'Fiber' expands substation
communications capabilities
Palmetto Electric Cooperative uses fiber optic cable – "fiber" for short -- to communicate with substations and to connect its four district offices.
To reduce costs and thereby save its members money, the co-op partnered with local telecom carriers to install new lines and to share existing lines
constructed by one of the partners when this is beneficial. If there is no joint benefit, the co-op constructs lines on its own.
"The purpose used to be just to communicate with the substation to run the SCADA system," says Berl Davis, vice president of engineering and
operations. (SCADA stands for Supervisory Control and Data Acqusition.) "Now there are more things to do, and you need bigger bandwidth to do them.
The best way to achieve this is with fiber." Palmetto is using the additional bandwidth for AMR applications and to add security and video capabilities
to their substations.
The switch from microwave to fiber improved communications speed and capacity and reduced maintenance, such as dish and tower repairs due to lightning
strikes. The new system and other Smart Grid components (i.e., microprocessor controls) also provide diagnostic information that was not available before.
"There is a gain in productivity, because we do not have to dispatch as many people," Davis says. "The information helps us diagnose and trouble shoot
issues and discover problems before an outage occurs."
The fiber optics, being non-conductive, are immune to lightning strikes. Members reap the benefits with faster response in outages and, indirectly,
through reduced operations costs. "We are all working together to minimize costs," Davis says.
Electric Utilites can slightly
reduce the voltage flowing
through their substations
and still maintain the
quality of power distributed
to their consumers.
"It's called conservation
voltage reduction [CVR],"
said Berl Davis, vice
president of engineering
and operations at Palmetto
Electric Cooperative,
during a recent panel
discussion sponsored by
the Cooperative Research
Network.
With proper planning
and vigilant monitoring, the
operational technique can
be a useful addition to a
load management program.
Palmetto Electric realized a
savings of nearly $1.5 million
in 2010 through the
controlled reduction of
voltage by 3.5 percent as
part of its demand-side
management program, he
said.
Palmetto Electric's CVR
program involves all 25
of its substations. It was
designed to comply with
Rural Utilities Service
guidelines on power quality,
and meet American National
Standards Institute requirements
mandating 120 volts,
plus or minus 5 percent,
throughout its system.
"That works out to be
114 volts to 126 volts,"
Davis said. The slightly
lower voltage is within the
voltage tolerance range
for consumer appliances,
electronics or commercial
devices.
"Most motors are rated
at 115 volts, so when you
lower the voltage a lot of
motors will actually run
more efficiently," said Davis.
"You won't have any impact
on power quality, but you'll
reduce your demand,
reduce your energy and
reduce your losses."
Distribution co-ops
that routinely get advance
notice of peak demand
projections from their G&Ts
can use the technique for
peak shaving purposes, said
Davis. Palmetto Electric
currently uses CVR as part
of its load management
program, which includes
control of about 36,500
water heaters. The
co-op also has about 75
interruptible accounts
that can be suspended to
manage demand.
"For every 1 percent
change in voltage reduction,
you're seeing an average
of 0.8 percent reduction
in kilowatt load," said
Davis, citing Electric Power
Research Institute data.
The National Rural Electric
Cooperative Association's
Cooperative Research
Network has partnered
with EPRI and the National
Electric Energy Testing,
Research and Applications
Center on CVR projects.
Derrill Holly wrote this
story for the Electric Co-op
Today newsletter, published
by the National Rural Electric
Cooperative Association, of which
Palmetto Electric is a member.
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