Chapter 1 Distribution System Planning and Automation .......... 1
1.1 Introduction .............................................. 1
1.2 Distribution System Planning .............................. 2
1.3 Factors Affecting System Planning ......................... 4
1.3.1 Load Forecasting .................................... 4
1.3.2 Substation Expansion ................................ 5
1.3.3 Substation Site Selection ........................... 5
1.3.4 Other Factors ....................................... 6
1.4 Present Distribution System Planning Techniques ........... 8
1.5 Distribution System Planning Models ...................... 10
1.5.1 Computer Applications .............................. 11
1.5.2 New Expansion Planning ............................. 12
1.5.3 Augmentation and Upgrades .......................... 12
1.5.4 Operational Planning ............................... 12
1.5.5 Benefits of Optimization Applications .............. 13
1.6 Distribution System Planning in the Future ............... 13
1.6.1 Economic Factors ................................... 13
1.6.2 Demographic Factors ................................ 13
1.6.3 Technological Factors .............................. 14
1.7 Future Nature of Distribution Planning ................... 14
1.7.1 Increasing Importance of Good Planning ............. 14
1.7.2 Impacts of Load Management ......................... 14
1.7.3 Cost / Benefit Ratio for Innovation ................ 15
1.7.4 New Planning Tools ................................. 15
1.8 The Central Role of the Computer in Distribution
Planning ................................................. 15
1.8.1 The System Approach ................................ 16
1.8.2 The Database Concept ............................... 16
1.8.3 New Automated Tools ................................ 17
1.9 Impact of Dispersed Storage and Generation ............... 17
1.10 Distribution System Automation ........................... 21
1.10.1 Distribution Automation and Control Functions ..... 22
1.10.2 The Level of Penetration of Distribution
Automation ........................................ 24
1.10.3 Alternatives of Communication Systems ............. 28
1.11 Summary and Conclusions .................................. 30
References ..................................................... 31
Chapter 2 Load Characteristics ................................ 35
2.1 Basic Definitions ........................................ 35
2.2 The Relationship Between the Load and Loss Factors ....... 48
2.3 Maximum Diversified Demand ............................... 57
2.4 Load Forecasting ......................................... 62
2.4.1 Box-Jenkins Methodology ............................ 65
2.4.2 Small-Area Load Forecasting ........................ 65
2.4.3 Spatial Load Forecasting ........................... 66
2.5 Load Management .......................................... 70
2.6 Rate Structure ........................................... 72
2.6.1 Customer Billing ................................... 73
2.6.2 Fuel Cost Adjustment ............................... 75
2.7 Electric Meter Types ..................................... 79
2.7.1 Electronic Meters .................................. 80
2.7.2 Reading Electric Meters ............................ 82
2.7.3 Instantaneous Load Measurements Using Watt-Hour
Meters ............................................. 83
Problems ....................................................... 87
References ..................................................... 91
Chapter 3 Application of Distribution Transformers ............ 93
3.1 Introduction ............................................. 93
3.2 Types of Distribution Transformers ....................... 95
3.3 Regulation ............................................... 98
3.4 Transformer Efficiency .................................. 103
3.5 Terminal or Lead Markings ............................... 107
3.6 Transformer Polarity .................................... 107
3.7 Distribution Transformer Loading Guides ................. 108
3.8 Equivalent Circuits of a Transformer .................... 108
3.9 Single-Phase Transformer Connections .................... 111
3.9.1 General ........................................... 111
3.9.2 Single-Phase Transformer Paralleling .............. 113
3.10 Three-Phase Connections ................................. 121
3.10.1 The Δ-Δ Transformer Connection ................... 121
3.10.2 The Open-Δ Open-Δ Transformer Connection ......... 130
3.10.3 The Y-Y Transformer Connection ................... 134
3.10.4 The Y-Δ Transformer Connection ................... 135
3.10.5 The Open-V Open-Δ Transformer Connection ......... 137
3.10.6 The Δ-Y Transformer Connection ................... 141
3.11 Three-Phase Transformers ................................ 142
3.12 The T or Scott Connection ............................... 144
3.13 The Autotransformer ..................................... 159
3.14 The Booster Transformers ................................ 161
3.15 Amorphous Metal Distribution Transformers ............... 162
Problems ...................................................... 163
References .................................................... 168
Chapter 4 Design of Subtransmission Lines and Distribution
Substations ........................................ 169
4.1 Introduction ............................................ 169
4.2 Subtransmission ......................................... 169
4.2.1 Subtransmission Line Costs ........................ 173
4.3 Distribution Substations ................................ 173
4.3.1 Substation Costs .................................. 174
4.4 Substation Bus Schemes .................................. 176
4.5 Substation Location ..................................... 178
4.4 The Rating of a Distribution Substation ................. 181
4.7 General Case: Substation Service Area with n Primary
Feeders ................................................. 184
4.8 Comparison of the Four- and Six-Feeder Patterns ......... 186
4.9 Derivation of the К Constant ............................ 189
4.10 Substation Application Curves ........................... 198
4.11 Interpretation of the Percent Voltage Drop Formula ...... 203
4.12 Supervisory Data and Data Acquisition ................... 216
4.13 Advanced SCADA Concepts ................................. 218
4.13.1 Substation Controllers ........................... 218
4.14 Advanced Developments for Integrated Substation
Automation .............................................. 220
4.15 Capability of Facilities ................................ 223
4.16 Substation Grounding .................................... 224
4.16.1 Electric Shock and Its Effects on Humans ......... 224
4.16.2 Ground Resistance ................................ 226
4.16.3 Substation Grounding ............................. 228
4.17 Transformer Classification .............................. 230
Problems ...................................................... 232
References .................................................... 234
Chapter 5 Design Considerations of Primary Systems ........... 235
5.1 Introduction ............................................ 235
5.2 Radial-Type Primary Feeder .............................. 237
5.3 Loop-Type Primary Feeder ................................ 239
5.4 Primary Network ......................................... 240
5.5 Primary-Feeder Voltage Levels ........................... 240
5.6 Primary-Feeder Loading .................................. 244
5.7 Tie Lines ............................................... 245
5.8 Distribution Feeder Exit: Rectangular-Type
Development ............................................. 247
5.8.1 Method of Development for High-Load Density
Areas ............................................. 249
5.8.2 Method of Development for Low-Load Density
Areas ............................................. 249
5.9 Radial-Type Development ................................. 251
5.10 Radial Feeders with Uniformly Distributed Load .......... 252
5.11 Radial Feeders with Nonuniformly Distributed Load ....... 256
5.12 Application of the A, B, C, D General Circuit
Constants to Radial Feeders ............................. 258
5.13 The Design of Radial Primary Distribution Systems ....... 264
5.13.1 Overhead Primaries ............................... 265
5.13.2 Underground Residential Distribution ............. 265
5.14 Primary System Costs .................................... 280
Problems ...................................................... 280
References .................................................... 282
Chapter 6 Design Considerations of Secondary Systems ......... 283
6.1 Introduction ............................................ 283
6.2 Secondary Voltage Levels ................................ 284
6.3 The Present Design Practice ............................. 285
6.4 Secondary Banking ....................................... 285
6.5 The Secondary Networks .................................. 288
6.5.1 Secondary Mains ................................... 289
6.5.2 Limiters .......................................... 290
6.5.3 Network Protectors ................................ 290
6.5.4 High-Voltage Switch ............................... 292
6.5.5 Network Transformers .............................. 293
6.5.6 Transformer Application Factor .................... 294
6.6 Spot Networks ........................................... 295
6.7 Economic Design of Secondaries .......................... 295
6.7.1 The Patterns and Some of the Variables ............ 296
6.7.2 Further Assumptions ............................... 297
6.7.3 The General TAC Equation .......................... 297
6.7.4 Illustrating the Assembly of Cost Data ............ 298
6.7.5 Illustrating the Estimation of Circuit Loading .... 299
6.7.6 The Developed TAC Equation ........................ 299
6.7.7 Minimization of the TAC ........................... 301
6.7.8 Other Constraints ................................. 301
6.8 Unbalanced Load and Voltages ............................ 309
6.9 Secondary System Costs .................................. 318
Problems ...................................................... 319
References .................................................... 321
Chapter 7 Voltage Drop and Power Loss Calculations ........... 323
7.1 Three-Phase Balanced Primary Lines ...................... 323
7.2 Nonthree-Phase Primary Lines ............................ 323
7.2.1 Single-Phase Two-Wire Laterals with Ungrounded
Neutral ........................................... 323
7.2.2 Single-Phase Two-Wire Unigrounded Laterals ........ 325
7.2.3 Single-Phase Two-Wire Laterals with
Multigrounded Common Neutrals ..................... 327
7.2.4 Two-Phase Plus Neutral (Open-Wye) Laterals ........ 328
7.3 Four-Wire Multigrounded Common Neutral Distribution
System .................................................. 333
7.4 Percent Power (or Copper) Loss .......................... 357
7.5 A Method to Analyze Distribution Costs .................. 357
7.5.1 Annual Equivalent of Investment Cost .............. 360
7.5.2 Annual Equivalent of Energy Cost .................. 360
7.5.3 Annual Equivalent of Demand Cost .................. 361
7.5.4 Levelized Annual Cost ............................. 361
7.6 Economic Analysis of Equipment Losses ................... 366
Problems ...................................................... 367
References .................................................... 369
Chapter 8 Application of Capacitors to Distribution
Systems ............................................ 371
8.1 Basic Definitions ....................................... 371
8.2 Power Capacitors ........................................ 371
8.3 Effects of Series and Shunt Capacitors .................. 373
8.3.1 Series Capacitors ................................. 373
8.3.2 Shunt Capacitors .................................. 375
8.4 Power Factor Correction ................................. 376
8.4.1 General ........................................... 376
8.4.2 A Computerized Method to Determine the Economic
Power Factor ...................................... 382
8.5 Application of Capacitors ............................... 382
8.5.1 Capacitor Installation Types ...................... 392
8.5.2 Types of Controls for Switched Shunt Capacitors ... 395
8.5.3 Types of Three-Phase Capacitor Bank Connections ... 395
8.6 Economic Justification for Capacitors ................... 397
8.6.1 Benefits Due to Released Generation Capacity ...... 397
8.6.2 Benefits Due to Released Transmission Capacity .... 398
8.6.3 Benefits Due to Released Distribution Substation
Capacity .......................................... 398
8.6.4 Benefits Due to Reduced Energy Losses ............. 399
8.6.5 Benefits Due to Reduced Voltage Drops ............. 399
8.6.6 Benefits Due to Released Feeder Capacity .......... 400
8.6.7 Financial Benefits Due to Voltage Improvement ..... 400
8.6.8 Total Financial Benefits Due to Capacitor
Installations ..................................... 401
8.7 A Practical Procedure to Determine the Best Capacitor
Location ................................................ 404
8.8 A Mathematical Procedure to Determine the Optimum
Capacitor Allocation .................................... 405
8.8.1 Loss Reduction Due to Capacitor Allocation ........ 406
8.8.2 Optimum Location of a Capacitor Bank .............. 415
8.8.3 Energy Loss Reduction Due to Capacitors ........... 418
8.8.4 Relative Ratings of Multiple Fixed Capacitors ..... 425
8.8.5 General Savings Equation for Any Number of Fixed
Capacitors ........................................ 426
8.9 Capacitor Tank Rupture Considerations ................... 427
8.10 Dynamic Behavior of Distribution Systems ................ 429
8.10.1 Ferroresonance ................................... 429
8.10.2 Harmonics on Distribution Systems ................ 431
Problems ...................................................... 437
References .................................................... 439
Chapter 9 Distribution System Voltage Regulation ............. 441
9.1 Basic Definitions ....................................... 441
9.2 Quality of Service and Voltage Standards ................ 441
9.3 Voltage Control ......................................... 442
9.4 Feeder Voltage Regulators ............................... 444
9.5 Line-Drop Compensation .................................. 445
9.6 Distribution Capacitor Automation ....................... 474
9.7 Voltage Fluctuations .................................... 475
9.7.1 A Shortcut Method to Calculate the Voltage Dips
Due to a Single-Phase Motor Start ............... 478
9.7.2 A Shortcut Method to Calculate the Voltage Dips
Due to a Three-Phase Motor Start ................ 479
Problems ...................................................... 480
References .................................................... 484
Chapter 10 Distribution System Protection .................... 485
10.1 Basic Definitions ....................................... 485
10.2 Overcurrent Protection Devices .......................... 485
10.2.1 Fuses ............................................ 485
10.2.2 Automatic Circuit Reclosers ...................... 489
10.2.3 Automatic Line Sectionalizers .................... 493
10.2.4 Automatic Circuit Breakers ....................... 498
10.3 Objective of Distribution System Protection ............. 499
10.4 Coordination of Protective Devices ...................... 502
10.5 Fuse-to-Fuse Coordination ............................... 504
10.6 Recloser-to-Recloser Coordination ....................... 506
10.7 Recloser-to-Fuse Coordination ........................... 506
10.8 Recloser-to-Substation Transformer High-Side Fuse
Coordination ............................................ 512
10.9 Fuse-to-Circuit-Breaker Coordination .................... 512
10.10 Recloser-to-Circuit-Breaker Coordination ................ 512
10.11 Fault Current Calculations .............................. 515
10.11.1 Three-Phase Faults .............................. 516
10.11.2 L-L Faults ...................................... 517
10.11.3 SLG Faults ...................................... 518
10.11.4 Components of the Associated Impedance to the
Fault ........................................... 520
10.11.5 Sequence Impedance Tables for the Application
of Symmetrical Components ....................... 523
10.12 Fault Current Calculations in Per Units ................. 529
10.13 Secondary System Fault Current Calculations ............. 535
10.13.1 Single-Phase 120/240-V Three-Wire Secondary
Service ......................................... 535
10.13.2 Three-Phase 240/120- or 480/240-V Wye-Delta or
Delta-Delta Four-Wire Secondary Service ......... 536
10.13.3 Three-Phase 240/120- or 480/240-V Open-Wye
Primary and Four-Wire Open-Delta Secondary
Service ......................................... 538
10.13.4 Three-Phase 208Y/120-V, 480Y/277-V, or 832Y/
480-V Four-Wire Wye-Wye Secondary Service ....... 539
10.14 High-Impedance Faults ................................... 543
10.15 Lightning Protection .................................... 544
10.15.1 A Brief Review of Lightning Phenomenon .......... 544
10.15.2 Lightning Surges ................................ 546
10.15.3 Lightning Protection ............................ 547
10.15.4 Basic Lightning Impulse Level ................... 548
10.15.5 Determining the Expected Number of Strikes on
a Line .......................................... 550
10.16 Insulators .............................................. 555
Problems ...................................................... 556
References .................................................... 557
Chapter 11 Distribution System Reliability ................... 559
11.1 Basic Definitions ....................................... 559
11.2 National Electric Reliability Council ................... 561
11.3 Appropriate Levels of Distribution Reliability .......... 563
11.4 Basic Reliability Concepts and Mathematics .............. 567
11.4.1 The General Reliability Function ................. 567
11.4.2 Basic Single-Component Concepts .................. 572
11.5 Series Systems .......................................... 576
11.5.1 Unrepairable Components in Series ................ 576
11.5.2 Repairable Components in Series .................. 579
11.6 Parallel Systems ........................................ 581
11.6.1 Unrepairable Components in Parallel .............. 581
11.6.2 Repairable Components in Parallel ................ 584
11.7 Series and Parallel Combinations ........................ 591
11.8 Markov Processes ........................................ 596
11.8.1 Chapman-Kolmogorov Equations ..................... 602
11.8.2 Classification of States in Markov Chains ........ 606
11.9 Development of the State Transition Model to Determine
the Steady-State Probabilities .......................... 606
11.10 Distribution Reliability Indices ........................ 610
11.11 Sustained Interruption Indices .......................... 610
11.11.1 System Average Interruption Frequency Index
(Sustained Interruptions) (SAIFI) ............... 610
11.11.2 System Average Interruption Duration Index
(SAIDI) ......................................... 611
11.11.3 Customer Average Interruption Duration Index
(CAIDI) ......................................... 611
11.11.4 Customer Total Average Interruption Duration
Index (CTAIDI) .................................. 611
11.11.5 Customer Average Interruption Frequency Index
(CAIFI) ......................................... 612
11.11.6 Average Service Availability Index (ASAI) ....... 612
11.11.7 Average System Interruption Frequency Index
(ASIFI) ......................................... 612
11.11.8 Average System Interruption Duration Index
(ASIDI) ......................................... 613
11.11.9 Customers Experiencing Multiple Interruptions
(CEMIn) ......................................... 613
11.12 Other Indices (Momentary) ............................... 613
11.12.1 Momentary Average Interruption Frequency Index
(MAIFI) ......................................... 613
11.12.2 Momentary Average Interruption Event Frequency
Index (MAIFIE) .................................. 614
11.12.3 Customers Experiencing Multiple Sustained
Interruptions and Momentary Interruption
Events (CEMSMIn) ................................ 614
11.13 Load- and Energy-Based Indices .......................... 614
11.13.1 Energy Not Supplied Index (ENS) ................. 615
11.13.2 Average Energy Not Supplied (AENS) .............. 615
11.13.3 Average Customer Curtailment Index (ACCI) ....... 615
11.14 Usage of Reliability Indices ............................ 617
11.15 Benefits of Reliability Modeling in System
Performance ............................................. 618
11.16 Economics of Reliability Assessment ..................... 619
Problems ...................................................... 621
References .................................................... 626
Chapter 12 Electric Power Quality ............................. 629
12.1 Basic Definitions ........................................ 629
12.2 Definition of Electric Power Quality ..................... 630
12.3 Classification of Power Quality .......................... 631
12.4 Types of Disturbances .................................... 631
12.4.1 Harmonic Distortion .............................. 632
12.4.2 CBEMA and ITI Curves ............................. 635
12.5 Measurements of Electric Power Quality .................. 637
12.5.1 RMS Voltage and Current .......................... 637
12.5.2 Distribution Factors ............................. 638
12.5.3 Active (Real) and Reactive Power ................. 639
12.5.4 Apparent Power ................................... 640
12.5.5 Power Factor ..................................... 641
12.5.6 Current and Voltage Crest Factors ................ 643
12.5.7 Telephone Interference and the I•T Product ....... 645
12.6 Power in Passive Elements ............................... 647
12.6.1 Power in a Pure Resistance ....................... 647
12.6.2 Power in a Pure Inductance ....................... 648
12.6.3 Power in a Pure Capacitance ...................... 649
12.7 Harmonic Distortion Limits .............................. 650
12.7.1 Voltage Distortion Limits ........................ 650
12.7.2 Current Distortion Limits ........................ 650
12.8 Effects of Harmonics .................................... 653
12.9 Sources of Harmonics .................................... 654
12.10 Derating Transformers ................................... 655
12.10.1 The K-Factor .................................... 655
12.10.2 Transformer Derating ............................ 656
12.11 Neutral Conductor Overloading ........................... 657
12.12 Capacitor Banks and PF Correction ....................... 660
12.13 Short-Circuit Capacity or MVA ........................... 661
12.14 System Response Characteristics ......................... 662
12.14.1 System Impedance ................................ 662
12.14.2 Capacitor Impedance ............................. 663
12.15 Bus Voltage Rise and Resonance .......................... 663
12.16 Harmonic Amplification .................................. 667
12.17 Resonance ............................................... 671
12.17.1 Series Resonance ................................ 671
12.17.2 Parallel Resonance .............................. 673
12.17.3 Effects of Harmonics on the Resonance ........... 675
12.17.4 Practical Examples of Resonance Circuits ........ 678
12.18 Harmonic Control Solutions .............................. 683
12.18.1 Passive Filters ................................. 684
12.18.2 Active Filters .................................. 690
12.19 Harmonic Filter Design .................................. 690
12.19.1 Series-Tuned Filters ............................ 691
12.19.2 Second-Order Damped Filters ..................... 694
12.20 Load Modeling in the Presence of Harmonics .............. 697
12.20.1 Impedance in the Presence of Harmonics .......... 697
12.20.2 Skin Effect ..................................... 698
12.20.3 Load Models ..................................... 698
Problems ...................................................... 700
References .................................................... 704
Appendix A Impedance Tables for Lines, Transformers, and
Underground Cables ................................ 707
References .................................................... 766
Appendix В Graphic Symbols Used in Distribution System
Design ............................................ 767
Appendix С Glossary for Distribution System Terminology ...... 777
References .................................................... 791
Appendix D The Per-Unit System ............................... 793
D.1 Introduction .............................................. 793
D.2 Single-Phase System ....................................... 793
D.3 Three-Phase System ........................................ 795
Problems ...................................................... 798
Notation ...................................................... 799
Answers to Selected Problems .................................. 809
Index ......................................................... 813
|
