POWER August 2017 - 36

COMMERCIAL & INDUSTRIAL GENERATION AWARD
3. Master control. A Tucson Proving Ground worker checks on the Microgrid Master Controller
unit at the facility. The MMC allows the system to run more efficiently; Caterpillar officials
say it has enabled twice the fuel savings that would be achieved with a third-party controller.
Courtesy: Caterpillar
business, told POWER the company took
into account " the declining cost of renewable
energy sources and rapid advances in energy
storage technology " when deciding to pursue
the microgrid strategy. He noted it is a " financially
viable way to incorporate sustainable
sources of energy into our existing portfolio
of traditional power generation offerings. "
Technical Specifications
Caterpillar's experience with technological
innovation and engineering across a range of
industries proved invaluable for the project,
which involved team members from across
the company. When it was commissioned
in May 2016, Dave Damerell, the global
director of product validation, noted " The
microgrid project has moved from concept
to commercialization at an incredibly rapid
pace, helping to bring sustainability to life
here at TPG. It just goes to show you the
power of collaboration and innovation. We
can do big things when we work together. "
The innovation is obvious as the project
uses a variety of Caterpillar-manufactured
products (Figure 2).
" We use Cat brand thin-film PV panels,
a Cat Energy Storage System, Cat generator
sets, and a Cat Microgrid Master Controller, "
Johnston said. " Our solar array is made
up of 4,800 panels of thin-film PV cells. At
the time the microgrid was constructed, each
panel was rated at 110 W of power for a total
peak power capability of 528 kW DC.
" We connected these PV panels using 20
x 25 kW AC string inverters for a total output
of 500 kW AC from the entire PV plant, "
Johnston said. " Half of the panels are mounted
on single-axis trackers that follow the mo36
tion
of the sun. The other half are mounted as
a fixed-tilt array. "
Because the sun is not always shining
on the site, the microgrid uses bidirectional
inverters and its energy storage system to
balance the load, and the diesel gensets remain
available as a redundant power source
to ensure a reliable supply of electricity. As
Johnston explained: " The system includes a
Cat Energy Storage System (ESS) comprised
of Cat Bi-Directional Power inverters, which
connect ultracapacitors and lithium-ion batmicrogrid's
performance is provided by Cat
Connect, the company's web-enabled data
and reporting service.
Cat Connect allows power plant operators,
managers, and others to see the current
and past operating states of the microgrid,
and provides real-time awareness of any issues.
It also documents whether the technology
is saving the expected amount of fuel,
and helps identify ways that the power system
could be improved in its design and operation
at the site.
" From an equipment perspective, the Cat
Microgrid Master Controller and Cat BiDirectional
Power converter technologies accomplish
[an integration of solar and genset
power] while enabling roughly twice the fuel
saving versus third-party controllers, " Johnston
said. " These Cat products enable shutdown
of all diesel generators to run on solar
photovoltaic (PV) and energy storage alone
during daylight hours when solar PV meets
the site load. We also wanted to be able to
track our usage and visualize the power management
data to know that we are maximizing
the savings from our renewable energy
source, and our Cat Connect solution provides
this visibility. "
Energy Savings
Providing energy to the TPG facility was the
major goal of the microgrid project, but saving
on energy usage at the site was also an
important consideration for those working on
the system.
" Before the microgrid, our generator sets
" The project was something we wanted to
do, but it took the right timing and circumstances
for the project to take flight. "
-Tony Cazzato, Tucson Proving Ground facility manager
teries in parallel with the PV panels and the
generator sets. This provides the system with
unprecedented stability during transient power
variation, improved power factor, as well
as 12 minutes of supplementary power. "
The technology has proven itself as a viable
source of power generation, and it also
has proven efficient in terms of energy usage
at the TPG, a major goal of Caterpillar's
sustainability initiatives. Johnston noted that
the system includes integrated switchgear
and is managed by a Cat Microgrid Master
Controller (MMC) module (Figure 3). The
microgrid technology allows for generator
shutoff as needed, and visualization of the
www.powermag.com
used about 250,000 gallons of diesel fuel
each year. With our remote location, [the
fuel was] delivered by truck from Tucson.
This is expensive and requires due diligence
on the part of our logistics team to keep the
fuel tanks full, " Cazzato said. " With the
microgrid, we've been able to reduce our
reliance on diesel, as well as lower engine
maintenance and exhaust emissions. Using
less diesel means fewer deliveries and
increased energy security in case of a fuel
supply interruption. The price of diesel fluctuates,
of course, but the typical annual savings
are expected to exceed $200,000, not
including intangible benefits. "
POWER | August 2017

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POWER August 2017

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