IEEE Power & Energy Magazine - July/August 2017 - 66

Operating Modes of the IIT-Bronzeville
Networked Microgrids

Display Layer
Web-Based User Interface

Data Layer
Historical Data

Real-Time Data Predicted Data

Control Layer
Demand-Side
Management

Islanding and
Supply-Side
Resynchronization Management

figure 3. The implementation of a microgrid master controller.

layers: data, control, and display. The data layer collects and
archives measured field device data and predicts the microgrid
operating state. The control layer continuously receives data
from the data layer and issues supervisory control signals to
dispersed field devices. The display layer, implemented in a
web-based application, visualizes the pertinent data required
by human operators.

Operational Characteristics of
Networked Microgrids
The operation of networked microgrids is more complicated
than that of a single microgrid as the microgrids cooperate
based on specifically proposed configurations. Accordingly, the
energy management system of the networked microgrids coordinates individual microgrid operations to achieve operational
efficiency and security for the entire cluster of microgrids.

Networked microgrids can be operated in either an islanded
or a grid-connected mode. In a grid-connected mode, they
are normally connected to the utility grid in a radial or loop
topology configuration. When the utility grid fails to function properly, networked microgrids will be reconfigured to
be islanded from the utility grid upon the detection of any
frequency or voltage excursion at the PCCs. In Figure 2, if
the IC switch S3 is open, there will not be any exchanges
between the ICM and BCM, and the operation of the two
microgrids will be decoupled and controlled independently.
Otherwise, the operation of the two microgrids will be
tightly controlled via the IC, which enhances the operational
efficiency and security of the individual microgrids.
Table 1 lists the possible operating modes of the networked microgrids depicted in Figure 2. The two microgrids
are operated independently in modes 1-4 (whether or not they
are connected to the utility grid), whereas the operation of
the two microgrids is coordinated in modes 5-8. Generally,
the operation of the networked microgrids can be switched
seamlessly between any two modes listed in Table 1. In each
mode, the networked microgrids satisfy operational requirements posed by customers and contractual obligations with
the utility grid (if any).
Figure 4 shows four possible types of networked microgrid
configurations listed in Table 1, when the two microgrids are
interconnected and their operation is coordinated for demonstrating the potential benefits.

Two-Layer Energy Management Mechanism for
Networked Microgrids
The operation of the networked microgrids in Figure 2 is
managed in a leader-follower mode, in which the BCM
acts as the leader (i.e., the BCM determines power exchanges of the networked microgrids with the utility grid and
between the two microgrids) and the ICM cooperates with

table 1. Operating modes of individual microgrids in the networked microgrids.

Mode

ICM

BCM

Configuration
of Networked
Microgrids

Open

Islanded

Independent

Closed

Open

Grid connected

Islanded

Independent

Open

Closed

Open

Islanded

Grid connected

Islanded

Independent

Closed

Open

Grid connected

Independent

Open

Closed

Islanded

Coordinated

Open

Closed

Islanded

Grid connected

Coordinated

Closed

Open

Closed

Grid connected

Islanded

Grid connected

Coordinated

Closed

Grid connected

Coordinated

ieee power & energy magazine

Operation of
Networked
Microgrids

july/august 2017

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