Realizing the smart grid of
the future through AMI
technology
Carl LaPlace
Robert W. Uluski
Copyright © 2009 by Elster.
No part of this document may be reproduced, transmitted, processed or
recorded by any means or form, electronic, mechanical, photographic or
otherwise, translated to another language, or be released to any third party
without the express written consent of Elster.
ALPHA, ALPHA Plus, REX, TRACE and EnergyAxis are registered trademarks of
Elster. AlphaPlus, REX2, REX2-EA, Route Manager and Metercat are trademarks
of Elster. Other products may be trademarks and/or registered trademarks of
their respective owners.
NOTICE
The information contained in this document is subject to change without notice.
Product specifications cited are those in effect at time of publication.
Elster shall not be liable for errors contained herein or for incidental or
consequential damages in connection with the furnishing, performance, or use of
this material.
Elster expressly disclaims all responsibility and liability for the installation, use,
performance, maintenance and support of third party products. Customers are
advised to make their own independent evaluation of such products.
Document number: WP42-1003A
01 June 2009
Realizing the smart grid of the future through AMI technology
1
Contents
Executive summary .......................................................................................... 2
Current situation.............................................................................................. 2
Smart metering .................................................................................... 2
Distribution system remote monitoring and control .................................... 3
AMI technology and realizing the smart grid......................................................... 4
Supports system monitoring through low cost sensors ................................ 5
Future distribution grid using EnergyAxis System for AMI.......................................
EnergyAxis System data access methods ..................................................
Periodic polling ..........................................................................
Triggered data access .................................................................
5
6
6
6
EnergyAxis System for AGI in realizing the smart grid ...........................................
AGI and the smart grid ..........................................................................
AGI and distribution automation ..............................................................
AGI and outage management .................................................................
AGI and power quality ...........................................................................
AGI and loss detection ...........................................................................
AGI and state estimation........................................................................
AGI and integrated volt-VAR control ........................................................
7
8
8
8
8
9
9
9
Conclusion .....................................................................................................10
About the authors ...........................................................................................10
Carl LaPlace ........................................................................................10
Robert W. Uluski, PE.............................................................................10
Realizing the smart grid of the future through AMI technology
Executive summary
Advanced metering infrastructure (AMI) technology is a vital
component within the smart grid of the future. AMI technology
provides utilities with a wealth of new information that was not
readily available with automated meter reading (AMR) technology
or cost effective with today’s distribution automation (DA)
systems. AMI technology provides information that can be used to
optimize business operations, such as system engineering,
maintenance or customer service. AMI systems also provide a
ubiquitous communication infrastructure that supports continual
monitoring and remote control of power system components and
greatly improved visibility and optimal control of the power
system.
This paper identifies how utilities can utilize the information
provided by an AMI communication infrastructure to build and
support the smart grid of the future.
Current situation
Many electric utilities have deployed one or more systems for
automatically monitoring and, in some cases, controlling portions
of the transmission and distribution system from a central
location. The extent to which these automated systems have been
deployed varies widely from utility to utility based on individual
business cases. Typically, these systems operate completely
independent of one another with little or no sharing of facilities
and information between systems. Consequently, these systems
form islands of automation that must be bridged to realize the
smart grid of the future.
A growing number of utilities are implementing AMI systems
because it provides two-way communications that allow utilities to
collect more than monthly consumption data used for billing. AMI
systems can now provide load profile data, demand, time-of-use
(TOU), voltage profile data, and power quality data. AMI systems
also allow widespread deployment of TOU rates, which historically
have been offered only to the utility company’s largest customers
(large commercial and industrial customers). Despite these
significant advancements in the metering process, most
information and infrastructure provided by the metering system
has primarily been used to support billing, on-demand reads, and
demand response.
Smart metering
Smart metering systems eliminate many labor-intensive business
processes, such as manual meter reading, field trips for service
connects and disconnects, on-demand reads, power outage and
restoration management, and other metering support functions.
Smart metering systems that continually communicate with smart
meters are able to report loss of voltage to an outage
management system (OMS). A well-designed OMS system can
group and analyze customer calls using feeder models that
provide information about likely fault locations. This information,
01 June 2009
2
Realizing the smart grid of the future through AMI technology
in turn, is passed along to crews that are working in the field to
resolve fault conditions.
AMI systems with two-way communications enable the utility to
send pricing signals to alert customers of critical peak pricing
(CPP) periods. Direct communication to the customer encourages
conservation during such periods and enables utilities to
implement direct control of demand side management (DSM)
features. Figure 1 shows a conceptual diagram of a typical AMI
deployment.
An AMI system with smart meters has many other benefits
beyond delivering advanced metering data. Electric utilities have
only begun to tap the valuable resources available through AMI
technology, however. Greatly improved transformer load
management, proactive feedback when abnormal voltage
conditions exist on the feeders, and generation of accurate load
models for improved engineering analysis and decision making are
just a few of the added benefits utilities can realize using AMI
technology.
Figure 1. AMI system
Distribution system remote monitoring and
control
Distribution system supervisory control and data acquisition
(SCADA) facilities enable system operators to continuously
monitor the health and performance of the distribution system and
in some cases to control distribution equipment from a central
location. Distribution SCADA also furnishes information needed by
planning and design engineers, and provides information to
support equipment maintenance scheduling. See Figure 2.
In almost all cases, distribution SCADA is limited to substation
equipment. Operators, engineers, and maintenance personnel
typically have little visibility of the electrical conditions on the
distribution feeders because there are no continual monitoring
facilities for feeder equipment. Some electric utilities can obtain
data from the substation end of each feeder, but that data
provides minimal insight about the electrical conditions on the
feeders themselves. Engineering analysis tools model the feeders
using statistical estimates of the customer load distributed along
01 June 2009
3
Realizing the smart grid of the future through AMI technology
the feeder. This is a traditional analytical technique that yields an
approximation to the actual conditions on the feeder that is only
as good as the accuracy of the load estimates.
Very few utility companies have monitoring and control facilities
on the feeders themselves (outside the substation fence). So
operators must rely on periodic routine inspections, reports from
customers and local authorities, and other such sources to
determine the status, performance and loading of equipment. The
primary reason only a few utilities have deployed widespread
distribution monitoring and control facilities is that the benefits do
not warrant the deployment costs, a large part of which are
communication costs.
Remote monitoring and control of distribution feeder equipment
offers benefits that go well beyond the benefits of distribution
substation SCADA. The incremental benefits of deploying
distribution feeder automation include reliability improvement,
reduced electrical losses, and early detection of abnormal
conditions out on the feeders. Electric utilities can reduce the total
cost to achieve these benefits by leveraging AMI technology to
provide the communications network for remote monitoring and
control of distribution feeder equipment.
Figure 2. Distribution SCADA
AMI technology and realizing the smart grid
AMI technology will play a significant role in realizing the
distribution system of the future: the smart grid. Historically,
information acquired from customer meters was used only for
01 June 2009
4
Realizing the smart grid of the future through AMI technology
billing purposes. This information can now be used to create and
fine tune the feeder and load models used by advanced DMS
applications such as integrated volt-VAR control and automatic
service restoration, thereby allowing these software tools to play a
key role in optimizing the performance and reliability of the
distribution network.
AMI systems can supply key measurements (voltage, current,
equipment status, etc.) in near real time (within minutes) from
strategic locations across the distribution network. This greatly
improves the visibility of the distribution system, and empowers
distribution system operators with the information needed to
make informed decisions during crisis conditions and control the
system in the most optimal manner during normal conditions.
The AMI communication infrastructure can be leveraged to provide
connectivity to the high voltage equipment located on the
distribution feeders. Thus, the AMI communication infrastructure
becomes an enabler for the advanced monitoring and control
applications that are the foundation of the future smart grid.
While SCADA communication infrastructure is typically limited due
to cost, AMI deployments involve all customer sites across the
distribution grid and are extremely cost sensitive. This introduces
an opportunity in today’s systems by having a pervasive, low cost
communications network deployed across the power grid. This
provides a unique opportunity to gather more information on
voltage, current, power, and outages across the distribution grid
to enable new and exciting applications. This is the premise for
the advanced grid infrastructure - AGI – leveraging the AMI
infrastructure to realize the smart grid.
Supports system monitoring through low cost
sensors
The smart grid of the future will include numerous low cost
sensors that are installed all along the distribution feeders. These
sensors support asset management and condition-based
maintenance of distribution facilities.
One barrier to the successful deployment of such sensors is the
lack of suitable cost-effective communication facilities for
reporting the state of these sensors to operators and other
responsible parties. Utility companies that have recently deployed
AMI systems have been able to leverage the AMI communication
system to provide near real time access to low cost sensors such
as circuit fault indicators.
AMI technology is a foundational element of the smart grid. The
communications backbone of the AMI system should provide
connectivity for distributed sensors and control devices to a
distribution control center and create an intelligent self-healing
network.
Future distribution grid using EnergyAxis
System for AMI
AMI has the ability to provide information from across the
distribution network: end points, feeders, and substations. The
01 June 2009
5
Realizing the smart grid of the future through AMI technology
EnergyAxis System provides an effective platform to acquire new
information that can greatly improve future distribution system
automation and associated applications. Technical applications
include functions that support the needs of distribution operations,
engineering, maintenance of distribution assets, and other
functions outside the baseline billing revenue collection and
protection use of the data.
Figure 3 shows the future use of AMI data and communication
infrastructure across the distribution network.
EnergyAxis System data access methods
The EnergyAxis System has two methods of data access: periodic
polling and triggered access. EnergyAxis System uses both
methods for obtaining data as described below.
Periodic polling
This is the normal method of acquiring meter information.
Periodically, each meter is requested to provide a predetermined
set of data. Typical polling intervals are once every four to six
hours. This is significantly less frequent than electric utility SCADA
systems used for operational purposes. SCADA polling intervals
range from every few seconds for the most critical data items
(equipment alarms) to once every several minutes for less critical
items (for example, equipment loading). As previously indicated,
SCADA polling intervals cannot be economically achieved by
advanced metering systems for all meters due to the sheer
volume of metered points. However, it is possible to poll a
strategic number of meters to retrieve critical meter data on a
near real time basis.
Triggered data access
Upon occurrence of an abnormal system condition, or upon
demand from an operator or system, additional data items beyond
that needed for billing purpose may be collected from selected
meters or monitoring nodes. For example, an AMI meter can
detect that an electrical parameter (such as voltage, current, or
load) has varied from a specified threshold for a certain period of
time and send a message to the head-end AMI system. The AMI
meter is configured to provide exception reports whenever an
electrical parameter varies from the specified operational band
limits.
When an AMI meter or node detects that an electrical parameter
has exceeded a specified threshold for a certain period of time,
the DMS is notified. Upon receiving notification of such conditions,
the DMS runs the system optimization program and initiates
appropriate actions (for example, operates a capacitor bank
controller, voltage regulator, or load tap changer) to restore
optimal conditions.
01 June 2009
6
Realizing the smart grid of the future through AMI technology
Figure 3. Future distribution grid using EnergyAxis System for AMI
EnergyAxis System for AGI in realizing the
smart grid
Elster’s AGI Initiative provides the utility industry with a powerful
set of hardware, software, and communications solutions needed
to more effectively manage power distribution networks. AGI
builds on Elster’s EnergyAxis System’s communications and
metering infrastructure by adding advanced measurement and
monitoring nodes and software applications to extend the reach of
the AMI system to the distribution system itself.
An AMI system may be the largest single automation investment
that a utility will make in its power monitoring system. AGI
leverages the capabilities of the AMI system to cover key
measurements from strategic locations across the distribution
network. By improving the measurements received from the
distribution system, utilities obtain vital information to help them
make strategic decisions during crisis conditions and to control the
system in an optimal manner during normal conditions. With the
EnergyAxis System’s two-way communications, the utility can cost
effectively extend its smart grid reach into the distribution
network.
The AGI Initiative is a collaborative effort between utilities, Elster,
and key technology partners to embed innovative sensing and
01 June 2009
7
Realizing the smart grid of the future through AMI technology
monitoring technology in combination with Elster’s proven AMI
technology for the smart grid of the future.
AGI and the smart grid
The smart grid of the future starts with the foundation of an
advanced metering infrastructure re-enforced by Elster’s AGI
measurement and distribution automation nodes. AGInodes™
provide a wealth of previously unavailable information that
improves the electric utilities’ knowledge about the reliability and
quality of the distribution system. The AGI Initiative allows Elster
and its partners to offer smart grid, standards-based solutions
that enable utilities to improve the operation of their distribution
network by leveraging their AMI investment.
AGI and distribution automation
DA applications implemented by the utility require two-way
communications with voltage regulators, capacitor banks,
automated switches, and reclosers located on the feeders. One of
the most significant barriers to widespread deployment of remote
monitoring and control of distribution feeder equipment is the lack
of reliable and cost effective facilities for communicating with this
equipment. The lack of suitable communication facilities is often
the reason why electric utilities do not implement continual
monitoring and control on the feeder.
To address this problem, utilities can leverage their EnergyAxis
System LAN and WAN communication systems linked to AGInodes
to provide alternative communication channels to the DA feeder
devices. AGInodes distributed throughout the feeder network reenforce the AMI communication network.
AGI and outage management
When the power fails, utilities need to find the fault
location quickly so trouble crews can restore power.
AGInodes can be equipped with last gasp capabilities that
allow the OMS software to narrow down fault locations
within the protection zone of the device. AGInodes can
also confirm power restoration to verify that service has
been restored.
Additionally, utilities can more quickly determine the fault location
by adding AGInodes throughout the distribution network. The
AGInode information enables the utility to narrow down possible
fault locations, reducing the overall investigation time.
AGI and power quality
Power quality (PQ) events such as voltage sags, surges, and
momentary outages can result in consequences that are as minor
as a light flicker to as serious as equipment damage. The ability to
monitor such PQ characteristics can be a powerful tool to reduce
peak system delivery losses. Additionally, the ability to track PQ
profiles allows for more effective management of energy peaks
during high demand, thereby allowing utilities to realize significant
savings both in rate penalties and generation avoidance.
01 June 2009
8
Realizing the smart grid of the future through AMI technology
With AGI, utilities can install smart meters or AGInodes to monitor
and report PQ quantities for both current and voltage at selected
customer locations. Power quality data from customer meters that
are distributed throughout the feeder can help determine the
location and cause of a power quality problem. Smart meters and
AGInodes can also be programmed to report detection of potential
PQ problems automatically so that utilities can take preventative
actions.
AGI and loss detection
Protecting revenue is an important attribute of an AMI system. By
installing smart meters and AGInodes at distribution transformers
and along the feeder, utilities have an affordable ability to narrow
down the cause of potential energy loss due to theft or technical
losses. To quickly pinpoint the source of potential energy loss, a
utility can compare time synchronized energy measurements at
targeted feeder boundary points to aggregated downstream smart
meter and AGInode distribution transformer readings.
AGI and state estimation
Estimating the power flow for distribution feeders helps the utility
respond to the state of their distribution network. By installing
AGInodes at strategic locations in the distribution system, utilities
can improve their on-line power flow measurement of their
distribution feeders. By continuous monitoring of power flow
measurements from a strategic number of AGInodes utilities will
be able to more effectively optimize energy delivery across the
feeder network. Benefits include the following:
•
Feeder load balancing: operators can routinely transfer
feeder sections to balance loads between adjacent
feeders that have substantial load diversity.
•
Improved service restoration activities: operators can
make informed decisions when restoring service after a
fault because the system will know the pre-fault load on
each feeder.
•
Feeder automation override: having more accurate load
flow calculations, operators can determine whether
blocking actions by feeder automation can be safely
overridden.
AGI and integrated volt-VAR control
Demand management is designed to reduce electrical demand
while minimizing electrical losses. Utilities use an integrated voltVAR control (IVVC) system to determine the optimal settings for
all distribution voltage regulating and control devices. Typical IVVC
systems use on-line power flow estimates with stale data,
however. Since utilities are required to maintain a set voltage to
their customers, most integrated volt-VAR systems use overly
conservative values to prevent unacceptable low voltage
conditions.
By collecting feeder voltage measurements from selected
AGInodes at strategic feeder locations (for example, at feeder
extremities), the AGInodes can report these measurements on a
01 June 2009
9
Realizing the smart grid of the future through AMI technology
periodic basis. The integrated volt-VAR system can use this
information to maintain the required level of service to customers.
Conclusion
Advanced metering can be much more than automated billing. The
information provided by AMI systems can be used to support
improved decision making by system operators, engineers,
maintenance managers, and other persons throughout the
enterprise. The AMI communication infrastructure should be
leveraged to link feeder devices to distribution management
systems. This will greatly improve the visibility of the distribution
network, and will enable the electric utility to optimize the
performance of field equipment. AMI should be a foundational
element and a vital part of the communication backbone of
electric utility’s Smart Grid vision.
About the authors
Carl LaPlace
Carl LaPlace has been involved in the development and product
management of power distribution automation products with
several companies over the past 25 plus years. More recently he
holds the position of strategic senior product manager for Elster’s
Advanced Grid Infrastructure (AGI) Initiative in Raleigh, North
Carolina. Previously Carl was R&D Manager for ABB MV
Distribution Automation group in Raleigh, North Carolina where his
main responsibility was for feeder control and feeder automation
product development. Carl was also engineering manager for the
Advanced Electronic Development group within Siemens Energy &
Automation where he was responsible for the development and
product management of specialized controls and systems for
application in both industrial and utility power markets. He is a
long time member of IEEE.
Robert W. Uluski, PE
Robert W. Uluski has served as a lead technical consultant in the
areas of distribution automation, feeder automation, and power
system reliability improvement for numerous North American and
International electric utilities. With over 30 years experience in the
electric utility industry, Mr. Uluski's work experience includes
twelve years as an engineer and engineering manager at New
England Electric System (NEES). Mr. Uluski specializes in
developing the business case for implementing substation and
feeder automation, and has developed computer programs to
assist in performing the detailed benefit cost analysis for such
projects.
01 June 2009
10
Realizing the smart grid of the future through AMI technology
01 June 2009
11
www.elster.com