Next Generation AMI:
Utilities Benefit from Optimizing AMI Network Operation Using Multi-Channel Allocation
White Paper
Advanced Metering Infrastructures (AMI) were once just ideas being touted as the replacement
for Automated Metering Reading (AMR) and its narrowly focused vision of reducing utility
operating costs. However, in the past 10 years there has been a shift in the utility industry’s focus
toward AMI technology. Regulations such as EPACT 2005 set industry goals for better energy
management across the U.S. and served as a catalyst to drive the strong growth of AMI we see
today. In the early stages of AMI, there were lofty claims made about the operational and financial
benefits the technology could deliver. Eight years later, is the industry realizing these envisioned
benefits? What obstacles remain for utilities, and is the industry ready to embrace the next
generation AMI technology?
AMI technology has changed the way utilities do business in
the 21st century. Simple AMI functionalities — such as reading
interval data, remote service connects and disconnects, and
outage alarms — have all delivered significant operational
savings and improved the bottom lines for many utilities.
This early success of AMI is creating the need to move more
data faster between distinct devices and is raising the bar for
what utilities expect in an AMI communications network.
The initial requirement of remote meter reading and support
of basic metering functions has given way to a complex set of
activities and applications that affect multiple areas of a utility’s
operations. These include Supervisory Control and Data
Acquisition (SCADA), Distribution Automation (DA), Demand
Response (DR), Direct Load Control (DLC), Load Profiling
(LP), outage management and Conservation Voltage Reduction
(CVR).
How does today’s technology stack up to the challenge of
providing a cost effective, flexible, and scalable solution that
can support these complex applications? Utilities must have
a solution that can continue to evolve with the perpetually
changing utility business case driven by the need to streamline
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operations, reduce costs, improve customer satisfaction, and
overcome regulatory challenges. With this in mind, it serves to
examine and compare how well the two major AMI network
topology schemes being utilized today have fared in delivering
on their promises.
How Far Has AMI Come?
Under EPACT 2005, the Federal Energy Regulatory
Commission (FERC) is required to provide yearly reports that
assess the state of demand response and AMI within the U.S.
The most recent Assessment of Demand Response & Advanced
Metering, published December 2012, states the following in the
executive summary:
“According to information provided by survey respondents
to the Federal Energy Regulatory Commission (FERC) 2012
Demand Response and Advanced Metering Survey, the
potential demand response resource contribution from all U.S.
demand response programs is estimated to be nearly 72,000
megawatts (MW), or about 9.2 percent of U.S. peak demand.
This is an increase of about 13,000 MW from the 2010 FERC
Survey.”
“With regard to advanced metering, penetration reached
approximately 22.9 percent in 2011 in the United States,
compared to approximately 8.7 percent in the 2010 FERC
Survey (covering calendar year 2009). Florida, Texas, and
the West have advanced meter penetrations exceeding 30
percent. As in previous surveys, electric cooperatives have
the largest penetration, nearly 31 percent, among categories of
organizations.”
Based on the FERC’s 2012 assessment, AMI still has ample
room to grow to meet the needs of demand response and smart
metering. It is also clear that the implementation of AMI is just
beginning to handle the data and applications envisioned years
ago, and that some evolution of the technology will be needed
to handle the complex, data-intensive applications utilities
now require. As the industry continues to move forward with
implementing SCADA, DA, DLC, voltage conservation and DR
programs, will existing technology fully support these initiatives
or will utilities be forced to bridge together a hybrid of mixed
technologies?
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Comparing Wireless AMI Network Topologies
There are two predominant and distinct wireless AMI network
topologies used by electric, gas and water utilities:
•
FCC-licensed spectrum utilized on a point-to-multipoint
network
•
Unlicensed spectrum carried over a mesh network
In a licensed spectrum point-to-multipoint network, the data
collector can talk to all endpoints individually, and endpoints
can transmit information back to the data collector. In an
unlicensed spectrum carried over mesh networks, each point
on the network can receive, store and transmit signals to other
endpoints within a limited geographical area. With this method,
endpoints out of range must rely on other endpoints to act
as repeaters and provide a hop back to the data collector, an
approach that increases latency.
Prior to AMI, unlicensed spread spectrum radio was widely
acknowledged as the AMI network technology that could
fully deliver the operational benefits now being sought by
utilities. However, the shortfalls of unlicensed mesh networks
soon became apparent, including range limitations, spectrum
interference and reliability issues. Additionally, the notion of
network scalability took on a somewhat simplistic approach. By
adding data collectors, the localized WAN networks were able
to support additional metering endpoints. However, the system
would still need to support the more complex applications and
functionality that utilities expect of AMI technology, such as
SCADA, DA, DLC, and more robust DR combined with Home
Area Networks (HAN).
In addition to not fully conceptualizing what AMI network
scalability should encompass, the race to bring AMI to market
narrowly focused on the vision and concept of Total Cost of
Ownership (TCO). Early on, it was a generally accepted notion
that because unlicensed spectrum is free, it would result in
lower upfront costs and therefore it must be the best TCO
solution available. As the use of AMI continues to expand,
utilities are realizing that the TCO of deploying wireless
networks is not just based on initial costs, but the financial
return from overall benefits derived from the technology. TCO
is not just a consideration from a financial point of view, but
also a longer term consideration of engineering economics,
support and risk mitigation. The goal behind good AMI
network engineering and design upfront is to have a network
structure that lends itself to expansion beyond just meter
reading and outage reporting. It is a long term solution that
allows utilities to grow over the life of the technology without
having to fill the gaps along the way. Utility companies are now
looking more holistically at the real costs associated with free,
unlicensed radio spectrum for wireless communication. They
are asking whether smart grid wireless networks would be better
operated on licensed wireless spectrum, in which the airwaves
are owned by the customer and protected by federal law.
Next Generation AMI
The next generation of AMI is already here, driven by growing
demands. Next generation AMI is an open standards-based,
long-range radio solution that communicates via primary-use
FCC-licensed spectrum. It serves as a dedicated and secure
two-way communications network that transmits at two watts
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of power. This enables wide coverage that reaches all points in
a utility’s service area. It also prioritizes multiple interoperable
utility applications without the need for deploying additional or
hybrid networks.
Key attributes of next generation AMI include:
True end-to-end IPv6 communication across all
platforms — For electric, gas, water, and lighting control. IPv6
compatibility transforms the system from a single application
AMI network to a truly open and interoperable smart grid
infrastructure enabling industry standard addressing to be used
between all endpoints and applications.
The ability to optimize every endpoint on a utility’s system
using power control — By utilizing power control, next
generation AMI ensures that the network manages the power of
every transmission based on need. In essence, the network can
whisper to devices in close range and shout at those far away
with equal results. Additionally, redundant coverage built into
the network ensures that every endpoint can be reached, which
reduces data backfill requirements. Redundancy also helps
build robustness for mission critical distribution automation,
outage management, demand response management systems
and billing.
Using larger amounts of licensed spectrum with advanced
modulation schemes that increase data rates — With up to
525 kHz in licensed spectrum, utilities can transmit nearly 10
times the amount of data. With larger amounts of spectrum,
software defined radios (SDR) and advance modulation
schemes, the system supports communication rates of 1.2
Mbps which provides utilities with increased interoperable
application capabilities for the future.
The ability to dedicate distinct channels to specific
applications — Other aspects of licensed spectrum that greatly
reduce latency are multiple and distinct channels. Delivering
data faster is more than just the speed of transfer. With
licensed spectrum and multi-channel optimization, utilities
can prioritize time-sensitive applications, such as distribution
automation, remote shut off (for gas to address safety concerns)
and demand response. This ensures the applications are not
forced to compete with other network traffic.
Of all the operational improvements next generation AMI
offers, the ability to provide channelized spectrum is essential
for utilities to achieve optimal AMI network performance.
Open-standards based networks built on multi-channel licensed
spectrum allow utilities to transcend the limits of unlicensed
mesh AMI networks and realize a consistent return on
investment over the course of a low risk life cycle.
Distribution Automation (DA) requirements have also evolved
with AMI. Once considered a means to backhaul monitoring
devices, the demands and growth of smart grid applications are
now requiring AMI networks to support low latency applications
including control of DA devices, peer-to-peer networking and
over-the-air upgrades — all of which greatly increase the need
for network bandwidth. With multi-channel capable licensed
spectrum, even retrieval of real-time meter voltage information
can be placed on a dedicated channel.
A Closer Look at Multi-Channel Next Generation AMI
The benefits utilities can realize from next generation AMI
are clearly evident. The urgency with which a utility needs to
ping a meter for billing is much less critical than distribution
system communications such as real-time notification of outages
or reporting costly leaks in a water system. Effective AMI
solutions are not just about how fast the system can obtain data,
but what data has the highest priority or right-of-way in the
communications network.
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To fully understand the benefits of utilizing licensed spectrum
AMI with multiple channel capability, above is a side by side
comparison of it with a mesh AMI network. Figure 2 shows how
multiple prioritized channels can be allocated to handle specific
applications. By design, utilities can determine the priority of
network data traffic prioritizing its assigned channel within
licensed spectrum. Mesh based AMI networks are limited to
a single channel for all network data traffic transmissions and
replies.
Attributes of Channelized Licensed
Spectrum AMI Networks
•
Modeled off of proven cellular architecture
•
•
Independent forward and reply with full duplex for
each channel
Traffic type and priority must be throttled by a
master scheduler
•
•
Channels can be added via remote configuration
without adding collectors
Fixed Baud Rate, not variable matched to
environment
•
•
Channel size and corresponding endpoint
configurations can be managed remotely
System expandability and scalability is limited to
adding collectors to create localized WANs
•
•
Applications can be physically isolated
•
No application contention conflicts
•
Applications that rely on low latency can have
predictable and reliable round trip performance of
less than 5 seconds
One large channel (using frequency hopping
spread spectrum transmissions) is set to the highest
transmission rate, which lowers transmission range
and requires endpoints to communicate via a mesh
network
•
Mesh networks are driven by poll and response
creating outage and priority event delays
•
The effective size of a large single channel
diminishes with the number of hops in each mesh
network created by an individual collector
•
Changes in mesh routing over time due to
environment changes cannot provide long term
predictable performance
•
Channels do not have to create or rebuild broken
transmission paths like mesh networks must do;
channels from adjacent collectors can overlap,
creating redundancy without self-healing delays
Next generation AMI is designed to provide utilities with all
the capacity and support to meet future network performance
requirements. To remain relevant and viable to the changing
business case needs of energy and natural resource providers,
AMI must be able to transcend the plateau of simply collecting
meter data and performing small metering support tasks. Next
generation AMI is unique in its ability to provide multiple,
parallel channels for various applications such as SCADA, DA
messaging, automated volt-var management, DLC and priority
alarm notifications. Open and interoperable multi-channel AMI
is only possible through the use of licensed spectrum. AMI
networks that rely on unlicensed spectrum are forced to share
these more complex AMI applications on the same channel with
basic outage updates, revenue integrity information and normal
daily meter data transactions. The only way AMI systems using
unlicensed mesh technology can support such expansion of AMI
capabilities without seriously reducing system performance is to
layer on additional communications networks and create hybrid
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Attributes of Single Channel Unlicensed
Spectrum Mesh AMI Networks
systems which increases TCO. Multi-channel next generation
AMI allows utilities to receive critical network updates and
manage advanced non-metering applications on a single network
topology without interruption or delay to normal day-to-day
traffic.
Realizing the Smart Grid with Next Generation AMI
The major shortfall of an unlicensed spectrum mesh system
is that it cannot channelize the spectrum for specific data
transmissions. The network must open the entire available
spectrum upon initial deployment to avoid capacity issues with
competing metering messaging. While this technology may
accommodate current metering requirements, industry leaders
have voiced concerns about future smart grid applications. EPRI
stated in its December 2010 WFANSA report, “Interference
on unlicensed bands makes them unsuitable for critical smart
grid applications.” All mission-critical networks in practice
today, such as police, fire, and emergency medical services,
have adopted FCC licensed band point to multipoint as the gold
standard of wireless communications for its resiliency, lack of
interference, and recourse against potential and real interferers.
For utilities to fully realize all the business and operational
benefits of the smart grid, the old misconceptions about AMI
must be abandoned and give way to the new realities of next
generation AMI with a multi-channel capability. Eight years
after EPACT 2005, the industry is beginning to realize that
strategic deployment means more than deploying a meter
collector in a neighborhood to create a neighborhood LAN
and a backhaul WAN for a few thousand meters. Likewise, the
ease of installing meter collectors that utilize unlicensed mesh
technology provides only one dimension of scalability. The
networks can scale by adding hundreds to thousands of meter
collectors to provide support for additional endpoints, but do
not provide the increased network capacity for complex nonmetering applications. A hybrid network can be layered on top
of the mesh network to support additional applications, but at an
additional TCO and complexity to the utility. Figure 3 illustrates
potential growth in AMI data handling requirements through the
proliferation of smart grid applications.
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Multi-channel next generation AMI — the future of smart grid
— delivers a comprehensive and unified network topology that
redefines what the industry considers strategic deployment. It
can be deployed over existing AMR systems without deploying
a single AMI endpoint to establish a network. Once deployed,
a next generation AMI network will support a full AMI system
without the need to layer on supplemental networks for system
expansion and smart grid application support. Strategic system
deployment and scalability is now a matter of configuring
and assigning channels using a pre-calculated number of
high capacity data collectors which instantly provides the
infrastructure for utilities to:
•
Migrate their meter population to AMI over time
•
Deploy distribution automation to devices that previously
would have been too costly to automate and replace
existing cellular or Plain Old Telephone Service (POTS)
communications to other devices
•
Recruit demand response and HAN customers across their
service territory
•
Strategically deploy remote service disconnect meters and
begin using immediately
•
Strategically deploy AMI meters to premises that
require TOU, Demand, and Load Profile billing
capabilities, eliminating costly meter reads or dedicated
communications through cellular or POTS communications
•
Strategically deploy AMI meters in locations to gather
voltage information to improve customer power quality
•
Greatly improve outage and restoration management by
deploying AMI meters at strategic locations
Another key attribute of this approach is that electric, water
and gas metering can operate on the same network using the
same infrastructure, but the water and gas endpoints are not
dependent on the electric meters for connection to the AMI
network. If there is a large power outage, gas and water AMI
networks remain operational. Applications such as remote
service connect and disconnect, and remote gas shutoff can be
deployed without the need to build out an entire neighborhood
network of meters. Optional applications such as street lighting
control, DLC, DA and voltage conservation can be implemented
easily with available spectrum channels or by adding additional
spectrum and channels. Primary-use licensed spectrum is the
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only system solution on the market able to provide the next
generation functionality that enables utilities to fully build and
leverage the smart grid. No other system can support future
smart grid applications and functionality within its existing
AMI infrastructure. With next generation AMI, utilities can
fully realize the smart grid through one unified solution that
offers lower TCO, true scalability and strategic deployment
capabilities.
About Sensus
Sensus is a leading utility infrastructure company offering smart
meters, communication systems, software and services for the
electric, gas, and water industries. Sensus technology helps
utilities drive operational efficiency and customer engagement
with applications that include advanced meter reading, data
acquisition, demand response, distribution automation, home
area networking and outdoor lighting control. Customers
worldwide trust the innovation, quality and reliability of Sensus
solutions for the intelligent use and conservation of energy and
water. Learn more at www.sensus.com.
© 2013 Sensus USA, Inc.