management,’” Laval said.
Putting that use case into action, the Mount Holly microgrid
will soon help the utility regulate voltage and improve power quality on the local circuit.
CPS Energy’s microgrid is already feeding into the grid. “We
have a 20-kw solar PV installation and 75 k W battery energy storage system,” explained Boston. The microgrid can feed back into
the CPS distribution system after power gets stepped up from 480
volts to 13,000 volts with a 500-kv transformer.
What is unique about the CPS Energy microgrid is that it also
has a meteorological station for weather observation as part of a
solar- and load-forecasting research project being conducted by
scholars at the University of Texas-San Antonio.
“They have a sky imaging camera out there. They found an
inexpensive way to take pictures of the sky and apply some algorithms on that and begin to project what would be the effects
of cloud cover on the solar generation,” Boston said. The forecasts cover three intervals: 15 minutes ahead, hour ahead and
24 hours ahead.
Boston said predictive capabilities are vitally important with a
microgrid powered by renewables, an energy source that isn’t dis-
patchable. “If the sun is out, we’re producing energy at a high rate,”
he explained. “When cloud cover comes in, we can have sporadic
output. The better we get at forecasting the need, the better pre-
pared we’ll be to support an irregular flow of energy.”
CPS Energy also coordinated its grid-edge devices using
the microgrid management system with help from Open-
FMB. “We were able to demonstrate with this project that not
only were we reading data from different pieces of equipment
using different communications protocols, we were also able
to set control points from the microgrid management system
to the battery,” Boston said.
At the same time, CPS Energy had grid-edge control active, as
well. “We had apps built and put on devices that weren’t in our
enterprise system but they were running on field computers. Instead of bringing back information and making a decision in one
central location, we can distribute that through our system, which
increases speed, resiliency and lowers the need for large amounts
of bandwidth,” Boston notes.
CONTROL HERE, THERE, EVERYWHERE
While grid-edge intelligence and control is one way to support
DER integration, the OMNETRIC Group team thinks centralized
coordination could at times be crucial, so a hierarchical approach
is what they focused on delivering with the system tested at the
Duke Energy and CPS Energy microgrids.
“The big idea is that we should aggregate distributed energy
resources,” said James Waight, senior manager of grid operations
at OMNETRIC Group. He includes non-critical loads among the
DER, along with generation, storage and control technology associated with each microgrid.
“Each microgrid has its own controller, but these microgrids
exist in a larger framework.” Waight explained.
He said a utility could use controllers at several levels of the grid
that report in a hierarchical fashion to speed up and simplify communications through the system.
Why the hierarchy?
“A large utility may have millions of customers,” Waight said,
which means there could be tens of thousands of microgrids on
its system. “A distribution-level controller would do things like
monitoring and outage management. Then it would report to a
higher-level controller on the transmission system, and that in
turn might report to a market like PJM or MISO. Each level of the
hierarchy sees a simplification of what’s below. It’s a more manage-
able way to handle complexity.”
There may be differences in each microgrid, but the microgrid
management systems are still able to handle the quirks of each
microgrid, such as the no-feed-in constraint Duke Energy had to
In part, that’s due to the versatility of OpenFMB. “Depending
on your facility, you might have different assets and requirements,”
Duke Energy’s Laval said. “The INTEGRATE project proved the
framework was transferrable because it was easily leveraged at
three different sites.”
CPS Energy’s James Boston adds: “From a utility perspective,
we’re in an age where our equipment and technology is moving
at a faster pace than ever before. How can we be sure the technol-
ogy we’re putting in today will be able to communicate and work
along with the technology we put in tomorrow? We strongly be-
lieve that interoperability is one way to bridge that gap, and Open-
FMB delivers it.”
OpenFMB is an interoperability catalyst, and it delivered flexibility for Duke, CPS, NREL and OMNETRIC Group in these implementations. SEPA and the OpenFMB Technical Working Group
would like to see more utilities participate and bring their use cases for the team to solve. They would also like to see more vendors
and solution providers explore possibilities to deliver interoperability using the framework. | PGI
There may be differences in each microgrid, but the microgrid management
systems are still able to handle the quirks of each microgrid.