IEEE Electrification Magazine - June 2017 - 39

load can be fed by the power originated from either ac or dc subsystem, such a redundant structure
enables the Keating Nanogrid to be
more resilient to power disruptions.
In case of a campus power emergency, the Keating Nanogrid can be
islanded from the rest of the IIT
Microgrid and operated as a standalone power system for keeping the
lights on inside the building. The
Keating Nanogrid can represent a
critical infrastructure within any
large microgrid.

Keating Nanogrid
PV Array

PV Array

Rooftop PV System
dc Subsystem

dc/dc
Converter

dc Load

Battery

dc Bus (48 Vdc)

The Rest of the IIT
Microgrid

Bidirectional
ac/dc
Converter

Battery
ac Load

Implementation of
the Keating Nanogrid

dc/ac
Inverter

ac Subsystem

Bidirectional
ac/dc
Converter

ac Bus (208Y/120 Vac)

The Keating Nanogrid was implemented in three phases, as shown
in Figure 4. In Phase 1, a total of Figure 3. The complete architecture of the Keating Nanogrid.
180 kW of polycrystalline PV modules were installed on the roof of Keating Hall. PV modfrom the IIT Microgrid while serving its load by utilizing
ules were segmented into several arrays by installing
on-site resources.
eight rooftop disconnect-combiner boxes so that they
Table 1 lists the components that were placed into the
can be connected to either an ac or dc subsystem in the
nanogrid operation. Approximately a mile of conduit was
subsequent phases of the project. Figure 5 shows the
installed for interconnecting the dispersed components.
rooftop PV array installation, which is hidden if viewed
In particular, a specific room was constructed and desigfrom the street level because Keating Hall is architecturnated under an exterior stairwell in Keating Hall, as
ally significant. Phase 2 constructed the dc subsystem
shown in Figure 7, for placing batteries and power electhat accommodated 20% of the power output of PV
tronic devices. This room is equipped with fire protecarrays. This phase included the installation of a batterytion, climate control, and emergency response systems
based energy-storage system, the replacement of fluofor protecting occupants and providing accessibility for
rescent lights with dc LED lights, and the distribution of
emergency responders.
dc lines throughout the building for supporting the LED
Distinctive Components of the Keating Nanogrid
lighting system. Figure 6 shows the power electronics
devices, which were manufactured by Schneider Electric,
Sustainable Battery Storage
that were installed in this phase. Phase 3 included the
Energy-storage devices utilizing the Aquion Energy's
construction of the ac subsystem for utilizing the
Aqueous Hybrid Ion (AHI) technology were installed as
remaining 80% of the PV array power output. More batthe backbone of the Keating Nanogrid operation. These
tery units, power electronic devices, and additional consaltwater electrolyte-based AHI batteries are engineered
trol and monitoring components were installed in this
to meet cradle-to-cradle certification standards and are
phase of the Keating Nanogrid. At the end of Phase 3,
not flammable, corrosive, or explosive under any
the Keating Nanogrid was capable of islanding itself

Phase 1

Phase 2

Phase 3

Install the Rooftop PV System

Construct the dc Subsystem

Construct the ac Subsystem

173.5-kW Grid-Interactive PV Array

94 High-Bay LED Lighting Fixtures

170.4-kWh Hybrid-Ion Battery

(638 Trina Solar PV Modules)

160-kWh Hybrid-Ion Battery

Five dc/ac Inverters

Six Bidirectional ac/dc Converters

(Funded by the DOE)

(Funded by the ANL/DOE,

(Funded by the ICECF, IIT)

IDCEO, IIT)
Figure 4. Three phases of implementing the Keating Nanogrid. DOE: U.S. Department of Energy; LED: light-emitting diode; ANL: Argonne
National Laboratory; IDCEO: Illinois Department of Commerce and Economic Opportunity; ICECF: Illinois Clean Energy Community Foundation.

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Table of Contents for the Digital Edition of IEEE Electrification Magazine - June 2017