Energy Processing and Smart Grid
Description
This book provides an overview of how multiple sources and loads are connected via power electronic devices. Issues of storage technologies are discussed, and a comparison summary is given to facilitate the design and selection of storage types. The need for real-time measurement and controls are pertinent in future grid, and this book dedicates several chapters to real-time measurements such as PMU, smart meters, communication scheme, and protocol and standards for processing and controls of energy options.
Organized into nine sections, Energy Processing for the Smart Grid gives an introduction to the energy processing concepts/topics needed by students in electrical engineering or non-electrical engineering who need to work in areas of future grid development. It covers such modern topics as renewable energy, storage technologies, inverter and converter, power electronics, and metering and control for microgrid systems. In addition, this text:
* Provides the interface between the classical machines courses with current trends in energy processing and smart grid
* Details an understanding of three-phase networks, which is needed to determine voltages, currents, and power from source to sink under different load models and network configurations
* Introduces different energy sources including renewable and non-renewable energy resources with appropriate modeling characteristics and performance measures
* Covers the conversion and processing of these resources to meet different DC and AC load requirements
* Provides an overview and a case study of how multiple sources and loads are connected via power electronic devices
* Benefits most policy makers, students and manufacturing and practicing engineers, given the new trends in energy revolution and the desire to reduce carbon output
Energy Processing for the Smart Grid is a helpful text for undergraduates and first year graduate students in a typical engineering program who have already taken network analysis and electromagnetic courses.
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Person
JAMES A. MOMOH, PHD, is a Fellow at the Institute of Electronics and Electrical Engineering (IEEE) and a Distinguished Fellow at the Nigerian Society of Engineers (NSE). His current research activities for utility firms and government agencies span several areas in systems engineering, optimization, and energy systems control of terrestrial, space and naval complex and dynamic networks. Momoh was Chair of the Electrical Engineering Department at Howard University and Director of the Center for Energy Systems and Control.
Content
PREFACE xi
ACKNOWLEDGMENTS xiii
FOREWORD xv
CHAPTER 1 INTRODUCTION 1
1.1 Introduction 1
Bibliography 4
CHAPTER 2 ELECTRIC NETWORK ANALYSIS IN ENERGY PROCESSING AND SMART GRID 5
2.1 Introduction 5
2.2 Complex Power Concepts 5
2.3 Review of AC-Circuit Analysis Using Phasor Diagrams 8
2.4 Polyphase Systems 9
2.5 Three-Phase Loads with Impedence Loads 13
2.6 Transformation of Y to Delta and Delta to Y 17
2.7 Summary of Phase and Line Voltages/Currents for Balanced Three-Phase Systems 19
2.8 Per-Unit Systems 22
2.9 Chapter Summary 27
Exercises 27
Bibliography 29
CHAPTER 3 MAGNETIC SYSTEMS FOR ENERGY PROCESSING 31
3.1 Introduction 31
3.2 Magnetic Fields 31
3.3 Equivalent Magnetic and Electric Circuits 34
3.4 Overview of Magnetic Materials 35
3.5 Hysteresis Loops and Hysteresis Losses in Ferromagnetic Materials 35
3.6 Definitions 38
3.7 Magnetic Circuit Losses 38
3.8 Producing Magnetic Flux in Air Gap 40
3.9 Rectangular-Shaped Magnetic Circuits 41
3.10 Chapter Summary 45
Exercises 45
Bibliography 47
CHAPTER 4 TRANSFORMERS 49
4.1 Introduction 49
4.2 First Two Maxwell's Laws 50
4.3 Transformers 51
4.4 Ideal Single-Phase Transformer Models 56
4.5 Modeling a Transformer into Equivalent Circuits 59
4.6 Transformer Testing 65
4.7 Transformer Specifications 71
4.8 Three-Phase Power Transformers 72
4.9 New Advances in Transformer Technology: Solid-State Transformers 72
4.10 Chapter Summary 78
Exercises 78
Bibliography 82
CHAPTER 5 INDUCTION MACHINES 83
5.1 Introduction 83
5.2 Construction and Types of Induction Motors 83
5.3 Operating Principle 85
5.4 Basic Induction-Motor Concepts 86
5.5 Induction-Motor Slip 88
5.6 Rotor Current and Leakage Reactance 88
5.7 Rotor Copper Loss 91
5.8 Developing the Equivalent Circuit of Polyphase, Wound-Rotor Induction Motors 92
5.9 Computing Corresponding Torque of Induction Motors 96
5.10 Approximation Model for Induction Machines 97
5.11 Speed Control of Induction Motors 100
5.12 Application of Induction Motors 101
5.13 induction-Generator Principles 101
5.14 Chapter Summary 103
Exercises 104
Bibliography 106
CHAPTER 6 SYNCHRONOUS MACHINES 107
6.1 Introduction 107
6.2 Synchronous-Generator Construction 107
6.3 Exciters 108
6.4 Governors 110
6.5 Synchronous Generator Operating Principle 110
6.6 Equivalent Circuit of Synchronous Machines 112
6.7 Synchronous Generator Equivalent Circuits 113
6.8 Over Excitation and Under Excitation 114
6.9 Open-Circuit and Short-Circuit Characteristics 115
6.10 Performance Characteristics of Synchronous Machines 118
6.11 Generator Compounding Curve 122
6.12 Synchronous Generator Operating Alone: Concept of Infinite Bus 122
6.13 Initial Elementary Facts about Synchronous Machines 123
6.14 Cylindrical-Rotor Machines for Turbo Generators 125
6.15 Synchronous Machines with Effects of Saliency: Two-Reactance Theory 125
6.16 The Salient-Pole Machine 126
6.17 Synchronous Motors 128
6.18 Synchronous Machines and System Stability 131
6.19 Chapter Summary 135
Exercises 136
Bibliography 137
CHAPTER 7 DC MACHINES 139
7.1 Introduction 139
7.2 Conductor Moving in a Uniform Magnetic Field 139
7.3 Current-Carrying Conductor in a Uniform Magnetic Field 139
7.4 DC-Machine Construction and Nameplate Parameters 141
7.5 DC Machine Pertinent Nameplate Parameters 142
7.6 Development and Configuration of Equivalent Circuits of DC Machines 142
7.7 Classification of DC Machines 147
7.8 Voltage Regulation 151
7.9 Power Computation for DC Machines 151
7.10 Power Flow and Efficiency 152
7.11 DC Motors 155
7.12 Computation of Speed of DC Motors 155
7.13 DC-Machine Speed-Control Methods 163
7.14 Ward Leonard System 164
7.15 Chapter Summary 166
Exercises 167
Bibliography 168
CHAPTER 8 PERMANENT-MAGNET MOTORS 169
8.1 Introduction 169
8.2 Permanent-Magnet DC Motors 169
8.3 Permanent-Magnet Synchronous Motors 177
8.4 Variants of Permanent-Magnet Synchronous Motors 186
8.5 Chapter Summary 190
Bibliography 190
CHAPTER 9 RENEWABLE ENERGY RESOURCES 193
9.1 Introduction 193
9.2 Distributed Generation Concepts 193
9.3 DG Benefits 194
9.4 Working Definitions and Classifications of Renewable Energy 195
9.5 Renewable-Energy Penetration 218
9.6 Maximum Penetration Limits of Renewable-Energy Resources 218
9.7 Constraints to Implementation of Renewable Energy 219
Exercises 221
Bibliography 222
CHAPTER 10 STORAGE SYSTEMS IN THE SMART GRID 223
10.1 Introduction 223
10.2 Forms of Energy 223
10.3 Energy Storage Systems 223
10.4 Cost Benefits of Storage 239
10.5 Chapter Summary 244
Bibliography 244
CHAPTER 11 POWER ELECTRONICS 247
11.1 Introduction 247
11.2 Power Systems with Power Electronics Architecture 248
11.3 Elements of Power Electronics 249
11.4 Power Semiconductor Devices 249
11.5 Applications of Power Electronics Devices to Machine Control 276
11.6 Applications of Power Electronics Devices to Power System Devices 280
11.7 Applications of Power Electronics to Utility, Aerospace, and Shipping 281
11.8 Facts 282
11.9 Chapter Summary 286
Bibliography 287
CHAPTER 12 CONVERTERS AND INVERTERS 289
12.1 Introduction 289
12.2 Definitions 289
12.3 DC-DC Converters 290
12.4 Inverters 296
12.5 Rectifiers 301
12.6 Applications 312
12.7 Chapter Summary 320
Exercises 320
Bibliography 322
CHAPTER 13 MICROGRID APPLICATION DESIGN AND TECHNOLOGY 323
13.1 Introduction to Microgrids 323
13.2 Types of Microgrids 324
13.3 Microgrid Architecture 325
13.4 Modeling of a Microgrid 330
13.5 Chapter Summary 332
Bibliography 333
CHAPTER 14 MICROGRID OPERATIONAL MANAGEMENT 335
14.1 Perfomance Tools of a Microgrid 335
14.2 Microgrid Functions 337
14.3 IEEE Standards for Microgrids 344
14.4 Microgrid Benefits 346
14.5 Chapter Summary 349
Bibliography 349
CHAPTER 15 THE SMART GRID: AN INTRODUCTION 351
15.1 Evolution, Drivers, and the Need for Smart Grid 351
15.2 Comparison of Smart Grid with the Current Grid System 352
15.3 Architecture of a Smart Grid 353
15.4 Design for Smart-Grid Function for Bulk Power Systems 353
15.5 Smart-Grid Challenges 362
15.6 Design Structure and Procedure for Smart-Grid Best Practices 363
15.7 Chapter Summary 365
Bibliography 365
CHAPTER 16 SMART-GRID LAYERS AND CONTROL 367
16.1 Introduction 367
16.2 Controls for the Smart Grid 367
16.3 Layers of Smart Grid Within the Grid 373
16.4 Command, Control, and Communication Applications in Real Time 390
16.5 Hardware-in-the-Loop for Energy Processing and the Smart Grid 394
16.6 Evolution of Cyber-Physical Systems 394
16.7 Chapter Summary 396
Bibliography 397
CHAPTER 17 ENERGY PROCESSING AND SMART-GRID TEST BEDS 401
17.1 Introduction 401
17.2 Study of Available Test Beds for the Smart Grid 401
17.3 Smart Microgrid Test-Bed Design 403
17.4 Smart-Grid Test Beds 404
17.5 Smart-Grid Case Studies 405
17.6 Simulation Tools, Hardware, and Embedded Systems 408
17.7 Limitations of Existing Smart-Grid Test Beds 411
17.8 Chapter Summary 412
Bibliography 412
INDEX 415
CHAPTER 2
ELECTRIC NETWORK ANALYSIS IN ENERGY PROCESSING AND SMART GRID
2.1 INTRODUCTION
In modern AC electric power systems (Figure 2.1), power is generated, transmitted, and distributed as balanced, three-phase AC. The three-phase system was independently invented by Galileo Ferraris, Mikhail Dolivo-Dobrovolsky, Jonas Wenström, and Nikola Tesla in the 1880s and is the most widely used means of transferring power through power grids. The three-phase system has the advantage of economy over the single-phase system because more power can be transmitted with significant cost savings in conductors per unit line length. The three-phase system may be configured as three-wire star, four-wire star, or three-wire delta system.
Figure 2.1 Simplified single-line diagram schematics of a modern electric power system.
Because of advances in electronics, the future electric power system is headed in the direction of microgrids and smart grids. In anticipation of demands, researchers and students need to be equipped with relevant knowledge on the emerging trends in this area. This chapter introduces the fundamentals of electric power systems and the basic computational tools needed for the design and analysis of the future-generation power system.
2.2 COMPLEX POWER CONCEPTS
In electrical power systems, we are mainly concerned with flow in the electrical circuit, such as Voltage (V), Frequency (f), Current (I), and Power (P). To treat sinusoidal, steady-state behavior of an electric current, some further definitions are necessary.
Let
(2.1)and
(2.2)and
(2.3)where
(2.4)In polar form,
(2.5)or
(2.6)It is important to recall the following trigonometric identities:
(2.7) (2.8)For a voltage signal represented in terms of root mean square (rms) value:
(2.9) (2.10) (2.11) (2.12)For impedance, if the circuit is purely resistive, inductive, or capacitive, there will be difference in current and angle phase shift.
2.2.1 Purely Resistive Circuit
In a purely resistive circuit, Figure 2.2, the current is in phase with voltage:
(2.13)Figure 2.2 Phasor diagram of a purely resistive circuit.
2.2.2 Purely Inductive Circuit
Current lags behind V by 90° as seen in Figure 2.3:
(2.14)Figure 2.3 Phasor diagram of purely inductive circuit.
2.2.3 Purely Capacitive Circuit
In a purely capacitive circuit Figure 2.4, current leads voltage by 90°:
(2.15)Figure 2.4 Phasor diagram of a purely capacitive circuit.
2.2.4 Instantaneous Power
The instantaneous power is given by:
(2.16) (2.17) (2.18) (2.19)where Cos? is the power factor.
2.2.5 Power Factor
The power factor of a system is defined as:
(2.20)where P = VICos? and Q = VISin?.
Q is the reactive power measured in kilo-var (kvar).
2.2.6 Complex Power
The apparent power S is then:
(2.21) (2.22)and
(2.23) (2.24)If the load impedance is Z, then,
(2.25)In terms of load admittance,
(2.26) (2.27)2.3 REVIEW OF AC-CIRCUIT ANALYSIS USING PHASOR DIAGRAMS
Consider the AC circuit of Figure 2.5. The load, operating at a voltage VL, draws a current IL from the source whose voltage is Vs, through resistance R and inductive reactance jX.
Figure 2.5 AC circuit analysis with phasor diagram.
By Kirchhoff's voltage rule:
(2.28) (2.29)where
(2.30) (2.31)If the load is operated at power factor Cos? and voltage VL then
(2.32) (2.33)Then Equation 2.29 may be rewritten as:
(2.34) (2.35)A phasor diagram Figure 2.6 may be constructed based on Equation 2.35 from which the source voltage Vs may be determined.
Figure 2.6 Phasor relationships of power system quantities.
2.4 POLYPHASE SYSTEMS
One of the methods of transmitting and distributing AC electric power is by means of polyphase systems. This is a system with three or more energized AC currents carrying conductors with a phase deviation between them. For a balanced n-phase system, the phase difference is given by:
(2.36)For two-, three- . six-phase systems, voltages will be out of phase by 90°, 120°, .60°, respectively.
Polyphase systems are particularly useful for transmitting power as more power can be transmitted than when a single phase is used.
2.4.1 Three-Phase Circuits
Power generation, transmission, and distribution are usually connected in a type of polyphase system for heavy utilization of AC electric power. These types of connections provide economic advantages as well as system stability and capacity control. Both voltage and currents are sinusoidal waveforms equal in magnitude, but are displaced from one another by 120° in time phase. Stator windings are connected in three-phase through a ground wire, leading to four wires. The center of the four wires (Figure 2.7) leads to a Y-connected system, where each is referred to as a phase and the fourth conductor is called the neutral wire, which has four-wire balanced connection.
Figure 2.7 Equivalent Y diagram.
2.4.2 Balanced Y-Connected Three-Phase Source
In vector (phasor) form
(2.37) (2.38) (2.39) (2.40) (2.41) (2.42)Similarly, for ?-connected system
(2.43)2.4.3 Phase and Line Voltages: Delta Connected
The line-neutral and line-line voltages with proper relations are shown in Figure 2.8.
Figure 2.8 Phase and line voltage representation.
(2.44)Line-Neutral, VBA leads VNA by 30°, VCB leads VNB by 30°.
2.4.4 Equivalent Y-Connected Voltage Phasor Representation
Taking VNA as a reference from Figure 2.9,
Figure 2.9 Equivalent Y-connected voltage phasor representation.
(2.45) (2.46) (2.47)2.4.5 Mesh or Delta Connection
(2.48) (2.49) (2.50)
These connections are not properly balanced to maintain balanced voltage across each load. A delta-connected generator Figure 2.10 is possible but not desirable for two main reasons:
- Grounding is not possible with a delta-connected generator. For safety, a generator-neutral point typical of Y is the logical point of connection to ground.
- A delta connection of the coils of the generator provides a short-circuited path in which current can flow. Third harmonics in the coil voltages cause a disturbance, which produces power loss and lowers the efficiency of the generator.
Figure 2.10 Mesh or delta connection.
2.5 THREE-PHASE IMPEDENCE LOADS
A delta-connected load or Y-connected load (Figure 2.11) uses the same configuration as discussed in Section 2.8.
Figure 2.11 Delta-connected three-phase loads.
(2.51) (2.52) (2.53)From which the individual phase currents may be computed as
(2.54) (2.55) (2.56)The line currents...
