Electric distribution utilities have come under increasing pressure to find
innovative ways to improve efficiency and generate new revenue. With the deregulation
of the electric power industry, separation of generation, transmission and distribution
has put more emphasis on the stand-alone performance of distribution systems
than in the past when electric utilities were more vertically integrated.

Historically, distribution has accounted for 28 percent of the costs of delivering
electricity, with generation and transmission accounting for 64 percent and
8 percent respectively.[1] Events such as the increasing congestion on transmission
grids and the blackout of 2003 have focused attention on transmission. Meanwhile,
distribution companies have been faced with the issues of aging infrastructure,
loss of valuable knowledge and skills in the utility workforce due to retirement,
increasing reliability and power quality issues, limited options to increase
revenue and an increasing gap between customer expectations and the ability
of the distribution utility to meet these demands, especially in the areas of
local grid reliability and power quality.

BPL Value Shift

To meet each of these challenges, some electric utilities have turned to broadband
over power lines (BPL). BPL makes use of digital signal processing technology
to implement advanced modulation techniques capable of overcoming the severe
shortcomings of electric distribution grids as communication media. BPL was
originally touted as a way for the utility to generate new revenue from existing
infrastructure by using the distribution wiring in conjunction with BPL to deliver
broadband digital services such as Internet connectivity to consumers.

While BPL was supposed to become a third alternative to digital cable and DSL
for consumer broadband service delivery, the utility industry view of its value
has shifted since its initial debut in the 1990s. The technology has gradually
improved, but its deployment and operational complexity and costs have remained
significant, and the business case for delivery of broadband services via power
lines has not proven adequate to justify an electric utility venturing into
an area removed from its core business.

A number of electric utilities have carried out pilot projects with various
BPL vendors, and some commercial ventures have been created to deliver consumer
broadband services via BPL. But increasingly, electric utilities are seeing
BPL as only one of many options to transport data for utility operations, especially
in the context of an intelligent power grid. PPL Utilities Corp of Allentown,
Pa., for example, cancelled its commercial BPL venture,[2] but CenterPoint Energy
of Houston, Texas, is exploring the use of BPL to support core utility functions
such as transporting electric meter data; supporting distributed sensors for
grid monitoring and diagnosis; and aiding in automatic outage detection and
localization.[3] In addition, the company is considering BPL as a mechanism
to enable advanced energy delivery services such as time-of-day rate structures
as well as off-peak usage discounting and remote energy management and load
shedding.

Positioning BPL

Positioning BPL has proven to be a challenging proposition for electric utilities
for several reasons. Electric utilities have traditionally been operated for
reliability and long-term stability and their primary mission still centers
on this concept. Utilities have therefore been uncomfortable with the degree
of risk that comes with a new technology. In addition, after the spectacular
implosion of the dot-com boom, new Internet-based business models (such as those
associated with early BPL efforts) have been viewed as counter to the current
“back to basics” trend in the electric utility industry. Furthermore, rapid
changes in the technology have made it a moving target in terms of costs and
performance, making analysis difficult.

The intense competition in the broadband delivery industry has also been a
significant concern, since the broadband provider concept would require the
electric utility or a third party wishing to use utility BPL infrastructure,
to compete against entrenched incumbents who have proven capable of increasing
service speeds to levels not supportable by practical BPL implementations. These
incumbents have made and are continuing to make large investments in infrastructure
and new services and are well ahead of BPL in terms of market penetration.

To date, there has been no utility industry consensus on standards or best
practices for BPL implementation, and benefits associated with BPL are not well
quantified. In many states, public utility commissions have set no definitive
policy regarding rate relief for BPL investment, although Texas and California
are exceptions. More than 20 communication technologies are available to carry
digital data, and BPL must compete with them for use in intelligent grid data
transport applications. In addition, many utilities have significant investment
in legacy communication systems and are reluctant to invest in yet another communication
infrastructure. Finally, radio amateurs have voiced strong opposition to BPL
on the grounds that the technology causes interference in radio frequency bands
used by amateurs, emergency services and government agencies.

Nonetheless, BPL can be a winning technology because it is able to deliver
modern network management capabilities and sufficient bandwidth to provide functionality
for present applications while providing expansion capacity for future functions.
BPL is still the subject of much research and development and, therefore, it
is reasonable to assume that there will be improvements in the overall capabilities
and costs of the technology, so that business cases will become easier to close
as the technology matures.

BPL can act as the data transport backbone for many core utility functions
in the areas of grid state measurement, meter data transport, power quality
and reliability measurement and monitoring, grid equipment state and health
monitoring, outage and failure detection and localization, and safety and security
applications. BPL is unique among broadband telecommunications technologies
in that it is embedded in the power system infrastructure itself. This makes
it the only data transport technology that can reach every electric utility
asset on a distribution grid. While other technologies may be able to reach
above-ground assets, only BPL provides a unified means to reach both above-ground
and underground assets for communications purposes. Underground distribution
poses an especially difficult problem for distributed sensing and control because
the wireless technologies are essentially ineffective here. This feature becomes
especially important as utilities extend asset management to include real-time
asset monitoring and as utilities extend grid and device-state monitoring to
improve system performance metrics such as SAIDI and SAIFI.

The architecture of BPL systems is such that BPL devices not only provide data
transport but are located ideally to make many of the key measurements that
support full grid observability. For example, BPL devices, properly designed,
could measure local AC voltage, current, and real and reactive power flow. They
could sample the AC current and voltage waveforms and then compute displacement,
distortion and total power factor as well as total harmonic distortion and total
demand distortion. They could compute and monitor distribution transformer demand,
including peaks, so that distribution transformer demand management could be
carried out with confidence. They could perform signal analyses to detect and
locate highimpedance faults. Existing BPL systems do not perform these functions
and are not likely to until BPL manufacturers realize that the potential for
BPL goes well beyond broadband communication. In addition, BPL could still become
a conduit for the delivery of specialized broadband-based services for utility
customers, including home automation and more flexible energy delivery rate
plans (e.g., time-of-day demand, etc.).

Business Transformation With BPL

The embedded nature and broad coverage characteristics of BPL can open the
door to a utility business transformation that goes well beyond the obvious
benefits of simple automated meter reading and outage location applications.
By increasing grid observability, the utility can change the fundamental way
it performs basic business functions, from inventory management to strategic
planning. The utility can move from the traditional focus on “keeping the lights
on” to a focus on true business drivers:

  • Delivery of high-quality power over a stable grid;
  • Asset utilization optimization and asset life cycle management;
  • Cost containment;
  • Optimal asset replacement/upgrade and expansion;
  • End-to-end power delivery chain integration;
  • Infrastructure security;
  • Ability to meet or exceed customer quality and performance
    expectations; and
  • Facilitating the still-evolving digital ecosystem.

Ultimately,
BPL can become a key portion of a grid intelligence system that supports these
business drivers by acting as the data transport layer (and possibly, to some
extent, as a smart sensor) in intelligent power grid architecture. If we embed
BPL as a data transport technology in the framework of an intelligent power
grid (see Figure 1), we provide a context for determining its value. BPL is
a unique telecommunications technology in that its intimate association with
the power grid gives it the potential to act both as data transport and as a
data source.

Seeing BPL in this way, utility business analysts and strategic planners can
balance its cost against the definable benefits of core utility functions enabled
by BPL and examine the costs of BPL compared to alternate technologies. To perform
a proper analysis, we must be careful to not only include the benefits of the
applications enabled by BPL but also do a careful accounting of the various
cost elements associated with BPL network deployment and operation. These include:

  • Network design cost;
  • Preliminary RF survey cost;
  • BPL equipment costs;
  • Head-end equipment costs;
  • BPL equipment installation cost;
  • BPL equipment installation project management cost;
  • Post-installation RF survey and system-tuning costs;
  • Backhaul communication installation cost;
  • Network operations center cost;
  • Backhaul monthly communication cost;
  • Network management cost;
  • Technical and help desk support cost; and
  • Maintenance and system refresh costs.

Network design costs can be significant for BPL. Network designers must learn
the entire feeder system in the proposed BPL service area and identify solutions
for dealing with distribution transformers, switches, reclosers, capacitors
and other potential infrastructure impediments to proper BPL operation. It may
be necessary to install additional optical fiber runs or wireless links to complete
connectivity for the BPL network in some cases. These items may become apparent
only after network architects have performed a design study.

Since BPL deployments attract opposition from radio amateurs, it is prudent
for the utility to allocate costs for outreach to the amateur radio community
and plan for efforts to adjust the BPL system to notch out frequencies that
would cause interference with radio systems in the BPL service area. The utility
should perform and document a baseline RF survey before deploying BPL equipment.
Once the utility has deployed the BPL equipment, it should repeat the RF survey
and make any adjustments necessary to avoid interference problems. Involving
the amateur radio community in these processes can smooth the introduction of
BPL technology.

Conclusion

BPL is still an emerging technology with much to be done before it becomes
a mainstream electric utility tool. Standards are just beginning to emerge,
best practices are not yet defined and business cases are still inconclusive
or remain to be validated by actual experience.

We are now emerging from the peak of the hype cycle for BPL and are entering
into a period of practical refinement and application. As long as utilities
continue to focus BPL equipment vendors on issues of cost and functionality,
standards and interoperability and robust performance, then BPL should continue
to move toward its proper place as another tool for the electric utility to
apply to its operations.

Even though BPL is very unlikely to become a primary channel for delivery of
broadband connectivity to consumers, it still may find a role as a carrier of
broadband services to end users in areas where traditional providers do not
offer workable or affordable options and may eventually prove to be a prime
means of bringing specialized services to the home. It is clear, however, that
BPL’s greatest value will be as an enabler of intelligent grid functions that
support the distribution utility’s core business.

Endnotes

  1. U.S. Electric Utility Overview http://www.techadvantage.org/eprise/
    main/TechAdvantage2005/NRECA/Overview.ppt
  2. “End of Internet over Power Lines?” testmy.net. October 16, 2005.
    http://www.testmy.net/articles/article-186
  3. “CenterPoint, IBM Roll out Smart Grid in Houston” at http://www.leadingthecharge.
    com/stories/news-00137427.html and “CenterPoint Energy
    and IBM examine innovative ways to use broadband over power line (BPL)
    technology” at http://www.hoise.com/primeur/05/articles/weekly/AE-PR-
    08-05-43.html