IEEE Electrification - December 2020 - 74

algorithms have been proposed, the Open Field Message
Bus (OpenFMB) is a reference architecture that has been
proven in field validations with commercial off-the-shelf
(COTS) equipment, using open source software adaptors.
OpenFMB is a framework and reference architecture that
enables the coordination of grid-edge devices, facilitated
by interoperability and distributed controls, as shown in
the layered architecture of Figure 2.
The OpenFMB framework reduces the need for centralized control and allows the management of distributed
systems at the device level. Open source OpenFMB software adapters enable communication between such varied
protocols as distributed network protocol 3 (DNP-3), Modbus, American National Standards Institute (ANSI) C12,
Message Queuing Telemetry Transport, Data Distributed
Service (DDS), IEC 61850, Generic Object Oriented Substation Event (GOOSE) messages, Advanced Message Queuing
Protocol, and the network address translation (NATS) messaging system. Numerous OpenFMB adapters have been
developed, tested, and placed in the open source.
As shown in Figure 2, the OpenFMB framework allows
the simultaneous use of multiple protocols. This is essential in distributed control systems because multiple protocols are often used by an array of vendors. For example,
distribution utilities in North America typically use DNP-3
for endpoint devices, such as line sensors and shunt
capacitors. However, the majority of PV and battery energy

storage systems (BESS) controllers use Modbus, while
smart meters use ANSI C12. As a result, the interoperability challenges associated with coordinating these devices
can be significant.
Building on the early implementations of OpenFMB,
the general framework has been developed into an OpenFMB harness. This is a deployable concept where containerized OpenFMB adaptors are loaded onto COTS
intelligent electronic devices. This allows devices, such as
microgrid controllers, to be quickly interconnected and
configured to communicate on a publish/subscribe bus
using modern telecommunication systems. Figure 3
depicts an idealized structural view of the OpenFMB harness that can be used for networked microgrid operations.
The idealized structural view of Figure 3 shows how the
complexity of a layered architecture is abstracted into a
distributed control that can be used to coordinate the
operation of networked microgrids.

Implementing Fractal Operations With
Networked Microgrids
Fractal operations of electric power systems can occur in
the form of microgrid functioning, where individual
microgrids coordinate their performance. To form a functional microgrid, it is necessary to have the generating
units, controls, and capabilities to maintain a stable frequency and voltage and to supply the end-use loads.
Firewall

Battery
Inverter

Legacy Protocol
Adapter
Common Data
Model Profile(s)
OpenFMB
Protocol

Legacy Protocol
Adapter

T
MQ

Common Data
Model Profile(s)

OpenFMB
Protocol

Solar PV
Inverter

Legacy Protocol
Adapter
us

b
od

Common Data
Model Profile(s)
OpenFMB
Protocol

DNP

OpenFMB

S
NAT

DS,
S, D QP
T
A
N
AM
TT,
MQ

, MQ
DDS

Virtual Firewall
Figure 2. The layered architecture of the OpenFMB control system. IoT: Internet of Things.

I E E E E l e c t r i f i cati o n M agaz ine / DECEMBER 2020

GIS

DMS OMS

Head
Ends

SCADA

Legacy Protocol Adapter
Common Data Model

TS
NA

Capacitor
Bank

MDM

DN
P

DNP

Higher-Tier Node
Central Office
(Utility Datacenter)

- +
Modbus

Line
Sensor

Battery
Relay

C12

Middle-Tier Nodes
(e.g., Substation)

GOOS

Smart
Meter

Lower-Tier Nodes
(e.g., Grid)

Other

End-Point
Devices

OpenFMB Protocol

Legend
Legacy Protocol Translation
Common Semantic Model
Open FMB IoT Protocol
Client/Server Polling
Pub/Sub Messaging

IEEE Electrification - December 2020

Table of Contents for the Digital Edition of IEEE Electrification - December 2020