Smart Grid E-Book

Stephen F. Bush

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Wiley - IEEE
• Sprache: Englisch

Seitenzahl: 1275

Veröffentlichungsjahr: 2014

Beschreibung

This book bridges the divide between the fields of power systems engineering and computer communication through the new field of power system information theory.

Written by an expert with vast experience in the field, this book explores the smart grid from generation to consumption, both as it is planned today and how it will evolve tomorrow. The book focuses upon what differentiates the smart grid from the "traditional" power grid as it has been known for the last century. Furthermore, the author provides the reader with a fundamental understanding of both power systems and communication networking. It shows the complexity and operational requirements of the evolving power grid, the so-called "smart grid," to the communication networking engineer; and similarly, it shows the complexity and operational requirements for communications to the power systems engineer.

The book is divided into three parts. Part One discusses the basic operation of the electric power grid, covering fundamental knowledge that is assumed in Parts Two and Three. Part Two introduces communications and networking, which are critical enablers for the smart grid. It also considers how communication and networking will evolve as technology develops. This lays the foundation for Part Three, which utilizes communication within the power grid. Part Three draws heavily upon both the embedded intelligence within the power grid and current research, anticipating how and where computational intelligence will be implemented within the smart grid. Each part is divided into chapters and each chapter has a set of questions useful for exercising the readers' understanding of the material in that chapter.

Key Features:

• Bridges the gap between power systems and communications experts
• Addresses the smart grid from generation to consumption, both as it is planned today and how it will likely evolve tomorrow
• Explores the smart grid from the perspective of traditional power systems as well as from communications
• Discusses power systems, communications, and machine learning that all define the smart grid
• It introduces the new field of power system information theory

Leseprobe

Contents

Cover

Title Page

Copyright Page

About the Author

Preface

Objective

Genesis

Approach and Content

Acknowledgements

Acronyms

Part One: Electric Power Systems: The Main Component

1: Introduction to Power Systems Before Smart Grid

1.1 Overview

1.2 Yesterday’s Grid

1.3 Fundamentals of Electric Power

1.4 Case Studies: Postmortem Analysis of Blackouts

1.5 Drivers Toward the Smart Grid

1.6 Goals of the Smart Grid

1.7 A Few Words on Standards

1.8 From Energy and Information to Smart Grid and Communications

1.9 Summary

1.10 Exercises

2: Generation

2.1 Introduction to Generation

2.2 Centralized Generation

2.3 Management and Control: Introducing Supervisory Control and Data Acquisition Systems

2.4 Energy Storage

2.5 Summary

2.6 Exercises

3: Transmission

3.1 Introduction

3.2 Basic Power Grid Components

3.3 Classical Power Grid Analytical Techniques

3.4 Transmission Challenges

3.5 Wireless Power Transmission

3.6 Summary

3.7 Exercises

4: Distribution

4.1 Introduction

4.2 Protection Techniques

4.3 Conservation Voltage Reduction

4.4 Distribution Line Carrier

4.5 Summary

4.6 Exercises

5: Consumption

5.1 Introduction

5.2 Loads

5.3 Variability in Consumption

5.4 The Consumer Perspective

5.5 Visibility

5.6 Flexibility for the Consumer

5.7 Summary

5.8 Exercises

Part Two: Communication and Networking: The Enabler

6: What is Smart Grid Communication?

6.1 Introduction

6.2 Energy and Information

6.3 System View

6.4 Power System Information Theory

6.5 Communication Architecture

6.6 Wireless Communication Introduction

6.7 Summary

6.8 Exercises

7: Demand-Response and the Advanced Metering Infrastructure

7.1 Introduction

7.2 Demand-Response

7.3 Advanced Metering Infrastructure

7.4 IEEE 802.15.4, 6LoWPAN, ROLL, and RPL

7.5 IEEE 802.11

7.6 Summary

7.7 Exercises

8: Distributed Generation and Transmission

8.1 Introduction

8.2 Distributed Generation

8.3 The Smart Power Transmission System

8.4 Wireless Power Transmission

8.5 Wide-Area Monitoring

8.6 Networked Control

8.7 Summary

8.8 Exercises

9: Distribution Automation

9.1 Introduction

9.2 Protection Coordination Utilizing Distribution Automation

9.3 Self-healing, Communication, and Distribution Automation

9.4 Summary

9.5 Exercises

10: Standards Overview

10.1 Introduction

10.2 National Institute of Standards and Technology

10.3 International Electrotechnical Commission

10.4 International Council on Large Electric Systems

10.5 Institute of Electrical and Electronics Engineers

10.6 American National Standards Institute

10.7 International Telecommunication Union

10.8 Electric Power Research Institute

10.9 Other Standardization-Related Activities

10.10 Summary

10.11 Exercises

Part Three: Embedded and Distributed Intelligence for a Smarter Grid: The Ultimate Goal

11: Machine Intelligence in the Grid

11.1 Introduction

11.2. Machine Intelligence and Communication

11.3 Computing Models for Smart Grid

11.4 Machine Intelligence in the Grid

11.5 Machine-to-Machine Communication in Smart Grid

11.6 Summary

11.7 Exercises

12: State Estimation and Stability

12.1 Introduction

12.2 Networked Control

12.3 State Estimation

12.4 Distributed State Estimation

12.5 Stability

12.6 Stability and High-Penetration Distributed Generation

12.7 Summary

12.8 Exercises

13: Synchrophasor Applications

13.1 Introduction

13.2 Synchrophasors

13.3 Phasor Measurement Unit

13.4 Networking Synchrophasor Information

13.5 Synchrophasor Applications

13.6 Summary

13.7 Exercises

14: Power System Electronics

14.1 Introduction

14.2 Power System Electronics

14.3 Power Electronic Transformer

14.4 Protection Devices and Current Limiters

14.5 Superconducting Technologies

14.6 Summary

14.7 Exercises

15: Future of the Smart Grid

15.1 Introduction

15.2 Geomagnetic Storms as Generators

15.3 Future Microgrids

15.4 Nanoscale Communication Networks

15.5 Emerging Technologies

15.6 Near-Space Power Generation

15.7 Summary

15.8 Exercises

Appendix: Smart Grid Simulation Tools

Simulators

OpenDSS

PowerWorld Simulator Version 16

Matpower

Network Simulator: ns-2 and ns-3

GridSim

GridLab-D

References

Index

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Library of Congress Cataloging-in-Publication Data

Bush, Stephen F.    Smart grid – communication-enabled intelligence for the electric power grid / Dr Stephen F. Bush.       pages cm.    Includes bibliographical references and index.    ISBN 978-1-119-97580-9 (hardback)    1. Smart power grids. I. Title.    TK3105.B87 2013    621.319′1–dc23

2013036264

A catalogue record for this book is available from the British Library.

ISBN: 978-1-119-97580-9

About the Author

Stephen F. Bush graduated from Carnegie Mellon University and worked at General Electric Information Services. From there, he obtained his PhD while working as a researcher at the Information and Telecommunications Technologies Center at the University of Kansas, participating in the design of a self-configuring, rapidly deployable, beamforming wireless radio network.

Stephen currently enjoys his role as senior scientist at the General Electric Global Research Center, where he has published numerous conference papers, journal articles, and book chapters, and taught international conference tutorials on novel communication- and network-related topics. His previous book publication, Active Networks and Active Network Management: A Proactive Management Framework, explained the development and operation of the intriguing and controversial active networking paradigm. Dr Bush was presented with a gold cup trophy awarded by Defense Advanced Research Projects Agency (DARPA) for his work in active-network-related research. Dr Bush has been the principal investigator for many DARPA and Lockheed Martin sponsored research projects, including: Active Networking (DARPA/ITO), Information Assurance and Survivability Engineering Tools (DARPA/ISO), Fault-Tolerant Networking (DARPA/ATO), and Connectionless Networks (DARPA/ATO), involving energy-aware sensor networks. Stephen also likes creative interaction with students while teaching Quantum Computation and Communication at the Rensselaer Polytechnic Institute and Computer Communication Networks at the University at Albany. Stephen has written “Nanoscale Communication Networks,” which has helped to define this new field. He is Director of the IEEE Communications Society Standardization Program Development Board and also serves on the IEEE Smart Grid Communications Emerging Technical Subcommittee and is Chair of the IEEE P1906.1 Recommended Practice for Nanoscale and Molecular Communication Framework standards working group. Stephen also served as an IEEE Distinguished Lecturer on Smart Grid Communications.

Preface

Objective

The center of your culture is left without electric power for a few hours only, and all of a sudden crowds of American citizens start looting and creating havoc. The smooth surface film must be very thin. Your social system must be quite unstable and unhealthy.

—Alexander Solzhenitsyn at Harvard Class Day Afternoon Exercises

Thursday, June 8, 1978

It is natural for the reader who is not fully versed in both power systems and communications to be curious about many aspects of the evolving technologies. For example, how did power systems and communication develop to their present states where something like the term “smart grid” could be coined? Certainly power systems and communications are both offshoots of electrical engineering and both involve the manipulation of power. Why have the two fields diverged so radically? Thinking about these questions leads to more fundamental questions. What is the relationship between electric power and information? And more specifically, what is the fundamental relationship between power systems and communication theory? Thinking about these questions helps us address more practical questions. What are the potential impacts of communication on efficiency in electric power transmission and distribution efficiency? What types of communication are most appropriate for different portions of the power grid? It is also intriguing to consider the more distant future. What will the power grid look like in the decades to come? How could wireless power transmission revolutionize the power grid? What are the fundamental limiting factors? Is there a fundamental limit to the amount of distributed generation that is possible and, if so, how can this limit be overcome? Will communication in the power grid really enable more consumer participation, machine intelligence, and self-organization as many are predicting? What are the opportunities for your particular research to contribute to the future of the power grid? This book will provide you with the background needed to form your own conclusions to these and many other questions on this fascinating journey through the intersection of power systems and communications. It is important for information and graph theorists and network science researchers to better understand power systems to advance information theory and network analysis in order to implement fast, efficient, and realistic approaches within the power systems domain. If not, these theorists could remain in a world of simplified toy problems, not understanding how the power grid really works or simply become constrained within the strait jacket of existing theory.

The primary objective of this book is to bridge the divide between the fields of power systems engineering and computer communication. In my experience within these early stages of this round of “modernization” of the electric power grid, many power systems engineers tend to be a little overconfident in the capability of communication systems to work reliably, with sufficient capacity, and with low latency under any condition. This is not surprising given that communication networks are nearly ubiquitous and embedded within increasingly smaller devices. It is natural for noncommunication engineers to assume that communication networking is a solved problem, ready for application anywhere and everywhere. On the other hand, the power grid is also so ubiquitous and reliable that most nonpower systems engineers take electric power for granted. In fact, most of us tend to assume that an electric power socket will always be within easy reach and that our electronic devices will work perfectly once plugged into that socket. Rarely does anyone think about the complexity of the electric power grid when inserting a plug into a socket or operating their electronic devices. In a sense, both the power grid and communications have suffered from their own respective successes – the electric power grid tends to be taken for granted and communication networks are assumed to work perfectly under almost any condition and for any application. The reader will soon find that both the electric power grid and communications are each highly complex systems in their own right; the manner in which they are integrated will have far-reaching consequences.

Another objective of this book is to remove the previously mentioned dangerous assumptions: to show the complexity and operational requirements of the evolving power grid, the so-called “smart grid, ” to the communication networking engineer, and similarly to show the complexity and operational requirements for communications to the power systems engineer. At the time this is being written, there are few practitioners who have depth of knowledge in both power systems and computer communications and networking. Thus, another objective of this book, and probably the most important, is to provide a path towards a fundamental understanding in both power systems and communication networking. Just as power systems require a broad set of knowledge ranging from high-power device physics to protection mechanisms to power flow and stability analysis, so too communication networking requires an understanding of topics ranging from signal processing, information theory, and graph theory to cybersecurity. It is my hope that these fundamental topics of power systems and communications combine in novel ways to form far more than the sum of their parts. In other words, it would be a shame for power systems engineers to remain restricted to thinking only about their traditional discipline while directing communication engineers where to implement communications; that is, losing the chance to incorporate new ideas into their repertoire. Similarly, it would be a shame for communication engineers to blindly submit to the direction of power systems engineers and implement communications without looking at new ways to better integrate power systems and communications. My hope is that this book may serve as the impetus leading to the discovery of fundamental new relationships between the properties of electric power, energy, and information.

An overriding objective of this book is to focus on fundamentals – underlying concepts that are most resistant to change. Smart grid standards and technology are currently undergoing rapid evolution; this evolution will continue into the foreseeable future. Thus, standards and technologies as they exist today will soon change or disappear no matter how strongly their advocates may feel. Understanding more fundamental concepts that reside closer to the physics of operation will pay higher dividends for the reader. Thus, for example, understanding information entropy in the power grid per kilowatt of power delivered or the radio frequency communication power expended within the power grid per kilowatt of power delivered will be more valuable than understanding the detailed packet structure of a half-dozen supervisory control and data acquisition protocols. In particular, Section 6.3 develops the fundamental relationship among energy, communication, and computation. These are beautiful relationships that even an expert in communications or power systems should not overlook. Given rapid changes in technology, it is important to understand that technology undergoes predictable evolutionary processes, not unlike a biological organism. For example, the pressures of the market and the nature of the intellectual property processes drive technology to follow the predictable path that we see the smart grid following. It is possible, using this general knowledge of technology evolution, to predict how the power grid will evolve and thus anticipate future challenges.

Finally, many books on the topic of the smart grid, and renewable energy in particular, utilize the notion of global warming and impending environmental catastrophe to promote the importance and urgency of their topic. The reader will note that I purposely avoid discussion of this controversial topic. I believe that we can all agree upon the need for efficient power delivery, lower cost, and less reliance on imported energy. If these can be accomplished in a clean and environmentally friendly manner, then that is an added bonus.

Genesis

My prior books have always focused upon fundamental new ideas; for example, active networks or nanoscale communication networks. So readers may wonder why I have chosen to write about a topic as seemingly practical and mundane as the recent advances in power systems. As the reader will notice, I have not lost interest for thinking “outside the box.” While conveying the required practical information, I have attempted to find new ways of looking at the problem wherever possible in order to add new perspectives that hopefully add deeper insight.

There is no doubt in my mind that the definition of smart grid will continue to change over time. At the time this book is being written, smart grid is synonymous with communications coupled with the power grid to accomplish novel power applications. However, smart grid will, and should, expand over time to encompass machine learning applied within the power grid and the development and incorporation of smarter power components. However, it is always important to keep in mind that without underlying communications most of the other advancements will not be possible.

There are a few fundamental trade-offs that apply to communication and networking that recur often; namely, trade-off among performance metrics such as latency, bandwidth, availability, energy consumption, transmission range, and so on. To a first order, designing the smart grid is about determining the correct trade-offs in the correct part of the power grid. For example, the so-called advanced meter reading infrastructure has very different communication requirements, and thus a different design philosophy than power protection. Understanding the reason for the different requirements is critical.

This book had its genesis in 2010 when I became involved in smart-grid-related projects and could not find a comprehensive source for communications within the electric power grid. This book also became intertwined with my IEEE Distinguished Lecture Tours in 2011. It became clear from audiences on the lecture tours that there was, and continues to be, widespread and intense interest in the “smart grid.” It also became clear, as previously mentioned, that there is a fundamental lack of understanding between the fields of electric power systems and communications.

It is also evident from my experience on smart grid projects that communications is often assumed to exist when in reality it may not. Complex algorithms are developed that rely upon geographically dispersed information under the assumption that communications can be easily engineered later into the process. It is important for power systems engineers to be aware of the challenges involved in communication networking. As a simple example, establishing point-to-point wireless communication through ground clutter is a nontrivial task. Relying on a cellphone carrier introduces problems of coverage, availability, and often uncertainty regarding the bandwidth available at any specific time, in addition to excessive cost. Power line carrier suffers many problems, not the least of which is the loss of communication through a downed power line; that is, communication may be lost when it is needed most. These form only a small subset of the challenges faced by communications in the power grid; hopefully, the point that there is no simple, trivial solution will become clear.

I also noticed that, just as local regions develop their own dialects in human language, power systems and communication engineers continue to develop their own independent and unique terminology, sometimes attributing very different meaning to the same terms, causing potential confusion. For example, “security” to a power systems engineer means something that is entirely different to a communication and networking engineer. Take an “active network” or “active networking” as another example; to a power engineer it refers to a microgrid, while to a communication engineer it refers to an advanced form of programmable network. Another source of terminological confusion is “power routers”: is it literally a device that routes electric power or is it just a “communication network router” that serves to control the routing of power? These and other differences in terminology are explained in detail in the text. It can be said that power systems and communications are separated by a common language. The origin of this book grew out of an attempt to understand the similarities and differences between the two disciplines.

But why is a holistic approach towards smart grid – such as that proposed in this book – expected or desired? A common example can be found in the evolution of the Internet and telecommunications, which drove exploration for the relationship between communications and information and ultimately led to information theory. The Internet and telecommunications in turn created a platform for applications that could never have been conceived at the time. A more holistic approach allows us to be more innovative – to see how components interact in a deeper manner in order to find efficiencies and develop entirely new applications. It was the drive to make the system more efficient and reduce the cost of transporting a product that drove the theory, just as the power grid is doing today in the so-called smart grid. For information theory, in Shannon’s case, it was an industrial research laboratory rather than a university that created the key innovation. Again, as typically happens, it is the case today that fundamental innovation and insight are driven by, and come from, industry.

Approach and Content

The power grid is in a state of rapid evolution. Any attempt to convey a comprehensive state of the policies, standards, and even specific technologies will likely be out of date even before going to print. Thus, this book focuses upon fundamentals as much as possible; information theory and power electronics will change more slowly than policy, regulation, and standards. The reader can be confident that the material presented will always be relevant; only its implementation may change. Reliability, safety, low cost, and high efficiency have been, and will likely remain, key drivers of the technology regardless of how business models change.

In fact, the technology for what we call the “smart grid” did not suddenly appear, but has been in development for some time. Attempting to draw a precise boundary between the “legacy power grid” and the “smart grid” would not be a simple task and would perhaps not even be sensible to attempt. Communication has been an integral part of the power grid since the last century, so the idea of simply adding communication is neither novel nor does it make the grid smart. Part of the approach of this book is to explore, and perhaps sometimes debunk, why the word “smart” is in smart grid. In that regard, it has been important in writing this book to separate fact from proposed idea: what really exists and is likely to exist in the power grid from what academics often incorrectly “think” exists in the power grid.

This book covers the evolving electric power grid and its integration with communications assuming as little prerequisite knowledge as possible. We begin with a brief and intuitive introduction to the fundamentals of power systems and progressively build upon that foundation while pointing out relationships with communications and networking wherever appropriate along the way.

The book is organized into three parts with five chapters in each part. Figure 1 shows the organization of the book. Part One of the book will ground the reader in the basic operation of the electric power grid. This part covers fundamental knowledge that will be assumed in Parts Two and Three of the book. Part Two introduces communications and networking, which are critical enablers for a smart grid. The manner in which communication and networking are integrated into the power grid is an ongoing process; thus, we also consider how communication and networking are anticipated to evolve as technology develops. This part lays the foundation for Part Three, which utilizes communication within the power grid. The smart grid will ultimately become “smart” when intelligence is implemented upon the communication framework explained in Part Two. Thus, Part Three must draw heavily upon both past embedded intelligence within the power grid and current research to anticipate how and where computational intelligence will be implemented within the smart grid.

Figure 1 Selected reading arrangements are illustrated for readers interested in specific subtopics. Those interested in power generation could start from Chapter 2 and follow the dashed lines; those interested in power transmission could begin with Chapter 3 and follow the dashed lines; those interested in power distribution could start with Chapter 4 and follow the dashed lines.

Each part is divided into chapters and each chapter has a set of questions useful for exercising the reader’s understanding of the material in that chapter. The book is written so that when the chapters are read in consecutive order the material will flow well, each chapter building upon the previous chapters. However, there are other ways to read the book for readers with different backgrounds and perspectives. A power systems engineer would presumably have a strong background in the traditional power grid and would not need to read Part One of the book, so could begin reading starting with Part Two. On the other hand, a communications engineer could potentially skip Chapter 6, with the exception of Section 6.4 on power system information theory. A reader who is interested only in a summary of the technology could simply read the first chapter of each part, namely Chapters 1, 6, and 11.

One of the interesting aspects of the evolving power grid is that as it has evolved, it has become harder to neatly divide the power grid into the traditional components of generation, transmission, distribution, and consumption. These parts are becoming more interrelated. If one were interested only in generation, then Chapters 1, 8, and 15 (nanoscale power generation) would be most relevant. If one were interested only in transmission, then Chapters 3, 6, 12, and 13 might be most appropriate. If one were interested in distribution, then Chapters 4, 9, 12, and 13 would perhaps be most relevant. However, aspects of distributed generation, demand-response, and fault detection, isolation, and restoration, state estimation and stability, synchrophasors, and so on. will all be taking place simultaneously within the power distribution network.

As will be seen throughout this work, the smart grid communication vision presented here foreshadows a high degree of integration between information theory and power systems. Specifically, fundamental relationships between information theory and Maxwell’s equations could yield new insight into understanding exactly where to place communication, since entropy would be known at a low level within the power grid. Today, this placement is done in a rather ad hoc manner. We may also someday know the precise theoretical “bits per kW” needed to distribute electric power safely. Finally, we can imagine that new forms of efficiency resulting from advances in small-scale power generation could lead to widespread use of nanoscale power generation and distribution and the required nanoscale communication to support such systems. For example, a consumer’s electric vehicle may be recharged by extraneous electromagnetic fields from radio transmissions. Research and references on both extracting energy from extraneous electromagnetic transmissions and nanoscale communications are provided in later chapters of this book. In the distant future, we might even imagine the quantum teleportation of energy. All of these topics are covered in the last chapter of the book.

Acknowledgements

First and foremost, I thank my wife for her kind patience and understanding. I would also like to thank the hosts and audiences on my IEEE Communications Society Distinguished Lecture Tours on smart grid in 2011. Their stimulating questions, comments, and discussions helped shape this book. I would also like to thank all the folks involved in the IEEE Smart Grid Vision 2030 Project, including Alex Gelman, Sanjay Goel, David Bakken, and Bill Ash, among many others. Stimulating discussion among smart individuals willing to explore new ideas can lead to great things.

Stephen F. Bush

Acronyms

6LoWPANIPv6 over low-power wireless personal area networksACEarea control errorACFFIaverage communication failure frequency indexACIDIaverage communication interruption duration indexACKacknowledgmentACOant colony optimizationACSEassociation control service elementACSRaluminum conductor steel-reinforced cableADAadvanced distribution automationADIadvanced distribution infrastructureADPadaptive dynamic programmingAGCautomatic grid controlAHPanalytical hierarchical programmingAIEEAmerican Institute of Electrical EngineersAMIadvanced metering infrastructureAMRautomated meter readingANSIAmerican National Standards InstituteAODVad hoc on-demand distance-vectorAPDUapplication protocol data unitAPIapplication program interfaceARQautomatic repeat-requestASCIIAmerican Standard Code for Information InterchangeASKamplitude-shift keyingASN.1abstract syntax notation 1ATMasynchronous transfer modeBANbody-area networkBASbuilding automation systemBCSBardeen–Cooper–SchriefferBEbest-effortBFSKbinary frequency-shift keyingBMCbest master clockBPLbroadband over power lineBPSKbinary phase-shift keyingBSbase stationCAcontingency analysisCAEScompressed air energy storageCAIDIcustomer average interruption duration indexCAIFIcustomer average interruption frequency indexCANcontroller-area networkCBRconstant-bit rateCCcontrol centerCCITTComité Consultatif International Téléphonique et Télégraphique (International Telegraph and Telephone Consultative Committee)CIDconnection identifierCIGREConseil International des Grands Reseaux Electriques (International Council on Large Electric Systems)CIMcommon information modelComSocIEEE Communications SocietyCOSEMcompanion specification for energy meteringCRCcyclic redundancy checksumCSMcommon signaling modeCSMAcarrier-sense multiple-accessCSMA-CAcarrier-sense multiple-access with collision avoidanceCSMA-CDcarrier-sense multiple-access with collision detectionCTcurrent transformerCTAIDIcustomer total average interruption duration indexCVRconservation voltage reductionCVTconstant voltage transformerDAdistribution automationDAGdirected acyclic graphDAUdata aggregation unitDCFdistribution coordination functionDCTdiscrete cosine transformDESSdistribution energy storage systemDGdistributed generationDHPdual heuristic programming dielectricDIODODAG information objectDLMSdevice language message specificationDMIdistribution management infrastructureDMSdistribution management systemDNPdistributed network protocolDNP3distributed network protocol 3DODAGdestination-oriented directed acyclic graphDRdemand-responseDSLdigital subscriber lineDSMdemand-side managementDSPdigital signal processorDSSSdirect-sequence spread-spectrumDVRdynamic voltage restorerEDFAerbium-doped fiber-optic amplifierEHVextra-high voltageEIAUnited States Energy Information AgencyEMCelectromagnetic compatibilityEMFelectromotive forceEMSenergy management systemENS-Cenergy not served due to communication failureEPRIElectric Power Research InstituteEPSelectric power systemertPSextended-real-time-polling serviceESIenergy services interfaceETSIEuropean Telecommunications Standards InstituteEPSEMextended protocol specification for electronic meteringFACTSflexible alternating current transmission systemFANfield-area networkFCLfault current limiterFCSframe check sequenceFDIRfault detection, isolation, and restorationFDMfrequency-division multiplexingFERCFederal Energy Regulatory CommissionFETfield-effect transistorFFDfull function deviceFFTfast Fourier transformFHSSfrequency-hopping spread-spectrumFNfalse-negative isolated fault segment vectorFSKfrequency-shift keyingGenCogenerating companyGFCIground-fault circuit interrupterGICgeomagnetically induced currentGISgeographic information systemGOOSEgeneric object-oriented substation eventsGPSglobal positioning systemHANhome-area networkHARThighway addressable remote transducerHDPheuristic dynamic programmingHEMPhigh-altitude electromagnetic pulseHMACkeyed-hash message authentication codeHTShigh-temperature superconductorHTS-ISMhigh-temperature superconducting induction-synchronous machineHVDChigh-voltage direct-currentIAEintegral absolute errorICCPinter-control center communications protocolICTinformation and communications technologyIEinformation elementIECInternational Electrotechnical CommissionIEDintelligent electronic deviceIEEEInstitute of Electrical and Electronics EngineersIEMintelligent energy managementIETFInternet Engineering Task ForceIFFTinverse fast Fourier transformIFMintelligent fault managementIGBTinsulated-gate bipolar transistorIHDin-home displayIMFinterplanetary magnetic fieldIoTInternet of thingsIPInternet protocolIPv6Internet protocol version 6IREInstitute of Radio EngineersISEintegral squared errorISOindependent system operator or International Standards OrganizationITinformation technologyITAEintegral time-weighted absolute errorITICInformation Technology Industry CouncilITUInternational Telecommunication UnionIVVCintegrated volt-VAr controlL2TPlayer 2 tunneling protocolL2TPv3layer 2 tunneling protocol version 3LACL2TP access concentratorLANlocal-area networkLBRLLN border routerLCinductor–capacitorLDPlabel distribution protocolLEDlight-emitting diodeLEOlow Earth orbitLERlabel edge routerLLClogical-link controlLLNlow-power and lossy networkLM/LEload modeling/load estimationLMPlocation marginal pricingLMSload management systemLNSL2TP network serverLPDUlink protocol data unitLRClongitudinal redundancy checkLR-WPANlow rate-wireless personal-area networkLSEload serving entityLSRlabel-switch routerLTCload tap changingLVlow voltageM2Mmachine-to-machineMACmedia-access controlMAIFImomentary average interruption event frequency indexMANmetropolitan-area networkMDLminimum description lengthMDMSmeter data management systemMFRMAC footerMHRMAC headerMIBmanagement information baseMMSmanufacturing message specificationMOSFETmetal-oxide-semiconductor field-effect transistorMPDUMAC protocol data unitMPLSmultiprotocol label switchingMPPTmaximum powerpoint trackingMRFMarkov random fieldMR-FSKmultirate-frequency-shift keyingMRImagnetic resonance imagingMR-OFDMmultirate orthogonal frequency-division multiplexingMR-OQPSKmultirate-offset quadrature phase-shift keyingMSmobile stationMSDUMAC service data unitMSH-DSCHmesh-distributed scheduling messageMSH-NENTmesh network entry request messageMSH-NCFGmesh network configurationMTUmaximum transmission unitNACKnegative acknowledgmentNANneighborhood-area networkNISTNational Institute of Standards and TechnologyNLDNNational Lightning Detection NetworknrtPSnon-real-time polling serviceOFDMorthogonal frequency-division multiplexingOFDMAorthogonal frequency-division multiple accessOGWoptical ground wireOMSoutage management systemONRoptimal network reconfigurationOpenADRopen automated demand response communication standardsOpenDSSopen distribution system simulatorOQPSKoffset-quadrature phase-shift keyingOSIopen systems interconnectionPANpersonal-area networkPAPpriority action planPCAprincipal component analysisPCBpolychlorinated biphenylPCFpoint coordination functionPCSpower conditioning systemPDCphasor data concentratorPDUprotocol data unitPERpacket error ratePESIEEE Power and Energy SocietyPEVplug-in electric vehiclePHRphysical-layer headerPMPpoint-to-multipoint modePMUphasor measurement unitPNpseudorandom sequencePPDUphysical-layer protocol data unitPPPpoint-to-point protocolPQreal and reactive powerPSDUphysical-layer service data unitPSEMprotocol specification for electronic meteringPSKphase-shift keyingPSOparticle swarm optimizationPSTphase-shifting transformerPTpotential transformerPTPprecision time protocolpuper-unitPVreal power and voltage magnitude or photovoltaicQAMquadrature amplitude modulationQoSquality of serviceQPSKquadrature phase-shift keyingRANradio access networkRBACrole-based access controlRDFresource description frameworkRFradio frequencyRFCrequest for commentsRFDreduced function deviceRFIDradio-frequency identificationRMSroot-mean-squareRMTrandom matrix theoryROLLrouting over low-power and lossy networksRPCrelay protection coordinationRPLrouting protocol for low-power and lossy networksRPMrotations per minuteRSrelay stationRSVP-TEresource reservation protocol for traffic engineeringRTOregional transmission organizationRTPreal-time pricingrtPSreal-time polling serviceRTUremote terminal unitSAsubstation automationSAIDIsystem average interruption duration indexSAIFIsystem average interruption frequency indexSCAshort circuit analysisSCADAsupervisory control and data acquisitionSCFCLsuperconducting fault current limiterSCLsubstation configuration languageSDNsoftware-defined networkSDRsoftware-defined radioSERASmart Energy Reference ArchitectureSGIPSmart Grid Interoperability PanelSHRsynchronization headerSILsurge impedance loadingSMESsuperconducting magnetic energy storageSNMPsimple network management protocolSONETsynchronous optical networkingSPSstandard positioning serviceSPSSsupervisory power system stabilizerSREslack-referenced encodingSSsubscriber stationSNTPSimple Network Time ProtocolSUNsmart utility networkSuperPDCsuper phasor data concentratorSVCstatic VAr compensatorSVDsingular value decompositionT1transmission system 1TAIinternational atomic timeTAMtechnology acceptance modelTASEtele-control application service elementTCCtime–current characteristicTCPtransmission control protocolTDDtime-division duplexTDMAtime-domain multiple accessTHDtotal harmonic distortionTLStransport layer securityTPDUtransport protocol data unitTSOtransmission system operatorTVATennessee Valley AuthorityTVEtotal vector errorUCAUtility Communications ArchitectureUDPuser datagram protocolUSGunsolicited grant serviceUSNubiquitous sensor networkUTCuniversal time coordinateVAvolt–ampereVArvolt–ampere reactiveVFTvariable-frequency transformerVOvoltage optimizationVPLSvirtual private LAN serviceVSIvoltage stability indexVVOvolt-VAr optimizationWACSwide-area control systemWAMwide-area monitoringWAMPACwide-area monitoring, protection, and controlWAMSwide-area monitoring systemWANwide-area networkWAPSwide-area protection systemWASAwide-area situational awarenessWDMwavelength division multiplexingWEPwired equivalent protectionWiFiWireless FidelityWiMAXWorldwide Interoperability for Microwave AccessWLSweighted least squaresWPANwireless personal-area networkXMLextensible markup languageXPathXML path language

Part One

Electric Power Systems: The Main Component

1

Introduction to Power Systems Before Smart Grid

This ‘telephone’ has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us.

—Western Union internal memo, 1876

Those who say it cannot be done should not interfere with those of us who are doing it.

—S. Hickman

1.1 Overview

Power systems and communications are close cousins. This may not be apparent at first, but that is how we will generally view these twin subtopics of electrical engineering. Communications and power systems are the same field with a different emphasis. Both transmit power. Communications seek to minimize power and maximize information content. Power systems seek to maximize power and minimize information content. It is particularly interesting to see what happens when these fields physically come together in technologies such as a power line carrier and wireless power transmission. In a power line carrier, communication attempts to become physically similar to power, following the same conductive path. In wireless power transmission, power seeks to become physically similar to wireless communication, propagating through space similar to wireless communication. It is at these intersections of communication and power systems that the differences between the two fields comes into sharpest contrast. The initial hyperbole regarding the fundamental shift in power systems toward what is being labeled as the “smart grid” will have died down or disappeared altogether by the time the reader has this book in hand. However, the technological change that initiated the smart grid established a platform that will enable revolutionary enhancements in intelligence for power systems. Our goal is to explore both the theoretical and technological underpinnings of this shift in power systems, focusing upon the incorporation of communications and networking technology. There are those who suggest that the integration of communications into the power grid will enable a revolution in electric power distribution, perhaps thinking of the analogy with the explosive growth of the Internet in the 1990s. The simple act of providing data interconnections (for example, via the Internet, cell phone, and other portable computing devices) has spawned new applications, ideas, and solutions that no one could have predicted. Communications in the power grid may indeed enable new and unforeseen applications in power systems. At the same time, we should temper our enthusiasm by noting that communications have already been part of the power grid for over a century, as we will see later.

As a motivation for smart grids, it has often been stated that power systems have evolved slowly while communication and networking have advanced much more rapidly: Alexander Graham Bell would not recognize the phone system of today, whereas Thomas Edison would still recognize much of today’s electric power grid. However, this is, of course, not quite true. In fact, power systems has been evolving, and it is difficult to precisely define when and where the so-called smart grid began; much of the technology enabling the smart grid has existed for some time. Part One of this book covers power systems fundamentals; these are fundamentals that existed long before the smart grid and will exist long after, so they are well worth the time and effort to understand, although, as just mentioned, drawing the line between the pre- and post-smart grid is somewhat arbitrary and perhaps still ongoing, as we will see. Part Two defines what we mean by the term “smart grid” and focuses upon communications. Part Three goes on to explore what communications has enabled and could enable, including synchrophasor applications and machine intelligence.

Each new scientific discovery or advance in engineering and technology does not deplete the set of new ideas; on the contrary, it exponentially increases the number of new possibilities to be explored. This book will provide you, the student, academic or industry professional, or casual reader, with the basic building blocks of the smart grid; however, it will be you who will supply the creativity and innovation to combine these building blocks in new ways that may not yet have been considered. Please continue with the thought in mind that these are building blocks for new ideas, innovations, or even products, not as an end in themselves. One of the exciting things about the smart grid is that it is a highly dynamic and evolving system, one that you will be able to participate in, whether as a researcher, designer, developer, or consumer.

This part, Part One, consisting of Chapters 1–5, introduces the electric power grid and fundamental concepts of power systems. The goals for this part are to provide prerequisite material for understanding the power grid, to provide historical perspective on the evolution of the power grid, and to provide motivation for the concept of the smart grid.

This chapter, Chapter 1, provides a general overview of the electric power grid, including the fundamentals necessary to understand the rest of the material that will be covered. The remaining chapters in this part focus upon the topics introduced in this chapter in more detail. Because this part of the book is focused on the historical or legacy power grid, it is divided into standard electric power grid components: Chapter 2 focuses upon generation, Chapter 3 on transmission, Chapter 4 on distribution, and Chapter 5 on the consumption of electric power.

This chapter begins with an overview of the physics of electricity as it relates primarily to power systems, but also as it relates to communications as well. Then we discuss the electric power grid as it has evolved over the last century until the dawn of the smart grid; this provides us with a brief historical perspective. Then we look at the equipment in the legacy power grid; much of the equipment, or at least its functionality, will be the same or similar in the smart grid. It will be this equipment that will be monitored and interconnected via communications within the smart grid. Next, we return to basic power analysis that applies to the legacy power system, and because the fundamental physics does not change, will apply to the smart grid as well. This analysis provides insight into the operation of the power grid as well as provides our first hints at the communication and computational requirements within the smart grid. Simulation and modeling tools are introduced in the appendix; while the reader may be curious as to what tools currently exist, this information will likely become rapidly outdated and is thus not incorporated in the main text. This information may be relatively quickly outdated, but it provides a look at some of the modeling challenges for the smart grid. Next, we briefly consider blackouts in the legacy power grid. This provides us with a sobering look at what we would hope the smart grid would improve. The goals for the smart grid involve extending the capability of the power grid in many different ways, however, if the smart grid cannot reduce the likelihood of a blackout, then all of its other features are pointless. Sections 1.5 and 1.6 discuss the drivers and goals of the smart grid. Finally, we take an excursion back to fundamental theory in Section 1.8 to discuss energy and information. The goal is to intuitively motivate the reader to consider that incorporating communication and computation with the power grid may benefit from a fundamental understanding of the relationship between energy and information. The chapter ends with a summary of the important points. Finally, the exercises at the end of the chapter are available to help solidify understanding of the material.

The term “smart grid” has been used numerous times in this text already and, since it is the main topic of this book, will be used frequently throughout the remainder of the book. Before continuing further, a definition of this term is in order. Let us begin with a simple, broad, intuitive definition and refine it as we progress. The smart grid is an electric power grid that attempts to intelligently respond to all the components with which it is interconnected, including suppliers and consumers, in order to deliver electric power services efficiently, reliably, economically, and sustainably. The details of the definition and the means by which these goals are accomplished vary from one region to another throughout the world. This is in part due to the fact that different regions of the world have different infrastructures, different needs, and different expectations, as well as different regulatory systems. However, even without these differences, the power grid is a very broad system comprised of many different components and technologies. Researchers focusing on a narrow aspect, such as developing smart meters or developing new types of demand-response (DR) mechanisms, sometimes inadvertently equate their areas with the sum total of the smart grid, as illustrated in Figure 1.1. Each blind man equates the elephant with the part he can feel. The areas shown are

advanced metering infrastructure (AMI) – systems that measure, collect, and analyze energy usage;distribution automation (DA) – the extension of intelligent control over electrical power grid functions to the distribution level and beyond;distributed generation (DG) – generating electricity from many smaller energy sources and microgrids;substation automation (SA) – automating electric power distribution and transmission substations;flexible alternating current transmission system (FACTS) – a power electronics-based system to enhance controllability and increase power transfer capability of the network; andDR – systems that manage customer consumption of electricity in response to supply conditions.

Figure 1.1 What is the smart grid? There is a risk of perceiving the smart grid as only one of many different emerging systems. It is critical for the development of smart-grid communications to understand the complete view of a smart grid. Source: Stebbins C. M. and Coolidge M. H. (1909), Golden Treasury Readers: Primer, American Book Co., New York, NY, p. 89, via Wikimedia Commons.

While these topic areas provide a feel for the smart-grid goals and we will cover these topics in detail in this book, no single subset of these areas defines the smart grid. In fact, these individual components should be viewed as only a subset of the possible components of the smart grid. Some of these components may reach maturity as planned, others may not survive, and many new ones will certainly be created as innovation continues. It is important, then, to understand the fundamentals of both power systems and communications in order to make intelligent decisions regarding how these components will progress and to identify the potential for new ones.

Smart grid is about the evolution of the power grid. In that respect, we discuss where the grid came from, its current state, and its transition into a power grid comprised of DG and microgrids. However, this book should also be of lasting value in terms of a longer term vision for the power grid; that is, how it could evolve further in the coming decades. At this point, it would be instructive to take a risk and predict how the grid could look far into the future. It is a common trend for any technology to evolve from a monolithic structure to become more dynamic, flexible, and eventually merge with its environment. The ultimate advancement is to evolve into a physical field, such as an electric or magnetic field. Figure 1.2 depicts a series of progressively more sophisticated uses of wireless power: from centralized generation and wireless transmission to hard-to-reach places today, to offshore microgrids tomorrow, and to harvesting power from literal nanogrids and stray electromagnetic radiation. The concept in this vision is that any power source, including large numbers of nanoscale power generation sources, can connect to the grid and provide power that is then appropriately aggregated into a higher power delivery system. Note that the delivery system is entirely wireless in nature; power is beamed in a wireless manner to consumers. Of course, at the time this is being written this is in the realm of science fiction for power utilities. However, individual components to accomplish this on a small scale exist today and will be discussed in later chapters of the book. The reason for including this futuristic vision up front is to keep the reader’s mind open to the possibility of very different requirements for communication that may be required from those that are foreseen today.

Figure 1.2 The power grid of the future may contain centralized generation with wireless power transfer, microgrids with wireless power transmission, nanogrids and electromagnetic energy harvesting among many other innovations. Smart-grid communication should anticipate how power grid technologies will be evolving so that it can remain viable for the future. Source: Bush, 2013. Reproduced with permission of IEEE.

1.2 Yesterday’s Grid

The classic view of the power grid is shown in Figure 1.3. It is comprised of a relatively few, but very large power generation stations, bulk transport across relatively long distances over the transmission system to areas of denser consumer populations, a distribution substation in which power fans out through feeders to the distribution system, and, finally, delivery through the distribution system to individual power consumers. Power flows primarily in one direction, from large centralized generators to the consumer. As will be explained later, even in this pre-smart-grid architecture, there are aspects of power flow that are not strictly one way; namely, reactive power flow, which oscillates within the power grid, and circulating currents between generators. However, ignore these complicating factors until they are explained in detail later.

Figure 1.3 The classic view of the power grid has typically been a one-way flow of electric power from generation through transmission, distribution, to consumption. Source: U.S. Canada Power System Outage Task Force, Final Report on the August 14, 2003. Blackout in the United States and Canada: Causes and Recommendations, April 2004.

From an operational standpoint, the power grid is divided into what are known as “synchronous zones, ” or “interconnects” in North America. Synchronous zones are areas in which the power grid is highly interconnected and operating at the same frequency. As an example, the interconnects of North America are shown in Figure 1.4. The power grid (remember we are talking about the pre-smart-grid power grid) is one of the most complex machines ever created by man. The National Academy of Engineering ranks the electrification of North America as the greatest single achievement of the twentieth century. So how did this complex achievement come about?

Figure 1.4 Interconnects, or synchronous zones, are areas of relatively dense power interconnectivity where the alternating current cycle is in phase. Source: By Bouchecl (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons.

The Edison Electric Illuminating Company of New York constructed the first generating station in 1881. This generation station had 250-hp steam boilers, each delivering 110 V direct current via an underground distribution network. As we will see, the means and benefits of using alternating current had not yet been discovered. Because voltage is required to move current and the early generating stations could not transmit or distribute their power very far, many stations appeared primarily throughout urban areas to serve only local demand for power. They were, in a sense, the first primitive microgrids. The power grid grew rapidly; electric power grew by over 400 times from the early 1900s to the 1970s. This is significant if you compare it with all other forms of energy, which only grew by 50 times over the same period.

The need for communication to support the power grid was recognized almost immediately. Communication over telegraph lines for automated meter reading was utilized in the late 1800s and patents on power line carrier for meter reading were issued in Britain in 1898 and the USA in 1905 (Schwartz, 2009).

The invention of the transformer allowed high-voltage alternating current power to be efficiently and safely distributed via 1000 V power lines. The first alternating current generation system was developed by Westinghouse in 1866. Nikola Tesla invented the induction motor in 1888, which uses alternating current and helped spread the demand for alternating current power as opposed to direct current power. By 1893, the first three-phase system was developed by the Southern California Edison Company. The result of this early progress was a large number of relatively small electric companies. For example, in 1895, Philadelphia alone had 20 electric companies operating with two-wire direct current lines at 100 V and 500 V, 220 V three-wire direct current lines, single-, two-, and three-phase alternating current at frequencies of 60, 66, 125, and 133 cycles per second and with feeders at 1000–1200 V and 2000–2400 V. The point of this historical interlude is that there was efficiency to be gained by reducing diversity and seeking an economy of scale.

Economy of scale is reflected in the 1973 Cumberland Station of the Tennessee Valley Authority, which inaugurated generating units of up to 1300 MW, a long way from the initial generation stations measured in hundreds of horse power. As generator size increased and the demand grew, the need to transmit and distribute power required higher voltages to both move power efficiently over larger distances to reach consumers and move large amounts of power between power producers. Today’s distribution voltages commonly range in classes of 5, 15, 25, 35, and 69 kV.

It is interesting to note that, in a sense, the smart grid is returning to larger numbers of smaller generators via encouraging DG and is also attempting to conserve power by reducing distribution voltages. This is because part of the smart-grid concept is to enable the ability to figuratively “reach out” with many smaller generators to extract energy from the environment; specifically, the sun and wind in many cases. However, in theory, there is no need to stop there; we could continue the trend toward smaller generators reaching deeper into the environment down to the molecular scale. More will be said about this when we discuss the smart grid and future directions.

The ability to move large amounts of power between producers enables power to be generated by the most economical generators and also allows power to be shared so that peak demand can be satisfied when and where it occurs. Peak demand is a problem that occurs today due to the cost and inefficiency of powering up large generators that run for short periods of time. A large amount of consideration has gone into flattening the demand; this is incorporated as a component of the smart grid. An efficient means of sharing power over long distance and between synchronous zones is the use of high-voltage direct-current (HVDC) lines. In 1954, the first HVDC power line went into operation in the Baltic. It is 60 miles long and operates at 100 kV. High voltage provides the same power with less current, and thus less power loss. The fact that power is converted to direct current before transmission and then converted back to alternating current upon reception allows the sending and receiving synchronous zones to be out of phase with each other without causing stability problems. This will be discussed in much more detail later; the point of this subsection is simply to understand the historical development of the technology.

1.2.1 Early Communication Networking in the Power Grid

As mentioned in the brief historical vignette above, communication has been vital to the power grid from the beginning. The telegraph was used for meter reading, soon followed by power line carrier at the beginning of the twentieth century. Power line communication was used for voice communication in 1918 (Schwartz, 2009). However, there are at least two key characteristics of the power grid that worked against the rapid and widespread deployment of modern communication throughout the power grid. They are economies of scale and safety. Economy of scale implies huge investment in large systems; systems that will produce large amounts of relatively low-cost power. But once constructed, they are designed to remain in operation for decades without change. Thus, they are not amenable to removing and reinstalling large amounts of equipment simply to keep pace with every incremental technological advance. These advances accumulated rapidly for communications. Also, safety and reliability in high-power electrical equipment are paramount; any perceived vulnerabilities must be mitigated or avoided. Thus, except where absolutely necessary, power grid control was designed to be accomplished locally, without the need for communication (Tomsovic et al., 2005). In fact, power system engineers have, perhaps unwittingly, become experts at extracting communication signals directly from the power grid’s operation and developing a self-organizing system. This statement will become more apparent as the book progresses.

We will go into great detail on the power grid technology and fundamentals soon, but for now consider a high-level discussion of the relation between communication and control in the classical power grid. By classical power grid we are referring to the power grid before the term smart grid was coined. We can consider control divided into high-level areas of protection, generation, voltage, power flow, and stability. Points to consider while reading this book are (1) how well all of these can be accomplished without communication, (2) how well they would be improved with communication, (3) what the requirements of the communication system are in terms of qualities such as cost, latency, bandwidth, and availability among others, and (4) what new features that might be added are given communication capability.

Power system protection is one of the most critical control systems because it involves personal safety. The goal of protection is to isolate faults, such as broken power lines, while keeping power flowing safely to as many consumers as possible. Protection control must be quick and accurate. The common approach is as simple as detecting excessive current flow. However, protection can be applied when needed based upon other characteristics, such as excessive frequency deviation, excessive voltage deviation, or excessive instability. Through careful design and placement, known as protection coordination, it is possible to ensure that the proper relay will open at the proper time by having each relay controlled by locally detected information. However, configuring and managing such a system is a manual process requiring manual effort to adjust every time there is a change. Differential protection relays monitor current on each end of a line and compare the current input to the line with current output from the line; any excessive difference indicates a potential fault. In this case, some form of feedback is required in order to determine whether there is a difference in input and output current (Voloh and Johnson, 2005).

Generator governor control simply refers to keeping the generator producing the required amount of power. The mechanical power applied to the shaft is adjusted to keep the rotor moving at the correct operating speed. Again, this has been done locally.

Voltage control can be accomplished by a variety of mechanisms; for example, by increasing or decreasing the current through the generator rotor coils, known as the exciter, or by changing line tap transformers, which effectively change the winding ratios, and capacitors/reactors (inductors). The exciter can be controlled locally by sensing the generator output voltage and maintaining a given constant voltage. Line tap transformer and capacitor/reactor changes are relatively slow and often predetermined by the load profile and time of day.

Power flow control involves controlling the amount of power flowing over particular power lines in the grid. The classical technique is to use a phase-shifting transformer (Verboomen et al., 2005). However, similar to a line tap changing transformer, this is a relatively slow and predetermined process. A FACTS is a more advanced form of control using power electronics. However, again, it is possible to operate the system with manually configured power flow control.