Citation
Comparative analysis of communication architectures and technologies for smart grid distribution network

Material Information

Title:
Comparative analysis of communication architectures and technologies for smart grid distribution network
Creator:
Hammoudeh, Monther A
Publication Date:
Language:
English
Physical Description:
1 electronic file : ;

Subjects

Subjects / Keywords:
Smart power grids ( lcsh )
Electric power distribution ( lcsh )
Communication and traffic ( lcsh )
Communication and traffic ( fast )
Electric power distribution ( fast )
Smart power grids ( fast )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Review:
A critical piece of the Smart Grid infrastructure is the ommunications network for data gathering, control and supervision capabilities that extend to the customer demarcation point. Over several decades, the electric utilities built a robust communications networks connecting electric grid subsystems except for the "last mile" connecting to the end user premise. A primary goal of Smart Grid (SG) is to expand the communications network throughout the Distribution Network (DN) thus enabling a holistic management and control of electric grid from generation to consumption. In order for the Smart Grid goals to be realized, two-way communications network must extend to the Distribution Network allowing two-way data flow e.g., real-time energy pricing and real-time demand data back to the Utilities and Operators. This thesis presents five communications architectures and viable technologies for deployment within the Distribution Network of the Smart Grid. Then apply selected metrics to these architectures and technologies combinations and select top five scoring combinations.
Bibliography:
Includes bibliographical references.
Statement of Responsibility:
by Monther A. Hammoudeh.

Record Information

Source Institution:
|University of Colorado Denver
Holding Location:
|Auraria Library
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
857790160 ( OCLC )
ocn857790160

Auraria Membership

Aggregations:
Auraria Library
University of Colorado Denver

Downloads

This item has the following downloads:


Full Text
COMPARATIVE ANALYSIS OF COMMUNICATION ARCHITECTURES AND
TECHNOLOGIES FOR SMART GRID DISTRIBUTION NETWORK
by
Monther A. Hammoudeh
B.S.E.E., Virginia Polytechnic Institute and State University, 1995
A thesis submitted to the
University of Colorado Denver
in partial fulfillment
of the requirements for the degree of
Masters of Science Electrical Engineering
Electrical Engineering
2012


This thesis for the Masters of Science Electrical Engineering
degree by
Monther A. Hammoudeh
has been approved
by
Fernando Mancilla-David
Titsa Papantoni
Dan Connors
Date: May 4, 2012


Hammoudeh, Monther A. (M.S., Electrical Engineering)
Comparative Analysis of Communication Architectures and Technologies for Smart
Grid Distribution Network
Thesis directed by Assistant Professor Fernando Mancilla-David
ABSTRACT
A critical piece of the Smart Grid infrastructure is the communications
network for data gathering, control and supervision capabilities that extend to the
customer demarcation point. Over several decades, the electric utilities built a robust
communications networks connecting electric grid subsystems except for the last
mile connecting to the end user premise. A primary goal of Smart Grid (SG) is to
expand the communications network throughout the Distribution Network (DN) thus
enabling a holistic management and control of electric grid from generation to
consumption. In order for the Smart Grid goals to be realized, two-way
communications network must extend to the Distribution Network allowing two-way
data flow e.g., real-time energy pricing and real-time demand data back to the
Utilities and Operators. This thesis presents five communications architectures and
viable technologies for deployment within the Distribution Network of the Smart
Grid. Then apply selected metrics to these architectures and technologies
combinations and select top five scoring combinations.


This abstract accurately represents the content of the candidates thesis. I recommend
its publication.
Approved: Fernando Mancilla-David


DEDICATION
All thanks and praise is due to Allah for his blessing and guidance.
I dedicate this thesis to my loving parents, especially my father (the late Professor
Abed El-Rahman Hammoudeh) who gave me the appreciation of education and
taught me the value of perseverance and resolve. I also dedicate this thesis to my
wife, Suhad, and my daughters (Mona, Hoda and Ayah) for their understanding and
sacrifice while I was completing this thesis. I would like to thank all my family and
friends who supported me to successfully finish this work.


ACKNOWLEDGMENT
My thanks to my advisor, Dr. Fernando Mancilla-David, for his contribution and
support of my research. I also wish to thank all the members of my thesis committee
for their valuable participation and insights.


CONTENTS
Figures...............................................................x
Tables................................................................ix
Chapter
1. Introduction---------------------------------------------------------- 1
1.1 Scope of This Study----------------------------------------------------2
1.2 Organization of Thesis-------------------------------------------------4
2. What is Smart Grid?----------------------------------------------------5
2.1 Recent American Laws Driving Smart Grid Deployment---------------------6
2.2 Smart Grid Functions and Goals----------------------------------------7
2.3 Smart Grid Benefits----------------------------------------------------9
3. Data Collection in The Distribution Network---------------------------11
3.1 Consumer Energy Usage Data--------------------------------------------12
3.2 Device Status Data and Control----------------------------------------12
4. Communications for The Distribution Network---------------------------15
4.1 The Need for Communications-------------------------------------------15
4.2 Communications Requirements-------------------------------------------16
4.3 Are Smart Grid Standards Required?------------------------------------19
4.4 Emerging Smart Grid Standards-----------------------------------------19
5. Communications Architectures--------------------------------------------21
5.1 Direct Connect Architecture--------------------------------------------22
5.2 Local Access Aggregators Architecture----------------------------------23
5.3 Interconnected Local Access Aggregators Architecture-------------------26
5.4 Mesh Architecture------------------------------------------------------27
vii


5.5 The Internet Cloud Architecture-------------------------------------28
6. Technology Options---------------------------------------------------31
6.1 Wireline Technology Options-----------------------------------------31
6.2 Wireless Technologies-----------------------------------------------35
7. Analysis Methodology and Approach------------------------------------39
7.1 Metrics-------------------------------------------------------------39
7.2 Analysis Methodology------------------------------------------------43
7.3 Summary of Results--------------------------------------------------44
7.4 Conclusion----------------------------------------------------------51
Bibliography............................................................52
viii


FIGURES
Figure
5.1 A view of the Utility Information Systems ................................22
5.2 Direct Connect Architecture ..............................................23
5.3 Overview of AMI Network with NAN .........................................24
5.4 Local Access Aggregator Architecture .....................................25
5.5 Interconnected Local Access Aggregators Architecture......................26
5.6 Mesh Architecture.........................................................27
5.7 The Internet Cloud Architecture...........................................30
IX


TABLES
Table
2.1 The Smart Grid vs. The Existing Grid......................................8
2.2 Cost of One-hour Service Outage...........................................9
3.1 Sample Data Requirements.................................................13
4.1 Communications From Customers Gateway and Requirements..................17
4.2 Communications To Customers Gateway and Requirements....................18
6.1 Qualitative Characteristics of Wireline Communication Media Types........35
6.2 Qualitative Characteristics of Wireless Communication Technologies.......38
7.1 Metrics Guidelines.......................................................43
7.2 Summary of Architecture 1 Metrics........................................45
7.3 Summary of Architecture 2 Metrics........................................46
7.4 Summary of Architecture 3 Metrics........................................47
7.5 Summary of Architecture 4 Metrics........................................48
7.6 Summary of Architecture 5 Metrics........................................49
7.7 Top Five Architecture and Technology Combinations........................50
x


1. Introduction
Over several decades, the electric utilities built a robust communications
networks connecting electric grid subsystems except for the Distribution Network
(DN) feeding the end customer premise. A primary goal of Smart Grid is to expand
the communications network to the consumption segment thus enabling a holistic
management and control of electric grid from generation to consumption.
With the recent emphasis on deployments of Smart Grid within the United
States of America and the passing of EISA (Energy Independent and Security Act of
2007) into law [1], the race is on to begin deployment of Smart Grid. Under Title
XIII of EISA 2007, the U.S. Department of Energy (DoE) established a Federal
Smart Grid Task Force. In its Grid 2030 vision, the objectives are to construct the
21st century electric system to provide abundant, affordable, clean efficient and
reliable electric power anytime, anywhere [2], A key enabler of Smart Grid
deployment is the communications network that interconnects the numerous devices,
users smart meters and the electric grid subsystems. The first step of designing a
robust communications network is establishing an architecture that outlines data flow
among various parts of the system.
The North American power grids are made up of almost 3,500 utility
organizations [3], The basic principle of supplies and demand must be at equilibrium
all times. Extensive communications networks that span hundreds of thousands of
1


miles enable electricity grid operators to manage the demand and keep this supply
demand equation balanced. However, the existing communications architecture is
several decades old and has not benefited from recent technology advances.
Additionally, the existing communications network primary function is to connect
electrical substation with operators control centers leaving the distribution subsystem
lacking adequate situational awareness [3], To remedy the current limitations of the
electrical grid, the U.S. Congress passed the EISA law in 2007 establishing goals for
modernizing the electrical grid.
1.1 Scope of This Study
A critical piece of the Smart Grid infrastructure is the communications
network that will extend the control and supervision capabilities to the end users. As
described in [4], the Smart Grid communications network can be divided into four
distinct segments:
Core or metro segment connects substations to the utilities headquarters.
Backhaul segment connects data aggregators to substation/distribution
automation at broadband speeds
Neighborhood Area Network (NAN) or last-mile connects the customers
smart meter or gateway to the data aggregators, and
2


Home Area Network (HAN) this is the customers home or building
automation.
The generation subsystem enjoys full automation while transmission and
substation have very high levels of automation, but the distribution network has poor
automation level [5], Additionally, the transmission-system level, area control
centers and regional reliability coordination centers have been exchanging system
status information. The communication links between these systems now cover the
country with increasing exchange of information among electric utility companies
[6].
The distribution segment of the electric grid is the least communicated with
and least controlled segment of all the electric grid segments. The Distribution
Automation (DA) is primarily led by substation automation with feeder equipment
automation still lagging [6], Because feeder automation lags other automation efforts
widely, this area should be addressed directly in future work [6], As discussed in [7],
the Distribution Network remains outside the utility companies real-time control.
Additionally, nearly 90% of all power outages and disturbances have their roots in
the Distribution Network [7], While 84% of utilities has substation automation and
integration underway in 2005, the feeder penetration is still limited to about 20% [6],
So, it makes sense to begin Smart Grid at the bottom of the chain, in the Distribution
Network [7],
3


The scope of this thesis is limited to the communications networks in the
Distribution Network of the Smart Grid to address the aforementioned gaps. In other
words, the focus is on the last mile communications segment. This thesis
documents the results of a thorough survey of technical papers and governmental
agencies reports then provides the authors critical analysis of communications
architectures and technologies for Smart Grid Distribution Network.
1.2 Organization of Thesis
This thesis is organized into chapters. Chapter 2 covers Smart Grid
objectives, functions and benefits. Chapter 3 describes data collection in the
Distribution Network for both end-users and service providers usage. Chapter 4
addresses the needs for communications networks in the Distribution Network.
Chapter 5 discusses five communications architectures. Chapter 6 provides an
overview of wireline and wireless technology options. Lastly, chapter 7 describes the
analysis methodology and presents three dimension comparison matrix with a
conclusion.
4


2. What is Smart Grid?
The United States of America and several other countries have made it a
national strategic goal to modernize their electric grid [8] to make it more robust,
secure, expand overall control and make it capable of supporting renewable energy
resources and anticipated growth demand. Many definitions of Smart Grid (SG) exist
all around the world [9], Smart Grid is the modernization and automation of the
electric power grid changing from a producer-controlled network to one that is less
centralized and more consumer-interactive and is more than just smart meters. The
use of two-way communications and advanced control capabilities will result in the
realization of a host of benefits and new applications. One can think of SG as an
Information and Communication Technologies (ICT) based power system [9], The
National Institute of Standards and Technology (NIST) defines the Smart Grid as:
a modernization of the electricity delivery system so it monitors, protects and
automatically optimizes the operation of its interconnected elements from
the central and distributed generator through the high-voltage network and
distribution system, to industrial users and building automation systems, to
energy storage installations and to end-use consumers and their thermostats,
electric vehicles, appliances and other household devices [9],
In general, all definitions refer to an advanced power grid through the use of digital
computing and communications technologies [8],
5


2.1 Recent American Laws Driving Smart Grid Deployment
Starting with the Energy Policy Act of 2005 (EPACT 2005) Section 103
titled Energy Else Measurements and Accountability that established a deadline of
October 1, 2012 for all federal building to have some sort of advanced meters that
provide data of the electricity consumption [10], Additionally, EPACT 2005 Section
1252 titled Smart Metering obligates electric utilities to supply each of its
customers upon request, a time-based rate schedule.
On December 19, 2007, the United States Congress passed the Energy
Independent and Security Act (EISA) of 2007 into law that mandated the
modernization of the electric grid with an end goal of Smart Grid [1], Finally, the
American Recovery and Reinvestment Act of 2009 (ARRA) included $10 billion in
investments to encourage transformation to a smarter grid [8], All these federal laws
brought visibility and attention to the need for modernizing the electric grid.
Additionally, several states and electric utilities initiated infrastructure deployments
in preparation for Smart Grid. Common deployments include the installation of
advanced meters by utilities companies and Smart Grid test beds as the case with
Xcels project in Boulder, Colorado known as SmartGridCity.
6


2.2 Smart Grid Functions and Goals
In December 2007, the Energy Independence and Security Act (EISA) was
signed into law. This law established clear national goals to implement Smart Grid.
Some of the stated benefits include:
Self-healing from power disturbances
Enables active participation by consumers in demand response
Operates resiliently against physical or cyber attack
Provides power quality for 21 st century needs
Accommodates all generation and storage options
Enables new products, services, and markets
Optimizes assets and operational efficiency
A Smart Grid provides the flexibility to adapt to a changing mix of demand-
side resources, including changeable load, dispatchable distributed generation and
storage, as well as output local generation such as wind and solar [6], Smart-grid-
enabled distributed controls within the electric delivery system will aide in
dynamically balancing electrical supply and demand, thus resulting in a more
adaptable system to imbalances and limit their propagation when they occur [6], A
Smart Grid is needed at the distribution system to manage voltage level, reactive
7


power, potential reverse power flows and power conditioning, which are critical to
running grid-connected Distributed Generation (DG) systems [6],
Table 2.1 provides a side by side comparison of key attributes of the existing
electric grid and the Smart Grid, which is also referred to as Intelligent Grid. There
is clear need for Smart Grid at the distribution level to manage: voltage levers,
reactive power, potential reverse power flows and power conditioning [6],
Table 2.1: The Existing Grid vs. The Smart Grid [7]
Existing Grid Smart Grid
Electromechanical Digital
One-Way Communication Two-Way Communication
Centralized Generation Distributed Generation
Hierarchical Network
Few Sensors Sensors Throughout
Blind Self-Monitoring
Manual Restoration Self-Healing
Failures and Blackouts Adaptive and Islanding
Manual Check/Test Remote Check/Test
Fimited Control Pervasive Control
Few Customer Choices Many Customer Choices
The expected functions of Smart Grid are detailed in [11] and summarized below:
Operation Reliability and Blackout Prevention
Condition Monitoring and Asset Management
Protection and Station Automation
Distribution Network Management
8


Distribution Network Automation
Smart Metering
2.3 Smart Grid Benefits
The benefits of Smart Grid show up in many areas including the
infrastructure management and protection, the gained efficiency, economic benefits
for the consumer and reducing business losses from blackouts. Data from wide-area
measurement system could have eliminated the $4.5 billion in losses as a result of
the 2003 blackout of the eastern U.S. and Canada [6], Another study results show
that Smart Grid technologies would reduce power disturbance costs to the U.S.
economy by $49 billion per year [12], Table 2.2 provides an average estimated cost
of one-hour power interruption for selected enterprises businesses.
Table 2.2: Cost of One-hour Service Outage [12]
Industry Average Cost of 1-Hour Interruption
Cellular communications $41,000
Telephone ticket sales $72,000
Airline reservation system $90,000
Semiconductor manufacturer $2,000,000
Credit card operation $2,580,000
Brokerage operation $6,480,000
9


Smart Grid can enable reduced overall energy consumption through
consumer education and participation in energy efficiency and demand response/load
management programs [13], Additionally, shifting electricity use to less expensive
off-peak hours can optimize use of existing power generation that could add $5
billion to $7 billion per year back into the U.S. economy [12], Smart Grid would
reduce the need for huge infrastructure investments between $46 billion and $117
billion over the next 20 years [12], The Federal Energy Regulatory Commission
(FERC) study reported that a moderate amount of demand response could save about
$7.5 billion annually [14], Finally and most recently, EPRI prepared a new set of
cost of power interruption and power quality estimates ranging from $119 billion to
$188 billion per year [15],
10


3. Data Collection in The Distribution Network
At the Distribution Network and end-user levels, there are opportunities for
automation and advanced data collection [16], There are two methods for
gathering end-user data: Automated Meter Reading (AMR) and Automated
Metering Infrastructure (AMI). AMR enables the electric utility to remotely read
power meters. But it does not address the major issue utilities need to solve,
which is demand-side management [7], On the other hand, AMI is much more
powerful since it is the basic building block for a two-way communications
between the end users and utilities operators [16], As described in [17], an AMI
system consists of four main components:
Smart digital meter, which functions as premise gateway
Home portal that offers display of information from the gateway
Neighborhood access point that aggregates end-users data before
transmitting it to the substation
Central office (usually a substation) where all customers data is
aggregated.
There is often a reference to an AMI meter, which is defined as a digital meter
with two-way communications, automated meter data collection, outage
management, dynamic rate structures and demand response for load control [17],
11


Managing Smart Grid metering data is difficult due to the sheer size and
complexity of the number of data point [18], Useful data in the Distribution
Network can be classified as: consumer specific data or device and control data.
Each of these data types is explained in the next two sections.
3.1 Consumer Energy Usage Data
Smart meter system involves large amount of data transfer between the
utility company, smart meter and home appliances connected to the network [19],
The smart meter data will be used by the utilities operators for further analysis,
control and real time pricing method [20], The customer gateway will interact
with all smart appliances and the Distribution Network and functions: integrated
operation and control of supply and demand and demand response [21],
3.2 Device Status Data and Control
A major benefit of Smart Grid containing renewable Distributed Generation
(DR) is the possibility of forming islands when separation from the main electric
system occurs due to fault condition or system failure [22], So, continuing to
communicate with the islanded section of the grid is required. Table 3.1 provides
a sample of the data requirements.
12


Table 3.1: Sample Data Requirements [22]
System Component Inputs Outputs Computed Values
Breakers Switches Protective elements (Fuses) Breaker Status Enable/Disable Breaker Status Voltages Currents
Generators: Wind Solar (PV) Enable Dispatch Voltages Currents Phase Power Quality Availability Health index Power
Transformers Tap Positions Temperature Pressure Gas, Vibration Noise Reliability
Lines Enable/Disable Voltages Currents Real Power Reactive Power
Reactive Power Elements Status Enable/Disable Voltages Currents Power Quality
Loads: Active Passive Status Enable/Disable Rate (Tier Demand Management) Demand Voltages Currents Power Quality
As explained in [21], devices in the Distribution Network include the
Distribution Automation System (DAS) and the Meter Data Management System
(MDMS). The customers gateway interacts with the DAS for integrated
operation and control of supply and demand of electricity. Where the MDMS
collects and stores data from customers and provide them to the utilities
13


operators for accounting and customer service [21], The customers will be able to
schedule appliances operation and request loads using real time pricing data,
thus reducing electricity usage during peak hours, which benefits both end users
and utilities.
14


4. Communications for The Distribution Network
4.1 The Need for Communications
Without a robust communication system in the Distribution Network, only
parts of the Smart Grid vision could be realized [5], The Smart Grid is all about
extending remote monitoring and control of devices in the Distribution Network
and gathering real-time data. All of these functions require two-way
communications [13], The Distribution Network is facing increased frequency of
unpredictable catastrophic events due to limited knowledge and management of
these complex systems [23], The current communications system deployed over
the Distribution Network are oriented to support specific services, so that, the
development of new services over the DN and the addition of new agents may
result as very expensive [24], The original design of Distribution Networks did
not account for two-way power flows or active demand, hence, changes are
needed in the way they are designed and operated to realize these functions
through the use of advanced communications and information technologies [25],
Automation and communication infrastructures are needed to enable demand
response and to make widespread end-user participation possible in support of
Smart Grid and market operation [26],
15


4.2 Communications Requirements
A communication system is the key component of the Smart Grid
infrastructure [20], Smart Grid communication technologies must allow the
utilitys Control Center access to each connected meter several times a second
[27], As detailed in [28], communications network for the energy management
must provide distinct qualities including: high reliability and availability,
automatic redundancy, high coverage and distances, supports large number of
nodes, has low delays, security and ease of deployment and maintenance.
The various functions of the Distribution Network have different
requirements for a communications network. For example, meter reading can be
scheduled for anytime and does not require permanent real-time
communications. On the other hand, event or fault data must be communicated in
real-time with maximum allowed delay of 300 milliseconds [21], Additionally,
depending on the communications architecture selected, communications among
adjacent end-users gateways could be required. Tables 4.1 and 4.2 summarize
the communications requirements to and from customers gateway.
16


Table 4.1: Communications From Customers Gateway and Requirements [21]
Data The other end Frequency Allowable Delay No. of Entry Applications
From Customer Gateway Request for reactive power Other customer Gateway On demand 1 second 1 Keeping output power of distributed power generation during voltage regulation
Measured values for generation / consumption SCADA system Every 30 minutes 1 minute 121 *1 Optimal control of grid equipment Power flow leveling, Demand-supply balancing Meter reading, Customer service
Forecasted values for generation / consumption Twice per day Several minutes 192 *2 Optimal control of grid equipment
*1: 4 items (active/reactive power of generation/distribution) *30 (Value for 1 minute) +
Time stamp
*2: 4 items mentioned above x 48 (data for 1 day)
17


Table 4.2: Communications To Customers Gateway and Requirements [21]
Data The other end Frequency Allowable Delay No. of Entry Applications

To Customer Gateway Request for reactive power Other customer Gateway On demand 1 second 1 Keeping output power of distributed power generation during voltage regulation
Event information (e.g. earth fault) SCADA system At event 50 ~ 300 milliseconds 1 Power system protection
Threshold of reverse power flow, Generation forecast Every 30 minutes 1 minute Power flow leveling, Demand-supply balancing
Tomorrow tariff Tariff server Every day Several minutes 48 *3 Optimal control of grid equipment
Current tariff Every 30 minutes 1 minute 1 Demand response
DR event DR server Every 1 minute 10 seconds 1 Demand response
*3: Tariff per 30 minutes x 48 (for 1 c ay)
18


4.3 Are Smart Grid Standards Required?
Standards are the first and required step to ensuring interoperability
between equipment from various vendors and enabling interconnection among
different users and operators, which are necessary functions in the vast electric
grid that is owned and operated by hundreds of stakeholders. Standards is an
important issue that must be resolved before Smart Grid becomes a reality [29],
The evidence from other industries indicate that interoperability generates
tangible and intangible benefits around 0.3% 0.4% in cost savings and avoided
infrastructure construction, which could net a $12.6 billion per year in Smart
Grid benefits [12],
Under Section 1305 of EISA, the National Institute of Standards and
Technology (NIST) has the primary responsibility of coordinating the
development of framework including protocols and standards for information
management to achieve interoperability [1], NIST recognized the urgent need for
Smart Grid standards by developing a three phase plan to identify existing
standards as well as the need for new ones [8],
4.4 Emerging Smart Grid Standards
For the Smart Grid to be fully integrated, universal standards must be
applied [30], Several well known standards bodies including the International
19


Electrical and Electronics Engineers (IEEE), International Standards
Organization (ISO), International Electrotechnical Commission (IEC) and
Internet Engineering Task Force (IETF) are actively developing new standards
that are required for the proper and secure deployment of Smart Grid. NIST
identified 16 specifications and 15 standards that are important for Smart Grid
[8], Additional standards are under review. There is a consensus on a set of
standards regarded as core information technology standards for the future
Distribution Network of a Smart Grid [31], These standards are listed below [31]:
IEC 61970/61968: Common Information Model (CIM)
IEC 61850: Substation Automation Systems (SAS) and DER (Distributed
Energy Resources)
IEC 62351: Security for the Smart Grid
IEC 62357: TC 57 Seamless Integration Architecture
IEC 60870: Communication and Transport Protocols
IEC 61400-25: Communication and Monitoring for Wind Power Plants
IEC 61334: DLMS (Device Language Message Specification (originally
Distribution Line Message Specification)
IEC 62056: COSEM (Companion Specification for Energy Metering)
IEC 62325: Market Communications using CIM
20


5. Communications Architectures
Architecture describes how systems and components interact and embodies
high-level principles and requirements for Smart Grid applications and systems [8],
Like the Internet, the Smart Grid is a network of different networks that must interact
together on regular basis. So, the Smart Grid architecture will be a composite of
many system and subsystem architectures [8] rather than a single architecture. The
communication architecture of the future Smart Grid is yet to be defined [32], The
rest of this chapter addresses architecture options for the Distribution Network.
Designing a communication system architecture that meets the Grids
complex requirements is essential to the successful implementation of Smart Grid
[22], In general, coordination and information exchange between devices can be
implemented via different communication architectures. Four possible
communications architectures are illustrated in [33],
This thesis report describes five communication architectures for possible
deployment in the Distribution Network. The Distribution Network is similar to the
last mile problem in the telecommunications network design. In the utilitys
communications network, the last mile connects the customers smart meter to the
backhaul network as depicted in figure 5.1. Each architecture is covered in the
remainder of this chapter.
21


Figure 5.1: A view of the Utility Information Systems [34]
5.1 Direct Connect Architecture
This is most basic architecture where each smart meter has a dedicated
linear connection to the data hub inside a substation. This setup is often referred
to as hub and spoke network. In this scenario, there are no other devices, like
aggregators, between the smart meter and the data hub inside the substation. In
other aspects, this architecture is a star topology with the data hub inside the
substation has hundreds to thousands of dedicated communication links out to the
customers smart meters. Each communication link can be of any medium type:
wireline or wireless. Due to the large number of smart meters in urban areas, this
architecture is not attractive. However, it could be a viable option for low
22


population density areas. In this case, a single communication link from each
home to a substation is low cost and does not require an elaborate
communications infrastructure build or aggregators. Depending on the selected
communication media type, this architecture has limitation. Figure 5.2 depicts the
main components of this architecture.
5.2 Local Access Aggregators Architecture
The essence of the Local Access Aggregators architecture is aggregating
smart meters data at a neighborhood level before transmitting it to a data hub
23


inside the substation. The aggregator device sits between the smart meters and
the data hub inside the substation. This model builds on the Neighborhood
Access Network (NAN) where NAN ensures communications between the smart
meter and the data aggregators [35], The concept of NAN is recent and as such
no standard NAN definition yet exists [17], In general, the NAN aggregator
connects with the customer home network on one end and with the Wide Area
Network (WAN) on the substation end as illustrated in figure 5.3.
Figure 5.3: Overview of AMI Network with NAN
This architecture has advantages over the direct connect architecture because
it reduces the number of dedicated communication links to the substation and
benefits from data aggregation at the neighborhood level thus optimizing the
24


communications links into the substation by using trunks. Additionally, the ability to
collect and process data locally will not only reduce communication bandwidth
requirements, but also reduce vulnerability to hacker attacks and reduce cyber
security concerns [16],
Key:
Communication Link
(wireline or wireless)
Backbone Communication Link
Trunk
Communication Link ^ ^
Sub-station

==
Aggregation A

tB-Bt
Neighborhood
A
Aggregation B
f
tEfflat
Neighborhood
B
Figure 5.4: Local Access Aggregator Architecture
Figure 5.4 shows main segments of this architecture including: smart meter
at the premise, aggregator in the neighborhood installed on a structure that is
owned by the utilities e.g., pole or cabinet and data hub inside the substation.
25


5.3 Interconnected Local Access Aggregators Architecture
This architecture is similar to the previous architecture with one exception,
which is adjacent NAN networks have interconnected trunks as shown in figure
5.5. These additional communication trunks provide redundancy for the
aggregators thus allowing more routes to communicate with the substations data
hub and enable local communications among NANs should communication trunk
with the substation is lost. This last feature is important for effective sharing of
Distributed Generation (DG) resources available in adjacent neighborhoods
during an islanding situation.
Figure 5.5: Interconnected Local Access Aggregators Architecture
26


5.4 Mesh Architecture
This architecture builds on the previous one with additional degree of
connectivity at the smart meters level in addition to the aggregators level as
shown in figure 5.6. Because of the additional required communication links
among smart meters that are do not have wireline connections, wireless Radio
Frequency (RF) technology is well suited for interconnecting smart meters in a
particular area.
27


Additionally, RF has the ability to dynamically establish ad hoc
communications links between adjacent networks [36], Another advantage is that
communications range can be increased by establishing multiple hops until
reaching the final destination. RF mesh operates in the unlicensed Industrial
Scientific and Medical (ISM) frequency band ranging from IEEE 802.11
Wireless Local Area Networks (WLAN), Wi-Fi, Bluetooth and Microwave [20],
This fact makes RF less attractive for use in Smart Grid application due to high
possibility of interference with commonly deployed private networks. Another
disadvantage that is common to wireless communications is security concerns.
However, strong data encryption is an effective way to remedy such security
issues.
The wireless-wired architecture is the most popular approach and has been
adopted in some pilot projects where smart meters in the neighborhood
communicate with an aggregator through a wireless mesh network and the
aggregator communicates with the central management facility through wired
communication [37],
5.5 The Internet Cloud Architecture
The premise of this architecture is leveraging the customers existing
Internet service as a communication link between the end user and the utilities
28


operator. The majority of houses subscribe to Internet service where service is
available. Rural areas are the exception since Internet service is not always
available. Under this architecture, the smart meter uses the existing Internet
connection inside the house as a communication link via Ethernet port or Wi-Fi
to transmit information to a utilities server that most likely is hosted in a data
center. The biggest advantage of this architecture is low cost since no additional
monthly charges for communications are required. Another big advantage is for
the utility companies since customers data can be easily stored on servers
without having expensive aggregators in the neighborhoods or inside the
substation. Of course, the assumption is customers already have Internet service
or can get it.
This architecture has many benefits including low cost for the customer by
leveraging an existing Internet service and quick deployment due to minimal
infrastructure build. It also allows for both peer to peer communications as well
as centralized decision capability. This architecture facilitates the use of cloud
services to gather, store, and analyze huge volumes of data and make it available
for those with appropriate level of access.
29


30


6. Technology Options
Both wireline and wireless communication technologies are possible
deployment options for Smart Grid. Some of the popular communication
technologies are Power Line Communications (PLC), cellular, licensed and
unlicensed radio, existing internet connection, Wi-Fi and WiMAX [19], In
certain situations, wireless technology have advantages over wired technologies,
such as low cost and ease of connection but suffers from interference and signal
attenuation [20], On the other hand, wireline communication technologies are
more reliable, less prone to interference, but very expensive to deploy especially
if new infrastructure is required. Wired communication network can be
established for smart meters, but it will be complicated and expensive solution,
while wireless communication network can be implemented even on ad-hoc basis
[38], The Smart Grid, as a complex system, requires a heterogeneous
communication technologies to meet its diverse needs [32],
6.1 Wireline Technology Options
Wireline communication media include: twisted pair copper cables, coaxial
cables, power line and fiber optic cables. Each of these media types has unique
characteristics that will be discussed in the remainder of this section.
31


Twisted Pair (TP) copper cables are the traditional telephone wiring, which
are present in almost every home and connect back to a telecommunications
carrier Central Office (CO). These copper wires have varying specifications and
quality that is determined by their age. Unshielded Twisted Pair (UTP) is older
cable that is prone to cross talk and interference. However, Shielded Twisted Pair
(STP) is newer cable type that is less prone to cross talk and interference.
Additionally, these wires are usually configured in a star topology where
hundreds of homes and buildings have dedicated connections back to the
carriers CO. Hence, the existing cables would not support mesh architecture
based on their physical routes. Hence, mesh requires placing additional cables,
which is very expensive and takes a long time to deploy.
Coaxial cable is another wireline media type. These cable plants are used
by cable companies to provide video services and in recent years voice and data.
The cable plant is shared resource in a single neighborhood and as such shares
bandwidth. This architecture has two fundamental issues: lower data rates during
peak usage hours in densely populated areas especially for those customers
located at the end of the cable route in a neighborhood and presents security
concerns for customers confidential data since the main cable is a shared
medium in the last mile segment. With the introduction of DOCSIS 3.0, cable
companies are offering Internet services using coaxial cable with high bandwidth
32


rates, but it is still a shared bandwidth. Additionally, coaxial cables presence is
limited to metropolitan areas and rarely found in rural areas.
Fiber Optics is the most advanced wireline media type with many superior
characteristics like extremely high data rates, long distance reach and immunity
from electromagnetic interference. There are two types of optical fiber cables:
Single Mode (SM) and Multi Mode (MM) fiber. SM is used for long distances,
while MM is used for short distances less than two kilometers. The trend is to use
SM fiber for most applications. However, fiber optic cables are the most
expensive wireline media type to install and the least widespread in homes and
buildings. Most new buildings and homes are wired with fiber optic cables. New
deployments include Fiber-To-The-Home (FTTH) or Fiber-To-The-Premise
(FTTP), which typically use Gigabit Passive Optical Network (GPON). GPON is
a network architecture that uses a point-to-multipoint scheme to serve multiple
buildings. Encryption is used in this shared environment to ensure data security.
Power lines represent the densest network in this country, where every
building has a power line connection and power line termination [39], As such,
Power Line Communication (PLC) system appears to be well suited to
implement the Smart Grid network [40], [41], These power lines can be used to
transmit Smart Grid data from the home back to the substation directly. This is
the most direct wireline media connecting the end-user with the substation. PLC,
33


under normal operations, has an advantage that all smart meters can be reached
as opposed to a wireless solution where 100 percent service coverage is not
always possible [42], However, using power lines for communications has its
drawbacks. First, the interference issues around high voltage power lines and the
need to bypass transformers where a bridge device is used to bypass the
transformer. Using power lines is preferred by utility companies since they will
have total control of the communication link from the substation to the end
customer and do not need to rely on third party providers for this communication
network. The biggest issue with using power lines for Smart Grid communication
is losing this vital communication network during electric power lines being
down, yet this is the time when communication is needed the most. Power line
cuts will stop communications with the isolated areas and as such make it
impossible to gather data, isolate problems and attempt to solve the problem
quickly. Simply put, under this condition, Smart Grid objective for the
Distribution Network wont be achieved.
Table 6.1: Qualitative Characteristics of Wireline Communication Media Types
Wireline Media Data Rate Distance Reach Existing Geographic Coverage
Twisted Pair (TP) high long distance high
Coax cable high medium distance low
Power lines (PLC) high high distance high
Fiber Optic Cable very high very long distance limited
34


6.2 Wireless Technologies
Wireless technology is very attractive for Smart Grid deployment. In
general, it is much faster to deploy than wireline medium due to minimal
construction areas when compared with digging streets to deploy new conduit
system and pull cables through it. Using wireless communications has many
benefits [43], Several wireless technology options, either licensed or unlicensed
frequencies are available. Most popular technologies include: Satellite,
microwave, WiMAX, cellular, Wi-Fi and Zigbee.
Satellite is the most expensive wireless technology and supports relatively
low data rates. It is not suitable for general deployment in the distribution
network, but may have role in the transmission segment. The signal receiver on
the ground must be within the satellite coverage footprint. There is limited
number of satellite operators or service providers due to high deployment cost of
these systems. Additionally, latency is a big issue due to large distances a signal
must travel from ground to the satellite and back to earth.
Microwave is based on licensed frequencies that are controlled by the
Federal Communication Commission (FCC). These frequencies are limited and
require line-of-sight between transmitter and receiver to operate. As such,
depending on the terrain, they usually require tall tower structure to meet line-of-
35


sight requirement. Microwave is not suitable for wide deployment in the
Distribution Network. However, it may have limited and targeted application in
rural areas where no other communications medium is available.
WiMAX stands for Worldwide Interoperability for Microwave Access that
focuses on fixed wireless applications and is based on IEEE 802.16 standard. It
supports data rates up to 72 Mb/s and a range up to 6 miles. Earlier version of the
WiMAX standard requires line-of-sight, but not later version [11], Additionally,
WiMAX has limited deployment in the United States and it will be expensive to
deploy an extensive WiMAX network to meet Smart Grid requirements in the
Distribution Network.
Wi-Fi stands for Wireless Fidelity, which is a trademark of the Wi-Fi
Alliance [44], It is based on IEEE 802.11 standard and operates in the unlicensed
2.4 GHz Industrial Scientific and Medicine (ISM) band and has reach from 20
feet indoors to about 300 feet outdoors with the potential for even longer reach. It
is widely used in home networks and several deployments by local municipalities
to cover a citywide. Because Wi-Fi networks are common for use in-home
applications and use unlicensed spectrum, interference is a big concern.
Additionally, reach is limited and is not suitable for communications in the
Distribution Network.
36


Zigbee is a low-power wireless protocol that operates in the unlicensed
Industrial Scientific and Medicine band of 2.4 GHz. It is based on IEEE 802.15.4
standard. Zigbee, WirelessHART and ISA 100.11a are three protocols that use
the 802.15.4 PHY standard but define their own Media Access Control (MAC)
and network [11], Zigbee and Zigbee Smart Energy Profile (SEP) have been
realized as the most suitable communication standards for Smart Grid residential
network domain by NIST [20], However, they are not suitable for deployment in
the Distribution Network due to short reach and serious security issues.
Cellular is a radio network distributed over a geographic area called cells.
Cellular networks has several advantages including increased capacity, reduced
power use, large coverage area and reduced interference from other signals
through spectrum reuse. Initial roll out of cellular service is called first
generation (1G), which is an analog signal followed by second generation (2G),
which is a digital service followed by third generation (3G) and most recently
fourth generation (4G). There is 2.5G, which is based on either General Packet
Radio Service (GPRS) or Enhance Data Rates for GSM Evolution (EDGE).
GSM is the abbreviation for Global System for Mobile Communications. While
EDGE is still available in fringe areas not upgraded to 3G, GPRS have been
mostly replaced by 3G networks [11], The 3G and 4G technologies support
higher data rates and faster service. Currently, select wireless communications
37


providers deployed 4G networks. Cellular service is very attractive for use in the
Distribution Network due to its widespread coverage. The broadband wireless
communications technology has many inherent advantages when used in Smart
Grid [45], The qualitative summary in Table 6.2 is the result of combining
wireless technology specifications presented in [20] and qualitative analysis
presented in [11] except for satellite and microwave technologies.
Table 6.2: Qualitative Characteristics of Wireless Communication Technologies
Technology Data Rate Distance Reach Existing Geographic Coverage
Satellite high high high
Microwave high high low
Cellular (2.5G) low high good
Cellular (3G) medium high good
Cellular (4G) high high good
WiMAX high high low
Wi-Fi high low low
Zigbee low low low
38


7. Analysis Methodology and Approach
7.1 Metrics
The success and failure of the Smart Grid rests on a communication
system that is intelligent, secure, reliable and cost effective [16], The communication
network for the Smart Grid requires data transfer in a timely manner with adequate
bandwidth and reliability [3] via two-way communication with low latency.
Communication technologies for Smart Grid must be cost efficient, provide good
transmittable range, excellent security features and adequate bandwidth [19],
Additionally, the selection of a communication technology should be based on
several criteria including: bandwidth requirement, topology of network, reliability,
security, feasibility of solution [33],
Based on the aforementioned discussion and general communication
network design guidelines, the following criteria are selected for comparing the
communication architectures described in chapter 5 and the wireline and wireless
communication technologies presented in chapter 6.
a) Bandwidth or Data rate: bandwidth often refers to a data rate measured in bits
per second. For digital signals, bandwidth is the data speed or rate, measured in
bits per second (bps). Various parts of the Smart Grid have different bandwidth
requirement [46], A communications throughput of (2 5) Mb/s was estimated
as a guideline for Smart Grid link to allow for transmitting voltage and current
39


measurements for three phases, phase amplitude, phase angle as well as
additional information like meter identification and overhead packets [22],
b) Latency: latency is a measure of time delay experienced in a communications
network. It can be measured as one-way, the time it takes a sender to transmit
data to the destination receiving it, or round trip, which is the time it takes for
data to travel from the sender to the receiver and back to the sender. Information
concerning faults on the Smart Grid must be transferred from the DAS to a
customer gateway with the shortest possible latency and must be completed
within 50 ms and communication involving a request for reactive power has the
second strictest latency requirement [21], Both rural islanding and urban meshed
distribution scenarios have tolerance for a maximum of six cycles or 100 ms
[22], This requirement imposes even stricter requirement on the communications
network. Latency in a WiMax link is 10 ms from the smart meter to the base
station, so, the communication network must be carefully designed to ensure the
latency end-to-end is less than 50 ms [22], Also, Long Term Evolution (LTE),
which is 4G wireless technology enjoys similar latency characteristics as WiMax,
with latency of (5 10) ms [22],
c) Security: network security is extremely important to ensure all customers data
remain private and no unauthorized access to the network. Several techniques
including user authentication, access control authorization and data encryption
40


are usually implemented to ensure network security. Because a wireless network
uses broadcast medium, it must be resistant to tampering of messages, preserving
confidentiality of information and prevents unauthorized access [11], In general,
wireline medium is more secure than wireless media, but Smart Grid requires a
higher level of security. The legacy cyber security techniques for enterprise
networks can hardly fit well for Smart Grid requirements to operate securely in
the public data communication networks like the internet [47],
d) Scalability: is the ability of a system or network to handle expansion without the
need for replacing major segments of the network. In the case of Distribution
Network, the network must be flexible to accommodate high volumes of smart
meters connecting new houses and businesses.
e) Resilience: is the ability of a network to function properly during interference
either random or intentional. In order for a network to be resilient, it must be
capable of continued operation even in the presence of localized faults [48], In
this respect, mesh architecture provides the maximum resiliency due to multiple
paths to get between nodes.
f) Reliability: is the ability of a network to perform within its normal operating
parameters to provide a specific level of service. Reliability can be measured as a
minimum performance rating over a specified interval of time. In general,
41


availability for communication networks ranges from 99.9% (3 nines
reliability).to 99.999% (5 nines reliability).
g) Interoperability: means devices and services from multiple vendors are
compatible with each other and can be integrated into a generic network.
Interoperability is very important consideration in network deployment. Ensuring
devices and subsystems are interoperable is of high importance to ensure Smart
Grid goals are achieved. Standards are key enabler to achieve interoperability.
For communications in the Smart Grid to be truly effective, they must exist in a
fully integrated system and to be fully integrated, universal standards must be
applied [30], Hence, the urgency for developing and updating many standards to
encourage Smart Grid deployment.
h) Distance Reach: each wireline and wireless communication technology has its
unique signal reach distances. Signal reach ranges from few meters to tens of
kilometers depending on the technology. Terrain characteristics affect wireless
signal reach and as such must be considered during technology evaluation stage.
i) Existing Geographic Coverage: the electric Distribution Network covers vast
geographic areas with varying terrain characteristics. Selecting technologies that
already cover the areas where Smart Grid will be deployed can reduce the
deployment cost. However, a single technology may not provide all coverage in
all area.
42


j) Cost of Ownership: capital expenditure (CAPEX) and operation expenditure
(OPEX) are practical considerations when designing any network. Given the high
numbers of smart meters requiring communications infrastructure, low CAPEX
and OPEX will be key for early adopters of Smart Grid.
7.2 Analysis Methodology
The methodology used to compare the architectures, technologies and metrics
for suitability in the Smart Grid Distribution Network is:
A) identify key communications architectures
B) select viable communications technologies
C) choose applicable metrics
D) assign weighting factors using the following scale from highest to lowest:
good fit = 3, moderate fit = 2, poor fit = 1 and not suitable = 0.
Additionally, the following metrics guidelines were adopted from [11],
Table 7.1: Metrics Guidelines [11]
Ave. Data Rate Ave. Latency Distance Reach Scalability
Good > 1.5 Mb/s < 250 ms > 1000 meters > 1000 nodes/ data hub
Moderate 500 Kb/s 1.5 Mb/s 250 ms 1 sec (100- 1000) meters (100 1000) nodes/ data hub
Poor <500 Kb/s > 1 sec <100 meters <100 nodes/ data hub
E) summarize the results in a multi dimension matrix
43


7.3 Summary of Results
Each technology option is analyzed against the five architectures using
the selected ten metrics. The result is a three dimension matrix. Then normalize
the total score for each architecture and technology combination and select the
top five scores representing the best overall solutions. The next series of tables
present the detailed scores for each architecture, all wireline and wireless
technologies against the ten criteria.
Table 7.2 provides summary of architecture 1 scenarios. Most wireless
technologies and one wireline technology i.e., power line communication are
suitable for this architecture since power lines already exist between the end user
facility and the utilities substation. However, copper twisted pairs, coax and fiber
optic cables do not exist and as such require significant installation and are very
expensive, which excludes them to be practical options for architecture 1.
Satellite service is very expensive to deploy and maintain in addition to high
monthly charges. Microwave communication network requires valuable and
scarce spectrum and significant capital investment to build such infrastructure. It
requires line-of-sight (LOS) between transmitter and receiver. Hence, microwave
is not suited for architecture 1 especially in residential areas. WiMAX also
requires large capital investment to build a network that covers all residents in
the U.S.A. Wi-Fi lacks the required distance reach and geographic coverage.
44


Some cities across the country partnered with private providers to build a
citywide Wi-Fi network. However, these examples are rare and a countrywide
Wi-Fi coverage wont be cheap to build nor practical. Zigbee is an in-home
network that will communicate with smart devices within a household. Hence, it
has very short distance reach, which makes it not suitable for Smart Grid
communication in the Distribution Network. For architecture 1, the best overall
options are those using cellular technology with 4G being the best since it
supports the higher data rates.
Table 7.2: Summary of Architecture 1 Metrics
Criteria Architecture #1 (Direct Connect)
Wireless Wireline
Satellite Microwave Cellular (2.5G) Cellular (3G) Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable o _l CL Fiber Optic Cable
Bandwidth / Data Rate 3 3 1 2 3 3 1 3 3 3 2 3
Latency 1 2 2 2 1 3 1 3 3 3 3 3
Security 3 3 2 2 3 3 2 2 3 2 2 3
Scalability 1 1 2 3 3 3 1 1 1 1 3 1
Reliability 2 2 2 2 2 2 1 2 3 3 2 3
Interoperability 2 2 2 2 2 1 1 3 3 3 2 2
Resilience 2 2 3 3 3 3 2 1 3 3 3 3
Distance Reach 3 3 3 3 3 3 0 1 2 2 2 3
Existing Geographic Coverage 2 0 2 2 2 0 0 0 0 0 1 0
Cost of Ownership 1 1 3 3 3 1 1 1 1 1 2 1
Sum of points: 20 19 22 24 25 22 10 17 22 21 22 22
Max. No. of Points 30 30 30 30 30 30 30 30 30 30 30 30
Normalized Score: 67% 63% 73% 80% 83% 73% 33% 57% 73% 70% 73% 73%
45


Table 7.3 presents summary of architecture 2 scenarios. The discussion
for architecture 1 listed above applies here as well. Hence, the best overall
technology options are those using cellular technology with 4G being the best
option since it supports the higher data rates. However, 4G is not available in all
areas and some areas may be limited to 3G or 2.5G only. Moreover, some remote
areas may not have any cellular service, so in these cases, PLC can be a viable
wireline option.
Table 7.3: Summary of Architecture 2 Metrics
Criteria Architecture #2 (Aggregator)
Wireless Wireline
Satellite Microwave Cellular (2.5G) Cellular (3G) Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable o _l CL Fiber Optic Cable
Bandwidth / Data Rate 3 3 1 2 3 3 1 3 3 3 2 3
Latency 1 2 2 2 1 3 1 3 3 3 3 3
Security 3 3 2 2 3 3 2 2 3 2 2 3
Scalability 1 1 2 3 3 3 1 1 1 1 3 1
Reliability 2 2 2 2 2 2 1 2 3 3 2 3
Interoperability 2 2 2 2 2 1 1 3 3 3 2 2
Resilience 2 2 3 3 3 3 2 1 3 3 3 3
Distance Reach 3 3 3 3 3 3 0 1 2 2 2 3
Existing Geographic Coverage 2 0 2 2 2 0 0 0 0 0 1 0
Cost of Ownership 2 1 3 3 3 1 1 1 1 1 2 1
Sum of points: 21 19 22 24 25 22 10 17 22 21 22 22
Max. No. of Points 30 30 30 30 30 30 30 30 30 30 30 30
Normalized Score: 70% 63% 73% 80% 83% 73% 33% 57% 73% 70% 73% 73%
46


Table 7.4 depicts scenarios for architecture 3. Once again, the same
analysis for architectures 1 and 2 applies here with one exception. Power line
communication is not as favorable for architectures 3. Under architecture 3,
additional power lines are required to interconnect the Aggregators since the
power lines are radial by design. This fact will increase the cost of ownership for
PLC technology under this architecture.
Table 7.4: Summary of Architecture 3 Metrics
Criteria Architecture #3 (Interconnected Aggregators)
Wireless Wireline
Satellite Microwave Cellular (2.5G) Cellular (3G) Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable Old Fiber Optic Cable
Bandwidth / Data Rate 3 3 1 2 3 3 1 3 3 3 2 3
Latency 1 2 2 2 1 3 1 3 3 3 3 3
Security 3 3 2 2 3 3 2 2 3 2 2 3
Scalability 1 1 2 3 3 3 1 1 1 1 3 1
Reliability 2 2 2 2 2 2 1 2 3 3 2 3
Interoperability 2 2 2 2 2 1 1 3 3 3 2 2
Resilience 2 2 3 3 3 3 2 1 3 3 3 3
Distance Reach 3 3 3 3 3 3 0 1 2 2 2 3
Existing Geographic Coverage 2 0 2 2 2 0 0 0 0 0 1 0
Cost of Ownership 2 1 3 3 3 1 1 1 1 1 2 1
Sum of points: 21 19 22 24 25 22 10 17 22 21 22 22
Max. No. of Points 30 30 30 30 30 30 30 30 30 30 30 30
Normalized Score: 70% 63% 73% 80% 83% 73% 33% 57% 73% 70% 73% 73%
47


Table 7.5 summarizes the results for architecture 4. Under the mesh
architecture, wireless communications has a major advantage over wireline options
due mainly to the high capital expenditure to implement a wireline technology in a
mesh configuration. However, satellite and microwave technologies are expensive
while Wi-Fi and WiMAX do not currently have the geographic coverage. Zigbee is
eliminated due to its short distance reach. The result is cellular technology is the best
option. Cellular networks cover the majority of United States residents with few
exceptions in the rural areas or areas with challenging terrain.
Table 7.5: Summary of Architecture 4 Metrics
Criteria Architecture #4 (Mesh)
Wireless Wireline
Satellite Microwave Cellular (2.5G) Cellular (3G) Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable Old Fiber Optic Cable
Bandwidth / Data Rate 3 3 1 2 3 3 1 3 3 3 2 3
Latency 1 2 2 2 1 3 1 3 3 3 3 3
Security 3 3 2 2 3 3 2 2 3 2 2 3
Scalability 1 1 2 3 3 3 1 1 1 1 2 1
Reliability 2 2 2 2 2 2 1 2 3 3 2 3
Interoperability 2 2 2 2 2 1 1 3 3 3 2 2
Resilience 2 2 3 3 3 3 2 1 3 3 3 3
Distance Reach 3 3 3 3 3 3 0 1 2 2 2 3
Existing Geographic Coverage 2 0 2 2 2 0 0 0 0 0 1 0
Cost of Ownership 2 1 3 3 2 1 1 1 1 1 2 1
Sum of points: 21 19 22 24 24 22 10 17 22 21 21 22
Max. No. of Points 30 30 30 30 30 30 30 30 30 30 30 30
Normalized Score: 70% 63% 73% 80% 80% 73% 33% 57% 73% 70% 70% 73%
48


Table 7.6 summarizes the results for architecture 5, which is based on using
existing Internet connections to the cloud. This architecture is unique because it
leverages existing Internet service the majority of end users have, which makes it
least expensive architecture to deploy. Hence, using the Internet for Smart Grid
communications is almost free for those who already have an Internet service. Based
on the overall criteria, Internet service over TWP, which is called Digital Subscriber
Line (DSL), is the best option due to its widespread geographic coverage.
Table 7.6: Summary of Architecture 5 Metrics
Architecture #5 (Internet Cloud)
Criteria Wireless Wireline
Satellite Microwave Cellular (2.5G) Cellular (3G) Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable Old Fiber Optic Cable
Bandwidth / Data Rate 3 3 1 2 3 3 1 3 3 3 2 3
Latency 1 2 2 2 1 3 1 3 3 3 3 3
Security 3 3 2 2 3 3 2 2 3 2 2 3
Scalability 1 1 2 3 3 3 1 1 3 2 2 1
Reliability 2 2 2 2 2 2 1 2 3 3 2 3
Interoperability 2 2 2 2 2 1 1 3 3 3 2 3
Resilience 2 2 3 3 3 3 2 1 3 3 3 3
Distance Reach 3 3 3 3 3 3 0 1 2 2 2 3
Existing Geographic Courage 2 0 1 2 2 0 0 0 2 1 1 0
Cost of Ownership 1 1 2 2 1 1 1 1 3 3 2 1
Sum of points: 20 19 20 23 23 22 10 17 28 25 21 23
Max. No. of Points 30 30 30 30 30 30 30 30 30 30 30 30
Normalized Score: 67% 63% 67% 77% 77% 73% 33% 57% 93% 83% 70% 77%
49


Since a specific technology and architecture combination may not be
available nationwide, it is important to provide few choices that can work in different
environments. Table 7.6 presents the top five scoring scenarios out of all possible
combinations i.e., scenarios presented in tables 7.2 7.6. It is clear that architecture
5, Internet Cloud, has the highest score for the overall metrics. Additionally, Internet
service over TWP and Coax cable are best media/technology options, due to existing
widespread coverage and relatively low monthly costs.
Table 7.7: Top Five Architecture and Technology Combinations
Criteria Architecture #1 (Direct Connect) Architecture #2 (Aggregator) Architecture #3 (Interconnected Aggregators) Architecture #5 (Internet Cloud)
Wireless Wireless Wireless Wireline
Cellular (4G) Cellular (4G) Cellular (4G) Twisted Pair (TP) Coaxial Cable
Bandwidth / Data Rate 3 3 3 3 3
Latency 1 1 1 3 3
Security 3 3 3 3 2
Scalability 3 3 3 3 2
Reliability 2 2 2 3 3
Interoperability 2 2 2 3 3
Resilience 3 3 3 3 3
Distance Reach 3 3 3 2 2
Existing Geographic Courage 2 2 2 2 1
Cost of Ownership 3 3 3 3 3
Sum of points: 25 25 25 28 25
Max. No. of Points 30 30 30 30 30
Normalized Score: 83% 83% 83% 93% 83%
50


7.4 Conclusion
After analyzing the five architectures and applicable wireline and wireless
technologies for deployment in the Distribution Network in support of Smart
Grid objectives, it is evident that each architecture and technology combination
has strengths and weaknesses. Additionally, a single architecture solution will
not be suitable for every deployment and in any environment. Hence, the author
provides the top five scoring architectures and technology combinations.
Architecture 5 is the overall favorable choice. This architecture functions with
both wireline and wireless technologies, provides most flexibility, least cost of
ownership, has widespread coverage and scales to support large deployments.
Two concerns about this architecture include security risks from using the
Internet to transport sensitive data and the utilities acceptance to use third party
providers for the communication networks. The first concern is manageable with
added security layers. Currently, the Internet is widely accepted for sensitive
financial transactions including online shopping, banking and stocks transactions.
As for the second concern, while most utilities prefer to have complete
ownership and total control of the communication networks that support Smart
Grid, deployment costs and implementation timelines will force utilities to
revaluate their position and start partnering with communication providers to
realize Smart Grid benefits sooner than later.
51


Future study opportunity is to evaluate a mixture of technologies to
implement each of the five architectures. For example, use PLC and cellular to
build mesh architecture. Such approach will leverage vast power lines for
primary link and use cellular links to complete the mesh network.
52


BIBLIOGRAPHY
[1] 110th Congress of the United States, Energy Independence and Security Act
of 2007. Dec-2007.
[2] Z. Jiang, F. Li, W. Qiao, H. Sun, H. Wan, J. Wang, Y. Xia, Z. Xu, and P.
Zhang, A vision of smart transmission grids, in IEEE Power & Energy
Society General Meeting, 2009. PES 09, 2009, pp. 1-10.
[3] C. H. Hauser, D. E. Bakken, and A. Bose, A failure to communicate: next
generation communication requirements, technologies, and architecture for the
electric power grid, IEEE Power and Energy Magazine, vol. 3, no. 2, pp. 47-
55, Apr. 2005.
[4] C. Lo and N. Ansari, The Progressive Smart Grid System from Both Power
and Communications Aspects, IEEE Communications Surveys & Tutorials,
vol. PP, no. 99, pp. 1-23.
[5] J. Heckel, Smart substation and feeder automation for a SMART distribution
grid, in 20th International Conference and Exhibition on Electricity
Distribution Part 1, 2009. CIRED 2009, 2009, pp. 1-4.
[6] U.S. Department of Energy, Smart Grid System Report, 2009.
[7] H. Farhangi, The path of the smart grid, IEEE Power and Energy Magazine,
vol. 8, no. 1, pp. 18-28, Feb. 2010.
[8] NIST, NIST Framework and Roadmap for Smart Grid Interoperability
Standards, Release 1.0, U.S. Department of Commerce, 2010.
[9] S. Rohjans, M. Uslar, R. Bleiker, J. Gonzalez, M. Specht, T. Suding, and T.
Weidelt, Survey of Smart Grid Standardization Studies and
Recommendations, in 2010 First IEEE International Conference on Smart
Grid Communications (SmartGridComm), 2010, pp. 583-588.
[10] 109th Congress of the United States, Energy Policy Act of 2005, Aug-2005.
[Online], Available:
http://www.fedcenter.gov/_kd/Items/actions.cfm?action=Show&item_id=2969
&destination=ShowItem. [Accessed: 04-Mar-2012],
[11] B. Akyol, H. Kirkham, S. Clements, and M. Hadley, A Survey of Wireless
Communications for the Electric Power System, U.S. Department of Energy,
PNNL-19084, 2010.
53


[12] Electricity Advisory Committee, Smart Grid: Enabler of the New Energy
Economy, U.S. Department of Energy, 2008.
[13] S. E. Collier, Ten steps to a smarter grid, in IEEE Rural Electric Power
Conference, 2009. REPC 09, 2009, pp. B2-B2-7.
[14] S. Mohagheghi, J. Stoupis, Z. Wang, Z. Li, and H. Kazemzadeh, Demand
Response Architecture: Integration into the Distribution Management System,
in 2010 First IEEE International Conference on Smart Grid Communications
(SmartGridComm), 2010, pp. 501-506.
[15] K. H. LaCommare and I. H. Eto, Understanding the Cost of Power
Interruptions to U.S. Electricity Consumers, Ernest Orlando Lawrence
Berkeley National Laboratory, Berkeley, California, LBNL-55718, Sep. 2004.
[16] S. Rahman, Smart grid expectations [In My View], IEEE Power and Energy
Magazine, vol. 7, no. 5, pp. 88, 84-85, Oct. 2009.
[17] C. Bennett and D. Highfill, Networking AMI Smart Meters, in IEEE Energy
2030 Conference, 2008. ENERGY 2008, 2008, pp. 1-8.
[18] A. Vojdani, Smart Integration, IEEE Power and Energy Magazine, vol. 6,
no. 6, pp. 71-79, Dec. 2008.
[19] S. S. S. Depuru, L. Wang, V. Devabhaktuni, and N. Gudi, Smart meters for
power grid Challenges, issues, advantages and status, in Power Systems
Conference and Exposition (PSCE), 2011 IEEE/PES, 2011, pp. 1-7.
[20] V. C. Gungor, D. Sahin, T. Kocak, S. Ergut, C. Buccella, C. Cecati, and G. P.
Hancke, Smart Grid Technologies: Communication Technologies and
Standards, IEEE Transactions on Industrial Informatics, vol. 7, no. 4, pp. 529-
539, Nov. 2011.
[21] T. Otani, A Primary Evaluation for Applicability of IEC 62056 to a Next-
Generation Power Grid, in 2010 First IEEE International Conference on Smart
Grid Communications (SmartGridComm), 2010, pp. 67-72.
[22] V. K. Sood, D. Fischer, I. M. Eklund, and T. Brown, Developing a
communication infrastructure for the Smart Grid, in 2009 IEEE Electrical
Power & Energy Conference (EPEC), 2009, pp. 1-7.
[23] I. A. Momoh, Smart grid design for efficient and flexible power networks
operation and control, in Power Systems Conference and Exposition, 2009.
PSCE 09. IEEE/PES, 2009, pp. 1-8.
54


[24] F. Lobo, A. Cabello, A. Lopez, D. Mora, and R. Mora, Distribution Network
as communication system, in SmartGrids for Distribution, 2008. IET-CIRED.
CIRED Seminar, 2008, pp. 1-4.
[25] X. Mamo, S. Mallet, T. Coste, and S. Grenard, Distribution automation: The
cornerstone for smart grid development strategy, in IEEE Power & Energy
Society General Meeting, 2009. PES 09, 2009, pp. 1-6.
[26] E. Peeters, R. Belhomme, C. Batlle, F. Bouffard, S. Karkkainen, D. Six, and
M. Hommelberg, ADDRESS: Scenarios and architecture for Active Demand
development in the smart grids of the future, in 20th International Conference
and Exhibition on Electricity Distribution Part 1, 2009. CIRED 2009, 2009,
pp. 1-4.
[27] G. N. Srinivasa Prasanna, A. Lakshmi, S. Sumanth, V. Simha, J. Bapat, and G.
Koomullil, Data communication over the smart grid, in IEEE International
Symposium on Power Line Communications and Its Applications, 2009. ISPLC
2009, 2009, pp. 273-279.
[28] T. Sauter and M. Lobashov, End-to-End Communication Architecture for
Smart Grids, IEEE Transactions on Industrial Electronics, vol. 58, no. 4, pp.
1218-1228, Apr. 2011.
[29] R. DeBlasio and C. Tom, Standards for the Smart Grid, in IEEE Energy
2030 Conference, 2008. ENERGY 2008, 2008, pp. 1-7.
[30] National Energy Technology Laboratory (NETL), A Systems View of The
Modern Grid, 2007.
[31] M. Uslar, S. Rohjans, R. Bleiker, J. Gonzalez, M. Specht, T. Suding, and T.
Weidelt, Survey of Smart Grid standardization studies and recommendations
Part 2, in Innovative Smart Grid Technologies Conference Europe (ISGT
Europe), 2010 IEEE PES, 2010, pp. 1-6.
[32] Z. Fan, P. Kulkami, S. Gormus, C. Efthymiou, G. Kalogridis, M.
Sooriyabandara, Z. Zhu, S. Lambotharan, and W. Chin, Smart Grid
Communications: Overview of Research Challenges, Solutions, and
Standardization Activities, IEEE Communications Surveys & Tutorials, vol.
PP, no. 99, pp. 1-18.
[33] C. Yuen, R. Comino, M. Kranich, D. Laurenson, and J. Barria, The role of
communication to enable smart distribution applications, in The 20th
International Conference and Exhibition on Electricity Distribution Part 2,
2009. CIRED 2009, 2009, pp. 1-10.
55


[34] A. Ipakchi and F. Albuyeh, Grid of the future, IEEE Power and Energy
Magazine, vol. 7, no. 2, pp. 52-62, Apr. 2009.
[35] R. Berthier, W. H. Sanders, and H. Khurana, Intrusion Detection for
Advanced Metering Infrastructures: Requirements and Architectural
Directions, in 2010 First IEEE International Conference on Smart Grid
Communications (SmartGridComm), 2010, pp. 350-355.
[36] B. Lichtensteiger, B. Bjelajac, C. Mu Her, and C. Wietfeld, RF Mesh
Systems for Smart Metering: System Architecture and Performance, in 2010
First IEEE International Conference on Smart Grid Communications
(SmartGridComm), 2010, pp. 379-384.
[37] F. Li, B. Luo, and P. Liu, Secure Information Aggregation for Smart Grids
Using Homomorphic Encryption, in 2010 First IEEE International Conference
on Smart Grid Communications (SmartGridComm), 2010, pp. 327-332.
[38] A. Mahmood, M. Aamir, and M. I. Anis, Design and implementation of AMR
Smart Grid System, in Electric Power Conference, 2008. EPEC 2008. IEEE
Canada, 2008, pp. 1-6.
[39] M. Huczala, T. Lukl, and J. Misurec, Capturing Energy Meter Data over
Secured Power Line, in International Conference on Communication
Technology, 2006. ICCT 06, 2006, pp. 1-4.
[40] S. Bannister and P. Beckett, Enhancing powerline communications in the
Smart Grid using OFDMA, in Power Engineering Conference, 2009.
AUPEC 2009. Australasian Universities, 2009, pp. 1-5.
[41] S. Galli, A. Scaglione, and Z. Wang, Power Line Communications and the
Smart Grid, in 2010 First IEEE International Conference on Smart Grid
Communications (SmartGridComm), 2010, pp. 303-308.
[42] A. G. Van Engelen and J. S. Collins, Choices for Smart Grid
Implementation, in 2010 43rd Hawaii International Conference on System
Sciences (HICSS), 2010, pp. 1-8.
[43] M. Souryal, C. Gentile, D. Griffith, D. Cypher, and N. Golmie, A
Methodology to Evaluate Wireless Technologies for the Smart Grid, in 2010
First IEEE International Conference on Smart Grid Communications
(SmartGridComm), 2010, pp. 356-361.
56


[44] G. Li, H. Sun, H. Gao, H. Yu, and Y. Cai, A Survey on Wireless Grids and
Clouds, in Eighth International Conference on Grid and Cooperative
Computing, 2009. GCC 09, 2009, pp. 261-267.
[45] Z. Feng and Z. Yuexia, Study on smart grid communications system based on
new generation wireless technology, in 2011 International Conference on
Electronics, Communications and Control (ICECC), 2011, pp. 1673-1678.
[46] Y. Gobena, A. Durai, M. Birkner, V. Pothamsetty, and V. Varakantam,
Practical architecture considerations for Smart Grid WAN network, in Power
Systems Conference and Exposition (PSCE), 2011 IEEE/PES, 2011, pp. 1-6.
[47] Y. Yan, Y. Qian, H. Sharif, and D. Tipper, A Survey on Cyber Security for
Smart Grid Communications, IEEE Communications Surveys & Tutorials,
vol. PP, no. 99, pp. 1-13.
[48] J. Wang and V. C. Leung, A survey of technical requirements and consumer
application standards for IP-based smart grid AMI network, in 2011
International Conference on Information Networking (ICOIN), 2011, pp. 114-
119.
57


Full Text

PAGE 1

COMPARATIVE ANALYSIS OF COMMUNICATION ARCHITECTURES AND TECHNOLOGIES FOR SMART GRID DISTRIBUTION NETWORK by Monther A. Hammoudeh B.S.E.E., Virginia Polytechnic Institute and State University, l995 A thesis submitted to the University of Colorado Denver in partial fulfillment of the requirements for the degree of Masters of Science Electrical Engineering Electrical Engineering 2012

PAGE 2

This thesis for the Masters of Science Electrical Engineering degree by Monther A. Hammoudeh has been approved by Fernando Mancilla-David Titsa Papantoni Dan Connors Date: May 4, 2012

PAGE 3

Hammoudeh, Monther A. (M.S., Electrical Engineering) Comparative Analysis of Communication Architectures and Technologies for Smart Grid Distribution Network Thesis directed by Assistant Professor Fernando Mancilla-David ABSTRACT A critical piece of the Smart Grid infrastructure is the c ommunications network for data gathering, control and supervision capabilities that ex tend to the customer demarcation point. Over several decades, the electric utilities built a robust communications networks connecting electric grid subsystems except for the “last mile” connecting to the end user premise. A primary goal of Smart G rid (SG) is to expand the communications network throughout the Distribution Network (DN) t hus enabling a holistic management and control of electric grid from ge neration to consumption. In order for the Smart Grid goals to be realized, two -way communications network must extend to the Distribution Network allowing two-way data flow e.g., real-time energy pricing and real-time demand data back to the Utilities and Operators. This thesis presents five communications architectures and viable technologies for deployment within the Distribution Network of t he Smart Grid. Then apply selected metrics to these architectures and technologies combinations and select top five scoring combinations.

PAGE 4

This abstract accurately represents the content of the candidateÂ’s thesis I recommend its publication. Approved: Fernando Mancilla-David

PAGE 5

DEDICATION All thanks and praise is due to Allah for his blessing and guidance. I dedicate this thesis to my loving parents, especially my fa ther (the late Professor Abed El-Rahman Hammoudeh) who gave me the appreciation of education and taught me the value of perseverance and resolve. I also dedicate thi s thesis to my wife, Suhad, and my daughters (Mona, Hoda and Ayah) for their understanding and sacrifice while I was completing this thesis. I would like to thank all my family and friends who supported me to successfully finish this work.

PAGE 6

ACKNOWLEDGMENT My thanks to my advisor, Dr. Fernando Mancilla-David, for his contribution and support of my research. I also wish to thank all the members of my thesis committee for their valuable participation and insights.

PAGE 7

vii CONTENTS Figures Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…. x Tables Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…. ix Chapter 1. Introduction ------------------------------------------------------------------------------1 1.1 Scope of This Study ------------------------------------------------------------------2 1.2 Organization of Thesis---------------------------------------------------------------4 2. What is Smart Grid? --------------------------------------------------------------------5 2.1 Recent American Laws Driving Smart Grid Deployment ----------------------6 2.2 Smart Grid Functions and Goals -------------------------------------------------------7 2.3 Smart Grid Benefits ----------------------------------------------------------------------9 3. Data Collection in The Distribution Network --------------------------------------11 3.1 Consumer Energy Usage Data ----------------------------------------------------12 3.2 Device Status Data and Control ---------------------------------------------------12 4. Communications for The Distribution Network -----------------------------------15 4.1 The Need for Communications ----------------------------------------------------15 4.2 Communications Requirements ---------------------------------------------------16 4.3 Are Smart Grid Standards Required? --------------------------------------------19 4.4 Emerging Smart Grid Standards --------------------------------------------------19 5. Communications Architectures ---------------------------------------------------------21 5.1 Direct Connect Architecture -----------------------------------------------------------22 5.2 Local Access Aggregators Architecture ---------------------------------------------23 5.3 Interconnected Local Access Aggregators Architecture --------------------------26 5.4 Mesh Architecture ----------------------------------------------------------------------27

PAGE 8

viii 5.5 The Internet Cloud Architecture ------------------------------------------------------28 6. Technology Options ----------------------------------------------------------------------31 6.1 Wireline Technology Options ---------------------------------------------------------31 6.2 Wireless Technologies -----------------------------------------------------------------35 7. Analysis Methodology and Approach -------------------------------------------------39 7.1 Metrics ------------------------------------------------------------------------------------39 7.2 Analysis Methodology -----------------------------------------------------------------43 7.3 Summary of Results --------------------------------------------------------------------44 7.4 Conclusion -------------------------------------------------------------------------------51 Bibliography Â…Â…Â…Â…Â…Â… ......................... Â…Â…..Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…Â…52

PAGE 9

ix FIGURES Figure 5.1 A view of the Utility Information Systems ....................................................... 22 5.2 Direct Connect Architecture ............................................................................. 23 5.3 Overview of AMI Network with NAN ............................................................. 24 5.4 Local Access Aggregator Architecture ............................................................. 25 5.5 Interconnected Local Access Aggregators Architecture ................................... 26 5.6 Mesh Architecture ............................................................................................. 27 5.7 The Internet Cloud Architecture ........................................................................ 30

PAGE 10

x TABLES Table 2.1 The Smart Grid vs. The Existing Grid ................................................................. 8 2.2 Cost of One-hour Service Outage ........................................................................ 9 3.1 Sample Data Requirements ................................................................................ 13 4.1 Communications From CustomerÂ’s Gateway and Requirements ...................... 17 4.2 Communications To CustomerÂ’s Gateway and Requirements .......................... 18 6.1 Qualitative Characteristics of Wireline Communication Media Types ............. 35 6.2 Qualitative Characteristics of Wireless Communication Technologies............. 38 7.1 Metrics Guidelines ............................................................................................. 43 7.2 Summary of Architecture 1 Metrics ................................................................... 45 7.3 Summary of Architecture 2 Metrics ................................................................... 46 7.4 Summary of Architecture 3 Metrics ................................................................... 47 7.5 Summary of Architecture 4 Metrics ................................................................... 48 7.6 Summary of Architecture 5 Metrics ................................................................... 49 7.7 Top Five Architecture and Technology Combinations ...................................... 50

PAGE 11

1 1. Introduction Over several decades, the electric utilities built a robust communications networks connecting electric grid subsystems except for the Di stribution Network (DN) feeding the end customer premise. A primary goal of Sma rt Grid is to expand the communications network to the consumption segment thus enabling a holist ic management and control of electric grid from generation to consumption. With the recent emphasis on deployments of Smart Grid within the U nited States of America and the passing of EISA (Energy Independent and Security Act of 2007) into law [1], the race is on to begin deployment of Smart Grid. U nder Title XIII of EISA 2007, the U.S. Department of Energy (DoE) established a Federal Smart Grid Task Force. In its Grid 2030 vision, the objectives are t o construct the 21 st century electric system to provide abundant, affordable, clean ef ficient and reliable electric power anytime, anywhere [2]. A key enabler of Smart Grid deployment is the communications network that interconnects the numero us devices, usersÂ’ smart meters and the electric grid subsystems. The f irst step of designing a robust communications network is establishing an architecture that outline s data flow among various parts of the system. The North American power grids are made up of almost 3,500 utility organizations [3]. The basic principle of supplies and demand must be at equilibrium all times. Extensive communications networks that span hundreds of thous ands of

PAGE 12

2 miles enable electricity grid operators to manage the demand a nd keep this supply demand equation balanced. However, the existing communications architect ure is several decades old and has not benefited from recent technology a dvances. Additionally, the existing communications network primary function is to connect electrical substation with operators control centers leaving t he distribution subsystem lacking adequate situational awareness [3]. To remedy the current limitations of the electrical grid, the U.S. Congress passed the EISA law in 2007 e stablishing goals for modernizing the electrical grid. 1.1 Scope of This Study A critical piece of the Smart Grid infrastructure is the c ommunications network that will extend the control and supervision capabilities to t he end users. As described in [4], the Smart Grid communications network can be divided i nto four distinct segments: Core or metro segment – connects substations to the utilities’ headquarters. Backhaul segment – connects data aggregators to substation/distribut ion automation at broadband speeds Neighborhood Area Network (NAN) or last-mile – connects the custome r’s smart meter or gateway to the data aggregators, and

PAGE 13

3 Home Area Network (HAN) – this is the customer’s home or bui lding automation. The generation subsystem enjoys full automation while transmiss ion and substation have very high levels of automation, but the distribution network has poor automation level [5]. Additionally, the transmission-system level, ar ea control centers and regional reliability coordination centers have been ex changing system status information. The communication links between these systems now cover the country with increasing exchange of information among electric util ity companies [6]. The distribution segment of the electric grid is the least comm unicated with and least controlled segment of all the electric grid segments. The Distribution Automation (DA) is primarily led by substation automation with fe eder equipment automation still lagging [6]. Because feeder automation lags othe r automation efforts widely, this area should be addressed directly in future work [6]. As discussed in [7], the Distribution Network remains outside the utility companies’ re al-time control. Additionally, nearly 90% of all power outages and disturbances have th eir roots in the Distribution Network [7]. While 84% of utilities has substation aut omation and integration underway in 2005, the feeder penetration is still limit ed to about 20% [6]. So, it makes sense to begin Smart Grid at the bottom of the chain, in the Distribution Network [7].

PAGE 14

4 The scope of this thesis is limited to the communications networks i n the Distribution Network of the Smart Grid to address the aforementioned gaps. In other words, the focus is on the “last mile” communications segment. This thesis documents the results of a thorough survey of technical papers and gov ernmental agencies’ reports then provides the author’s critical analysis of communications architectures and technologies for Smart Grid Distribution Network. 1.2 Organization of Thesis This thesis is organized into chapters. Chapter 2 covers Smart Gri d objectives, functions and benefits. Chapter 3 describes data collecti on in the Distribution Network for both end-users and service providers’ usage. Cha pter 4 addresses the needs for communications networks in the Distribution Net work. Chapter 5 discusses five communications architectures. Chapter 6 provi des an overview of wireline and wireless technology options. Lastly, chapte r 7 describes the analysis methodology and presents three dimension comparison matrix w ith a conclusion.

PAGE 15

5 2. What is Smart Grid? The United States of America and several other countries have made it a national strategic goal to modernize their electric grid [8] t o make it more robust, secure, expand overall control and make it capable of supporting renewabl e energy resources and anticipated growth demand. Many definitions of Smart Grid (SG) exist all around the world [9]. Smart Grid is the modernization and automati on of the electric power grid changing from a producer-controlled networ k to one that is less centralized and more consumer-interactive and is more than just “s mart meters”. The use of two-way communications and advanced control capabilities will result in the realization of a host of benefits and new applications. One can think of SG as an Information and Communication Technologies (ICT) based power system [9]. The National Institute of Standards and Technology (NIST) defines the Smart Gri d as: a modernization of the electricity delivery system so it monitor s, protects and automatically optimizes the operation of its interconnected element s – from the central and distributed generator through the high-voltage netwo rk and distribution system, to industrial users and building automation system s, to energy storage installations and to end-use consumers and their thermostats, electric vehicles, appliances and other household devices [9]. In general, all definitions refer to an advanced power grid through the use of digital computing and communications technologies [8].

PAGE 16

6 2.1 Recent American Laws Driving Smart Grid Deployment Starting with the Energy Policy Act of 2005 (EPACT 2005) Section 103 titled “Energy Use Measurements and Accountability” that esta blished a deadline of October 1, 2012 for all federal building to have some sort of advanced me ters that provide data of the electricity consumption [10]. Additionally, EPACT 2005 Section 1252 titled “Smart Metering” obligates electric utilities to suppl y each of its customers upon request, a time-based rate schedule. On December 19, 2007, the United States Congress passed the Energy Independent and Security Act (EISA) of 2007 into law that mandated t he modernization of the electric grid with an end goal of Smart Grid [1] Finally, the American Recovery and Reinvestment Act of 2009 (ARRA) included $10 bil lion in investments to encourage transformation to a smarter grid [8]. All these federal laws brought visibility and attention to the need for modernizing the electri c grid. Additionally, several states and electric utilities initiated infrastructure deployments in preparation for Smart Grid. Common deployments include the install ation of advanced meters by utilities companies and Smart Grid test beds as the case with Xcel’s project in Boulder, Colorado known as “SmartGridCity”.

PAGE 17

7 2.2 Smart Grid Functions and Goals In December 2007, the Energy Independence and Security Act (EISA) was signed into law. This law established clear national goals to i mplement Smart Grid. Some of the stated benefits include: Self-healing from power disturbances Enables active participation by consumers in “demand response” Operates resiliently against physical or cyber attack Provides power quality for 21st century needs Accommodates all generation and storage options Enables new products, services, and markets Optimizes assets and operational efficiency A Smart Grid provides the flexibility to adapt to a changing m ix of demandside resources, including changeable load, dispatchable distributed gen eration and storage, as well as output local generation such as wind and solar [ 6]. Smart-gridenabled distributed controls within the electric delivery system will aide in dynamically balancing electrical supply and demand, thus resulting in a more adaptable system to imbalances and limit their propagation when t hey occur [6]. A Smart Grid is needed at the distribution system to manage voltage level, reactive

PAGE 18

8 power, potential reverse power flows and power conditioning, which are cr itical to running grid-connected Distributed Generation (DG) systems [6]. Table 2.1 provides a side by side comparison of key attributes of the existing electric grid and the Smart Grid, which is also referred to as “Intelligent Grid”. There is clear need for Smart Grid at the distribution level to manag e: voltage levers, reactive power, potential reverse power flows and power conditioning [6]. Table 2.1: The Existing Grid vs. The Smart Grid [7] Existing Grid Smart Grid Electromechanical Digital One-Way Communication Two-Way Communication Centralized Generation Distributed Generation Hierarchical Network Few Sensors Sensors Throughout Blind Self-Monitoring Manual Restoration Self-Healing Failures and Blackouts Adaptive and Islanding Manual Check/Test Remote Check/Test Limited Control Pervasive Control Few Customer Choices Many Customer Choices The expected functions of Smart Grid are detailed in [11] and summarized below: Operation Reliability and Blackout Prevention Condition Monitoring and Asset Management Protection and Station Automation Distribution Network Management

PAGE 19

9 Distribution Network Automation Smart Metering 2.3 Smart Grid Benefits The benefits of Smart Grid show up in many areas including the infrastructure management and protection, the gained efficiency, ec onomic benefits for the consumer and reducing business losses from blackouts. Data fr om wide-area measurement system could have eliminated the $4.5 billion in losses a s a result of the 2003 blackout of the eastern U.S. and Canada [6]. Another study res ults show that Smart Grid technologies would reduce power disturbance costs to the U.S. economy by $49 billion per year [12]. Table 2.2 provides an average estima ted cost of one-hour power interruption for selected enterprises businesses. Table 2.2: Cost of One-hour Service Outage [12] Industry Average Cost of 1-Hour Interruption Cellular communications $41,000 Telephone ticket sales $72,000 Airline reservation system $90,000 Semiconductor manufacturer $2,000,000 Credit card operation $2,580,000 Brokerage operation $6,480,000

PAGE 20

10 Smart Grid can enable reduced overall energy consumption through consumer education and participation in energy efficiency and demand res ponse/load management programs [13]. Additionally, shifting electricity use to less expensive off-peak hours can optimize use of existing power generation that could add $5 billion to $7 billion per year back into the U.S. economy [12]. Smart Grid would reduce the need for huge infrastructure investments between $46 billion and $117 billion over the next 20 years [12]. The Federal Energy Regulatory Commission (FERC) study reported that a moderate amount of demand response could save about $7.5 billion annually [14]. Finally and most recently, EPRI prepared a ne w set of cost of power interruption and power quality estimates ranging from $119 billion to $188 billion per year [15].

PAGE 21

11 3. Data Collection in The Distribution Network At the Distribution Network and end-user levels, there are opportuniti es for automation and advanced data collection [16]. There are two methods for gathering end-user data: Automated Meter Reading (AMR) and Autom ated Metering Infrastructure (AMI). AMR enables the electric utility to remotely read power meters. But it does not address the major issue utilities need to solve, which is demand-side management [7]. On the other hand, AMI is much more powerful since it is the basic building block for a two-way communica tions between the end users and utilities operators [16]. As described in [17] an AMI system consists of four main components: Smart digital meter, which functions as premise gateway Home portal that offers display of information from the gateway Neighborhood access point that aggregates end-users data before transmitting it to the substation Central office (usually a substation) where all customersÂ’ da ta is aggregated. There is often a reference to an AMI meter, which is defined a s a digital meter with two-way communications, automated meter data collection, outage management, dynamic rate structures and demand response for load control [17].

PAGE 22

12 Managing Smart Grid metering data is difficult due to the s heer size and complexity of the number of data point [18]. Useful data in the Dis tribution Network can be classified as: consumer specific data or device and control data. Each of these data types is explained in the next two sections. 3.1 Consumer Energy Usage Data Smart meter system involves large amount of data transfer b etween the utility company, smart meter and home appliances connected to the network [19]. The smart meter data will be used by the utilities operators for further analysis, control and real time pricing method [20]. The customer gateway will interact with all smart appliances and the Distribution Network and functions: integrated operation and control of supply and demand and demand response [21]. 3.2 Device Status Data and Control A major benefit of Smart Grid containing renewable Distributed Generation (DR) is the possibility of forming islands when separation from the main electric system occurs due to fault condition or system failure [22]. So, conti nuing to communicate with the islanded section of the grid is required. Table 3.1 provides a sample of the data requirements.

PAGE 23

13 Table 3.1: Sample Data Requirements [22] System Component Inputs Outputs Computed Values Breakers Switches Protective elements (Fuses) Breaker Status Enable/Disable Breaker Status Voltages Currents Generators: Wind Solar (PV) Enable Dispatch Voltages Currents Phase Power Quality Availability Health index Power Transformers Tap Positions Temperature Pressure Gas, Vibration Noise Reliability Lines Enable/Disable Voltages Currents Real Power Reactive Power Reactive Power Elements Status Enable/Disable Voltages Currents Power Quality Loads: Active Passive Status Enable/Disable Rate (Tier Demand Management) Demand Voltages Currents Power Quality As explained in [21], devices in the Distribution Network include the Distribution Automation System (DAS) and the Meter Data Manage ment System (MDMS). The customerÂ’s gateway interacts with the DAS for int egrated operation and control of supply and demand of electricity. Where the MD MS collects and stores data from customers and provide them to the util ities

PAGE 24

14 operators for accounting and customer service [21]. The customers will be able t o schedule appliancesÂ’ operation and request loads using real time pr icing data, thus reducing electricity usage during peak hours, which benefits bot h end users and utilities.

PAGE 25

15 4. Communications for The Distribution Network 4.1 The Need for Communications Without a robust communication system in the Distribution Network, only parts of the Smart Grid vision could be realized [5]. The Smart G rid is all about extending remote monitoring and control of devices in the Distribution Ne twork and gathering real-time data. All of these functions require two-w ay communications [13]. The Distribution Network is facing increased f requency of unpredictable catastrophic events due to limited knowledge and management of these complex systems [23]. The current communications system de ployed over the Distribution Network are oriented to support specific services, so that, the development of new services over the DN and the addition of new agents may result as very expensive [24]. The original design of Distribution Net works did not account for two-way power flows or active demand, hence, changes are needed in the way they are designed and operated to realize these functions through the use of advanced communications and information technologies [25 ]. Automation and communication infrastructures are needed to enable dem and response and to make widespread end-user participation possible in support of Smart Grid and market operation [26].

PAGE 26

16 4.2 Communications Requirements A communication system is the key component of the Smart Grid infrastructure [20]. Smart Grid communication technologies must all ow the utilityÂ’s Control Center access to each connected meter several times a second [27]. As detailed in [28], communications network for the energy manage ment must provide distinct qualities including: high reliability and availa bility, automatic redundancy, high coverage and distances, supports large numbe r of nodes, has low delays, security and ease of deployment and maintenance. The various functions of the Distribution Network have different requirements for a communications network. For example, meter rea ding can be scheduled for anytime and does not require permanent real-time communications. On the other hand, event or fault data must be communicated in real-time with maximum allowed delay of 300 milliseconds [21]. Addi tionally, depending on the communications architecture selected, communications am ong adjacent end-usersÂ’ gateways could be required. Tables 4.1 and 4.2 summ arize the communications requirements to and from customerÂ’s gateway.

PAGE 27

17 Table 4.1: Communications From CustomerÂ’s Gateway and Requirements [21] Data The other end Frequency Allowable Delay No. of Entry Applications From Customer Gateway Request for reactive power Other customer Gateway On demand 1 second 1 Keeping output power of distributed power generation during voltage regulation Measured values for generation / consumption SCADA system Every 30 minutes 1 minute 121 *1 Optimal control of grid equipment Power flow leveling, Demand-supply balancing Meter reading, Customer service Forecasted values for generation / consumption Twice per day Several minutes 192 *2 Optimal control of grid equipment *1: 4 items (active/reactive power of generation/distribution) 30 (Value for 1 minute) + Time stamp *2: 4 items mentioned above 48 (data for 1 day)

PAGE 28

18 Table 4.2: Communications To CustomerÂ’s Gateway and Requirements [21] Data The other end Frequency Allowable Delay No. of Entry Applications To Customer Gateway Request for reactive power Other customer Gateway On demand 1 second 1 Keeping output power of distributed power generation during voltage regulation Event information (e.g. earth fault) SCADA system At event 50 ~ 300 milliseconds 1 Power system protection Threshold of reverse power flow, Generation forecast Every 30 minutes 1 minute Power flow leveling, Demand-supply balancing Tomorrow tariff Tariff server Every day Several minutes 48 *3 Optimal control of grid equipment Current tariff Every 30 minutes 1 minute 1 Demand response DR event DR server Every 1 minute 10 seconds 1 Demand response *3: Tariff per 30 minutes 48 (for 1 day)

PAGE 29

19 4.3 Are Smart Grid Standards Required? Standards are the first and required step to ensuring interoperabi lity between equipment from various vendors and enabling interconnection among different users and operators, which are necessary functions in the vast electric grid that is owned and operated by hundreds of stakeholders. Standards i s an important issue that must be resolved before Smart Grid becomes a reality [29]. The evidence from other industries indicate that interoperability gene rates tangible and intangible benefits around 0.3% 0.4% in cost savings and a voided infrastructure construction, which could net a $12.6 billion per year in S mart Grid benefits [12]. Under Section 1305 of EISA, the National Institute of Standards and Technology (NIST) has the primary responsibility of coordinating the development of framework including protocols and standards for information management to achieve interoperability [1]. NIST recognized the ur gent need for Smart Grid standards by developing a three phase plan to identif y existing standards as well as the need for new ones [8]. 4.4 Emerging Smart Grid Standards For the Smart Grid to be fully integrated, universal standards mus t be applied [30]. Several well known standardsÂ’ bodies including the Internati onal

PAGE 30

20 Electrical and Electronics Engineers (IEEE), International St andards Organization (ISO), International Electrotechnical Commission ( IEC) and Internet Engineering Task Force (IETF) are actively developi ng new standards that are required for the proper and secure deployment of Smart G rid. NIST identified 16 specifications and 15 standards that are important for S mart Grid [8]. Additional standards are under review. There is a consensus on a set of standards regarded as core information technology standards for the future Distribution Network of a Smart Grid [31]. These standards are listed below [31]: IEC 61970/61968: Common Information Model (CIM) IEC 61850: Substation Automation Systems (SAS) and DER (Distributed Energy Resources) IEC 62351: Security for the Smart Grid IEC 62357: TC 57 Seamless Integration Architecture IEC 60870: Communication and Transport Protocols IEC 61400-25: Communication and Monitoring for Wind Power Plants IEC 61334: DLMS (Device Language Message Specification (original ly Distribution Line Message Specification) IEC 62056: COSEM (Companion Specification for Energy Metering) IEC 62325: Market Communications using CIM

PAGE 31

21 5. Communications Architectures Architecture describes how systems and components interact and em bodies high-level principles and requirements for Smart Grid applicati ons and systems [8]. Like the Internet, the Smart Grid is a network of different net works that must interact together on regular basis. So, the Smart Grid architecture will be a composite of many system and subsystem architectures [8] rather than a sing le architecture. The communication architecture of the future Smart Grid is yet to be defined [32]. The rest of this chapter addresses architecture options for the Distribution Netw ork. Designing a communication system architecture that meets the Grid’s complex requirements is essential to the successful implementat ion of Smart Grid [22]. In general, coordination and information exchange between devices can be implemented via different communication architectures. Four possible communications architectures are illustrated in [33]. This thesis report describes five communication architectures for possible deployment in the Distribution Network. The Distribution Network is s imilar to the “last mile” problem in the telecommunications network design. In the utility’s communications network, the “last mile” connects the customer’s sm art meter to the backhaul network as depicted in figure 5.1. Each architecture is cove red in the remainder of this chapter.

PAGE 32

22 Figure 5.1: A view of the Utility Information Systems [34] 5.1 Direct Connect Architecture This is most basic architecture where each smart meter ha s a dedicated linear connection to the data hub inside a substation. This setup is oft en referred to as “hub and spoke” network. In this scenario, there are no other devi ces, like aggregators, between the smart meter and the data hub inside the subs tation. In other aspects, this architecture is a star topology with the data hub inside the substation has hundreds to thousands of dedicated communication links out to the customers’ smart meters. Each communication link can be of any me dium type: wireline or wireless. Due to the large number of smart meters in urban areas, this architecture is not attractive. However, it could be a viable option for low

PAGE 33

23 population density areas. In this case, a single communication link fr om each home to a substation is low cost and does not require an elaborate communications infrastructure build or aggregators. Depending on the sele cted communication media type, this architecture has limitation. Figure 5.2 depicts t he main components of this architecture. Figure 5.2: Direct Connect Architecture 5.2 Local Access Aggregators Architecture The essence of the Local Access Aggregators architecture is aggrega ting smart meters data at a neighborhood level before transmitting it to a data hub n r r nrnnn

PAGE 34

24 inside the substation. The aggregator device sits between the smart meters and the data hub inside the substation. This model builds on the Neighborhood Access Network (NAN) where NAN ensures communications between the sma rt meter and the data aggregators [35]. The concept of NAN is recent and as such no standard NAN definition yet exists [17]. In general, the NAN aggregator connects with the customer home network on one end and with the Wide Area Network (WAN) on the substation end as illustrated in figure 5.3. Figure 5.3: Overview of AMI Network with NAN This architecture has advantages over the direct connect architec ture because it reduces the number of dedicated communication links to the substation and benefits from data aggregation at the neighborhood level thus optimizing the

PAGE 35

25 communications links into the substation by using trunks. Additionally, the a bility to collect and process data locally will not only reduce communication ba ndwidth requirements, but also reduce vulnerability to hacker attacks and reduc e cyber security concerns [16]. Figure 5.4: Local Access Aggregator Architecture Figure 5.4 shows main segments of this architecture including: smart meter at the premise, aggregator in the neighborhood installed on a structure t hat is owned by the utilities e.g., pole or cabinet and data hub inside the substation.

PAGE 36

26 5.3 Interconnected Local Access Aggregators Architecture This architecture is similar to the previous architecture wit h one exception, which is adjacent NAN networks have interconnected trunks as shown in figure 5.5. These additional communication trunks provide redundancy for the aggregators thus allowing more routes to communicate with the subst ationÂ’s data hub and enable local communications among NANs should communication trunk with the substation is lost. This last feature is important for e ffective sharing of Distributed Generation (DG) resources available in adjacent nei ghborhoods during an islanding situation. Figure 5.5: Interconnected Local Access Aggregators Architecture

PAGE 37

27 5.4 Mesh Architecture This architecture builds on the previous one with additional degree of connectivity at the smart metersÂ’ level in addition to the aggre gatorsÂ’ level as shown in figure 5.6. Because of the additional required communication links among smart meters that are do not have wireline connections, wirel ess Radio Frequency (RF) technology is well suited for interconnecting smar t meters in a particular area. Figure 5.6: Mesh Architecture

PAGE 38

28 Additionally, RF has the ability to dynamically establish ad hoc communications links between adjacent networks [36]. Another advantage is that communications range can be increased by establishing multiple hops until reaching the final destination. RF mesh operates in the unlicensed I ndustrial Scientific and Medical (ISM) frequency band ranging from IEE E 802.11 Wireless Local Area Networks (WLAN), Wi-Fi, Bluetooth and Micr owave [20]. This fact makes RF less attractive for use in Smart Grid application due to high possibility of interference with commonly deployed private networ ks. Another disadvantage that is common to wireless communications is securit y concerns. However, strong data encryption is an effective way to remedy suc h security issues. The wireless-wired architecture is the most popular approach and has been adopted in some pilot projects where smart meters in the neighborhood communicate with an aggregator through a wireless mesh network a nd the aggregator communicates with the central management facility through wired communication [37]. 5.5 The Internet Cloud Architecture The premise of this architecture is leveraging the customerÂ’s existing Internet service as a communication link between the end user and th e utilities

PAGE 39

29 operator. The majority of houses subscribe to Internet service wh ere service is available. Rural areas are the exception since Internet service is not always available. Under this architecture, the smart meter uses the ex isting Internet connection inside the house as a communication link via Ethernet port or Wi-Fi to transmit information to a utilities’ server that most likely is hosted in a data center. The biggest advantage of this architecture is low cost sinc e no additional monthly charges for communications are required. Another big advantage is for the utility companies since customers’ data can be easily st ored on servers without having expensive aggregators in the neighborhoods or inside the substation. Of course, the assumption is customers already have Inte rnet service or can get it. This architecture has many benefits including low cost for the customer by leveraging an existing Internet service and quick deployment due to minimal infrastructure build. It also allows for both peer to peer communicati ons as well as centralized decision capability. This architecture facilita tes the use of “cloud” services to gather, store, and analyze huge volumes of data and make it available for those with appropriate level of access.

PAGE 40

30 Figure 5.7: The Internet Cloud Architecture

PAGE 41

31 6. Technology Options Both wireline and wireless communication technologies are possible deployment options for Smart Grid. Some of the popular communication technologies are Power Line Communications (PLC), cellular, licens ed and unlicensed radio, existing internet connection, Wi-Fi and WiMAX [19]. I n certain situations, wireless technology have advantages over wired t echnologies, such as low cost and ease of connection but suffers from interference and signal attenuation [20]. On the other hand, wireline communication technologies ar e more reliable, less prone to interference, but very expensive to deplo y especially if new infrastructure is required. Wired communication network can be established for smart meters, but it will be complicated and expe nsive solution, while wireless communication network can be implemented even on ad-hoc basis [38]. The Smart Grid, as a complex system, requires a heteroge neous communication technologies to meet its diverse needs [32]. 6.1 Wireline Technology Options Wireline communication media include: twisted pair copper cables coaxial cables, power line and fiber optic cables. Each of these media types has unique characteristics that will be discussed in the remainder of this section.

PAGE 42

32 Twisted Pair (TP) copper cables are the traditional telephone w iring, which are present in almost every home and connect back to a telecommunic ations carrier Central Office (CO). These copper wires have varyin g specifications and quality that is determined by their age. Unshielded Twisted Pa ir (UTP) is older cable that is prone to cross talk and interference. However, Shiel ded Twisted Pair (STP) is newer cable type that is less prone to cross talk and interference. Additionally, these wires are usually configured in a star topology w here hundreds of homes and buildings have dedicated connections back to the carrierÂ’s CO. Hence, the existing cables would not support mes h architecture based on their physical routes. Hence, mesh requires placing addi tional cables, which is very expensive and takes a long time to deploy. Coaxial cable is another wireline media type. These cable pla nts are used by cable companies to provide video services and in recent years voic e and data. The cable plant is shared resource in a single neighborhood and as suc h shares bandwidth. This architecture has two fundamental issues: lower data r ates during peak usage hours in densely populated areas especially for those cust omers located at the end of the cable route in a neighborhood and presents secur ity concerns for customerÂ’s confidential data since the main cable is a shared medium in the last mile segment. With the introduction of DOCSIS 3.0, cable companies are offering Internet services using coaxial cable with high bandwidth

PAGE 43

33 rates, but it is still a shared bandwidth. Additionally, coaxial ca bles presence is limited to metropolitan areas and rarely found in rural areas. Fiber Optics is the most advanced wireline media type with man y superior characteristics like extremely high data rates, long distance reach and immunity from electromagnetic interference. There are two types of optical fiber cables: Single Mode (SM) and Multi Mode (MM) fiber. SM is used for long distances, while MM is used for short distances less than two kilometers. The trend is to use SM fiber for most applications. However, fiber optic cables are t he most expensive wireline media type to install and the least widesprea d in homes and buildings. Most new buildings and homes are wired with fiber optic cable s. New deployments include Fiber-To-The-Home (FTTH) or Fiber-To-The-Pre mise (FTTP), which typically use Gigabit Passive Optical Network (GPON). GPON is a network architecture that uses a point-to-multipoint scheme to ser ve multiple buildings. Encryption is used in this shared environment to ensure data security. Power lines represent the densest network in this country, where every building has a power line connection and power line termination [39]. As s uch, Power Line Communication (PLC) system appears to be well suite d to implement the Smart Grid network [40], [41]. These power lines can be used to transmit Smart Grid data from the home back to the substation direc tly. This is the most direct wireline media connecting the end-user with the substation. PLC,

PAGE 44

34 under normal operations, has an advantage that all smart meters ca n be reached as opposed to a wireless solution where 100 percent service coverage is not always possible [42]. However, using power lines for communications ha s its drawbacks. First, the interference issues around high voltage power li nes and the need to bypass transformers where a bridge device is used to b ypass the transformer. Using power lines is preferred by utility com panies since they will have total control of the communication link from the substation to the e nd customer and do not need to rely on third party providers for this com munication network. The biggest issue with using power lines for Smart Grid communication is losing this vital communication network during electric power line s being down, yet this is the time when communication is needed the most. Power line cuts will stop communications with the isolated areas and as such m ake it impossible to gather data, isolate problems and attempt to solve t he problem quickly. Simply put, under this condition, Smart Grid objective for the Distribution Network wonÂ’t be achieved. Table 6.1: Qualitative Characteristics of Wireline Communication Media Types Wireline Media Data Rate Distance Reach Existing Geographic Coverage Twisted Pair (TP) high long distance high Coax cable high medium distance low Power lines (PLC) high high distance high Fiber Optic Cable very high very long distance limited

PAGE 45

35 6.2 Wireless Technologies Wireless technology is very attractive for Smart Grid deplo yment. In general, it is much faster to deploy than wireline medium due to minimal construction areas when compared with digging streets to deploy ne w conduit system and pull cables through it. Using wireless communications has many benefits [43]. Several wireless technology options, either licensed or unlicensed frequencies are available. Most popular technologies include: Satel lite, microwave, WiMAX, cellular, Wi-Fi and Zigbee. Satellite is the most expensive wireless technology and support s relatively low data rates. It is not suitable for general deployment i n the distribution network, but may have role in the transmission segment. The signal r eceiver on the ground must be within the satellite coverage footprint. There is limited number of satellite operators or service providers due to high deploym ent cost of these systems. Additionally, latency is a big issue due to large distances a signal must travel from ground to the satellite and back to earth. Microwave is based on licensed frequencies that are controlled b y the Federal Communication Commission (FCC). These frequencies are lim ited and require line-of-sight between transmitter and receiver to oper ate. As such, depending on the terrain, they usually require tall tower structure to meet line-of-

PAGE 46

36 sight requirement. Microwave is not suitable for wide deployment in the Distribution Network. However, it may have limited and targeted appli cation in rural areas where no other communications medium is available. WiMAX stands for Worldwide Interoperability for Microwave Acce ss that focuses on fixed wireless applications and is based on IEEE 802.16 stan dard. It supports data rates up to 72 Mb/s and a range up to 6 miles. Earlier version of the WiMAX standard requires line-of-sight, but not later version [11]. Addit ionally, WiMAX has limited deployment in the United States and it will be expensive to deploy an extensive WiMAX network to meet Smart Grid requirement s in the Distribution Network. Wi-Fi stands for Wireless Fidelity, which is a trademark of the Wi-Fi Alliance [44]. It is based on IEEE 802.11 standard and operates in the unl icensed 2.4 GHz Industrial Scientific and Medicine (ISM) band and has reach f rom 20 feet indoors to about 300 feet outdoors with the potential for even longer reach. It is widely used in home networks and several deployments by local muni cipalities to cover a citywide. Because Wi-Fi networks are common for use in -home applications and use unlicensed spectrum, interference is a big conce rn. Additionally, reach is limited and is not suitable for communicati ons in the Distribution Network.

PAGE 47

37 Zigbee is a low-power wireless protocol that operates in the unl icensed Industrial Scientific and Medicine band of 2.4 GHz. It is based on IE EE 802.15.4 standard. Zigbee, WirelessHART and ISA 100.11a are three protocols t hat use the 802.15.4 PHY standard but define their own Media Access Control (MA C) and network [11]. Zigbee and Zigbee Smart Energy Profile (SEP ) have been realized as the most suitable communication standards for Smart G rid residential network domain by NIST [20]. However, they are not suitable for deploy ment in the Distribution Network due to short reach and serious security issues. Cellular is a radio network distributed over a geographic area ca lled cells. Cellular networks has several advantages including increased capac ity, reduced power use, large coverage area and reduced interference from other s ignals through spectrum reuse. Initial roll out of cellular service is c alled first generation (1G), which is an analog signal followed by second gene ration (2G), which is a digital service followed by third generation (3G) and most recently fourth generation (4G). There is 2.5G, which is based on either General P acket Radio Service (GPRS) or Enhance Data Rates for GSM Evolution (ED GE). GSM is the abbreviation for Global System for Mobile Communications While EDGE is still available in fringe areas not upgraded to 3G, GP RS have been mostly replaced by 3G networks [11]. The 3G and 4G technologies support higher data rates and faster service. Currently, select wirel ess communications

PAGE 48

38 providers deployed 4G networks. Cellular service is very attracti ve for use in the Distribution Network due to its widespread coverage. The broadband wir eless communications technology has many inherent advantages when used in Sma rt Grid [45]. The qualitative summary in Table 6.2 is the result of c ombining wireless technology specifications presented in [20] and qualitati ve analysis presented in [11] except for satellite and microwave technologies. Table 6.2: Qualitative Characteristics of Wireless Communication Technologies Technology Data Rate Distance Reach Existing Geographic Coverage Satellite high high high Microwave high high low Cellular (2.5G) low high good Cellular (3G) medium high good Cellular (4G) high high good WiMAX high high low Wi-Fi high low low Zigbee low low low

PAGE 49

39 7. Analysis Methodology and Approach 7.1 Metrics The success and failure of the Smart Grid rests on a communicati on system that is intelligent, secure, reliable and cost effect ive [16]. The communication network for the Smart Grid requires data transfer in a timely manner with adequate bandwidth and reliability [3] via two-way communication with low lat ency. Communication technologies for Smart Grid must be cost efficient, provide good transmittable range, excellent security features and adequate bandwidth [19]. Additionally, the selection of a communication technology should be based on several criteria including: bandwidth requirement, topology of network, r eliability, security, feasibility of solution [33]. Based on the aforementioned discussion and general communication network design guidelines, the following criteria are selected for comparing the communication architectures described in chapter 5 and the wireline a nd wireless communication technologies presented in chapter 6. a) Bandwidth or Data rate : bandwidth often refers to a data rate measured in bits per second. For digital signals, bandwidth is the data speed or rat e, measured in bits per second (bps). Various parts of the Smart Grid have different bandwidth requirement [46]. A communications throughput of (2 – 5) Mb/s was estima ted as a guideline for Smart Grid link to allow for transmitting volt age and current

PAGE 50

40 measurements for three phases, phase amplitude, phase angle as we ll as additional information like meter identification and overhead packets [22]. b) Latency : latency is a measure of time delay experienced in a communi cations network. It can be measured as one-way, the time it takes a sender to transmit data to the destination receiving it, or round trip, which is the ti me it takes for data to travel from the sender to the receiver and back to the sender Information concerning faults on the Smart Grid must be transferred from the DAS to a customer gateway with the shortest possible latency and must be c ompleted within 50 ms and communication involving a request for reactive power ha s the second strictest latency requirement [21]. Both rural islanding and urban meshed distribution scenarios have tolerance for a maximum of six cycles or 100 ms [22]. This requirement imposes even stricter requirement on the com munications network. Latency in a WiMax link is 10 ms from the smart meter to the base station, so, the communication network must be carefully designed to ensur e the latency end-to-end is less than 50 ms [22]. Also, Long Term Evolution (LTE), which is 4G wireless technology enjoys similar latency characteristi cs as WiMax, with latency of (5 – 10) ms [22]. c) Security : network security is extremely important to ensure all custome rs data remain private and no unauthorized access to the network. Several t echniques including user authentication, access control authorization and data encr yption

PAGE 51

41 are usually implemented to ensure network security. Because a wi reless network uses broadcast medium, it must be resistant to tampering of messa ges, preserving confidentiality of information and prevents unauthorized access [11]. In gene ral, wireline medium is more secure than wireless media, but Smart Grid requires a higher level of security. The legacy cyber security technique s for enterprise networks can hardly fit well for Smart Grid requirements to opera te securely in the public data communication networks like the internet [47]. d) Scalability : is the ability of a system or network to handle expansion with out the need for replacing major segments of the network. In the case of Distribution Network, the network must be flexible to accommodate high volumes of s mart meters connecting new houses and businesses. e) Resilience : is the ability of a network to function properly during interferenc e either random or intentional. In order for a network to be resilient, it must be capable of continued operation even in the presence of localized faults [ 48]. In this respect, mesh architecture provides the maximum resiliency due to multiple paths to get between nodes. f) Reliability : is the ability of a network to perform within its normal opera ting parameters to provide a specific level of service. Reliability can be measured as a minimum performance rating over a specified interval of time. In general,

PAGE 52

42 availability for communication networks ranges from 99.9% (3 nines reliability).to 99.999% (5 nines reliability). g) Interoperability : means devices and services from multiple vendors are compatible with each other and can be integrated into a generic netw ork. Interoperability is very important consideration in network deployment. Ensuring devices and subsystems are interoperable is of high importance to ensure Smart Grid goals are achieved. Standards are key enabler to achieve int eroperability. For communications in the Smart Grid to be truly effective, they m ust exist in a fully integrated system and to be fully integrated, universal sta ndards must be applied [30]. Hence, the urgency for developing and updating many standards to encourage Smart Grid deployment. h) Distance Reach : each wireline and wireless communication technology has its unique signal reach distances. Signal reach ranges from few m eters to tens of kilometers depending on the technology. Terrain characteristics af fect wireless signal reach and as such must be considered during technology evaluation stage. i) Existing Geographic Coverage : the electric Distribution Network covers vast geographic areas with varying terrain characteristics. Sele cting technologies that already cover the areas where Smart Grid will be deployed c an reduce the deployment cost. However, a single technology may not provide all cover age in all area.

PAGE 53

43 j) Cost of Ownership : capital expenditure (CAPEX) and operation expenditure (OPEX) are practical considerations when designing any network. Given the high numbers of smart meters requiring communications infrastructure, l ow CAPEX and OPEX will be key for early adopters of Smart Grid. 7.2 Analysis Methodology The methodology used to compare the architectures, technologies and metrics for suitability in the Smart Grid Distribution Network is: A) identify key communications architectures B) select viable communications technologies C) choose applicable metrics D) assign weighting factors using the following scale from highe st to lowest: good fit = 3, moderate fit = 2, poor fit = 1 and not suitable = 0. Additionally, the following metrics guidelines were adopted from [11]. Table 7.1: Metrics Guidelines [11] Ave. Data Rate Ave. Latency Distance Reach Scalability Good > 1.5 Mb/s < 250 ms > 1000 meters > 1000 nodes/ data hub Moderate 500 Kb/s 1.5 Mb/s 250 ms 1 sec (100 1000) meters (100 1000) nodes/ data hub Poor < 500 Kb/s > 1 sec < 100 meters < 100 nodes/ data hub E) summarize the results in a multi dimension matrix

PAGE 54

44 7.3 Summary of Results Each technology option is analyzed against the five architectures us ing the selected ten metrics. The result is a three dimension matr ix. Then normalize the total score for each architecture and technology combination and s elect the top five scores representing the best overall solutions. The next s eries of tables present the detailed scores for each architecture, all wireline and wireless technologies against the ten criteria. Table 7.2 provides summary of architecture 1 scenarios. Most wireles s technologies and one wireline technology i.e., power line communication ar e suitable for this architecture since power lines already exis t between the end user facility and the utilities substation. However, copper twisted pair s, coax and fiber optic cables do not exist and as such require significant installat ion and are very expensive, which excludes them to be practical options for architect ure 1. Satellite service is very expensive to deploy and maintain in a ddition to high monthly charges. Microwave communication network requires valuable a nd scarce spectrum and significant capital investment to build such i nfrastructure. It requires line-of-sight (LOS) between transmitter and receiver Hence, microwave is not suited for architecture 1 especially in residential area s. WiMAX also requires large capital investment to build a network that covers al l residents in the U.S.A. Wi-Fi lacks the required distance reach and geographic c overage.

PAGE 55

45 Some cities across the country partnered with private providers to build a citywide Wi-Fi network. However, these examples are rare a nd a countrywide Wi-Fi coverage wonÂ’t be cheap to build nor practical. Zigbee is an i n-home network that will communicate with smart devices within a household. Hence, it has very short distance reach, which makes it not suitable for Sma rt Grid communication in the Distribution Network. For architecture 1, the bes t overall options are those using cellular technology with 4G being the best since it supports the higher data rates. Table 7.2: Summary of Architecture 1 Metrics Satellite Microwave Cellular (2.5G) Cellular (3G)Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable PLC Fiber Optic CableBandwidth / Data Rate331233133323Latency122213133333Security332233223223Scalability112333111131Reliability222222123323Interoperability222221133322Resilience223333213333Distance Reach333333012223Existing Geographic Coverage202220000010Cost of Ownership113331111121Sum of points:201922242522101722212222Max. No. of Points303030303030303030303030 Normalized Score: 67% 63% 73% 80% 83% 73% 33% 57% 73% 70% 73% 73% Criteria Architecture #1 (Direct Connect) WirelessWireline

PAGE 56

46 Table 7.3 presents summary of architecture 2 scenarios. The discus sion for architecture 1 listed above applies here as well. Hence, the best overall technology options are those using cellular technology with 4G being the best option since it supports the higher data rates. However, 4G is not available in all areas and some areas may be limited to 3G or 2.5G only. Moreover, som e remote areas may not have any cellular service, so in these cases, P LC can be a viable wireline option. Table 7.3: Summary of Architecture 2 Metrics Satellite Microwave Cellular (2.5G) Cellular (3G)Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable PLC Fiber Optic CableBandwidth / Data Rate331233133323Latency122213133333Security332233223223Scalability112333111131Reliability222222123323Interoperability222221133322Resilience223333213333Distance Reach333333012223Existing Geographic Coverage202220000010Cost of Ownership213331111121Sum of points:211922242522101722212222Max. No. of Points303030303030303030303030 Normalized Score: 70% 63% 73% 80% 83% 73% 33% 57% 73% 70% 73% 73% Criteria Architecture #2 (Aggregator) WirelessWireline

PAGE 57

47 Table 7.4 depicts scenarios for architecture 3. Once again, the same analysis for architectures 1 and 2 applies here with one exception. Power line communication is not as favorable for architectures 3. Under archit ecture 3, additional power lines are required to interconnect the Aggregators since the power lines are radial by design. This fact will increase t he cost of ownership for PLC technology under this architecture. Table 7.4: Summary of Architecture 3 Metrics Satellite Microwave Cellular (2.5G) Cellular (3G)Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable PLC Fiber Optic CableBandwidth / Data Rate331233133323Latency122213133333Security332233223223Scalability112333111131Reliability222222123323Interoperability222221133322Resilience223333213333Distance Reach333333012223Existing Geographic Coverage202220000010Cost of Ownership213331111121Sum of points:211922242522101722212222Max. No. of Points303030303030303030303030 Normalized Score: 70% 63% 73% 80% 83% 73% 33% 57% 73% 70% 73% 73% Criteria Architecture #3 (Interconnected Aggregators) WirelessWireline

PAGE 58

48 Table 7.5 summarizes the results for architecture 4. Under the m esh architecture, wireless communications has a major advantage ove r wireline options due mainly to the high capital expenditure to implement a wireline technology in a mesh configuration. However, satellite and microwave technologies are expensive while Wi-Fi and WiMAX do not currently have the geographic coverage Zigbee is eliminated due to its short distance reach. The result is cellula r technology is the best option. Cellular networks cover the majority of United States resi dents with few exceptions in the rural areas or areas with challenging terrain. Table 7.5: Summary of Architecture 4 Metrics Satellite Microwave Cellular (2.5G) Cellular (3G)Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable PLC Fiber Optic CableBandwidth / Data Rate331233133323Latency122213133333Security332233223223Scalability112333111121Reliability222222123323Interoperability222221133322Resilience223333213333Distance Reach333333012223Existing Geographic Coverage202220000010Cost of Ownership213321111121Sum of points:211922242422101722212122Max. No. of Points303030303030303030303030 Normalized Score: 70% 63% 73% 80% 80% 73% 33% 57% 73% 70% 70% 73% Criteria Architecture #4 (Mesh) WirelessWireline

PAGE 59

49 Table 7.6 summarizes the results for architecture 5, which is based on using existing Internet connections to the cloud. This architecture is unique because it leverages existing Internet service the majority of end user s have, which makes it least expensive architecture to deploy. Hence, using the Inte rnet for Smart Grid communications is almost free for those who already have an Int ernet service. Based on the overall criteria, Internet service over TWP, which is cal led Digital Subscriber Line (DSL), is the best option due to its widespread geographic coverage. Table 7.6: Summary of Architecture 5 Metrics Satellite Microwave Cellular (2.5G) Cellular (3G)Cellular (4G) WiMAX Zigbee Wi-Fi Twisted Pair (TP) Coaxial Cable PLC Fiber Optic CableBandwidth / Data Rate331233133323Latency122213133333Security332233223223Scalability112333113221Reliability222222123323Interoperability222221133323Resilience223333213333Distance Reach333333012223Existing Geographic Coverage201220002110Cost of Ownership112211113321Sum of points:201920232322101728252123Max. No. of Points303030303030303030303030 Normalized Score: 67% 63% 67% 77% 77% 73% 33% 57% 93% 83% 70% 77% Wireline Criteria Architecture #5 (Internet Cloud) Wireless

PAGE 60

50 Since a specific technology and architecture combination may not be available nationwide, it is important to provide few choices that can work in differ ent environments. Table 7.6 presents the top five scoring scenarios out of a ll possible combinations i.e., scenarios presented in tables 7.2 – 7.6. It is clear tha t architecture 5, Internet Cloud, has the highest score for the overall metrics. A dditionally, Internet service over TWP and Coax cable are best media/technology options, due to existing widespread coverage and relatively low monthly costs. Table 7.7: Top Five Architecture and Technology Combinations Cellular (4G)Cellular (4G)Cellular (4G) Twisted Pair (TP) Coaxial CableBandwidth / Data Rate33333Latency 11133 Security 33332 Scalability33332Reliability22233Interoperability22233Resilience33333Distance Reach33322Existing Geographic Coverage22221Cost of Ownership33333Sum of points:2525252825Max. No. of Points3030303030 Normalized Score: 83% 83% 83% 93% 83% Wireline Criteria Architecture #1 (Direct Connect) Architecture #2 (Aggregator) Architecture #3 (Interconnected Aggregators) Architecture #5 (Internet Cloud) WirelessWirelessWireless

PAGE 61

51 7.4 Conclusion After analyzing the five architectures and applicable wireli ne and wireless technologies for deployment in the Distribution Network in support of Sm art Grid objectives, it is evident that each architecture and technology combination has strengths and weaknesses. Additionally, a single architecture solution will not be suitable for every deployment and in any environment. Hence, the a uthor provides the top five scoring architectures and technology combinations Architecture 5 is the overall favorable choice. This architectur e functions with both wireline and wireless technologies, provides most flexibility, l east cost of ownership, has widespread coverage and scales to support large deployment s. Two concerns about this architecture include security risks from us ing the Internet to transport sensitive data and the utilitiesÂ’ acceptan ce to use third party providers for the communication networks. The first concern is managea ble with added security layers. Currently, the Internet is widely accept ed for sensitive financial transactions including online shopping, banking and stocks transactions As for the second concern, while most utilities prefer to have com plete ownership and total control of the communication networks that support Smar t Grid, deployment costs and implementation timelines will force uti lities to revaluate their position and start partnering with communication provide rs to realize Smart Grid benefits sooner than later.

PAGE 62

52 Future study opportunity is to evaluate a mixture of technologies t o implement each of the five architectures. For example, use PLC and cellular to build mesh architecture. Such approach will leverage vast power lines for primary link and use cellular links to complete the mesh network.

PAGE 63

53 BIBLIOGRAPHY [1] 110th Congress of the United States, “Energy Independence and Secu rity Act of 2007.” Dec-2007. [2] Z. Jiang, F. Li, W. Qiao, H. Sun, H. Wan, J. Wang, Y. Xia, Z. Xu, a nd P. Zhang, “A vision of smart transmission grids,” in IEEE Power & Energy Society General Meeting, 2009. PES ’09, 2009, pp. 1-10. [3] C. H. Hauser, D. E. Bakken, and A. Bose, “A failure to communicate: next generation communication requirements, technologies, and architecture f or the electric power grid,” IEEE Power and Energy Magazine, vol. 3, no. 2, pp. 4755, Apr. 2005. [4] C. Lo and N. Ansari, “The Progressive Smart Grid System f rom Both Power and Communications Aspects,” IEEE Communications Surveys & Tutorials vol. PP, no. 99, pp. 1-23. [5] J. Heckel, “Smart substation and feeder automation for a SMART distribution grid,” in 20th International Conference and Exhibition on Electricity Distribution Part 1, 2009. CIRED 2009, 2009, pp. 1-4. [6] U.S. Department of Energy, “Smart Grid System Report,” 2009. [7] H. Farhangi, “The path of the smart grid,” IEEE Power and E nergy Magazine, vol. 8, no. 1, pp. 18-28, Feb. 2010. [8] NIST, “NIST Framework and Roadmap for Smart Grid Interoperabi lity Standards, Release 1.0,” U.S. Department of Commerce, 2010. [9] nrn M. Specht, T. Suding, and T. Weidelt, “Survey of Smart Grid Standardization Studies and Recommendations,” in 2010 First IEEE International Conference on Smar t Grid Communications (SmartGridComm), 2010, pp. 583-588. [10] 109th Congress of the United States, “Energy Policy Act of 2005,” Aug-2005. [Online]. Available: http://www.fedcenter.gov/_kd/Items/actions.cfm?action=Show&item_id=2969&destination=ShowItem. [Accessed: 04-Mar-2012]. [11] B. Akyol, H. Kirkham, S. Clements, and M. Hadley, “A Survey of Wi reless Communications for the Electric Power System,” U.S. Department of Energy, PNNL-19084, 2010.

PAGE 64

54 [12] Electricity Advisory Committee, “Smart Grid: Enabler of t he New Energy Economy,” U.S. Department of Energy, 2008. [13] S. E. Collier, “Ten steps to a smarter grid,” in IEEE Rura l Electric Power Conference, 2009. REPC ’09, 2009, pp. B2-B2-7. [14] S. Mohagheghi, J. Stoupis, Z. Wang, Z. Li, and H. Kazemzadeh, “Demand Response Architecture: Integration into the Distribution Management System,” in 2010 First IEEE International Conference on Smart Grid Communica tions (SmartGridComm), 2010, pp. 501-506. [15] K. H. LaCommare and J. H. Eto, “Understanding the Cost of Power Interruptions to U.S. Electricity Consumers,” Ernest Orlando Lawrenc e Berkeley National Laboratory, Berkeley, California, LBNL-55718, Sep. 2004. [16] S. Rahman, “Smart grid expectations [In My View],” IEEE P ower and Energy Magazine, vol. 7, no. 5, pp. 88, 84-85, Oct. 2009. [17] C. Bennett and D. Highfill, “Networking AMI Smart Meter s,” in IEEE Energy 2030 Conference, 2008. ENERGY 2008, 2008, pp. 1-8. [18] A. Vojdani, “Smart Integration,” IEEE Power and Energy Magazine vol. 6, no. 6, pp. 71-79, Dec. 2008. [19] S. S. S. Depuru, L. Wang, V. Devabhaktuni, and N. Gudi, “Smart meter s for power grid — Challenges, issues, advantages and status,” in Power Sys tems Conference and Exposition (PSCE), 2011 IEEE/PES, 2011, pp. 1-7. [20] V. C. Gungor, D. Sahin, T. Kocak, S. Ergut, C. Buccella, C. Cecati and G. P. Hancke, “Smart Grid Technologies: Communication Technologies and Standards,” IEEE Transactions on Industrial Informatics, vol. 7, no. 4, pp. 529539, Nov. 2011. [21] T. Otani, “A Primary Evaluation for Applicability of IEC 62056 to a NextGeneration Power Grid,” in 2010 First IEEE International Conference on Smart Grid Communications (SmartGridComm), 2010, pp. 67-72. [22] V. K. Sood, D. Fischer, J. M. Eklund, and T. Brown, “Developing a communication infrastructure for the Smart Grid,” in 2009 IEEE Ele ctrical Power & Energy Conference (EPEC), 2009, pp. 1-7. [23] J. A. Momoh, “Smart grid design for efficient and flexible powe r networks operation and control,” in Power Systems Conference and Exposition, 2009. PSCE ’09. IEEE/PES, 2009, pp. 1-8.

PAGE 65

55 [24] F. Lobo, A. Cabello, A. Lopez, D. Mora, and R. Mora, “Distribution Netw ork as communication system,” in SmartGrids for Distribution, 2008. IET-CI RED. CIRED Seminar, 2008, pp. 1-4. [25] X. Mamo, S. Mallet, T. Coste, and S. Grenard, “Distribution automat ion: The cornerstone for smart grid development strategy,” in IEEE Power & Energy Society General Meeting, 2009. PES ’09, 2009, pp. 1-6. [26] E. Peeters, R. Belhomme, C. Batlle, F. Bouffard, S. Karkkaine n, D. Six, and M. Hommelberg, “ADDRESS: Scenarios and architecture for Active Demand development in the smart grids of the future,” in 20th International Conf erence and Exhibition on Electricity Distribution Part 1, 2009. CIRED 2009, 2009, pp. 1-4. [27] G. N. Srinivasa Prasanna, A. Lakshmi, S. Sumanth, V. Simha, J. Bapat and G. Koomullil, “Data communication over the smart grid,” in IEEE Inter national Symposium on Power Line Communications and Its Applications, 2009. ISPLC 2009, 2009, pp. 273-279. [28] T. Sauter and M. Lobashov, “End-to-End Communication Architecture fo r Smart Grids,” IEEE Transactions on Industrial Electronics, vol. 58, no. 4 pp. 1218-1228, Apr. 2011. [29] R. DeBlasio and C. Tom, “Standards for the Smart Grid,” in I EEE Energy 2030 Conference, 2008. ENERGY 2008, 2008, pp. 1-7. [30] National Energy Technology Laboratory (NETL), “A Systems View of The Modern Grid,” 2007. [31] M. Uslar, S. Rohjans, R. Bleiker, J M. Specht, T. Suding, and T. Weidelt, “Survey of Smart Grid standardization studies and recomme ndations — Part 2,” in Innovative Smart Grid Technologies Conference Europe (IS GT Europe), 2010 IEEE PES, 2010, pp. 1-6. [32] Z. Fan, P. Kulkarni, S. Gormus, C. Efthymiou, G. Kalogridis, M. Sooriyabandara, Z. Zhu, S. Lambotharan, and W. Chin, “Smart Grid Communications: Overview of Research Challenges, Solutions, and Standardization Activities,” IEEE Communications Surveys & Tutorial s, vol. PP, no. 99, pp. 1-18. [33] C. Yuen, R. Comino, M. Kranich, D. Laurenson, and J. Barria, “The role of communication to enable smart distribution applications,” in The 20th International Conference and Exhibition on Electricity Distribution Part 2, 2009. CIRED 2009, 2009, pp. 1-10.

PAGE 66

56 [34] A. Ipakchi and F. Albuyeh, “Grid of the future,” IEEE Power and Ene rgy Magazine, vol. 7, no. 2, pp. 52-62, Apr. 2009. [35] R. Berthier, W. H. Sanders, and H. Khurana, “Intrusion Detection f or Advanced Metering Infrastructures: Requirements and Architectur al Directions,” in 2010 First IEEE International Conference on Smart Grid Communications (SmartGridComm), 2010, pp. 350-355. [36] n ller, and C. Wietfeld, “RF Mesh Systems for Smart Metering: System Architecture and Perfor mance,” in 2010 First IEEE International Conference on Smart Grid Communications (SmartGridComm), 2010, pp. 379-384. [37] F. Li, B. Luo, and P. Liu, “Secure Information Aggregation for Smart Grids Using Homomorphic Encryption,” in 2010 First IEEE International Confere nce on Smart Grid Communications (SmartGridComm), 2010, pp. 327-332. [38] A. Mahmood, M. Aamir, and M. I. Anis, “Design and implementation of A MR Smart Grid System,” in Electric Power Conference, 2008. EPEC 2008. I EEE Canada, 2008, pp. 1-6. [39] M. Huczala, T. Lukl, and J. Misurec, “Capturing Energy Meter Dat a over Secured Power Line,” in International Conference on Communication Technology, 2006. ICCT ’06, 2006, pp. 1-4. [40] S. Bannister and P. Beckett, “Enhancing powerline communications i n the ‘Smart Grid’ using OFDMA,” in Power Engineering Conference, 2009. AUPEC 2009. Australasian Universities, 2009, pp. 1-5. [41] S. Galli, A. Scaglione, and Z. Wang, “Power Line Communications an d the Smart Grid,” in 2010 First IEEE International Conference on Smart Grid Communications (SmartGridComm), 2010, pp. 303-308. [42] A. G. Van Engelen and J. S. Collins, “Choices for Smart Grid Implementation,” in 2010 43rd Hawaii International Conference on System Sciences (HICSS), 2010, pp. 1-8. [43] M. Souryal, C. Gentile, D. Griffith, D. Cypher, and N. Golmie, “A Methodology to Evaluate Wireless Technologies for the Smart Grid,” in 2010 First IEEE International Conference on Smart Grid Communications (SmartGridComm), 2010, pp. 356-361.

PAGE 67

57 [44] G. Li, H. Sun, H. Gao, H. Yu, and Y. Cai, “A Survey on Wireless Grid s and Clouds,” in Eighth International Conference on Grid and Cooperative Computing, 2009. GCC ’09, 2009, pp. 261-267. [45] Z. Feng and Z. Yuexia, “Study on smart grid communications sys tem based on new generation wireless technology,” in 2011 International Conference on Electronics, Communications and Control (ICECC), 2011, pp. 1673-1678. [46] Y. Gobena, A. Durai, M. Birkner, V. Pothamsetty, and V. Varakantam, “Practical architecture considerations for Smart Grid WAN ne twork,” in Power Systems Conference and Exposition (PSCE), 2011 IEEE/PES, 2011, pp. 1-6. [47] Y. Yan, Y. Qian, H. Sharif, and D. Tipper, “A Survey on Cyber Secur ity for Smart Grid Communications,” IEEE Communications Surveys & Tutorial s, vol. PP, no. 99, pp. 1-13. [48] J. Wang and V. C. Leung, “A survey of technical requirements a nd consumer application standards for IP-based smart grid AMI network,” in 2011 International Conference on Information Networking (ICOIN), 2011, pp. 114-119.