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mandate to serve will continue to lie with the electric
distribution entity in our new deregulated world. If you have
any doubts, just look at the current federal and state level
boards of inquiry that are being established to look into a
few recent outages in key areas of the United States.
Presently, these boards are not reviewing the status of
generation, nor are they focusing their efforts on
transmission, but they are clearly intent on assessing the
role of distribution operations. These boards will undoubtedly
note that the industry if relying on control principles and
technology that has matured over the last three decades, but
has not grown to the point where the distribution network is
monitored and remotely controlled as a system, let alone
centrally managed.
Limiting the effects
and duration of unplanned outages is a top concern for many
distribution operations managers around the world. We are
seeing some progress in areas such as supervisory control,
data acquisition and distribution management systems
applications. However, in terms of distribution automation and
the implementation of intelligent electronic devices in the
field, growth is not constant among utility segments. In
addition, it seems to move in fits and starts, represented by
a few large procurements here and there around the world,
along with a few hundred pilot programs.
Let’s now take a
closer look at the dimensions of the distribution feeder
market. There are likely to be more than 750,000 primary
distribution feeders energized in the world as you read this
article, and as the lights come on in developing nations of
the world, this number will grow to more than one million
units.
The majority of
today’s feeders are overhead. In the United States, as one
example, the ratio is about 5-to-1, overhead to underground,
with the majority of new feeder installations being
underground. The “typical” feeder has at least three switching
devices in place along the feeder route. These devices include
reclosers, sectionalizers, disconnecting switches, air brake
switches and fuses. Around the world, there are a few million
reclosers and switches installed for feeder operations,
control and management. This is in addition to the millions of
installed fuses in several distribution network
implementations.
Large utilities
operate a thousand or more distribution feeders. In the United
States, even mid-sized public power and cooperative utilities
typically will operate more than 100 distribution feeders.
There are about 50,000 utility-operated distribution
substations installed in the United States, and about 250,000
on a worldwide basis.
In overhead
applications, reclosers are widely used as switching devices,
with sectionalizers next in importance. For underground feeder
applications, pad switches are commonly used, with manually
operated switches also of importance. Indoor switchgear often
supplements the use of pad switched in North America. Fuses,
vaults, submersible switches also are used in conjunction with
underground feeders.
Where feeder
automation programs have been justified, this typically has
been to improve the performance of the utility’s worst
performing feeders, followed by a reduction in operating
costs. Many utilities are developing feeder management
strategies. In addition to the role of improving feeder
performance, the issue of high-quality service to key accounts
is vital. Today, the strategy of improving overall network
performance as part of any substation automation strategy
should be linked with feeder automation programs, which are
dependent on substation automation to some extent, if the full
potential of feeder automation is to be realized.
Distribution
operations managers may want to move forward with more
automation programs sooner rather than later. After all,
“boards of inquiry” are not something that we need to hear
much about with all of the other changes permeating the
electric power industry at this time.
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