IEEE Electrification Magazine - September 2013 - 42

with each criterion. To achieve the optimal economics,
microgrids apply coordination with the utility grid and economical demand response in island mode. The short-term
reliability at load points would consider microgrid islanding
and resynchronization and apply emergency demand
response and self-healing in case of outages.

Campus Microgrid Components
In this section, the components of the IIT microgrid, including DERs, HRDS switches, meters and PMUs, and building
controllers, are introduced. DER units include -dispatchable
units such as natural-gas turbine generator and battery
storage units, and nondispatchable units such as solar PV
and wind turbine units. The storage unit includes a flow
battery and several lead-acid batteries. Building controllers
would provide control and monitoring functions for building loads on campus. Figure 2 depicts the seven-loop
-configuration established at IIT in which three loops are
connected to the North Substation and four loops are connected to the South Substation. The components of the IIT
microgrid are described in the remainder of this section.

Natural-Gas Turbine Synchronous Generation
The IIT microgrid is equipped with an 8-MW natural-gasfired power plant with two 4-MW Rolls Royce gas turbines.
The natural-gas turbine consists of five sections, including
air intake, compressor, combustor, turbine, and exhaust.
The air sucked into the inlet is compressed by the compressor and mixed with the fuel (natural gas) to form an
air-fuel mixture. The mixture is burned in the combustor
to form a high-pressure air, which drives the turbine. The
synchronous generator installed on the turbine shaft will
convert the mechanical energy into electrical energy.

- igure 3 shows the full-scale model of the natural-gas turF
bine generator located at the IIT campus.

Solar PV Generation
A total of 140 kW of solar PV cells are installed on three
building rooftops, including a 20-kW solar canopy (shown
in Figure 4) installed at the electric vehicle charging station
to supply portions of the IIT campus load. The solar PV
units are not dispatchable and use the maximum power
point tracking (MPPT) control system shown in Figure 5 to
maximize the solar power output for a given insolation. A
solar PV cell is a controlled-current source with a nonlinear
-current-voltage relationship corresponding to a given insolation and temperature. Generally, as the solar PV cell voltage increases, its output current will decrease. To achieve
the highest efficiency and capture maximum solar energy,
a solar PV array voltage-control mechanism is developed
for a given insolation. Here, the inverter output voltage Vo
of solar PV units is determined by the microgrid. The dc/ac
inverter uses an angle control to stabilize the dc bus voltage
Vdc based on the fixed Vo and also used a magnitude control to regulate the reactive power output at a reference
value (typically zero). Based on the stabilized Vdc , the dc/dc
converter adopts MPPT control to regulate the solar PV
array voltage VPV and reach the maximum real power output. The objective of solar PV generation control is to withdraw maximum real power without injecting any reactive
power to the microgrid.

Wind Turbine Unit
An 8-kW wind turbine unit is installed on the north side of
the campus in the Stuart soccer field, connected to Loop 1, as
shown in Figure 6. The wind turbine unit on the IIT campus

IIT Microgrid (Optimal and Reliable Operation)
Economical Operation

Tertiary
Control

Economical
Demand
Response

Unit
Commitment
and
Economical
Dispatch

Short-Term Reliability

Islanding
and
Resynchronization

Emergency
Demand
Response

SelfHealing

Secondary
Control

Primary
Control

Microgrid Components
Wind
Turbine

PV
Arrays

Gas
Turbines

Meters
and
PMUs

Coupling
Switch
at PCC

Battery
Storage

Building
Controllers

HRDS
Switches

Battery
Storage

Figure 1. The objectives and functions for the control and operation of the IIT microgrid.

I E E E E l e c t r i f i c atio n Magaz ine / september 2013

Set Point Values
Control Commands
Monitoring Signals

Gas
Turbines

Battery
Storage

Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2013