Smart Grid

Communication-Enabled Intelligence for the Electric Power Grid

Stephen F. Bush

• Editorial: Wiley-IEEE Press
• Año: 2014
• ISBN:
  9781118820247
• Edición: 1
• Categoría: Technology & Engineering
• Categoría: Power Resources

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

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; and
• DR – 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 reade...