The implementation of “distribution
automation” within the continental U.S. is as diverse and numerous
as the utilities themselves. Particular strategies of implementation
utilized by various utilities have depended heavily on environmental
variables such as size of the utility, urbanization, and available
communication paths.
The current level of interest in
distribution automation is the result of:
• The maturation of technologies
within the past 10 years in the areas of communication and RTUs/PLCs.
• Increased performance in host
servers for the same or lower cost; lower cost of memory.
• The threat of deregulation and
competition as a catalyst to automate.
• Strategic benefits to be derived
(e.g., potential of reduced labor costs, better planning from better
information, optimizing of capital expenditures, reduced outage time,
increased customer satisfaction).
While not meant to be all-inclusive,
this section on distribution automation attempts to provide some
dimension to the various alternatives available to the utility
engineer. The focus will be on providing insight on the elements of
automation that should be included in an scalable and extensible
system.
The approach will be to describe the
elements of a “typical” distribution automation system in a
simple
manner, offering practical observations
as required.
For the electric utility, justification
for automating the distribution system, while being highly desirable,
was not readily attainable based on a cost/benefit ratio due to the
size of the distribution infrastructure and cost of communication
circuits.
Still there have been tactical
applications deployed on parts of distribution systems that were
enough to keep the dream alive. The development of the PC (based on
the Intel architecture) and VME systems (based on the Motorola
architecture) provided the first lowcost SCADA master systems that
were sized appropriately for the small co-ops and municipality
utilities.
New SCADA vendors then entered the
market targeting solutions for small to medium-sized utilities.
Eventually the SCADA vendors who had been providing transmission
SCADA took notice of the distribution market.
These vendors provided host
architectures based on VAX/VMS (and later Alpha/Open- VMS) platforms
and on UNIX platforms from IBM and Hewlett-Packard. These systems
were required for the large distribution utility (100,000–250,000
point ranges). These systems often resided on company owned LANs with
communication front-end processors and user interface attached either
locally on the same LAN or across a WAN.
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