188 5.2.2 Discrimination by Current 189 5.2.3 Discrimination by Both Time and Current 189

5.3 Sensitive Earth Fault and Instantaneous Protection Schemes 190 5.4 Protection Using Fuses 192 5.5 Earth Fault and Overcurrent Protection for Solid/Resistance

Earthed Networks 197 5.6 Earth Faults on Compensated Networks 198 5.7 Earth Faults on Unearthed Networks 203 5.8 An Earth Fault Relay for Compensated and Unearthed

Networks 204 5.9 Fault Passage Indication 207

5.9.1 The Need for FPI on Distribution Networks with Manual Control 207

5.9.2 What Is the Fault Passage Indicator, Then? 209 5.9.3 The Need for FPI on Distribution Networks with

Extended Control or Automation 211 5.9.4 Fault Passage Indicators for Use on Closed Loop

Networks 212 5.9.5 Other Applications of Directional Indicators 213

5.10 Connection of the FPI to the Distribution System Conductor 214 5.10.1 Connection Using Current Transformers 214 5.10.2 Connections Using CTs on Underground Systems 215 5.10.3 Connections Using CTs on Overhead Systems 216 5.10.4 Connection without CTs on Overhead Systems

(Proximity) 216 5.11 Distribution System Earthing and Fault Passage Indication 218

5.11.1 Detection of Steady-State Fault Conditions 220 5.11.2 Detection of Transient Fault Conditions 221 5.11.3 Indication of Sensitive Earth Faults 222

5.12 AutoReclosing and Fault Passage Indicators 222 5.13 The Choice of Indication between Phase Fault and Earth Fault 223 5.14 Resetting the Fault Passage Indicator 224 5.15 Grading of Fault Passage Indicators 224 5.16 Selecting a Fault Passage Indicator 225 5.17 Intelligent Electronic Devices 225

5.17.1 Remote Terminal Unit 226 5.17.2 Protection-Based IED 229

5.18 Power Supplies for Extended Control 229 5.19 Automation Ready Switchgear — FA Building Blocks 234

5.19.1 Switch Options 237 5.19.2 Drive (Actuator) Options 237 5.19.3 RTU Options 237 5.19.4 CT/VT Options 237 5.19.5 Communications Options 238 5.19.6 FPI Options 238 5.19.7 Battery Options 238 SAQ& \Ba^NÄ%mMk \̂Ä<ää&%^VoKJE& .12&

5.20 Examples of Building Blocks 239 5.21 Typical Inputs and Outputs for Building Blocks 241

5.21.1 Sectionalizing Switch (No Measurements) 241 5.21.2 Sectionalizing Switch (with Measurements) 242 5.21.3 Protection-Based Recloser for Overhead Systems 243

5.22 Control Building Blocks and Retrofit 244 5.23 Control Logic 244

5.23.1 Option 1, Circuit A with 1.5 Switch Automation, FPI and Remote Control of Switches 245

5.23.2 Option 2, Circuit B with 2.5 Switch Automation, FPI and Remote Control of Switches 246

5.23.3 Options 3 and 4, No Fault Passage Indicators 247 5.23.4 Options 5 and 7, Local Control Only 248 5.23.5 Options 6 and 8, Local Control Only 249 5.23.6 Special Case of Multishot Reclosing and Automatic

Sectionalizing 249

Chapter 6 Performance of Distribution Systems 251

6.1 Faults on Distribution Networks 251 6.1.1 Types of Faults 251 6.1.2 The Effects of Faults 254 6.1.3 Transient Faults, Reclosers, and Compensated Networks 254

6.2 Performance and Basic Reliability Calculations 259 6.2.1 System Indices 259 6.2.2 Calculating the Reliability Performance of Networks 260 6.2.3 Calculation of Sustained Interruptions (SAIDI) 261 6.2.4 Calculation of Sustained Interruption Frequency (SAIFI) 263 6.2.5 Calculation of Momentary Interruption Frequency

(MAIFI) 264 6.2.6 Summary of Calculated Results 264 6.2.7 Calculating the Effects of Extended Control 266 6.2.8 Performance as a Function of Network Complexity

Factor 267 6.2.9 Improving Performance without Automation 268

6.3 Improving the Reliability of Underground Networks 272 6.3.1 Design Method 1 — Addition of Manually Operated

Sectionalizing Switches 272 6.3.2 Design Method 2 — Addition of Manually Switched

Alternative Supply 273 6.3.3 Design Method 3 — Add Automatic in Line Protection 274 6.3.4 Design Method 4 — Add Continuous Alternative Supply 275

6.4 Improving the Reliability of Overhead Networks (Design Methods 5, 6, and 7) 278

6.5 Improving Performance with Automation 281

6.6 Improvements by Combining Design Methods 1, 2, 3, 4, and 8 on Underground Circuits 282

References 287

Chapter 7 Communication Systems for Control and Automation 289

7.1 Introduction 289 7.2 Communications and Distribution Automation 289 7.3 DA Communication Physical Link Options 292 7.4 Wireless Communication 293

7.4.1 Unlicensed Spread Spectrum Radio 293 7.4.2 VHF, UHF Narrow Bandwidth Packaged Data Radio

(Licensed/Unlicensed) 293 7.4.3 Radio Network Theory '. 293 7.4.5 Trunked Systems (Public Packet-Switched Radio) 302 7.4.6 Cellular 303 7.4.7 Paging Technology 303 7.4.8 Satellite Communications — Low Earth Orbit 303

7.5 Wire Communications 304 7.5.1 Telephone Line 304 7.5.2 Fiber Optics 304 7.5.3 Distribution Line Carrier 304 7.5.4 Summary of Communications Options 331

7.6 Distribution Automation Communications Protocols 333 7.6.1 MODBUS 333 7.6.2 DNP3.0 336 7.6.3 IEC 60870-5-101 342 7.6.4 UCA 2.0, IEC 61850 345

7.7 Distribution Automation Communications Architecture 346 7.7.1 Central DMS Communication 346 7.7.2 Polling and Report by Exception 348 7.7.3 Intelligent Node Controllers/Gateways 349 7.7.4 Interconnection of Heterogeneous Protocols 349

7.8 DA Communications User Interface 350 7.9 Some Considerations for DA Communications Selection 350 7.10 Requirements for Dimensioning the Communication Channel 351

7.10.1 Confirmed and Nonconfirmed Communication 351 7.10.2 Characterization of Communication Systems 351 7.10.3 Communication Model 353 7.10.4 Calculation of the Reaction or the Response Time 353

Chapter 8 Creating the Business Case 357

8.1 Introduction 357

8.2 Potential Benefits Perceived by the Industry for Substation Automation 358 8.2.1 Integration and Functional Benefits of Substation Control

and Automation 358 8.2.2 SCADA vs. SA 360 8.2.3 Economic Benefits Claimed by the Industry 360

8.3 Potential Benefits Perceived by the Industry for Feeder Automation !...363

8.4 Generic Benefits 364 8.5 Benefit Opportunity Matrix 367 8.6 Benefit Flowchart 367 8.7 Dependencies, and Shared and Unshared Benefits 367

8.7.1 Dependencies 367 8.7.2 Shared Benefits 371 8.7.3 Unshared Benefits from Major DA Functions 372 8.7.4 Benefit Summary 378

8.8 Capital Deferral, Release, or Displacement 379 8.8.1 Deferral of Primary Substation Capital Investment 379 8.8.2 Release of Distribution Network Capacity 383 8.8.3 Release of Upstream Network and System Capacity 387 8.8.4 Displacement of Conventional Equipment with

Automation... 388 8.9 Savings in Personnel 388

8.9.1 Reduction in Substation/Control Center Operating Levels 389 8.9.2 Reduction in Inspection Visits 389 8.9.3 Reduction in Crew Time 390 8.9.4 Calculation of Crew Times Savings Associated with

Investment- and Operation-Related Savings 402 8.9.5 Reduced Crew Time and Effort for Changing Relay

Settings for CLPU •. 402 8.10 Savings Related to Energy 403

8.10.1 Reduction in Energy Not Supplied Savings Due to Faster Restoration 403

8.10.2 Reduced Energy Revenue Due to Controlled Load Reduction 404

8.10.3 Energy Savings Due to Technical Loss Reduction 405 8.10.3.1 Loss Reduction from Feeder Volt/VAR Control 405

8.11 Other Operating Benefits 407 8.11.1 Repair and Maintenance Benefits 408 8.11.2 Benefits from Better Information (DMOL) 408 8.11.3 Improved Customer Relationship Management 410

8.12 Summary of DA Functions and Benefits 411 8.13 Economic Value — Cost 412

8.13.1 Utility Cost 413 8.13.2 Customer Cost 421

8.13.3 Economic Value 422 8.14 Presentation of Results and Conclusions 426 References 428

Chapter 9 Case Studies 431

9.1 Introduction 431 9.2 Case Study 1, Long Rural Feeder 431

9.2.1 Evaluation of Performance 431 9.2.2 Crew Time Savings 433 9.2.3 Network Performance and Penalties 434

9.3 Case Study 2, Large Urban Network 437 9.3.1 Preparation Analysis — Crew Time Savings 437 9.3.2 Preparation Analysis — Network Performance 439 9.3.5 Summary of Cost Savings 446 9.3.6 Cost of SCADA/DMS System 447 9.3.7 Cost Benefits and Payback Period 448 9.3.8 Conclusions 448

Glossary 451

Index 459