IEEE Power & Energy Magazine - July/August 2017 - 64

A microgrid is a localized small-scale power system
that clusters and manages DERs and loads within
a defined electrical boundary.

sectionalization will be strategically deployed so that a fault
would only result in a local outage rather than an interruption
to the entire area. The BCM operation will comprise several types of distributed energy resources (DERs). A battery
energy storage system (BESS) located in close proximity to
photovoltaic panels provides an effective means to mitigate
the variability of renewable energy. The BESS is also effective in improving the power quality at customer sites.
The BCM is adjacent to an existing microgrid on the
campus of the Illinois Institute of Technology (IIT), which
owns, manages, and operates its electric distribution system.
The IIT campus microgrid (ICM) is bounded by 35th Street
on the south, 29th/30th Street on the north, Michigan Avenue on the east, and the Metra Rock Island train line on the
west. The on-site 12-MW DERs located at the ICM include
dispatchable units such as a natural-gas turbine and a BESS
as well as nondispatchable units such as photovoltaic panels
and wind turbines. The ICM features seven separate loops
for enabling a high-reliability electric distribution system,
which originates from two substations; three loops are connected to the north substation, and four loops are connected
to the south substation. Figure 1 shows the ICM's seven
loops, with each loop represented by a specific color.
An ongoing funded project, sponsored by the Office of
Electricity Delivery and Energy Reliability at the U.S. Department of Energy, aims at devising a master controller for
achieving a seamless integration of the BCM and ICM as networked microgrids to broaden the merits of microgrid-based
distributed power systems. The project team led by Commonwealth Edison comprises multiple universities, national laboratories, consultants, and industrial manufacturers. Through
strategic sharing and control of available resources in the two

figure 1. The seven loops at the IIT campus microgrid.
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microgrids, the proposed networked microgrids are expected
to further reduce the outage time of critical loads at lower costs,
improve the overall grid operation, enhance the grid efficiency,
and reduce the local emissions in the Chicago community.
We present the strategies and benefits of networking
multimicrogrids by prototyping the planned IIT-Bronzeville
networked microgrids. In practice, networked microgrids
can improve the efficiency, security, sustainability, reliability, resilience, and economics of the electric power supplied to end customers. We introduce the ongoing efforts for
connecting the planned BCM to the existing ICM to form
networked microgrids. We propose coordinated control strategies for overcoming the technical difficulties in operating the
networked microgrids when they are islanded from the utility
grid and discuss the significant role of networked microgrids
in realizing a smart grid.

Benefits of Implementing Microgrids
A microgrid is a localized small-scale power system that clusters and manages DERs and loads within a defined electrical
boundary. Through the strategic control of switchgear located
at the point of common coupling (PCC), each microgrid can
be operated in either grid-connected (when connected to the
utility grid) or islanded (when disconnected from the utility
grid) mode. Microgrids take advantage of locally available
resources and thus could reduce their dependence on the utility grid to serve on-site customers, in particular when critical circumstances are encountered. By interacting actively
with the utility grid, microgrids are also capable of supplying
surplus energy and auxiliary services (e.g., frequency regulation, voltage support, spinning reserve, black start support,
and economic and emergency demand response) to the utility
grid. Microgrids may vary in functional designs by considering the unique characteristics of individual power supplies
and demands. Although ac microgrids are dominant in present electric distribution systems, dc microgrids and hybrid
ac/dc microgrids are becoming increasingly prevalent due
to the proliferation of photovoltaic power generation and dc
loads (e.g., computers, mobile phones, and light-emitting diode
lighting). Microgrids may evolve to become the fundamental
building blocks of a smart grid. The emergence of microgrids
spurs interest for exploiting the benefits of DERs through the
utilization of advanced management and control strategies.
Moreover, the needs for enhancing energy efficiency, economics, security, sustainability, reliability, and resilience drive
microgrids within a region to form networked microgrids.
july/august 2017

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - July/August 2017