IEEE Power & Energy Magazine - January/February 2020 - 46

✔ extensive radial low-voltage systems feeding hundreds

of customers from a single distribution transformer, a
very typical configuration in most of the world outside
North America
✔ normally radial overhead and underground circuits,
including underground residential distribution loops
with varying numbers of distribution transformers
(medium/low voltage) on each phase and where each
phase "loop" is broken by a designated elbow switch,
normally open, at a pad-mount distribution transformer, which is very typical in North America
✔ normally meshed (or looped) configurations, typically
at the low-voltage level in central business districts,
where they provide highly resilient service to multiple
customers that looks much like a transmission system.
For physical accuracy, the DNOM must also support hundreds of permutations of distribution transformer winding
configurations. All conducting equipment, such as cables,
overhead lines, switching devices, transformers, and customer network service points, are modeled to the level of
their phasing detail and the terminal connectivity by which
various pieces of equipment are physically joined together
in the field. For the advanced applications analysis, the
model must include the impedance characteristics of all conducting equipment.
The ADMS should support updates to the as-built model
in a timely fashion for new construction or modifications to
existing circuits to be accurately represented in the DNOM
at least as soon as they are energized in the field. Updates to
the as-built DNOM should have no impact on online operations. This means that the system would remain available
and no manually entered information would be lost.
From an as-operated or as-switched perspective, the
DNOM must support an accurate representation of the
dynamic operational state of distribution network connectivity. While the as-built state refers to the connectivity of
the distribution network as it was designed and constructed
with all switching equipment in nominal open or closed
positions, the as-operated state refers to the actual connectivity for a specific point in time with some switching
equipment in abnormal positions. In addition to abnormal
switching, the dynamic as-operated state can be affected
by temporary line cuts and temporary switches and jumpers placed in the field to effect switching where no permanent switching equipment is available. Furthermore, abnormal switching, particularly with temporary switches and
jumpers, may be used to energize across normal phasing.
For example, a jumper from a phase A piece of live conductor may be used to energize a de-energized and isolated
segment of a normally phase B conductor. In this case, the
network analysis applications as well as the outage management system must recognize that the normally phase
B conductor is energized from phase A in the as-operated
state and allocate impacted customer services and loads
appropriately to phase A.
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ieee power & energy magazine

The ADMS should support updates to the as-operated
state of the DNOM as soon as the operational changes are
known. The most common changes to the as-operated state
are the opening and closing of switching devices. Whether a
change is indicated by a SCADA-monitored feeder breaker or
a manually entered fuse dropout, the ADMS, once aware of the
change, must update the network view to reflect the connectivity and energization changes. The advanced applications
should then be triggered to update the network's calculated
electrical state in the area affected by the change. Outage
management indices, such as de-energized customer counts
and customer minutes of interruption, should be automatically updated to reflect operational changes, such as partial
restoration activity.
All of the described complexities of real-world distribution network connectivity must be supported by the DNOM
for the ADMS to provide a correct outage management
accounting of customer outages and restoration as well as
accurate advanced application solutions. Perhaps even more
important is the accuracy of the visual presentation of the
as-operated distribution network through the UI/UX of the
ADMS. For operators, controllers, dispatchers, and, increasingly, field crews, the ADMS is a situational awareness hub.
Many types of operations-centric data are brought together
into the single UI/UX of the ADMS to create a very powerful
view of the as-operated distribution network. These include
✔ the relatively static as-built description of electrical
equipment outside the substation fence, primarily from
GIS data
✔ substation electrical equipment, typically presented in
schematic form
✔ near-real-time switching equipment statuses and measurements of monitored voltages and flows from the
SCADA system
✔ manual entries of nontelemetered switching equipment
statuses, temporary cuts and jumpers, equipment safety
tags, and informational annotations by various authorized users of the ADMS
✔ a connectivity analysis of the electrical equipment to determine the extents of energization and de-energization,
factoring in the open/close status of all switching devices
✔ advanced application solution results, such as estimated power flows and voltages, typically updated every
few minutes
✔ abnormal topology/connectivity situations and operational limit violations
✔ fault locations
✔ tags and safety permits for planned work and restoration switching activity
✔ customer/meter locations and connectivity to the distribution network
✔ smart meter power-off notifications, power-restoration notifications, voltage ping responses, and requested measurements of voltage and power via advanced metering
infrastructure (AMI) or meter data management systems
january/february 2020
IEEE Power & Energy Magazine - January/February 2020

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - January/February 2020
