Communication networks for smart grids

We begin in Chap.1with characterizing the Smart Grid in the broadest sense.The electric power grid consists of power plants of bulk electric energy generationconnected to a system of hig

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Marina Thottan

Communication Networks for Smart Grids

Making Smart Grid Real

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In its Framework and Roadmap for Smart Grid Interoperability Standards, the US

National Institute of Standards and Technology declares that a twenty-first-century

twenty-first century marked the acceleration of the Smart Grid evolution The goals

of this evolution are broad, including the promotion of widespread and distributeddeployment of renewable energy sources, increased energy efficiency, peak powerreduction, automated demand response, improved reliability, lower energy deliverycosts, and consumer participation in energy management This evolution will toucheach and every aspect of the electric power grid, a system that has changed littlesince its inception at the end of the nineteenth century Realizing the goals of theSmart Grid evolution will require modernization of grid components, introduction

of new control and monitoring technologies, and ongoing research and development

of new technologies

The “intelligence” of the Smart Grid relies upon the real-time exchange ofmeasurement and control data among a vast web of devices installed in homes andbusinesses, within the distribution and transmission grids, and at substations, controlcenters, generation stations, and other facilities Thus, a high-performance, reliable,secure, and scalable communication network is an integral part of the Smart Gridevolution

However, the communication networks of many utilities today are ill-equipped

to meet the challenges created by the Smart Grid evolution These communicationnetworks are largely purpose-built for the support of individual applications:separate networks for Supervisory Control and Data Acquisition (SCADA), forvideo surveillance, for Land Mobile Radio backhaul, and so on These networksrely heavily on circuit-based transport technologies The ever-expanding growth

of network endpoints and applications as Smart Grid expands makes these current

1National Institute of Standards and Technology, NIST Framework and Roadmap for Smart Grid Interoperability Standards, Release 2.0, NIST Publication 1108R2, U S Department of

Commerce, February 2012.

v

practices untenable A new, integrated network architecture is required, one that willcarry traffic from all applications while meeting their disparate reliability, security,and performance requirements.

This book is a contribution to this growing body of knowledge It is basedboth on our research into Smart Grid communications and on the consultingservices we have provided electric power companies on transforming their existingcommunication networks to meet the challenges of Smart Grid evolution

This book will be of interest to those engaged in the planning, deployment, neering, operation, and regulation of Smart Grids, including strategists, planners,utility practitioners, communication network technology providers, communicationnetwork service providers, Smart Grid product vendors, regulators, and academics.This book will also be a resource for upper-level undergraduate and graduate coursescovering Smart Grids

engi-We have taken an application-centric approach to the development of theSmart Grid communication architecture and network transformation based on thatarchitecture Therefore, a significant part of this book is devoted to describing theevolving Smart Grid applications such as Advanced Metering Infrastructure (AMI),distribution automation (DA), and traditional utility applications like SCADA

We begin in Chap.1with characterizing the Smart Grid in the broadest sense.The electric power grid consists of power plants of bulk electric energy generationconnected to a system of high-voltage transmission lines to deliver power toconsumers through electric distribution systems Communication networks havebeen used for grid monitoring in the latter part of the twentieth century but werelimited to the substation-based SCADA and teleprotection systems The needfor clean energy with large-scale deployment of renewable sources of energy,advantages of peak power reduction for environmental and economic reasons, gridmodernization, and consumer participation in energy management are some of themotivations for the evolution of Smart Grid While Smart Grid is a natural evolution

of the electric power grid, the evolution has taken a sense of urgency in the lastdecade

Topics in power systems and grid operations relevant to this book are presented

in Chap.2for the benefit of the readers with little background in power systems.After presenting the definitions of basic electric quantities like power and energy,

a quick overview of alternate current systems and phasors is presented Elements

of power generation, transmission, and distribution systems are briefly described toprovide background relevant to this book

In Chap.3, topics in communication networks relevant to this book are presentedfor the benefit of the readers with little background in networking After a briefpresentation of the data communication network architecture framework of theOpen System Interconnection (OSI) architecture, networking layers pertinent toSmart Grid network are presented in more detail Introduction to many wireless andwireline technologies is included Since IP will be the network protocol of choicefor the evolving smart networks, relevant IP networking features are described inmore detail Multiprotocol Label Switching (MPLS) technology is also included inthis review since MPLS provides many important features needed in the Smart Grid

communication network, in addition to supporting utility applications that cannot

be carried over an IP-only network

Before the Smart Grid evolution began, networking for utility operations wasgenerally limited to applications such as SCADA and teleprotection Utility mobileworkforce personnel use communication networks for their operations – mostly forpush-to-talk voice communications Some utilities have deployed network videosurveillance with closed circuit television (CCTV) cameras All these applicationswill continue to be supported in the Smart Grid network In Chap 4, theseapplications and their communication network requirements, networking protocols,and networking technologies are presented

In Chap.5, we present a comprehensive description of many of the new utilityapplications that can be attributed to the Smart Grid evolution In addition topresenting their communication network requirements, we briefly discuss net-work protocols and network technology options for some of these applications.Applications included in this chapter are AMI, DA, distributed generation (DG),distributed storage, electric vehicles (EVs), microgrids, home area networks, retailenergy markets, automated demand response, wide area situational awareness andsynchrophasors, flexible AC transmission system, and dynamic line rating (DLR).Contributions of the application of Chaps.4and5to one or more of the four broadcharacteristics of the Smart Grid are summarized in a table at the end of this chapter

In Chap.6, the Smart Grid communication network architecture is developed

A core-edge network architecture is well suited for the Smart Grid network withmany utility endpoints communicating with the application endpoints located in theutility data and control center (DCC) The concept of the wide area network (WAN)

is formalized for the Smart Grid network as an interconnection of aggregationrouters – called WAN routers Other utility endpoints connect to the WAN at theWAN routers over access networks – called field area networks (FANs) in the utilitycommunity While IP will be the overall network protocol, the architecture willsupport legacy applications and protocols for a period of time as desired by a utility

In addition to the physical network architecture, the logical network architecture isdescribed with the use of many examples

At the outset, it is important to understand that the networking requirements for autility network are different in many aspects compared to those for a network serviceprovider (NSP) network used for data services offered to its customers as well asfor data networks in most enterprises The NSP networks are primarily designed

to support their customers’ multimedia applications, while the Smart Grid networkmust support mission-critical applications such as SCADA, teleprotection, DA, andsynchrophasors Most enterprise data network requirements on reliability, security,and performance are less stringent than those of Smart Grid networks Therefore,the network design paradigm for Smart Grid networks is different in many respectsfrom that of the more established data network design practices Chapter7beginswith the characterization of Smart Grid logical connectivity and network traffic thatare the inputs to network design Design considerations are provided for the support

of the requirements on routing, quality of service (QoS), and network reliability

While security is briefly included in Chap.7in the context of network design,network security deserves a detailed treatment Chapter8discusses network securityfor Smart Grid communication networks Cybersecurity of the power grid hasbecome as important as physical security There has been a concerted effort byutilities, regulators, and standards bodies to implement a high level of communi-cation network security that will not only secure the networks but also minimize thepossibility of attacks on the grid and help mitigate and eliminate security threats Asecurity architecture with multiple security zones is presented.

Chapter9provides an overview of communication network technologies priate for WANs and the FANs For WAN, optical networks are discussed in detailsince many utilities already own or plan to deploy significant fiber infrastruc-ture with optical ground wire (OPGW) Both wireline and wireless networkingtechnologies are considered with special emphasis of their use as FANs A moredetailed treatment is provided for power line communication (PLC) technologysince it is not a very commonly deployed technology in NSP or most enterprisenetworks Similarly, long-term evolution (LTE) technology is described in detail inthis chapter, since LTE has the promise of the most appropriate wireless broadbandnetwork technology for Smart Grid endpoints that need to be connected overwireless networks Benefits and drawbacks of all technologies for their use in theFANs are summarized in a table The chapter ends with a discussion on benefitsand drawbacks of utility ownership of one or more of these network components incomparison to using carrier data networking services

appro-Smart Grid brings with it an enormous growth in data that must be managed foruse by an ever-growing number of utility applications Smart Grid data management

is discussed in Chap.10in the context of data collection, storage, and access acrossthe communication network The traditional practice of client-server communi-cation between individual applications and individual data source (such as smartmeters, intelligent electronic devices, and synchrophasor) is not scalable Further,this end-to-end communication has inherent security and data privacy risks Therehave been recent advances in secure data management that are particularly suitable

in the Smart Grid data management environment with network-based data storageand the corresponding middleware that affords highly secure and low-delay access

to the data In this chapter, a secure data-centric data management architecture isdiscussed The chapter ends with a brief presentation of the elements of Smart Griddata analytics

Chapter 11 brings together the concepts, technologies, and practices in therealization of communication networks for the Smart Grid In this chapter, wepresent network transformation from the present mode of utility operation – ofsupporting all utility applications over multiple disparate networks – to an integratednetwork based on the Smart Grid architecture framework developed in this book.The network transformation process must weigh all available alternatives towardoptimal network architecture and design that is sustainable for many years (typicallybetween 5 and 20 years depending on a utility’s planning horizon)

Planning for long-term network transformation described in this book is based

on reasonable assumptions on future developments in new network technologies,

Chapter 1: Introduction to Smart Grids

Chapter 2:Elements of Power Systems for Networking Practitioners Chapter 4: Conventional Applications in Utility Operations Chapter 3: Elements of Networking for Power Systems Practitioners

Chapter 5: Smart Grid Applications

Chapter 6: A Communication Network Architecture for the Smart Grid

Chapter 7: An Overview of Smart Grid Network Design Process

Chapter 8: Network Security

Chapter 9: WAN and FAN Technologies for the Smart Grid

Chapter 10: Smart Grid Data Management

Chapter 11: Communication Network Transformation

Chapter 12: Future of Smart Grid Communication Networks

Interdependence of the book chapters

their availability to the utility in its service area, possibilities of using networkingservices from network service providers, and costs While some of these futuristicelements and traits were considered in earlier chapters, a more focused discussion

is presented in Chap.12

Interdependence of chapters of the book are shown in the figure at the top.Readers of each chapter will benefit from the material covered in the previouschapters Power system professionals may skip Chap 2 or skim through it.Similarly, communication networking professionals may skip Chap 3 or skimthrough it Readers with a significant background in Smart Grid and communicationnetworking, or with an interest in the specific topics covered, may directly proceed

to Chaps.9,10, or11after skimming through earlier chapters

Jayant G DeshpandeMarina Thottan

We started working on Smart Grids about 6 years back when the vague ideaabout Smart Grids, its challenges, its benefits, and its potential were starting tomature Information and communication technologies (ICTs) were at the core oftransforming the power grid into the Smart Grid We quickly realized that SmartGrid requires a fresh look into how communication network technologies should

be used in realizing the Smart Grid For practitioners in power grid operations,communication networks were considered only as an expedient tool to supporttheir immediate needs What was more surprising to us was that the practitioners

in communication networking looked at the power grid as just another enterprisethat can be supported using the traditional and proven network architecture anddesign for network service provider and enterprise data networks That is simply notadequate when applied to critical infrastructure such as Smart Grid communicationnetworks We hope that this book addresses the needs of both the utility andcommunication network communities to make the Smart Grid evolution a success

In working with many utilities around the world, we had the valuable opportunity

to learn power systems and their operations in great detail from numerous experts

in the area and to learn and understand their needs as they work towards networktransformation to support the Smart Grid Our thanks to all of them in providing usthe necessary background in developing a Smart Grid application-centric networkarchitecture and a roadmap for network transformation to support the ever-evolvingapplications over an integrated network Our special thanks to our partners at EPB

of Chattanooga: the material on Smart Grid data analytics drew heavily on what wehave learned through our joint project

We are thankful to our colleagues in the Strategic Industries Division of Lucent for their invaluable help as we worked on many research, development, andcustomer projects on Smart Grid communication networks Our thanks to KamalBallout, Lynn Hunt, and Ken Rabedeau

Alcatel-We are thankful to Alan Mc Bride, Peter Merriman, and Carl Rajsic for theirreview of the manuscript and providing valuable suggestions and improvements tomake this a better and more useful book We also thank Tewfik Doumi, KimberleyHarris, Mark Madden, Andrew McGee, and Charles Sinno for their review of the

xi

manuscript We have learned a lot from our Smart Grid research team, which hasgreatly helped us in the writing of this book Our thanks to our team membersGary Atkinson, Young-Jin Kim, and Frank Feather We also thank Ed Eckert, BarryFreedman, Joe Moreno, and Stephane Thierry for their help in the process of writing

of this book

This book would not have been possible without our employer Alcatel-Lucentand their research and development arm Bell Labs for providing us an environmentconducive to undertake such a project We thank Rati Thanawala and Chris Whitefor their support and encouragement

We thank Springer for publishing this book and are particularly thankful tothe editors Simon Rees and Wayne Wheeler for making this book possible

We appreciate their patience through numerous postponements of delivering themanuscript We also thank G Kiruthika for support throughout the production ofthe book

Finally, our gratitude and thanks to our spouses Cynthia Curtis-Budka, ShubhaDeshpande, and Ashok Maliakal for their understanding, support, and encourage-ment during a good part of the last year and a half while we were working on thisbook We also thank our children Allyn Budka, Colin Budka, Purva Deshpande,Pari Deshpande, Cyril Maliakal, and Anna Maliakal

1 Introduction to Smart Grids 1

1.1 What Is a Smart Grid 4

1.1.1 Clean Energy 4

1.1.2 Energy Management 8

1.1.3 Consumer Participation in Energy Management 11

1.1.4 Grid Modernization 11

1.2 Smart Grid Domains and Their Interconnections 13

1.3 Objectives of the Smart Grid Communication Network 14

1.4 Overview of the Book 18

References 21

2 Elements of Power Systems for Networking Practitioners 23

2.1 Voltage, Current, Power, and Energy 23

2.1.1 Direct Current (DC) System 23

2.1.2 Alternating Current (AC) System 25

2.1.3 Phasors 31

2.2 Power Generation 34

2.3 Transmission Systems 36

2.4 Distribution Systems 41

2.5 Faults, Circuit Breakers, Switches, and Reclosers 42

References 45

3 Elements of Communication Networking for Power System Practitioners 47

3.1 Elements of Data Communication Networks 48

3.1.1 Links and Nodes 49

3.1.2 Connection-Oriented and Connectionless Services 50

3.1.3 Elements of Packet Communication 51

3.1.4 Classification of Networks 54

xiii

3.2 Protocols and Protocol Layers 54

3.2.1 OSI Reference Model 55

3.2.2 Practical Protocol Layering in Network Standards and Products 58

3.3 Data Networking Technologies 62

3.3.1 Physical Layer (PHY) 62

3.3.2 Link Layer 67

3.3.3 MPLS 74

3.3.4 Network Layer: IP 77

3.3.5 TCP and UDP 81

3.4 Protocol Emulation, Tunneling, Encapsulation, and Gateways 82

3.5 MPLS Services and Protocol Emulation 84

3.6 Networking Standards 87

References 88

4 Conventional Applications in Utility Operations 91

4.1 Distribution Management and Transmission Management 92

4.2 SCADA 93

4.2.1 Traditional SCADA 93

4.2.2 Substation Automation 95

4.2.3 SCADA Evolution with IEC 61850 Set of Standards 96

4.2.4 Networking for SCADA 98

4.3 Teleprotection 100

4.3.1 What Is Teleprotection 100

4.3.2 Teleprotection Requirements 101

4.3.3 Networking for Teleprotection 102

4.4 CCTV 104

4.4.1 Video Surveillance at Substations 104

4.4.2 Networking for CCTV 105

4.5 Mobile Workforce Communication 106

4.6 Business Voice and Data 108

References 108

5 Smart Grid Applications 111

5.1 Advanced Metering Infrastructure (AMI) 111

5.1.1 Smart Meter Measurements 112

5.1.2 Networking for AMI 113

5.1.3 Smart Meter Standards 115

5.2 Distribution Automation (DA) 117

5.2.1 Networking for DA 118

5.3 Distributed Generation (DG) 120

5.3.1 DG at Consumption Locations Versus Stand-Alone DG 120

5.3.2 AC Versus DC 121

5.3.3 Managing DG Connections to the Grid 121

5.4 Distributed Storage 122

5.5 Electric Vehicles (EVs) 125

5.6 Home Area Networks (HANs) 126

5.7 Microgrids 128

5.8 Retail Energy Markets 130

5.9 Demand Response 131

5.9.1 Demand Response Methods 133

5.10 Wide Area Situational Awareness and Synchrophasors 137

5.10.1 Synchrophasors 138

5.10.2 NASPInet 139

5.10.3 PMUs in Distribution Systems 141

5.11 Flexible AC Transmission System (FACTS) 141

5.12 Dynamic Line Rating (DLR) 142

5.13 Summary of Applications 143

References 145

6 A Communication Network Architecture for the Smart Grid 149

6.1 Architecture Framework 150

6.1.1 Core-Edge Architecture 150

6.1.2 Smart Grid Network Protocols 151

6.1.3 Smart Grid Domains and Smart Grid Communication Network 152

6.2 Wide Area Network 153

6.2.1 WAN Architecture 153

6.2.2 WAN over Network Service Provider Networking Service 155

6.3 Local Traffic Aggregation 157

6.4 Putting It All Together 160

6.5 Field Area Networks 161

6.5.1 FAN Protocol Options 161

6.5.2 Summary of FAN Networking Technologies 162

6.6 Logical End-to-End Connectivity (A Few Examples) 162

6.6.1 Automated Demand Response 162

6.6.2 Volt, VAR, Watt Control in Distribution System 164

6.6.3 Wide Area Situational Awareness and Control 166

References 167

7 An Overview of Smart Grid Network Design Process 169

7.1 An Overview of the Network Design Process 170

7.2 Network Traffic 172

7.2.1 Smart Grid Traffic Characterization 173

7.2.2 A Case Study: Smart Grid Bandwidth Requirement in an LTE Macrocell 179

7.3 Traffic Aggregation and Routing Architecture 182

7.3.1 Routing Protocols 184

7.3.2 Label-Switched Paths 185

7.4 Network Performance 186

7.4.1 Delays and Priorities 186

7.4.2 QoS Considerations in Smart Grid Network 189

7.4.3 Per-Hop Behavior 190

7.4.4 QoS Implementation Practices in Current Data Networks 191 7.4.5 Differentiated Services for Smart Grid Application Functions 194

7.4.6 QoS with MPLS 198

7.5 Network Reliability 199

7.6 Network Security Elements 203

7.7 Network Scalability 205

References 205

8 Network Security 209

8.1 Importance of Smart Grid Security 210

8.2 Regulations, Standards, and Best Practices 211

8.3 Smart Grid Security Architecture 212

8.4 Security Zones 216

8.4.1 Transmission Zone 216

8.4.2 Distribution SCADA Zone 218

8.4.3 Distribution Non-SCADA Zone 220

8.4.4 Interconnect Zone 223

8.5 Additional Security-Related Operations 223

References 224

9 WAN and FAN Technologies for the Smart Grid 227

9.1 Wide Area Network 229

9.1.1 Fiber Infrastructure 229

9.1.2 SONET/SDH 231

9.1.3 Ethernet 234

9.1.4 Optical Transport Network 237

9.1.5 WAN Extension with Microwave Infrastructure 238

9.1.6 WAN over Network Service Provider Networks 239

9.2 Wireline Technologies for Field Area Networks 239

9.2.1 Point-to-Point TDM Connections 239

9.2.2 Frame Relay Service 240

9.2.3 Metro Ethernet Service 241

9.2.4 MPLS Services 241

9.2.5 (Wireline) Broadband Services 242

9.2.6 Evolution of Power Line Communication for FANs 244

9.3 Wireless Technologies for Field Area Networks 249

9.3.1 Wireless Broadband Access Services 249

9.3.2 Private Wireless Networks 252

9.3.3 LTE for FANs 256

9.4 Network Ownership 260

9.4.1 Benefits of Private (Utility-Owned) Networks 260

9.4.2 Benefits of NSP Networks 261

9.4.3 Utility Options 262

References 262

10 Smart Grid Data Management 265

10.1 Characterization of Smart Grid Data 267

10.1.1 Technology Challenges 267

10.2 Secure Information and Data Management Architecture 268

10.2.1 Design Requirements 270

10.3 Secure Data Management 271

10.3.1 Secure End-to-End Protocols 272

10.3.2 Data Management Platform 275

10.4 Applications of Smart Grid Data 277

10.4.1 Utility-Centric Applications 279

10.4.2 Consumer-Centric Analytics 280

10.4.3 Market-Centric Analytics 281

References 282

11 Communication Network Transformation 285

11.1 Assessment of Present Mode of Operation and Gap Analysis 287

11.1.1 Applications 287

11.1.2 Utility-Owned Networking Assets and Networks 292

11.1.3 NSP Network Services 294

11.1.4 Network Elements and Network Configuration 295

11.1.5 Network Requirements 296

11.1.6 Network Operations and Network Management 298

11.2 Target Network Architecture and High-Level Network Design 298

11.3 WAN Expansion and Modernization 301

11.4 Evolution of FANs 303

11.5 Migration to the Target Network Architecture 308

11.5.1 Two-Phase Migration for Utilities with Significant Fiber Assets 309

11.5.2 Migration Phasing Based on Geographical Division 313

11.5.3 Migration Phasing Based on Application 314

11.5.4 Migration Phasing Based on a Greenfield WAN 315

11.5.5 Final Phase of Migration to the Target Network Architecture 315

11.6 Evolution of Operations Support Systems and Network Operations 321

11.6.1 Evolution of Operations Support Systems 321

11.6.2 Evolution of Network Operations and Network Management 323

References 324

12 Future of Smart Grid Communication Networks 325

References 330

A Icons Used in Figures 331

B Smart Grid Characterization 333

Reference 334

C Fourier Analysis 335

Reference 337

D Voice over IP and Quality of Service 339

References 340

Acronyms 341

Glossary 349

Index 361

Introduction to Smart Grids

Because of its broad scope, Smart Grid means different things to different people Inthis chapter, we describe the Smart Grid in its most general sense as well as changesthe electric power grid will undergo throughout the evolution of the Smart Grid

A simplified illustration of a traditional power grid is shown in Fig.1.1

The traditional power grid consists of power plants that generate bulk electricpower Transmission substations collocated at generation plants step up the voltagelevels for high-voltage transmission lines which carry electric power over longdistances with high efficiency A transmission system of transmission substationsand transmission lines is deployed to carry power closer to the consumers Beforethe power is delivered to the consumers, voltage levels are reduced (stepped down)

at distribution substations These distribution substations transfer power to theconsumers over feeders (also called distribution lines)

The high-level architecture of today’s electric grids looks much the same as whenthis one-way electric power delivery system was developed and deployed at theend of the nineteenth century Communication network technology introduced inthe latter part of the twentieth century supported the deployment of SupervisoryControl and Data Acquisition (SCADA) systems These SCADA systems allowedoperations personnel to remotely monitor and control transmission and distributionsubstation equipment from utility operations centers, enhancing operational effi-ciency In addition, communication networks found use in the remote support ofautomated circuit breakers known as teleprotection systems

The need for clean energy with large-scale deployment of renewable sources

of energy, peak power reduction for environmental and economic reasons, gridmodernization, and consumer participation in energy management are some of themotivations for the development of the Smart Grid While Smart Grid is a naturalevolution of the electric power grid, the process has experienced a sense of urgencywithin the last decade

K.C Budka et al., Communication Networks for Smart Grids: Making Smart Grid Real,

Computer Communications and Networks, DOI 10.1007/978-1-4471-6302-2 1,

© Springer-Verlag London 2014

1

of Transmission Lines Transmission Towers Transmission Substations

Distribution System

of Distribution Substations Feeders

Consumers

Residential Business Industrial Street lighting Other Electricity Flow

Fig 1.1 A simple schematic of traditional electric power grid

As the Smart Grid evolution continues, a large number of new grid elements andfunctions will be integrated into the grid Examples include the following:

1 Renewable and other alternate sources of energy will be deployed throughout thegrid When deployed at sufficiently high densities, these distributed generation(DG) sources can significantly alter the flow of power in the electric grid,stressing legacy components and controls designed primarily to support the one-way flow of energy from bulk power producers to consumers

2 Advanced Metering Infrastructure (AMI), also known as “smart meters,” will bedeployed at consumer locations In addition to measuring consumption, smartmeters measure voltages, power, reactive power, and other quantities

3 SCADA connectivity will be extended beyond substations to support the itoring and control of reclosers, capacitor banks, and other elements in thedistribution grid, a functionality known as distribution automation (DA)

mon-4 New measurement devices (called synchrophasors) will be deployed throughoutthe transmission grid These devices measure the real-time flow of power andare useful in the control of power flowing across the transmission grid, includingpower flowing across national boundaries

A large number of new grid operations and functions will also be developed –most requiring communication with the new grid elements as well as with theexisting SCADA and other application endpoints Communication networks used

to support these functions will be expanded, modernized, and integrated as theSmart Grid evolves The “intelligence” of the Smart Grid relies upon the real-time exchange of measurement and control data among a vast web of devicesinstalled in homes and businesses; within the distribution and transmission grids,

at substations, control centers, and generation stations, and other facilities Thus,

a high-performance, reliable, secure, and scalable communication network is anintegral part of the Smart Grid evolution

This book focuses on the principles and practices of communication networks

as applied to Smart Grid, including communication architecture, network design,network planning, and transformation of legacy utility communication networks toSmart Grid communication networks

Terminology Throughout this book, the term utility refers to an autonomous entity,

company, or organization responsible for transmission and distribution of electric

power to consumers Consistent with the deregulation of energy markets in manyparts of the world, unless otherwise specified, we assume utilities do not own

power generation However, where deregulation is not in force, the (vertically

integrated) utility also operates power plants for part of its generation needs, with

the rest satisfied by third-party generation companies Finally, there are utilities

that are solely responsible only for distribution (distribution-only utility) or only for transmission (transmission-only utility) The term system operator is also

sometimes used synonymously with the term utility

The term grid will refer to the power grid (traditional and extended with the Smart Grid evolution) operated and managed by the utility The term network is reserved for communication networks Without qualification, the terms energy and

power will imply electric energy and electric power, respectively When referring

to electricity in general terms, either term – power or energy – is used informally(without specifically distinguishing between power and energy as used in physics)

We use the following taxonomy for sources of electric power generation Notethat there is no formal classification scheme; therefore, some generation sources

may be classified differently by different people Bulk energy sources (or bulk

power generation plants) refer to power generation sources connected directly

to the transmission system They include traditional nuclear, thermal (coal, oil,natural gas, etc.), and large hydro power plants as well as large establishments ofrenewable and other alternate energy sources (such as wind farms, solar farms, andfuel cells) The capacity of these power plants is usually hundreds of megawatts

(MWs) Distributed energy generation or distributed generation (DG) refers to

power generation that connects into the distribution system Distributed generation

is also called distributed energy resources (DER) In addition to stand-alone DGestablishments, DG includes generation sources at consumer locations (such as solarpanels on the rooftop of a home) or combined heat and power (CHP) in a business

building Finally, clean energy refers to electricity generated from energy sources

that produce little or no greenhouse gas (GHG) emissions Depending on the energysource and size of a DG, the capacity may vary from several hundred watts for asingle solar panel to several hundred MWs for a large wind farm or geothermalpower source

Renewable energy sources (or simply renewables) are those for which the

“fuel” used in transforming energy to electricity is never exhausted Examples

of renewables are wind power, solar power, small hydro, biomass, biogas, and

geothermal energy sources Alternate energy sources are generally sources of

energy that are not the traditional bulk energy sources and include renewables aswell energy sources such as fuel cells and CHP Note that the alternate energysources can be both bulk energy sources and DG sources These classificationsare not universally accepted For example, fossil fuel sources are not consideredrenewables by most, while some argue that these sources may not be exhausted

in the foreseeable future In addition, fuel cells are considered renewable energysources by many However, since fuel cells generate green house gases, some maynot consider fuel cells as clean energy sources

Finally, we will call any provider of communication network services (whether

data or voice) a network service provider (NSP) Often an NSP is called a carrier.

We reserve the word carrier to refer to carrier frequency of a wireless system (seeChap.3)

1.1 What Is a Smart Grid

A collection of “visions,” concepts, and descriptions of the Smart Grid fromdifferent companies and organizations can be found in [GELL09] No single

“definition” or short description does justice to the meaning or the eventual end

goal of the Smart Grid The Smart Grid is best characterized by a set of objectives.

The United States Energy Independence and Security Act (EISA) of 2007 [EISA07]provided ten characteristics of the Smart Grid (seeAppendix B) In our opinion, theEISA characterization of the Smart Grid is the most complete version

To help reduce harmful GHG emissions attributable to the electric powerindustry, increased incorporation of clean energy sources is one of the objectives ofthe Smart Grid Further reduction in GHG emissions is expected through efficientenergy management, particularly in terms of peak power reduction Modernization

of the grid is at the heart of achieving the promise of the Smart Grid Finally, activeparticipation of consumers in their awareness of energy usage and in their individualenergy management is an important part of the overall Smart Grid

From 1973 to 2009, worldwide electricity consumption has increased more thanthreefold See [IEA11] for a comprehensive report from the International EnergyAgency Figure1.2is taken from this report

Fossil fuel–based generation (coal, oil, and natural gas, etc.) is the maincontributor to GHG emissions Though the contribution from fossil fuels hasdecreased somewhat (from about 75 % to 67 %) as a percentage of the total energygeneration, with the large increase in overall generation, GHG emissions haveincreased substantially The increased use of distributed renewable energy sources

is a welcome sign, but their contribution must increase substantially to reduce theconsumption of fossil fuels Also see [GSGF12] for a report on the mix of energygeneration technologies in several individual countries and Smart Grid projects inthose countries

According to a recent report “SMART 2020” [KRUS08], the electric powersector will contribute 14.26 GtCO2e (gigatons equivalent carbon dioxide) of GHGemissions by 2020, roughly 21.25 % of global GHG emissions They project that

“Smart Grid mechanisms” could reduce this by about 2.03 GtCO2e

Fig 1.2 Worldwide electric energy contribution of sources of electric energy generation

(Repub-lished with permission from 2011 Key World Energy Statistics © OECD/IEA, 2011)

Nuclear and hydroelectric (large hydro) power plants contribute very little toGHG emissions However, in light of safety concerns, environmental impact, andhigh capital costs, expansion of nuclear energy will be challenging Hydroelectricenergy is clean, but its expansion as bulk energy sources is also limited due to thelimited number of viable sites for additional hydroelectric power plants

Therefore, in the last few years, there has been a concerted effort in developmentand deployment of renewable sources of energy Brief descriptions of some of theserenewable resources of energy are presented here An introduction to many of thesetechnologies can be found in [NRDC12]

Wind Power Wind power transforms kinetic wind energy into electric energy.

Blades of a wind turbine capture wind energy and turn the rotor of the electricgenerator The generated electric energy can then be consumed locally or transferredover the grid Wind turbines can run alternating current (AC) generators as well asdirect current (DC) generators Most large wind farms generate AC, allowing thefarms to be connected to the grid without DC–AC conversion However, due to thevariable nature of the wind resulting in AC output with variations in amplitude andfrequency of the generated voltage, care must be taken in managing this connection

If the generated power is DC, inverters are required to convert it to AC beforeconnecting to the grid A wind power installation (often called wind farm) gathersenergy from many wind turbines Typically, a wind farm produces 1–5 megawatt(MW) of power; however, very large wind farms have capacities of several hundredMWs

The main advantages of wind power are that there is no “fuel” cost and thatthey are environmentally clean The main drawback is that the intermittent nature ofwind cannot assure a constant power output, thus requiring power stabilization forconnecting the wind power into the grid

Note The typical sizes of energy generation sources (in terms of the power

output) stated here are for broad comparison purposes only The actualnumbers vary and will generally increase as the technologies mature

Solar Power There are two methods for converting solar energy into electricity:

photovoltaic (PV) cells that directly convert sunlight into electric energy and thermalcollectors that absorb heat energy from the sun to heat water or other fluids that runthe power generators

Photovoltaic cells are arranged on rectangular panels which are exposed to thesun Panels can be deployed on the roofs of consumer dwellings where all or some ofthe generated energy is usually consumed, reducing the need for electricity receivedfrom the grid at that location Additionally, the consumer may transfer (sell) some

or all of the energy thus generated back to the grid

In large PV deployments, large numbers of panels are installed in “solar farms.”Solar farms have also been deployed on campuses or premises of large enterprises toaugment the energy needs of their owners Commercially, solar farms are deployed

as stand-alone DG sources that connect into the grid

The electric energy generated by a PV cell is DC This energy must be converted

to AC by invertors before connecting to the local electric circuits or into the grid

A typical residential rooftop solar deployment today generates about 2.5 kilowatt(kW) of electric power Depending on the size and technology, solar farms cangenerate upward of 200 kW to several MWs of power

Another method of generating electricity from solar energy is to use thermalcollectors to absorb heat energy from the sun to heat water or other fluids Thesefluids run turbines that run generators to produce electricity Parabolic mirrors areused to concentrate solar heat at the thermal collectors to increase the efficiency ofthe power plants These concentrated solar power (CSP) plants can generate manyMWs of power CSP plants of more than a gigawatt (GW) are being deployed

As with wind power, the main advantages of solar power are that there is no

“fuel” cost and that the power is environmentally clean The main drawbacks arethe lack of sunlight at night and nonuniform availability during the day depending

on the time of the day, cloud cover, and other factors Therefore, care must be taken

in managing the grid connectivity of solar installations

Geothermal In many traditional thermal power plants, steam turbines use steam

generated from water heated by burning coal In geothermal power generation,geothermal sources are used to drive electric turbines Geothermal power plants arebuilt where geothermal steam or hot water is naturally available Geothermal steamcan be directly used to run steam turbines In the case of geothermal water, it can beused to generate steam or to heat other working fluids that run the turbines.Once again, when available, geothermal power is clean and the “fuel” isfree Geothermal energy sources provide power anywhere from 1 to 1,000 MW,depending on their size

Small Hydro As the name suggests, small hydro power generation sources are

small hydroelectric energy sources They are generally located at the base of dams

at small bodies of water and typically generate less than 10 MW of power

There are other types of energy sources, though not necessarily directly contributing

to reduction in GHG emissions, that can provide some relief in GHG emissionsindirectly Some of these energy sources are described below

Biomass and Biogas Biomass refers to the burning of wood crop waste Due to

economic and other benefits, “energy” crops are grown specifically for biomassused for power generation Biogas refers to burning of methane gas (which is thepredominant part of natural gas) produced by animal manure Biogas is differentfrom natural gas as commonly referred to Natural gas was formed 150 million yearsago in pockets of the earth crust and in porous rock It is a non-renewable, fossilfuel recovered from deep gas wells Biogas is the product of the natural biologicalbreakdown of crop and animal waste when the supply of oxygen is restricted This

is a continuous, ongoing process in Nature and it also takes place under controlledconditions in our sewage plants and landfills Natural gas and biogas both containmethane If biogas is refined, with everything except methane being removed, itsproperties are then similar to those of natural gas This means that the technologythat has been developed for the distribution and use of natural gas can also beused for biogas While these fuels are renewable and “free,” they do contribute toGHG emissions However, these newer technologies produce less harmful emissionsthan coal In the case of biogas, natural methane emission from livestock into theatmosphere is curtailed (Note that methane itself is a very potent greenhouse gas.)These technologies are most useful on (crop or livestock) farms where such fuelsare readily available, reducing the local need for power from the grid

Fuel Cells Fuel cells are analogous to batteries in that the electricity is produced

by chemical reactions with hydrogen passing over one electrode (the anode) andoxygen (air) passing over another (the cathode) while both are immersed in anelectrolyte Hydrogen is often generated from hydrocarbon fuels such as naturalgas or biogas However, there is an important distinction between fuel cells andbatteries Unlike batteries, fuel cells require a continuous supply of fuel and air Inthat sense, fuel cells are not renewable sources of energy Since power generation isbased on chemical reaction and not combustion, the GHG emissions are lower than

in power plants that require combustion of fossil fuels Fuel cells can be arranged inseries and parallel combinations to provide higher electric energy supply at higherpower Typical fuel cell systems provide up to 100 kW of power Larger fuel celldeployments can provide several MWs of power Inverters are required to convert

DC power from fuel cells to AC to support electricity locally or to connect fuel cells

to the grid

Combined Heat and Power Combined heat and power (or cogeneration) is the

name given to an energy source that provides both electricity and heat, generallyusing a single fuel source like natural gas, oil, or biomass In any electric powergeneration system based on combustion of fuel, heat is always generated in addition

to electricity Often that heat is wasted by releasing it in the atmosphere InCHP plants, the generated heat contributes to useful functions such as heating ofbuildings The CHP system produces less GHG emissions and costs less than ifseparate systems are used for producing electricity and heat CHP is used in largebuildings and building complexes such as apartment buildings.

Electric Vehicles Electric vehicles (EVs) are not sources of energy; however, the

expected widespread use of EVs will reduce the overall GHG emissions fromgasoline or diesel used in conventional vehicles There will be an increased demand

on electricity for powering the EVs, thus adding to the GHG emissions associatedwith the coal or natural gas power plants The reason for including the EVs in the

“Clean Energy” section is that the EVs will actually amount to a net decrease in

GHG emissions since the efficiencies of modern power plants are higher than those

of the internal combustion engines used in conventional vehicles For a study on theassessment of GHG emissions from the use of EVs, see the Electric Power ResearchInstitute (EPRI) report [EPRI07] Note also that the increase in power generationattributable to EV consumption can be partially offset by the increased deployment

of clean sources of energy

Efforts are under way to deploy clean energy sources However, replacing all fossilfuel powered plants or significantly reducing their numbers may take decades In themeantime, coping with increasing demand will require a combination of deployment

of DG, increased efficiency, and peak power reduction through energy management

techniques

Total energy demand varies throughout the day, with typically higher demandsobserved during daytime hours Demand also changes seasonally depending onlocation: higher consumption during summer months when higher temperaturesdrive the use of air conditioning and higher consumption in winter months due toheating and lighting (in regions with colder climates) Building bulk power plants

to support the expected peak power at various times in a year is economicallyburdensome, since most of the time the demand is far less than the peak powercapacity For some bulk power generation technologies (such as nuclear powerplants and even some coal power plants), it is very difficult to respond to changingenergy demands in real time In addition, despite current advances in electric storagesystems such as large batteries, high-energy flywheels, ultra-capacitors, pumpedhydro, and compressed air energy systems, storage of large amounts of electricenergy over a period of time is either infeasible or cost-prohibitive

Energy management is an important element of the Smart Grid We brieflydescribe how the new and expected developments in energy markets, dynamic

pricing of energy consumption, and demand response will help improve energy

management

(Energy) Markets With deregulation of power markets throughout much of the

world, utilities buy electricity from bulk energy suppliers in (bulk) energy markets.Energy prices are determined by market dynamics based on supply and demand.Thus, during periods of high demand, energy prices are higher These high energyprices are due in part to the high energy generation costs associated with power

plants that can respond to the demand in real time (often called reserves).

Individual consumers today have limited participation in the bulk energy market:they can specify a bulk energy supplier who will “supply” their consumption ofenergy at the price determined by that supplier In regions where deregulation is ineffect, utilities may allow consumers to change their electricity suppliers at will atthe maximum rate of once a month Because of this time delay, the choice of supplier

is not based on real-time changes in energy pricing or market conditions Further,most consumers pay a fixed monthly price per unit (kWh) set by the supplier

DG will play an important role in the supply of bulk generation capacity and inthe temporary supply of energy to meet peak demands As a result, incorporating

DG into newly emerging retail energy markets (REMs) will play an important role

in the management of energy in the future In retail energy markets (REMs), DGowners will be market participants In addition, individual consumers may also beallowed to participate in retail energy markets to meet their energy demands in realtime at optimal pricing

Some utility customers will be both consumers and DG owners at the same time

This class of customers is referred to as prosumers With a very large number of

participants in retail energy markets, the utility may assign the function of market

management to an aggregator The role of the aggregator is to coordinate with

the utility, consumers, DG, and bulk energy markets to facilitate real-time energyexchange between the consumers and DG In addition, the controlled influx of DGpower into the grid will help the utility with energy management REMs will bediscussed in detail in Chap.5

Dynamic Pricing Traditionally, utilities have charged their customers a fixed price

for each unit (kWh) of energy consumed There have been a few variations inpricing, particularly for business and industrial consumers, who may be chargedfor power (kW or MW) in addition to charges for energy consumption (kWh).Some utilities have started offering dynamic pricing to their business, industrial,and residential customers The rationale behind dynamic pricing is to entice theconsumers to use less energy when the demand is high by charging them a muchhigher price during periods of high demand Some utilities may provide priceincentives in addition to or instead of dynamic pricing during periods of highdemand

There are several dynamic pricing methods used:

1 Time of Use (TOU) pricing: The consumer is charged a higher price during the

“peak” period of higher energy demand The utility specifies the peak periods,say, afternoon and evening hours of summer months on weekdays and, incold weather regions, mornings and evenings of winter months on weekdays

Typically, the peak price is 2–3 times the nonpeak price The peak and nonpeakprices are known in advance by the consumers and do not change in real time.Generally, the customer must subscribe to the TOU program; otherwise, the fixedprice that is in effect all the time will be higher than the nonpeak TOU price.

2 Critical Peak Pricing (CPP): CPP is used to control demand during the relatively

small number of days in the year when demand is significantly higher than thenorm (e.g., during heat waves) Under CPP, consumers are charged rates duringthe peak consumption intervals that are generally 4–6 times higher than nonpeak

or fixed pricings The utility may designate the days on which CPP will be ineffect a day or two in advance based on the expected demand (usually based

on weather forecast) Participation in CPP may be voluntary or the utility mayimpose it on consumers CPP may exist in addition to TOU pricing, in whichcase CPP pricing is used during the CPP hours

3 Real-Time Pricing (RTP): RTP refers to higher prices during high-demand hours

at any time that the utility designates The utility provides information on thesedesignated hours (many hours) in advance to the customers

Dynamic pricing can be advantageous to consumers with EVs: they may chargetheir vehicle batteries when energy prices are low and sell electric energy back tothe grid when prices are high

Demand Response Demand response refers to actions taken by a utility to reduce

energy consumption, increase energy supply, or both in response to an imbalancebetween energy supply and demand Construction of new power plants to meetfuture expected increase in demand can be considered a long-term demand response.TOU pricing can also be considered a long-term demand response in the sensethat the demand response mechanism is based on the natural cycle of demandvariations in over a year due to the weather cycle Of particular interest is demandresponse in real time – responding to high peak power demand within timescales of

a few minutes or shorter Such demand response actions are necessarily temporary.Meeting temporary demand by increasing supply from (bulk) reserves or DG is oneoption Additionally, and often as a last resort, utilities may reduce the suppliedvoltage to some or all customers by several percent of their nominal value (also

known as brownout).

Voluntary consumer participation in demand response for peak power reduction

is an important aspect of the Smart Grid Dynamic pricing or incentives to modifyenergy consumption are mechanisms that directly engage consumers in the process

of peak power reduction Consumers with local DG may draw less power fromthe grid to support utility demand response Consumers can subscribe to automateddirect load control programs offered by the utility, such as allowing the utility todirectly control the shutting off/turning on (“cycling”) of one or more appliances(such as electric water heaters, electric clothes driers, heat pumps, air conditioners,and thermostats) in their homes, in exchange for lower energy costs Such automateddemand response has the promise of real-time response to peak power reductionwith consumer participation

1.1.3 Consumer Participation in Energy Management

Consumer participation in energy management is one of the goals of Smart Gridevolution Several aspects of consumer participation in energy management, such

as subscription to dynamic pricing and direct load control of appliances, weredescribed earlier Further, as discussed earlier, consumers can offset some of theirenergy demand using local sources of energy such as rooftop solar panels and CHP,

or optionally sell energy generated locally to the grid from these energy sources.With the advent of retail energy markets, consumers can participate in the markets

as buyers or sellers of energy, or both, through real-time energy transactions

Home Area Networks Each consumer – residential, business, and industrial –

can use his or her local communication networks to support energy management.Residential customers may build a local network called a home area network (HAN)

to interconnect its electric appliances, smart meter, and local energy sources for

the purpose of energy management The HAN may include a home gateway (also

called energy services interface in [NIST12]) that connects to the utility energymanagement system or other third-party services for energy management purposes.Often the HAN is an extension of the home Wi-Fi network

Microgrid The extent of consumer participation in energy management depends

on several factors including whether the consumer is a residential, business, orindustrial consumer With the advent of Smart Grids, a special class of consumers –

microgrids – is emerging A microgrid is an interconnection of individual consumers

and at least one local energy source Each consumer in the microgrid receives energyfrom both the utility grid and the microgrid under normal operating conditions

The microgrid is considered autonomous if, in the case of the microgrid being

disconnected from the utility grid, the microgrid energy sources are sufficient tomeet the critical needs of its consumers A trivial example of a microgrid is aresidential customer with an energy source such as a rooftop solar (PV) panel.More interesting microgrids can involve apartment buildings, business and industrialcomplexes, universities, or even a small residential community While the term

“microgrid” is new, some businesses, industries, and universities have for some timeused local generation to support (part of) their energy demands and sometimes tocontribute power to the grid during emergencies

The energy management system in the microgrid is responsible for managing the

microgrid and energy distribution within the microgrid as well as managing energytransactions and electric connectivity with the utility Distribution ManagementSystem (DMS)

As was observed in the beginning of this chapter, electric grids have not changedsignificantly since they were first developed and deployed toward the end of the

nineteenth century Much of the grid monitoring and control today is limited toteleprotection and SCADA applications Teleprotection is used to remotely detectelectric faults on a transmission line and then trip the circuit that feeds the faultsusing communication between the substations connected by the transmission line.SCADA systems are used to measure voltages, currents, and other quantities atseveral points in a substation with the utility Data and Control Center (DCC) takingappropriate grid control action Intelligent Electronic Devices (IEDs) are replacingthe mechanical and oldelectric devices, and digital communication networks arereplacing the analog and relay-based communication systems used for these appli-cations.

Previously, the intelligence of control systems relied solely on monitoring andcontrolling substations equipped with these facilities, and therefore grid man-agement was rather limited in scope For example, outage management systems(OMS) at the DCC had no way of detecting power outages at customer premises

As a result, utilities had to rely on customer complaints of power outages fortrouble isolation and on troubleshooting for responding to the outages Mobileworkforce communication was limited to push-to-talk voice communication Whileautomated meter reading is being increasingly employed by utilities to read theconsumer meters remotely, meter measurements are generally used only to facilitatebilling

Power grid modernization has gained momentum with Smart Grid Utilitiesare modernizing their substation automation from legacy systems, protocols, andnetworks to those based on the newer IEC 61850 set standards [61850-01-10].With distribution automation, SCADA is being deployed outside of substations

at reclosers and distribution transformers at feeders Newer communication nologies are being deployed for communication between substations to supportapplications such as teleprotection [61850-90]

tech-Transmission system monitoring is expanded with new Flexible AC sion Systems (FACTS), real-time monitoring, and control systems that increasetransmission efficiencies Dynamic Line Rating (DLR) monitors at transmissiontowers further add to these efficiencies A widespread blackout in North America in

Transmis-2003 gave rise to new wide area situational awareness systems using synchrophasors

to monitor across utilities and even across national boundaries Synchrophasorscollect time-synchronized measurements in the grids 50 or 60 times a second,providing power system state information that can be used to stabilize the electricgrid Last but not the least, with AMI, smart meters are being deployed at everyconsumer location Smart meters collect and send measurements periodically (such

as every 5 or 15 min) Analytics based on data reported by smart meters cancontribute to a wide variety of applications such as demand response, distributionmanagement, asset management, and consumer energy management

Another component of grid modernization is maintenance of power quality.

Power quality generally refers to maintenance of delivered power within acceptedtolerances for voltage and frequency (see Chap.2) Incorporation of DG sourcesinto the grid creates multiple challenges in maintaining power quality To maintain

the integrity of the grid, the AC waveforms of DG sources must be synchronizedwith the grid AC waveform where the DG sources connect into the grid Many DGsources inherently are subject to frequent variations of their amplitudes, frequencies,and phase angles These variations must be controlled in real time; otherwise, the

DG source must be disconnected from the grid

Finally, the reliability and security of the grid must be maintained as newapplications and application endpoints are introduced

1.2 Smart Grid Domains and Their Interconnections

Smart Grid communication networks support interactions between entities (users,systems, and applications) within the many organizations and locations of the utility.These entities can be grouped into broad “domains” as shown in Fig.1.3

Figure1.3is based on the (US) National Institute of Standards and Technology(NIST) Smart Grid interaction conceptual model [NIST12] a few Traditionally,electricity flows from bulk generation sources to the transmission system of trans-mission lines and transmission substations to the distribution system, from where

it is delivered through the distribution substations to the customers (consumers ofenergy) over feeders (as illustrated in Fig.1.1) With Smart Grid, electricity is also

Distributed Generation Domain

Customer Domain

Operations Domain

Scope of Utility Smart Grid Communication Network

generated from DG sources connected into the distribution system Note that wehave defined a new domain of distributed generation in Fig.1.3 In [NIST12], DGwas included as part of the distribution domain and customer domain.

We have added the boundary for the interconnections that will be supported

entirely by the utility communication network (utility intranet) Communications for interconnections not included entirely within this boundary are either extranet

communications for the utility network (e.g., between the operation domain andthe market domain) or completely external to the utility network (e.g., between the

customer domain and the service provider domain) For the vertically integrated

utility that also owns power plants for part of its generation needs, the utilityboundary will include the part of the bulk generation domain covering those power

plants On the other hand, for the distribution-only utilities, the utility boundary

will not include the transmission and the bulk generation domains There areorganizations outside of the utility that perform power grid operations such ascompanies that manage an interconnection of multiple utility grids, and thus arepart of the operations domain [NIST12] Examples are the Independent SystemOperators (ISOs) and Regional Transmission Organizations (RTOs) which managethe interconnection of grids in North America Therefore, the boundary of a utilitySmart Grid communication network may not include the operations domain in itsentirety

The utility operations domain includes grid applications for monitoring andcontrolling transmission and distribution systems as well as grid connections tocustomers and DG Some of these applications also require interaction with marketsand, as a result, may require monitoring of the bulk generation used by the utility.Finally, interactions with providers of services that are external to the utilityare in the service provider domain Examples of services that can potentially beexternal include billing, engineering and maintenance, customer management, andoutsourced services

Many applications and classes of applications requiring the interactions inFig.1.3are described in detail in Chaps.4and5 For details of other entities withinthe various domains, see [NIST12]

1.3 Objectives of the Smart Grid Communication Network

The primary objective of the communication network for the Smart Grid is to

support traffic for all applications – both existing utility applications and planned

and future Smart Grid applications The currently predominant practice of buildingindividual network(s) to support each new emerging application is not efficient andincreases complexities in building new networks as well as in operating multiplenetworks With an integrated network, the additional capital and operation costsassociated with supporting new applications are minimal Some of the objectives ofthe Smart Grid communication network are described in this section

Standards-Based Network The Smart Grid communication network must be

based on well-established communication networking standards This allows theutilities to procure interoperable network products from multiple vendors, thusreducing costs Multi-vendor products help remove dependency on single-vendorsolutions that can become very expensive to maintain over a long time Further, asstandards evolve, it is easier to receive product upgrades, often without additionalhardware costs Network expansion also requires little modification or replacement

of the existing network assets NIST has compiled a comprehensive list of ing standards for basic communication standards as well as communication-relatedutility standards [NIST12]

network-Internet Protocol (IP) IP is the most common network protocol used in data

networks today From its inception, IP was developed to interconnect networkendpoints irrespective of the physical or logical connection technologies supportingsuch interconnections With the widespread support of IP, not only are there a largenumber of network products available at competitive prices, but there has also been

a concerted effort to develop new standards, methodologies, and tools to increaseefficiency in engineering, operations, and management of the IP networks In recentyears, there has been a trend in the migration of utility SCADA networks from serialconnections to IP connections Emerging Smart Grid applications such as AMI anddistribution automation are also supporting IP connectivity to utility DCCs NewCCTV communication products are often IP-based It is expected that IP will be thenetworking protocol of choice of the new Smart Grid applications

Multiprotocol Label Switching (MPLS) IP does not address all the challenges

of Smart Grid communication network Multiprotocol Label Switching (MPLS)technology provides many added benefits to the network With MPLS, not onlycan the integrated network support applications (like teleprotection) that cannot

be supported over the IP network at this time but the use of the MPLS servicescan also offer many other advantages MPLS services support isolation of trafficbetween “closed user groups” of applications and application endpoints, a propertythat helps facilitate network security Separation of the MPLS control and dataplanes of individual services adds robustness to network security implementation.MPLS affords additional network reliability with very fast recovery from networkoutages – otherwise possible only with more expensive network technology options.Legacy systems, interfaces (e.g., serial interfaces), and protocols can be supportedwith the corresponding MPLS services on the same integrated Smart Grid IPcommunication network Additionally, MPLS provides quality of service (QoS)capabilities in multiservice networks supporting different protocols For example,MPLS provides QoS capabilities required to guarantee delivery of high-prioritytraffic such as teleprotection (carried in an MPLS service) in a congested network

Support for Legacy Applications, Systems, and Protocols There are situations

in which IP may not be the appropriate choice for some utility network connections.Utilities may be required to support non-IP-based legacy applications, systems,and protocols for a period of time to save replacement costs In addition, some

utilities may opt to use legacy systems until their IP-based replacements can betested to meet their requirements For example, the utility may be reluctant toreplace a working SCADA RTU that connects to the SCADA control systemover a serial connection to avoid the cost of replacement Another example isthat a utility will not migrate its teleprotection applications to IP for a longtime, since the current IP network will not be able to support the stringent delayrequirements of the teleprotection traffic in a congested IP-only network Therefore,the network must be able to support legacy applications, systems, and protocolsfor a period of time Using MPLS services, multiple protocols needed by multiplesets of applications and endpoints are supported over the integrated Smart Gridcommunication network.

Network Performance In an integrated networking environment, the network

must support the performance requirements of the various individual applications.This is particularly the case for the end-to-end delay requirements for traffic carriedover the common network infrastructure A network QoS design is required thatwill provide the prioritization and delay performance needed to satisfy the end-to-end delay requirements of each individual application during both normal operatingconditions and network outages For example, a link connecting a substation routermay carry traffic for synchrophasor, SCADA, CCTV, and other applications located

at that substation with their individual and diverse requirements for delay, priority,and data rate on that link

Network Reliability Maintaining high power grid reliability and ensuring

avail-ability of power to consumers at all times are the primary goals of utility operations.Communication networks help support these goals through real-time monitoringand control of the grid Therefore, maintaining high levels of network reliability

is essential Further, the reliability requirements for some of the mission-criticalgrid applications are more stringent than typical requirements for communicationnetworks that support voice (VoIP) and business data applications For example,communication network availability of 99.96 % may be adequate for most businessdata networks, whereas even 99.999 % (“5 nines”) reliability may not be enoughfor supporting teleprotection applications (The 99.96 % and 99.999 % reliabilityobjectives translate to the average network “downtime” of 210 min per year and

5 min per year, respectively.) The use of redundant network equipment and linksand avoidance of single points of failure in critical parts of the network are some ofthe normal solutions for increased network reliability Additionally, reliable traffic

routing design adds to network reliability Deployment of utility-grade network

elements must also be considered since their product reliability is much higher withinternal redundancy in hardware configuration and “hitless” network upgrades Arelated aspect of reliability is disaster recovery of the utility DCC and other criticalutility locations

Network Security As with network reliability, network security is also of

paramount importance not only for the security of network operations but alsofor the integrity of the electric grid Loss of electric power caused by cyber

attacks on devices which monitor and control the electric grid can have severeeconomic consequences As a result, electric grids are considered national criticalinfrastructure in many countries Network security implementation should followutility security policies including implementation of hardware and software securitycontrols such as access lists, firewalls, and intrusion detection and preventionsystems, as well as security operation policies and procedures The communicationnetwork design can also take advantage of networking protocols that allow isolation

of traffic between closed groups of endpoints and applications In addition,applications may collect sensitive customer data from smart meters and otherdevices As a result, data privacy is also an important element of network security

Scalability The network architecture should be scalable in that introduction of new

Smart Grid applications should be possible with minimal changes in the physicalnetwork As much as possible, introduction of new applications should require onlyminimal network configuration changes Often at the beginning of a new applicationintroduction, the utility may add only a few new endpoints With proper planning,addition of a large number of application endpoints can be accommodated throughcapacity management Similarly, addition of only a few network endpoints such as

a substation, several DG locations, and smart meters should require few changes innetwork configurations (except for the ones that affect these new endpoints)

Efficient Traffic Aggregation and Routing One advantage of an integrated IP

network is that the network design takes a holistic view of the network To achievescale economies, traffic is aggregated at many points in the network based onthe locations of the endpoints and the volume of traffic generated Thus, it is notnecessary for the individual pairs of application endpoints to connect over costly,inefficient, and exclusive circuit connections Traffic routing determines the bestpath for data to travel from the source endpoint to the destination endpoint over thenetwork Routing protocols have the ability to dynamically change these networkpaths based on network conditions such as failure of a link or a network element

Secure Network-Based Data Management With new data management

technolo-gies, it is possible to support secure network-based data management The expectedexplosive growth in the volume of data collected in the Smart Grid for use by a largenumber of applications requires implementation of data management systems thatare secure, that provide low delays when the data is accessed, and that provide dataprivacy based on utility security policies

Unified Network Management The Smart Grid network is an evolving network.

To facilitate this evolution, the current set of networks must first be transformed to

an integrated network It will further evolve as new applications are introduced andendpoints added The network will often be based on network elements (routers,switches) provided by different vendors As a result, to provide a unified end-to-end network management solution for network provisioning and configuration,troubleshooting and alarm correlation, maintenance workforce dispatch and man-agement, capacity management, and network security, it is advisable for utilities

to deploy operations support systems (OSSs) that will work with the elementmanagement systems from multiple vendors Where possible, these OSSs shouldideally also integrate with the utility’s grid operations and management, assetmanagement, and financial systems.

Facilitate Well-Organized Network Transformation The Smart Grid

communi-cation network is not a “greenfield” network As a result, the network architecture

in general and the initial network design in particular should consider the inclusion

of the existing utility assets (such as fiber plant) to the extent possible The networktransformation is not a one-step process – several intermediate steps will be requiredwith rigorous planning to minimize network disruptions Implementation of MPLSservices can provide efficiency in the transformation process with reduced costs(details are provided in Chap.11)

Flexibility in Ownership of Network Segments There are many advantages to

a utility owning all of its network assets and operations Similarly, there are someadvantages to a utility using NSP networking services in its network Depending

on the existing networking assets of the utility, available resources for networktransformation to meet the Smart Grid goals, available and forecasted networktechnologies from NSPs, and networking requirements, the resulting Smart Gridcommunication network may be a combination of utility-owned network segmentsand network segments from NSP services It is important that the communicationnetwork architecture provide the flexibility for the utility to decide on the best mix

of utility-owned networks and NSP networking services

1.4 Overview of the Book

Readers of this book will need some familiarity with power systems and theiroperations Therefore, elements of power generation, transmission, and distributionsystems are presented in Chap 2, with special attention to functions which have

a bearing on grid monitoring, control, and operations requiring communicationnetworking

Similarly, readers of this book will need some familiarity with communicationnetworking Therefore, relevant topics in communication networks are presented

in Chap 3 for the benefit of the readers with little background in networking.After a brief presentation of the communication network architecture framework

of the Open System Interconnection (OSI) architecture, protocol layers pertinent

to the Smart Grid network are presented in more detail Network technologies aredescribed with their relative benefits and drawbacks for supporting the Smart Grid.Both wireless and wireline technologies are included Where appropriate, reliability,security, and QoS features of the technologies are conveyed Relevant IP and MPLSnetworking features are described in more detail

Traditional grid applications requiring communication are the subject of Chap.4.They include SCADA and teleprotection Other utility applications important forutility operations such as mobile workforce communication and physical security(including CCTV) are also included The emphasis in this chapter is on the legacynetworking as well as the new technologies that will be used Finally, the utilityitself being an enterprise, communication networks are used for business voice anddata communication In the authors’ experience, there is not much support in theutility community for the utility business voice and data to be considered a SmartGrid application Without taking a position on this issue, we will briefly describenetworking for these applications if they are indeed included in the Smart Gridnetwork.

We take an application-centric approach to developing the communicationnetwork architecture for the Smart Grid, based on our earlier work on Smart Gridnetwork architecture [BUDKA10] The Smart Grid network will be an integratednetwork supporting all existing utility applications as well as new Smart Gridapplications that are being introduced and that will be introduced in the future

In Chap 5, we present a comprehensive description of new utility applicationsrelated to the Smart Grid evolution Applications included are advanced meteringinfrastructure (AMI), distribution automation (DA), distributed generation (DG),distributed storage (DS), electric vehicles (EVs), microgrids, home area networks(HANs), automated demand response (ADR), wide area situational awareness andsynchrophasors, Flexible AC Transmission System (FACTS), Dynamic Line Rating(DLR), and retail energy markets (REMs)

Chapter 6 is at the heart of this book where we present the communicationnetwork architecture for the Smart Grid A core-edge communication networkarchitecture is well suited to the Smart Grid In this architecture, many utilityendpoints communicate with application endpoints located in the utility Data andControl Center (DCC) The core network, called a Wide Area Network (WAN) bythe utility community, will connect to the DCC(s) and other utility locations in theproximity of the core network Other utility endpoints will connect to the WAN overaccess networks, called Field Area Networks (FANs) While IP will be the ultimatenetwork protocol, the architecture will support legacy applications and protocolsfor a period of time as desired by the utility Further, the network architecture willprovide for easy introduction of new Smart Grid applications with few architecturalchanges and often without any need for physical changes in the network

Important topics in the design of the Smart Grid network are discussed inChap 7 Networking requirements for a utility network are different in manyrespects to those for NSP networks NSP networks are primarily designed to supporttheir customers’ multimedia applications, while the Smart Grid network mustsupport mission-critical applications like SCADA, teleprotection, and synchropha-sors in addition to many other applications Reliability, security, and performancerequirements for Smart Grid networks are more stringent than the correspondingrequirements for enterprise networks This chapter begins with the characterization

of Smart Grid logical connectivity and network traffic, which are the inputs tonetwork design Design considerations are provided for supporting the requirementsrelated to routing, QoS, and reliability MPLS design is discussed as MPLS canprovide many advantages in an integrated network including support of legacynetworks and protocols as well as QoS in a multiservice network.

Network security will be briefly addressed at many places throughout this bookwhile discussing applications, network architecture, and design Network securityrequires a more complete treatment and is the topic of Chap.8 Cybersecurity of thepower grid has become as important a concern as physical security There has been

a concerted effort by utilities, regulators, and standards bodies to implement a highlevel of communication network security that will not only secure the networks butwill also minimize the risk of security attacks on the grid and provide mitigation

of security threats Further, a comprehensive approach is required where networksecurity must be complemented by security policies and procedures With thelarge amount of data that must be collected from the ever-increasing number ofsensors including collection of the consumer data, data privacy is also of paramountimportance In this chapter, after presenting an overview of cybersecurity standards,

security architecture based on security zones is presented.

Chapter 9 deals with the network technology choices for the Smart GridWANs and FANs, including technologies used in what are sometimes known asNeighborhood Area Networks (NANs) Network transformation to the Smart Gridnetwork is a multiyear process Therefore, depending on the advances in networktechnologies, availability of resources, and schedule for introduction of the SmartGrid applications, the mix of FAN technologies deployed and used by a utility willchange over the planning period More detailed treatment is provided for PowerLine Communication (PLC) and for Long-Term Evolution (LTE) The chapter endswith a discussion on benefits and drawbacks of utility ownership of one or more ofthese network components in comparison to using NSP data networking services.Smart Grid brings with it an enormous growth in data that must be managed foruse by an ever-growing number of utility applications Data management is covered

in Chap 10 The traditional practice of client–server communication betweenindividual application and individual data source is not scalable Such client–server communication may also not satisfy the network delay requirements; moreimportantly, direct end-to-end communication has inherent security and data privacyrisks, such as the necessity of knowing the (IP) addresses of the communicatingpartners There have been recent advances in secure data management that areparticularly suitable to the Smart Grid data management environment with network-based data storage and the corresponding middleware that affords highly secure andlow delay access to the data Finally, an introduction to Smart Grid data analytics ispresented

Topics in transformation from the current utility communication networks tothe Smart Grid communication network is presented in Chap.11 The principalobjective of the network transformation is to plan, design, and implement a highlyreliable, highly secure, and high-performance integrated communication networkthat supports all Smart Grid applications The network transformation process must

also weigh all available alternatives toward an optimal network architecture anddesign that is sustainable for a multiyear planning horizon of the utility (depending

on the utility, the planning horizon may be between 5 and 20 years) Some ofthe topics discussed in this chapter are network technologies for use in WANs,FANs, and NANs, leveraging existing network communication assets, supportfor requirements of mission-critical applications in the integrated network, andinvestment options for introducing Smart Grid applications

In Chap.12, observations are made on some of the expected innovations in SmartGrids and networking that have a bearing on the future of Smart Grid networks

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