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ISBN: 978-1-119-50931-8

Cover design: Wiley
Cover images: (Top image) © Sam Robinson/Getty Images; (Center image) Courtesy of Om P. Malik

Contents

Preface

Acknowledgments

Part I: Fundamental Concepts

Chapter 1: Introduction
1. 1.1 Introduction and Background
2. 1.2 Power System Structure
3. 1.3 Distribution Level
4. 1.4 General
Chapter 2: Distribution System Structure
1. 2.1 Distribution Voltage Levels
2. 2.2 Distribution System Configuration
3. 2.3 General Comments
Chapter 3: Distribution System Planning
1. 3.1 Duties of Distribution System Planners
2. 3.2 Factors Affecting the Planning Process
3. 3.3 Planning Objectives
4. 3.4 Solutions for Meeting Load Forecasts
Chapter 4: Load Forecasting
1. 4.1 Introduction
2. 4.2 Important Factors for Forecasts
3. 4.3 Forecasting Methodology
4. 4.4 Spatial Load Forecasting (SLF)
5. 4.5 End-Use Modeling
6. 4.6 Spatial Load Forecast Methods

Part II: Protection and Switchgear

Chapter 5: Earthing of Electric Distribution Systems
1. 5.1 Basic Objectives
2. 5.2 Earthing Electrical Equipment
3. 5.3 System Earthing
4. 5.4 MV Earthing Systems
5. 5.5 Earthing Systems in LV Distribution Networks
6. Notes
Chapter 6: Short-Circuit Studies
1. 6.1 Introduction
2. 6.2 Short-Circuit Analysis
Chapter 7: Protection: Current-Based Schemes
1. 7.1 Introduction
2. 7.2 Types of Relay Construction
3. 7.3 Overcurrent Protection
4. 7.4 Directional Protection
5. 7.5 Differential Protection
Chapter 8: Protection: Other Schemes
1. 8.1 Overvoltage Protection
2. 8.2 Thermal Protection
3. 8.3 RECLOSERS, SECTIONALIZERS, FUSES
Chapter 9: Switchgear Devices
1. 9.1 Need for Switchgear
2. 9.2 MV Switchgear Devices
3. 9.3 LV Switchgear Devices
4. 9.4 Protection Classes
5. 9.5 Specifications and Implementation of Earthing
6. 9.6 Assessment of Switchgear
7. 9.7 Safety and Security of Installations
8. 9.8 Application Trends in MV Switchgear
Chapter 10: Switchgear Installation
1. 10.1 Steps for Installing Switchgear
2. 10.2 Switchgear Layout
3. 10.3 Dimensioning of Switchgear Installations
4. 10.4 Civil Construction Requirements
5. 10.5 ARC-Flash Hazards

Part III: Power Quality

Chapter 11: Electric Power Quality
1. 11.1 Overview
2. 11.2 Power Quality Problems
3. 11.3 Cost of Power Quality
4. 11.4 Solutions of Power Quality Problems
5. 11.5 Solution Cycle for Power Quality Problems
Chapter 12: Voltage Variations
1. 12.1 Voltage Quality
2. 12.2 Methods of Voltage Drop Reduction
3. 12.3 Voltage SAG Calculations
4. 12.4 Estimation of Distribution Losses
Chapter 13: Power Factor Improvement
1. 13.1 Background
2. 13.2 Shunt Compensation
3. 13.3 Need for Shunt Compensation
4. 13.4 An Example
5. 13.5 How to Determine Compensation
Chapter 14: Harmonics in Electric Distribution Systems
1. 14.1 What are Harmonics?
2. 14.2 Sources of Harmonics
3. 14.3 Disturbances Caused by Harmonics
4. 14.4 Principles of Harmonic Distortion Indications and Measurement
5. 14.5 Frequency Spectrum and Harmonic Content
6. 14.6 Standards and Recommendations
Chapter 15: Harmonics Effect Mitigation
1. 15.1 Introduction
2. 15.2 First Class of Solutions
3. 15.3 Second Class of Solutions
4. 15.4 Third Class of Solutions
5. 15.5 Selection Criteria
6. 15.6 Case Studies

Part IV: Management and Automation

Chapter 16: Demand-Side Management and Energy Efficiency
1. 16.1 Overview
2. 16.2 DSM
3. 16.3 Needs to Apply DSM
4. 16.4 Means of DSM Programs
5. 16.5 International Experience with DSM
6. 16.6 Potential for DSM Application
7. 16.7 The DSM Planning Process
8. 16.8 Expected Benefits of Managing Demand
9. 16.9 Energy Efficiency
10. 16.10 Scenarios Used for Energy-Efficiency Application
11. 16.11 Economic Benefits OF Energy Efficiency
12. 16.12 Application of Efficient Technology
Chapter 17: Scada Systems
1. 17.1 Introduction
2. 17.2 Definitions
3. 17.3 Scada Components
4. 17.4 Scada Systems Architectures
5. 17.5 Scada Applications
6. 17.6 Scada and Grid Modernization

Part V: Distributed Energy Resources and Microgrids

Chapter 18: Distributed Generation
1. 18.1 Power Systems And Distributed Generation
2. 18.2 Performance of Distributed Generators
3. 18.3 Case Study
Chapter 19: Electrical Energy Storage
1. 19.1 Introduction
2. 19.2 Electrical Energy Storage
3. 19.3 Role of Electrical Energy Storage
4. 19.4 Types of EES Systems
5. 19.5 Energy Storage Application
Chapter 20: Microgrids and Smart Grids
1. 20.1 Background
2. 20.2 MG Benefits
3. 20.3 MG Operation
4. 20.4 Challenges
5. 20.5 Handling the Challenges
6. 20.6 Control Methodology
7. 20.7 Case Study
8. 20.8 Protection for MGs
9. 20.9 Concluding Remarks on MGs
10. 20.10 Smart Grids

Appendix A: Data of Microgrid Components

Appendix B: Matlab Simulink Models

References

Index

IEEE Press Series on Power Engineering

Wiley End User License Agreement

List of Tables

Chapter 2

Table 2.1

Chapter 4

Table 4.1
Table 4.2
Table 4.3
Table 4.4
Table 4.5
Table 4.6

Chapter 5

Table 5.1
Table 5.2
Table 5.3
Table 5.4
Table 5.5
Table 5.6
Table 5.7

Chapter 6

Table 6.1
Table 6.2
Table 6.3

Chapter 7

Table 7.1
Table 7.2
Table 7.3

Chapter 8

Table 8.1
Table 8.2

Chapter 9

Table 9.1
Table 9.2

Chapter 10

Table 10.1
Table 10.2
Table 10.3
Table 10.4

Chapter 11

Table 11.1
Table 11.2
Table 11.3
Table 11.4
Table 11.5
Table 11.6

Chapter 12

Table 12.1
Table 12.2
Table 12.3
Table 12.4

Chapter 13

Table 13.1
Table 13.2

Chapter 14

Table 14.1
Table 14.2
Table 14.3
Table 14.4
Table 14.5
Table 14.6
Table 14.7

Chapter 15

Table 15.1

Chapter 16

Table 16.1
Table 16.2
Table 16.3
Table 16.4
Table 16.5
Table 16.6
Table 16.7
Table 16.8

Chapter 18

Table 18.1

Chapter 19

Table 19.1
Table 19.2

Chapter 20

Table 20.1

Appendix A

Table A.1

List of Illustrations

Chapter 1

Figure 1.1 Electricity supply system [2].
Figure 1.2 A typical electric supply system single-line diagram. CB = circuit breaker; N.O. = normal open.
Figure 1.3 Electric supply system to a big city.
Figure 1.4 Electric supply system to a small city.

Chapter 2

Figure 2.1 Distribution voltages for different loads (values written between parentheses describe the European practice; otherwise the values describe the North American practice).
Figure 2.2 MV supply network to DP with parallel feeders (CB = circuit breaker with overcurrent protection; F = feeder, DP = distribution point).
Figure 2.3 MV supply network to DP with independent feeders (ARS = automatic reserve switching, F = feeder, CB = circuit breaker, DP = distribution point).
Figure 2.4 Combined MV supply network to DP.
Figure 2.5 Ring bus scheme.
Figure 2.6 Radial nonreserved distribution network.
Figure 2.7 Multiradial distribution network with automatic reserve switching on MV side.
Figure 2.8 Open-loop distribution network.
Figure 2.9 Radial MV network with DP (ARS on LV bus-bar of TP). TP = transformer; DP = distribution point; ARS = automatic reserve switching; SWB = switchboard.
Figure 2.10 North American MV/LV distribution transformers. (a) 120/240 V single-phase service, (b) Typical 208 V, 3-phase Y-connected service.
Figure 2.11 Secondary spot network.
Figure 2.12 Supply system to a third-category customer.
Figure 2.13 Open-loop 0.4 kV network.
Figure 2.14 Combined open-/double-radial LV network.
Figure 2.15 Double-radial LV network. ARS = automatic reserve switching.
Figure 2.16 Double-radial LV network. Each radial is connected to a single distribution transformer point.
Figure 2.17 North American distribution layouts.
Figure 2.18 European distribution layouts.

Chapter 3

Figure 3.1 Flowchart of distribution system planning process.
Figure 3.2 Tasks of asset manager.
Figure 3.3 Main parts of a CM system.
Figure 3.4 Balancing of the direct cost of service and the indirect cost of interruption [2].
Figure 3.5 Types and factors affecting distribution losses.
Figure 3.6 Relationship between N rating and N-1 rating and energy at risk [2].

Chapter 4

Figure 4.1 Straight line fit to observations.
Figure 4.4 Forecast and actual load profile for 1 week in summer: (a) Saturday, (b) Sunday, (c) Monday, (d) Tuesday, (e) Wednesday, (f) Thursday and (g) Friday [33].
Figure 4.2 Hourly load curve over 1 week.
Figure 4.3 Autocorrelation and partial autocorrelation functions of 5 weeks in summer [33].
Figure 4.5 Load curves for traditional customer classes.
Figure 4.6 Load curve of one residential customer [34].
Figure 4.7 Water heater load behavior.
Figure 4.8 Load curves of different number of customers [34].
Figure 4.9 Effect of number of customers per group on (a) load per customer, (b) coincidence factor, (c) duration of peak.
Figure 4.10 Variation of length of sample period versus: (a) load/customer, (b) number of customers/group.
Figure 4.11 System end-use model categories.
Figure 4.12 Saturation growth curve (S-curve).
Figure 4.13 S-curves at different periods of historical data.
Figure 4.14 S-curves with horizon year load at different periods of historical data.

Chapter 5

Figure 5.1 (a, b) Effect of capacitive coupling.

Chapter 5

Figure 5.1 (c–e) Importance of appliance earthing.

Chapter 5

Figure 5.1 (f, g) Appliance earthing by earth wire.
Figure 5.2 (a) Origin of an electrostatic overvoltage [37]. (b) Diverting the lightning stroke into the earth.
Figure 5.3 Step and touch potentials. (a) Step voltage, (b) touch voltage. R_f = contact foot resistance; R_b = body resistance; R_g = ground resistance.
Figure 5.4 Time/current zones of AC effects (15-100 Hz) on persons [44]. 1 = perception zone; 2 = considerable discomfort; 3 = muscular contractions zone; 4 = risk of ventricular fibrillation zone (cardiac arrest); c1 = likelihood 5%; c2 = likelihood > 50%.
Figure 5.5 Fibrillation current versus body weight for various animals based on electrical shock of 3 seconds’ duration [39].
Figure 5.6 Factor c_s versus the depth of protective layer h_s [45].
Figure 5.7 Fall-of-potential method for measuring earth resistance of earth rod or small grid.
Figure 5.8 A method for measuring earth resistance.
Figure 5.9 (a) Square-shaped, nine-mesh earthing mat, (b) relation of (2rb/A) versus (πwR/ρ) [45].
Figure 5.10 Unearthed system.
Figure 5.11 Earthing systems boundaries [36].
Figure 5.12 Different methods of earthing.
Figure 5.13 Earthing when the neutral is accessible, (a) direct connection; (b) connection via single-phase transformer.
Figure 5.14 Main methods for creating an artificial neutral point in medium voltage networks. (a) Use of Y-Δ transformer with neutral earthing resistor; (b) use of Y-Δ transformer with resistor in the Δ; (c) use of zigzag coil; (d) neutral point transformer with compensation delta.
Figure 5.15 (a) Substation-frame and LV neutral are connected to the same earth. (b) All earthing connections are grouped to a single earth. (c) All earthing connections are earthed separately.
Figure 5.16 Unearthed or high-impedance-earthed neutral (IT system) in LV networks.
Figure 5.17 Directly earthed neutral (TT system) in LV networks.
Figure 5.18 TNC earthing system.
Figure 5.19 TNS earthing system.
Figure 5.20 MV/LV public distribution transformers. (a) Three-phase, MV/LV, Dy11 distribution transformer in compliance with the European system. (b) Single-phase distribution transformer in compliance with North American system.
Figure 5.21 TNS earthing system in the United States.

Chapter 6

Figure 6.1 Schematic diagram of distribution network. (a) Fault location far from the source. (b) Fault location at generator terminals.
Figure 6.2 Equivalent circuit of case 1.
Figure 6.3 short circuit fault current versus time.
Figure 6.4 Variation of K with time and (R/X).
Figure 6.5 Components of generator short-circuit current.
Figure 6.6 Symmetrical three-phase short circuit. (a) Three-phase symmetrical short circuit; (b) equivalent circuit.
Figure 6.7 Single-conductor cable.
Figure 6.8 Cable trefoil formation.
Figure 6.9 Distribution installation diagram.
Figure 6.10 Equivalent circuit for fault at F₁.
Figure 6.11 Equivalent circuit for fault at F₂.
Figure 6.12 Equivalent circuit for fault at F₃.
Figure 6.13 Equivalent circuit for fault at F₄.
Figure 6.14 Three types of unsymmetrical faults.
Figure 6.15 Original three-phase unbalanced system equivalents to three sets of three-phase balanced systems.
Figure 6.16 Equivalent single-phase impedance networks.
Figure 6.17 Sequence short circuit impedances of electrical element.
Figure 6.18 (a) Three-phase cable. (b) Three single-phase cables.
Figure 6.19 Layout of a distribution system.
Figure 6.20 (a) Positive-, (b) negative- and (c) zero-sequence networks.
Figure 6.21 Circuit diagram of a system with L-E fault.
Figure 6.22 Interconnection of sequence networks for L-E fault.
Figure 6.23 (a) L-E fault with network capacitance between phases and earth. (b) Sequence networks.
Figure 6.24 Simple distribution system.
Figure 6.25 Three-phase diagram of a distribution system with four outgoing feeders (one faulty and three healthy).
Figure 6.26 Circuit diagram of a system with L-L fault.
Figure 6.27 Interconnection of sequence networks for L-L fault.
Figure 6.28 Circuit diagram of a system with 2L-E fault.
Figure 6.29 Interconnection of sequence networks for 2L-E fault.
Figure 6.30 A simple distribution network.
Figure 6.31 A sample of distribution network.
Figure 6.32 Three-phase circuit diagram of TN system with L-E fault on phase a.
Figure 6.33 Three-phase circuit diagram of IT system with L-L fault (phase b at load #1 and c at load #2).
Figure 6.34 Three-phase circuit diagram of TT system with L-L fault (phase b to phase c).
Figure 6.35 Main steps of peak, rms and minimum short-circuit current calculations.

Chapter 7

Figure 7.1 Protection system components.
Figure 7.2 Block diagram of a digital relay [63].
Figure 7.3 An illustration of aliasing phenomenon: (a) in time domain and (b) in frequency domain.
Figure 7.4 Data window for sampling.
Figure 7.5 Time-current characteristics of overcurrent protection: (a) definite-current characteristic; (b) definite-time characteristic; (c) inverse-time characteristic.
Figure 7.6 Typical relay time-current characteristics [46]: (A) inverse; (B) very inverse; (C) extremely inverse; (D) instantaneous. TD = relay time-dial setting.
Figure 7.7 Fault detection by three protection units.
Figure 7.8 Time-delay coordination for (a) definite-time protection, (b) IDMT protection and (c) combined inverse-time and instantaneous protection.
Figure 7.9 Current-based coordination: (a) line diagram; (b) tripping curves.
Figure 7.10 Logic coordination principles.
Figure 7.11 System for Example 7.1. XLPE = cross-linked polyethylene.
Figure 7.12 Typical time-current characteristics for overcurrent inverse-time relays [46].
Figure 7.13 Relay coordination curves – Example 7.1.
Figure 7.14 Three-phase and third-harmonic currents.
Figure 7.15 Residual current measurements.
Figure 7.16 Bus bar supplied by two sources. CB = circuit breaker; Ct = current transformer; OCR = overcurrent relay; DOCR = directional overcurrent relay.
Figure 7.17 Polarizing voltage of (a) phase a and (b) phase c for a current in phase a.
Figure 7.18 Directional protection tripping zones on (a) phase a; (b) phase c for a characteristic angle θ = 45°.
Figure 7.19 Network with L-L fault at F.
Figure 7.20 Residual voltage measurements.
Figure 7.21 Block diagram representing differential protection scheme.
Figure 7.22 Connection diagram of three-phase differential protection against three-phase or L-L faults.
Figure 7.23 Connection diagram of differential protection against L-G fault.
Figure 7.24 Connection diagram indicating Cts equivalent circuits.
Figure 7.25 Simplified connection diagram.
Figure 7.26 connection diagram for internal solid fault.
Figure 7.27 Connection diagram with nonlinear resistor.
Figure 7.28 Motor or generator differential protection.
Figure 7.29 Differential protection of transformer with earthed neutral through limiting impedance.
Figure 7.30 Differential protection of unearthed neutral transformer.
Figure 7.31 Bus bar differential protection.
Figure 7.32 Schematic diagram of cables—percentage differential protection.
Figure 7.33 Current difference vs. input current.

Chapter 8

Figure 8.1 (a) Example of voltage surges, (b) main overvoltage characteristics.
Figure 8.2 Surge propagation modes (I_com and I_diff are the common and differential mode currents, respectively).
Figure 8.3 Equivalent circuit for overvoltage study when breaking small inductive current [38].
Figure 8.4 High-frequency oscillating current superimposed on fundamental current wave [38].
Figure 8.5 Switching surges representation by standardized waveforms [67].
Figure 8.6 Voltages of healthy phases B and C on the occurrence of phase A-to-earth fault [38].
Figure 8.7 The lightning stroke [67].
Figure 8.8 Potential profile along the earths of an electrical installation.
Figure 8.9 Air clearance and creepage distance [38].
Figure 8.10 (a) Arrester installation. (b) Typical structure of MV porcelain-housed arrester [67].
Figure 8.11 Arrester lead connection [38].
Figure 8.12 LV primary protection against lightning: (a) using lightning rod, (b) using meshed cage, (c) using overhead earth wire.
Figure 8.13 Installation of a surge limiter in IT earthing system. PIM = permanent insulation monitor.
Figure 8.14 Heat rise versus time for a cold machine.
Figure 8.15 Heat rise versus time for a hot machine.
Figure 8.16 Sequence of recloser operation.
Figure 8.17 Pole-mounted autorecloser (typical to Merlin-Gerin design).
Figure 8.18 Cross-section of a circuit breaker (typical to Merlin-Gerin three-phase circuit recloser). 1 = insulated cable tails; 2 = polymeric brushing boot; 3 = bushing; 4 = current transformer; 5 = lightning arresters (optional) and mountings; 6 = vacuum interrupter; 7 = contacts; 8 = stainless steel tank; 9 = contact pushrod; 10 = contact pressure spring; 11 = latch; 12 = trip bar armature; 13 = trip bar; 14 = trip coil, 15 = cable to control cabinet; 16 = cable entry cover; 17 = switch cable entry module (SCEM); 18 = mechanism plate; 19 = opening spring; 20 = closing solenoid; 21 = flexible connecting arm; 22 = gas-filled tank.
Figure 8.19 Open ring with single sectionalizing point [78].
Figure 8.20 Open ring with three sectionalizing points, IDMT and logic selectivity [78].
Figure 8.21 Typical sectionalizer and its controller. (a) Components of automatic controller sectionalizer (typical to Merlin-Gerin manufacturing). (b) Typical pole-mounted sectionalizer.
Figure 8.22 Typical melting TCC curves developed at 25°C [79].
Figure 8.23 Typical total clearing TCC curves developed at 25°C [79]
Figure 8.24 Typical current limitation showing peak let-through current and total clearing time [80].

Chapter 9

Figure 9.1 A typical ABB UniGear-type ZS1® (Courtesy of ABB), MV, arc-proof, air-insulated, metal-clad switchgear11.
Figure 9.2 Switchgear layout. (a) Switchgear with one incoming feeder. (b) Switchgear with two incoming feeders.
Figure 9.3 Ring main unit (RMU), ABB UniSwitch®. (a) Symbol of RMU in a distribution ring; (b) typical type of RMU (Courtesy of ABB).
Figure 9.4 MV knife-switch [81].
Figure 9.5 Knife-contact LBS type [77].
Figure 9.6 Slide-in LBS type [81].
Figure 9.7 Installation of earthing switch (E/S) [81]. (a) In the cable basement; (b) underneath the CB; (c) in the base of LBS.
Figure 9.8 Typical examples of most commonly used circuit breakers in MV primary distribution (courtesy of ABB). (a) SF₆ circuit breaker; (b) vacuum circuit breaker.
Figure 9.9 Forms of arc extinction process. (a) Equivalent circuit and waveforms of voltage and current for DC extinction. (b) Equivalent circuit and waveforms of voltage and current for AC extinction. t₁ = contact separation; t₂ = arc extinction; S = rate of recovery voltage rise.
Figure 9.10 Breaker voltage when connecting to various load types.
Figure 9.11 (a) Symbol of isolators; (b) typical type of isolator; (c) symbol of load-break switches; (d) typical type of load-break switch (Courtesy of ABB).
Figure 9.12 (a) Symbol of contactor, (b) contactor equipped with OCR, (c) symbol of nonautomatic fuse-switch, (d and e) typical types of fuse switch and contactor, respectively (courtesy of ABB).
Figure 9.13 Combinations of switching devices. (a) Fuse switch + contactor with OCR; (b) automatic isolator + fuse + OCR.
Figure 9.14 Principle parts of LV circuit breaker (Courtesy of ABB).
Figure 9.15 Performance of LV circuit breakers (short-circuit instantaneous relay trip-current setting vs. time).
Figure 9.16 Grounding system with equipotential bonding between MV, LV Indoor switchgear and building services. CR = cable racks; LV Sw/B = LV switchboard; MV Sw/B = MV switchboard; GP = gas pipes; MSt = metal structure; FR = floor reinforcement; EBC = equipotential bonding conductors; TR = transformer room; CSE = cable sealing end; AC = air conditioners; HP = heating pipes; WP = water pipes; EGR = elevator guide rail; Fd = foundations; EC = earthing conductor.
Figure 9.17 MV industrial distribution system (switchgears layout).
Figure 9.18 Examples of GIS technology. (a) Typical GIS primary panel; (b) three-function GIS RMU.

Chapter 10

Figure 10.1 The bus-bar arrangement [81].
Figure 10.2 k_1i factors for the mean effective distance between conductor elements with i = 1, 2,…, t [81].
Figure 10.3 Electromagnetic force F vs peak short-circuit current i_p at different center-line spacing a [81].
Figure 10.4 (a) Factor m vs. T_k for different values of decay factor, (b) factor n vs T_k at different surge factor values [81].
Figure 10.5 Rated short-time current density S_thr in relation to temperature (solid lines for copper and dotted lines for steel) [81].
Figure 10.6 Rated short-time current density S_thr in relation to temperature (aluminum, aldrey and Al/St.) [81].
Figure 10.7 Transformer room with natural ventilation (on left side) and forced ventilation (on right side) A₁ = air intake area. A₂ = air exhaust area, H = height of fan shaft, 1 = fan, 2 = exhaust louvers, 3 = inlet grille, 4 = skirting, 5 = baffle plate.
Figure 10.8 Transformer arrangements [81].
Figure 10.9 Switchgear ventilation, cooling and air conditioning systems.
Figure 10.10 Installation layout (all dimensions are in millimeters).
Figure 10.11 Installation layout for distribution switchboard (all dimensions are in mm, cables up to 50 mm²).
Figure 10.12 Arc propagation [91].
Figure 10.13 Burn injuries due to electric arcs [92]. (a) Leg burn; (b) hand burn; (c) shoulder burn; (d) foot burn.
Figure 10.14 Arc-flash approach limit regions.
Figure 10.15 Flash protection boundary [91] (a person at a distance D from arc source D_fb is the limit distance of the boundary).
Figure 10.16 Incident energy delivered by an arc [91].
Figure 10.17 Single fiber loop layout [95].

Chapter 11

Figure 11.1 Graphical Illustration of Power Quality Events.
Figure 11.2 ITI (CBEMA) Curve (Revised 2000) [109].
Figure 11.3 ITI (CBEMA) curve for voltage sag study [115].
Figure 11.4 Main basis of cost analysis.
Figure 11.5 Difference in commercial and industrial customer interruption cost (Duke Power data) [117].
Figure 11.6 Function of SPD.
Figure 11.7 LV entrance with backup generator.
Figure 11.8 Sectionalized bus bars with two utility sources and backup generator.
Figure 11.9 Main components of UPS [119].
Figure 11.10 Principles of half-bridge converter [118].
Figure 11.11 Differential and common-mode noises.
Figure 11.12 Common-mode transient propagation [120].
Figure 11.13 Motor-driven VR.
Figure 11.14 Main steps of power quality problems solution.

Chapter 12

Figure 12.1 Voltage profile along a feeder supplying residential customers [122].
Figure 12.2 Voltage ranges specified by ANSI.
Figure 12.3 Voltage sag characteristic parameters [127].
Figure 12.4 Waveform with high-frequency components and overshoots during and after the sag, respectively.
Figure 12.5 Voltage sag duration in a three-phase system.
Figure 12.6 Illustration of flicker problem.
Figure 12.7 Borderline of irritation [122].
Figure 12.8 Voltage swell.
Figure 12.9 Single-phase diagram for a radial line with a series capacitor and a concentrated load at the line end.
Figure 12.10 Phasor diagram for the line voltage for a simple radial line. (a) Without series capacitor. (b) With series capacitor.
Figure 12.11 A typical voltage profile for a radial line without and with series capacitor.
Figure 12.12 Studied system. (a) Lateral radial feeder. (b) Reduced lateral feeder.
Figure 12.13 Main steps of series compensation calculation (N = no. of load points, V_s(I) = source voltage at load point I).
Figure 12.14 Line diagram of case study.
Figure 12.15 Series capacitor locations on compensated line.
Figure 12.16 Voltage profile along the line.
Figure 12.17 Procedures of voltage control by adding new lines.
Figure 12.18 Typical voltage profile of a system at heavy and light loads [122].
Figure 12.19 Main steps for determining the feeder nodes using voltage regulator.
Figure 12.20 Voltage profile along a feeder with capacitors.
Figure 12.21 Overvoltages created by overcompensation.
Figure 12.22 Voltage-phasor diagrams for a feeder circuit of lagging power factor without (a, c) (a) and with (b, d) shunt capacitors.
Figure 12.23 Voltage divider model.
Figure 12.24 The voltage waveform at DP.
Figure 12.25 (a) Voltage sag (rms values). (b) Voltage sag (peak values).
Figure 12.26 rms voltage values versus time in cycles. (a) At window-length = one half cycle. (b) At window-length = one quarter cycle.
Figure 12.27 Sag type A. (a) Voltage phasor diagram; (b) voltage waveform. (- - - - - -), voltage before the fault (––––) voltage after the fault.
Figure 12.28 Sag type B. (a) Voltage phasor diagram; (b) voltage waveform, (- - - - - -), voltage before the fault; (––––) voltage after the fault.
Figure 12.29 Sag type C. (a) Voltage phasor diagram; (b) voltage waveform, (- - - - - -), voltage before the fault; (––––) voltage after the fault.
Figure 12.30 Sag type D. (a) Voltage phasor diagram; (b) voltage waveform, (- - - - - -), voltage before the fault; (––––) voltage after the fault.
Figure 12.31 Sag type E. (a) Voltage phasor diagram; (b) voltage waveform, (- - - - - -), voltage before the fault; (––––) voltage after the fault.
Figure 12.32 Sag type F. (a) Voltage phasor-diagram; (b) voltage waveform, (- - - - - -), voltage before the fault; (––––) voltage after the fault.
Figure 12.33 Sag type G. (a) Voltage phasor-diagram; (b) voltage waveform, (- - - - - -), voltage before the fault; (––––) voltage after the fault.

Chapter 13

Figure 13.1 Current components.
Figure 13.2 Power triangle.
Figure 13.3 Apparent power at ϕ₁ and ϕ₂.
Figure 13.4 Apparent current at ϕ₁ and ϕ₂.
Figure 13.5 Percentage reduction of line losses versus PF at constant active power.
Figure 13.6 Percentage increase in power transmitted versus PF at constant active losses.
Figure 13.7 The increase of active power.
Figure 13.8 Supplying a load without compensation.
Figure 13.9 Supplying a load with compensation.
Figure 13.10 Determination of Q_C.
Figure 13.11 Compensation modes.
Figure 13.12 Fixed compensation.
Figure 13.13 Automatic compensation.

Chapter 14

Figure 14.1 Distorted current wave form and its components [141].
Figure 14.2 Example of a load drawing a nonsinusoidal current from the supply.
Figure 14.3 Line-current i_line(t) flowing in the supply branch of the six-pulse thyristor bridge [146].
Figure 14.4 Comparison of current waveform i_line(t) with the waveform i₁(t) + i_h₅(t) [146].
Figure 14.5 Comparison of the current waveform i_line(t) with the waveform (i₁(t) + i_h₅(t) + i_h₇(t)) [146].
Figure 14.6 Schematic representation of the harmonic flow for the thyristor bridge load.
Figure 14.7 Representation of the current harmonics in the time domain (left) and in the frequency domain (spectrum) (right).
Figure 14.8 Illustration of the nonlinear magnetization characteristic of a transformer [146].
Figure 14.9 Single-phase rectifier with smoothing capacitor.
Figure 14.10 Supply voltage and current waveforms characterizing the single-phase rectifier bridge with smoothing capacitor [146].
Figure 14.11 Circuit topology of a three-phase diode with (a) a smoothing reactor and (b) a smoothing capacitor.
Figure 14.12 Line current waveform of a six-pulse diode bridge with (a) a smoothing reactor and (b) a smoothing capacitor.
Figure 14.13 Line current waveform of 12- and 24 pulse drive [146].
Figure 14.14 (a) Single-line diagram of an installation containing a drive, (b) corresponding equivalent diagram for one harmonic frequency.
Figure 14.15 (a) Single-line diagram of an installation containing a drive, a capacitor bank, (b) corresponding equivalent diagram for one harmonic frequency.
Figure 14.16 Impedance-versus-harmonic order graph for a parallel impedance topology.
Figure 14.17 (a) Single-line diagram of an installation with a capacitor bank connected to distorted supply, (b) equivalent diagram for harmonic studies.
Figure 14.18 Impedance versus frequency for a series impedance topology.
Figure 14.19 Single-line diagram showing the supply circuit impedance for h-order harmonic.
Figure 14.20 A distribution system connected to nonlinear load (a) flow of fundamental current, (b) flow of harmonic currents.
Figure 14.21 Flow of harmonic currents in a distribution system.
Figure 14.22 Evolution of the increase in peak value and the rms value of a waveform as more harmonic components are added [146].
Figure 14.23 Illustration of the addition of zero-sequence harmonics in the neutral.
Figure 14.24 Frequency spectrum of a square-wave signal.
Figure 14.25 Variation of PF versus THD_I.

Chapter 15

Figure 15.1 Disturbing load far from sensitive load.
Figure 15.2 Grouping of disturbing loads.
Figure 15.3 Supplying the loads from different sources.
Figure 15.4 Δ – Y – Δ prevents h₅ and h₇ propagation.
Figure 15.5 Passive filtering of harmonics.
Figure 15.6 Equivalent circuit for passive harmonic filtering.
Figure 15.7 Active filter installation (I_s = source current, I_act = current injected by active filter, I_har = harmonic current generated by nonlinear load).
Figure 15.8 Hybrid filter installation.
Figure 15.9 Main procedures of solution cycle.
Figure 15.10 Fixed shunt capacitor installation at motors with variable frequency drives VFD.
Figure 15.11 A network with shunt capacitor and its equivalent circuit (I_h = harmonic current).
Figure 15.12 Equivalent circuit of harmonics current flow.
Figure 15.13 Network detuning.
Figure 15.14 Pipe welding machine.
Figure 15.15 Plant electric distribution system.
Figure 15.16 Weld profile at different parameters [159].
Figure 15.17 Voltage and current: waveforms and spectrum (real measurements recorded during system operation). (a) Mains voltage and current (zoom); (b) voltage spectrum; (c) current spectrum.
Figure 15.18 A hybrid filter connected to a network.
Figure 15.19 Internal circuit diagram and installation of the active filter AccuSine®.
Figure 15.20 Construction of AccuSine® filter (Reprint permission by Square-D).
Figure 15.21 (a) Nonlinear load current waveform; (b) waveform injected by filter; (c) corrected current waveform.
Figure 15.22 (a) Nonlinear load current waveform with poor PF. (b) Corrected current waveform with imposed PF and harmonic reduction after filter installation.
Figure 15.23 (a) Inrush current without filter installation. (b) Inrush current with filter installation (real measurements recorded before and after filter installation).
Figure 15.24 Compensation and load variation versus time in cycles (results of HVC installation).
Figure 15.25 Schematic diagram of utility supply to SCCT.
Figure 15.26 Voltage increase after connection of capacitor banks at 14:00 p.m. (maximum value: 301 V; minimum value: 279 V). (–––), Voltage of phase #1, (- - - -), voltage of phase #2, (– –), voltage of phase #3.
Figure 15.27 PF goes leading after connection of capacitor banks at 14:00 p.m. (maximum value: 0.00; minimum value: − 0.01).
Figure 15.28 PF of each phase with no PF correction (average value: 0.78 lag). (—–), PF: phase #1; (– –), PF: phase #2; (— - -), PF: phase #3.
Figure 15.29 Total voltage and current harmonic distortion (%THD_V and %THD_I) for one crane with no PF correction. The maximum and minimum values of %THD_V are 5.7 and 0.0, respectively.
Figure 15.30 THD_V and THD_I before and after PF capacitors were added at 14:00 p.m. (maximum %THD_V: 19.5, minimum %THD_V: 1.9).
Figure 15.31 rms values of phase voltage and current, before and after PF capacitors were added at 14:00 p.m.
Figure 15.32 Phase voltage (at MV side) 14:55 switchover to AccuSine from PF capacitors (max. value: 12915 V; min. value: 12033 V).
Figure 15.33 %THD_V and %THD_I with AccuSine activated at 14:55 p.m.
Figure 15.34 Parallel operation of three AFs.
Figure 15.35 Two AFs in cascade configuration.
Figure 15.36 An AF for several feeders.
Figure 15.37 Three possible points of connection.

Chapter 16

Figure 16.1 Load shape for standard DSM load management.
Figure 16.2 (a) Domestic system peak forecast before DSM. (b) Domestic system peak growth rate forecast with DSM [171].
Figure 16.3 Flowchart of DSM planning process.
Figure 16.4 Energy distributions as percentage [174]. (a) Energy consumption distribution. (b) Light energy distribution.
Figure 16.5 Efficiency of different light sources.
Figure 16.6 Motor characteristics [174]. (a) Motor losses versus load. (b) Motor efficiency versus load.
Figure 16.7 Allowable number of switching versus motor rated power [174].
Figure 16.8 Energy conversion systems for different heating methods.
Figure 16.9 The main parts of a centrifugal pump [180].
Figure 16.10 Main elements of pump specification.
Figure 16.11 Pump characteristic (a) at H_st= 0, and (b) at H_st > 0.
Figure 16.12 Pump power consumption vs. flow rate [180].
Figure 16.13 Pump operating point at different static heads.
Figure 16.14 Pump characteristic when throttling the output by a valve.
Figure 16.15 Pump characteristic when bypassing by a valve.
Figure 16.16 Pump characteristic with on–off control.
Figure 16.17 Pump power consumption.
Figure 16.18 Pump characteristic with speed control.
Figure 16.19 Characteristics of two pumps in parallel.
Figure 16.20 Characteristics of two pumps in series.
Figure 16.21 Pump characteristic at different methods of flow rate control. (a) Throttle control; (b) bypassing; (c) on–off control; (d) variable speed control.

Chapter 17

Figure 17.1 Schematic drawing of main lines of feeding a commercial building.
Figure 17.2 Protection mechanism.
Figure 17.3 Testing of relay by using a simulator. V = voltage; I = current; f = frequency.
Figure 17.4 Elements of a SCADA system.
Figure 17.5 Remote-terminal unit: inputs/outputs.
Figure 17.6 Frequency-division multiplexing.
Figure 17.7 Time-division multiplexing.
Figure 17.8 MTU inputs/outputs.
Figure 17.9 Monolithic SCADA architecture.
Figure 17.10 Distributed SCADA architecture.
Figure 17.11 Networked SCADA architecture.
Figure 17.12 Substation with distributed SCADA and automation systems.
Figure 17.13 A SCADA system for a commercial office building.
Figure 17.14 Application of SCADA system to power-factor correction system.

Chapter 18

Figure 18.1 Power system arrangements with distributed generation [198].
Figure 18.2 Utility and DG interconnected system.
Figure 18.3 Line-to-earth fault contribution of a DG unit [202].
Figure 18.4 Loads subjected to line voltage during line-to-earth fault [202].
Figure 18.5 Microturbine systems.
Figure 18.6 Generator interconnection to local loads or utility grid.
Figure 18.7 Block diagram of microturbine and control system.
Figure 18.8 Power-speed characteristic of microturbines.
Figure 18.9 San Gorgino wind farm, Palm Springs, California, USA.
Figure 18.10 Typical speed-power curve of one MW wind turbine.
Figure 18.11 Rotor efficiency vs. λ.1 = rotor with two blades;2 = rotor with three blades; 3 = rotor with four blades; 4 = rotor with six blades; and 5 = rotor with multiple blades.
Figure 18.12 Wind turbine installations.
Figure 18.13 Wind energy conversion supplying a water pumping system.
Figure 18.14 Configuration of a rectangular-array wind farm.
Figure 18.15 Solar cells module for small power applications.
Figure 18.16 PV system feeding a DC consumer's load.
Figure 18.17 PV system feeding an AC consumer's load.
Figure 18.18 PV system associated with auxiliary source.
Figure 18.19 PV system connected to LV utility grid.
Figure 18.20 PV system connected to LV utility grid and feeding local loads.
Figure 18.21 Schematic diagram for an array consisting of two parallel strings, each composed of three series modules.
Figure 18.22 Equivalent circuits for (a) a PV cell and (b) an array.
Figure 18.23 Current–voltage curves for (a) a PV cell and (b) an array.
Figure 18.24 Typical I-V and power output curves for a PV system.
Figure 18.25 Passive glycol solar thermal system.
Figure 18.26 Active glycol solar thermal system (active indirect system).
Figure 18.27 Main outline of a solar power plant.
Figure 18.28 Physical structure and chemical reactions in an FC with acid electrolyte.
Figure 18.29 Fuel cell simple equivalent circuit.
Figure 18.30 Main components of diesel-generator set.
Figure 18.31 Per-phase equivalent circuit of an asynchronous induction generator.
Figure 18.32 US DG installed base (2003) [215].
Figure 18.33 US distributed generation capacity by application and interconnection status [215].
Figure 18.34 Availability of DG units as a function of number of units [215].
Figure 18.35 A comparison of availability factors for DG equipment and central station equipment (Source: NERC GAR 1997-2001) [215].
Figure 18.36 Electric demand flow diagram [215].
Figure 18.37 Comparison of projected load on a feeder with and without the addition of DG [215].
Figure 18.38 Line loading and reactive power losses [215]

Chapter 19

Figure 19.1 Remote house fed by renewable energy. (a) Physical illustration, (b) schematic line diagram.
Figure 19.2 Typical daily load curve [224].
Figure 19.3 Schematic diagram of SMES system.
Figure 19.4 Schematic diagram of a DLC structure.
Figure 19.5 Pumping hydro storage system.
Figure 19.6 Hydro power plant model [229].
Figure 19.7 Schematic diagram of CAES system.
Figure 19.8 Main components of a FES system.
Figure 19.9 Daily load curve without and with TES.
Figure 19.10 Schematic diagram of TES process.
Figure 19.11 Typical ESS ratings for application classes [224].

Chapter 20

Figure 20.1 DERs supplying a load (RES = renewable energy source, N-RES = nonrenewable energy source).
Figure 20.2 Schematic diagram for microgrid structure.
Figure 20.3 Performance of a PV plant with ESS.
Figure 20.4 MG with CMC unit and LCs.
Figure 20.5 Hierarchical control levels for utility grid connected to multiple MGs.
Figure 20.6 Layout of MG connected to utility grid.
Figure 20.7 Inverter-based DG unit with P-Q control scheme.
Figure 20.8 Inverter-based DG unit with CC scheme.
Figure 20.9 Microgrid response with master–slave control to five-cycle fault resulting in islanding. (a) PCC voltage, pu, (b) Frequency, Hz, (c) IM speed, r/min, (d) IM electromagnetic torque, N.m., (e) synchronous DG reactive power, pu, (f) inverter DG reactive power, pu, (g) synchronous generator speed, pu, and (h) IM reactive power.
Figure 20.10 Microgrid response with droop control to five-cycle fault resulting in islanding. (a) PCC voltage, (b) frequency, (c) IM speed, (d) IM electromagnetic torque, (e) synchronous DG reactive power, (f) inverter DG reactive power, (g) synchronous generator speed and (h) IM reactive power.
Figure 20.11 Microgrid response with droop control approach–based P-Q control. (a) PCC voltage, pu, (b) frequency, Hz, and (c) IM speed, r/min.
Figure 20.12 Microgrid response with droop control approach–based current control. (a) PCC voltage, pu, (b) frequency, Hz, and (c) IM speed, r/min.
Figure 20.13 Microgrid voltage waveform under inverter-based current-control scheme for 124 ms three-phase fault, resulting in islanding.
Figure 20.14 Frequency spectrum of microgrid load voltage under inverter-based P-Q control scheme. (a) Grid-connected, (b) island mode.
Figure 20.15 Frequency spectrum of microgrid load voltage under inverter-based current-control scheme. (a) Grid-connected, (b) island mode.
Figure 20.16 Various types of communication systems.
Figure 20.17 Perspective of a smart distribution system of the future.

Appendix A

Figure A.1 Schematic layout and parameters of the diesel generator governor model [274].

PREFACE

THANKS TO THE VERY GOOD response received by the first edition of this book, the authors were encouraged to revise and prepare a second edition. In taking advantage of this opportunity, the first edition has been thoroughly revised from the perspectives of

having a critical look at the organization and structure of the first edition, and
the inclusion of new developments that have taken place since the first edition was prepared.

Although the basic objective of the book remains the same as described in the preface to the first edition and the material is still grouped in five parts, the original edition had 14 chapters, whereas the new edition has 20 chapters. Some of the new chapters are the result of re-arrangement of the material in the original book, while the rest contain new material. A brief description of the five parts highlighting the changes is given in what follows.

PART I: FUNDAMENTAL CONCEPTS

The background and power system structure, in addition to the layout of the distribution system for both small and large distribution systems, is presented as an introduction in Chapter 1. The fundamental concepts of distribution systems are now the subject of Chapters 2 and 3. The duties of distribution engineers including the factors affecting the planning process are introduced here. It is aimed at identifying the key steps in planning. Examples of structures used in distribution systems at medium and low voltages are presented.

Definitions of load forecast terms and different methods of estimating the demand forecast with application examples are now explained in Chapter 4.

PART II: PROTECTION AND SWITCHGEAR

Earthing, protection schemes and distribution switchgear are included in this part. Various methods of earthing, as the protection system is based on it, are explained in Chapter 5. Computation of short-circuit current, on which the design of protection is based, is presented in Chapter 6. General description of the types of protection schemes in distribution systems is now split and is presented in Chapters 7 and 8.

Details about switchgear devices and switchgear installation, including the major factors affecting the design of switchboards, have also been reorganized in Chapters 9 and 10, respectively.

PART III: POWER QUALITY

The key elements of quality of power supply (voltage quality, power factor and harmonics) and means of their improvement are now explained in Chapters 11 through 15 with relatively minor revisions to the material in the original edition.

PART IV: MANAGEMENT AND AUTOMATION

Reliability, economics, investment aspects and methodologies applied to improve the performance of the distribution systems are explained in Chapter 16 by applying demand-side management and energy-efficiency policies.

The difference between system automation and monitoring, using supervisory control and data acquisition (SCADA) systems, and the conditions of using various architectures are given in Chapter 17. In addition, the role of SCADA to modernize the distribution system to become a smart grid is illustrated.

PART V: DISTRIBUTED ENERGY RESOURCES AND MICROGRIDS

Various types of distributed energy sources and the corresponding effect of integrating these sources with the distribution system are described in Chapter 18.

Energy storage systems are required to meet the intermittency of the power source when using solar or wind sources and to provide added benefits such as improved control, power quality, dynamic and transient stability, reliability and satisfactory operation. Various types of energy storage systems that can be used for this purpose are discussed in Chapter 19.

The integration of distributed generation, energy storage systems and consumption into one system, commonly referred to as a microgrid, in addition to the recent trend to modernize it to become a smart grid, is illustrated in Chapter 20.

Electric power distribution systems cover a broad spectrum of topics. To keep the overall length of the book within a reasonable limit, many of these topics are, per force, not covered in depth. However, all material is supported by an extensive list of references from which the interested reader can get more details for an in-depth study.

ABDELHAY A. SALLAM

OM P. MALIK

IEEE Press 445 Hoes Lane Piscataway, NJ 08854
IEEE Press Editorial Board Ekram Hossain, Editor in Chief
Giancarlo Fortino	Andreas Molisch	Linda Shafer
David Alan Grier	Saeid Nahavandi	Mohammad Shahidehpour
Donald Heirman	Ray Perez	Sarah Spurgeon
Xiaoou Li	Jeffrey Reed	Ahmet Murat Tekalp