Communication Challenges for the FREEDM system
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2009-12-02
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Abstract
The Future Renewable Electrical Energy Distribution and Management (FREEDM)
Center's proposal to incorporate the renewable resources of energy as source of electricity
into the existing power distribution system and allow for energy exchange between individ-
ual sites, is a revolutionary idea which will help us meet the energy needs of the future in an
environment friendly manner. The renewable resources of energy have certain characteris-
tics which make such an integration very challenging. They are available in large amounts
but not concentrated at an area and are intermittent in nature. Thus a lot of them need
to be deployed along with storage resources in order to obtain a steady source of electricity
resulting in a distributed energy generation environment. To maintain the stability of such
an electricity distribution grid, it is essential to monitor and control each site from a central
location using agents. These agents also need to communicate with each other to execute
any protection scheme or for energy management to utilize any excess electricity at a site.
Therefore, a reliable communication backbone becomes an essential platform which would
allow such a communication to take place. Since FREEDM is intrinsically a complex sys-
tem, the communication backbone must be a fault-tolerant in that distributed devices and
elements may become faulty or fail.
In this thesis, we investigate the challenges for such a communication backbone
in a distributed energy generation and energy exchange environment within an electricity
distribution system. We use the FREEDM system as a platform for our research. To our
knowledge, a power system proposed by the FREEDM, does not exist, which makes our job
more challenging. We need to identify the various communicating entities, communication
scenarios and their timing requirements within the FREEDM system and propose a com-
munication architecture which meets these criteria. We also need to identify the possible
communication protocol standards which will be used for message exchange.
In order to understand the communication needs of power system applications
which would be used in the FREEDM system, we conduct a survey of the existing power
system communication architectures (the SCADA and substation automation systems) and
communication protocols (DNP3 and IEC 61850). Further we detail the various levels
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of communication and communicating entities within the FREEDM system. We apply our
understanding of existing substation automation systems to the FREEDM system and iden-
tify the timing criticality and communication requirements for power system applications
within the FREEDM system. In order to quantify the timing requirements and to iden-
tify the various networking technologies which will be used to support the communication
backbone of the FREEDM system, we set up a distributed communication testbed using
ZigBee, WiFi and Ethernet communication technologies. A Web, SNMP{based monitoring
tool set up by us, as a means to keep track of the distributed devices forming the testbed is
also presented. We conclude the thesis by presenting the results of experiments performed
by us on the testbed and presenting a road-map for our future work.
This thesis, presents our ¯rst year e®orts towards setting up of a communication
backbone for the FREEDM system and identifying the communication challenges. The
reliability and security aspect of the communication backbone, will be taken up in our
future work. Our preliminary results have provided a fundamental platform to study unique
challenges in the future design and development of a reliable and secure FREEDM system.
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Keywords
Performance Evaluation, WiFi, Zigbee, DNP3, IEC61850, Smart Grids, FREEDM
Citation
Degree
M
Discipline
Computer Engineering
