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Electric Energy T&D - Index

Electric Energy T&D - EEMag March / April 2008 - Index

While some selected IEDs did not support Ethernet, the decision
was made to preserve the architecture so that serial devices were
connected to substation hardened serial device servers. This worked
well because the serial devices were usually located near each other.
Redundancy was not selected because the substation LAN is not
initially supporting protection functions and IEEE 1613 compliant
switches and routers are used along with fiber optic cables. Issues
with redundant LANs include the increased cost for a LAN that is
almost completely isolated inside the control house and segmenting
the architecture since some IEDs do not support redundant LANs.
Protocol Selection
There was a strong desire to use DNP3 in the substation. IEC 61850
was discussed, but it was decided that using IEC 61850 might be
too much to take on at the present time. In addition, the only devices
that would have supported IEC 61850 directly were the relays, data
concentrator, and HMI. By contrast, the one protocol almost all
selected IEDs supported was DNP3.
Performance
System availability was addressed by using substation hardened
equipment in all aspects of system design. All Ethernet equipment
meets IEEE 1613, including the substation computer. Any IEDs
that did not meet IEEE 1613 (e.g., meters, distributed I/O) were
connected to a media converter. In addition, fiber optic cables are
used to completely isolate the system cables from any interference.
The only equipment not meeting IEEE 1613 requirements was the
monitor for the substation computer, which was isolated behind a
DC-DC converter designed to meet IEEE C37.90.
System changeability includes ease of expansion, provision of spare
capacity, ease of replacement, and ease of maintenance. The system
architecture was based on Ethernet and is inherently modular and
easily scalable for expansion. By using distributed I/O, spare capacity
was easily provided and can be easily added, although there is already
a rather large upper limit in the number of I/O points and devices the
data concentrator can effectively handle.
Because of the modular nature of the system, replacement of portions
of the system can be accomplished without removing the whole system
from service. System maintenance considerations included the ability
to change operational parameters as well as the configuration. With
a modular system being supported by multiple vendors, changes to
some IEDs are easier than others, depending upon the evaluation
criteria. Generally speaking, however, all selected devices support
good user interfaces that are easy to work with to implement system
changes.
Today
In early 007, the conceptual design was finished and detailed design
was nearing completion. This was followed by a period of validation,
during which the system components were programmed and tested in
a laboratory setting. Today, the project is nearing completion and will
be energized soon. The internal team has received approval to build
an automation test center to be used for training, testing, and provide
a development environment for future automation programs. Notably,
this same system design process is already being applied to another
new substation.
About the Author
Craig Preuss is the Engineering Manager for Utility Automation
at Black & Veatch Corporation where he is involved in virtually all
facets of substation integration and automation. Craig earned his
bachelor’s degree in electrical engineering from Valparaiso University
in Valparaiso, IN and a master’s degree in power systems from
the Illinois Institute of Technology and is a registered professional
engineer in the states of Illinois and Washington.
During his 18-year career in the utility engineering and automation
field he has authored several papers, presentations, and articles on
topics dealing with substation integration and automation. Craig is
an active member of the IEEE where he serves as the new working
group chair for IEEE Standard C37.1. He was also involved in the
writing of IEEE Standard 1615 and IEEE Standard 1686 as well as
participating in other IEEE working groups. He is also a member of
the ISA (Instrumentation, Systems, and Automation Society).
March-April 2008 Issue I
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