IEEE Power & Energy Magazine - January/February 2020 - 22

economic performance of the distribution grid. ADMS functions being developed for electric utilities include locating
and isolating faults and restoring service, volt/volt-ampere
reactive optimization, energy conservation achieved through
voltage reduction, peak demand management, and support
for microgrids and electric vehicles (EVs).
An ADMS comprises three basic components: a distribution SCADA (D-SCADA) system, an OMS, and advanced
security applications for the utility's sub-T&D feeder systems, all of which are highly data intensive. This data intensity results from the large number of power system elements
and spatial information included in displays, analysis functions, and databases.
The ADMS enables distribution system operators to manage their responsibilities of monitoring and operating the grid,
coordinate outage clearances, create switching orders, and
support emergency and storm management. As a system, the
ADMS, for the most part, is the distribution equivalent of the
energy management system (EMS), which was developed for
transmission system applications. The advent of smart grid
has made the ADMS the cornerstone of meeting the distribution system operator's responsibilities.

Distributed Energy Resources
Management System
As DERs become more widely accepted and prevalent in the
industry, the need for coordinating distribution system operations and customer applications must be addressed. DER management systems (DERMS) achieve this through a combination
of customer interfaces to a SCADA system with associated
optimization mechanisms that support specific applications.
DERMS could either reside independently, exist in parallel with
the ADMS, or be integrated into the ADMS.
The DERMS is still an emerging technology that is
dependent on specific vendor definitions of the functionality
that exists in their offerings. Two major DERMS modules
stand out:
✔ Demand response (DR): DR management systems
enable communication of the various DR triggers to
the participating customers and track their responses.
This system performs all actions required by the DR
programs and provides situational awareness to distribution system operators.
✔ NWA solutions: Distribution operators must track and
manage the proliferation of energy storage mechanisms, EV charging, renewables, and other forms of
distributed generation. Key to the DERMS application suite is the ability to track generation/consumption, the different controls that can be updated, and
forecasts that assist the system operators in managing
the system.

Microgrid Energy Management System
A microgrid is a localized group of electricity sources and
loads that normally operates connected to and synchronous
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with the traditional wide area synchronous grid but can also
disconnect to island mode and function autonomously as
physical or economic conditions dictate. Microgrids effectively integrate various sources of distributed generation,
especially renewable energy sources that can supply emergency power, changing between island and connected modes.
Microgrids are much more popular outside the United States,
and several of them are coming into play in rural regions
of Africa, where it is easier to create a localized microgrid
than build a traditional T&D grid fed by centralized sources
of generation.
Microgrids provide multiple end-use needs, such as heating,
cooling, and electricity at the same time. Doing so allows energy
carrier substitution and increased energy efficiency achieved
through waste heat utilization for heating, domestic hot water,
and cooling purposes (cross-sectoral energy usage). The control
system for a microgrid, called a microgrid management system
or microgrid energy management system (MEMS), typically
communicates with the utility's systems.

Grid-Edge Systems
Grid edge is a broad term used for the grid location either
on the utility side of the smart meter or behind the meter on
the customer side. Customer-side equipment in this category
includes photovoltaics (PVs), EVs smart inverters, residential storage, and the smart home with its associated controls,
such as the smart thermostat. Newer systems are being developed for this segment of the industry that, depending on the
sophistication, sometimes communicate with the utility.
Newer terms, such as nanogrid, are also used for grid-edge
systems. Nanogrids typically supply houses with a solar PV
cell on the roof supported by a combination of energy storage
and a diesel genset, all designed to support a home with a few
lightbulbs, cellphone chargers, and electricity-based cooking.
Similar to microgrids, nanogrids are being developed in rural
regions of Africa.

Defining the Power System
Architecture of the Future
As discussed in the September 2019 issue of IEEE Power &
Energy Magazine, many ideas have been proposed for possible
future architectures of the grid. Figure 2 presents one conceptual view of the grid operations and planning architecture of
the future. Key characteristics of this particular conceptual
view include the following:
✔ Transmission security functions and wholesale electric market systems are shown at the top level.
✔ The next level shows typical utility systems, which are
either new or being repurposed to support operational
and planning requirements.
✔ The next level below illustrates two sets of business
entities and their supporting systems.
* Grid-edge and beyond: the primary systems of this
segment include home energy management systems
(HEMSs) and other systems that exist at the grid edge.
january/february 2020

IEEE Power & Energy Magazine - January/February 2020

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