Innovative Smart Grid Technologies
January 20, 2010
A Proposed Communications Infrastructure for the Smart
Grid
Amit Aggarwal, Swathi Kunta, Pramode K. Verma
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Agenda
• Limitations of the present grid
• Smart Grid
• The Distribution Network Architecture
– Present Distribution Architecture
– Overview of present and future distribution network
• Communication needs of Smart Grid
– Bandwidth evaluation
– Optical fiber for smart grid communications
• Conclusion
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Limitations of the Present Grid
• Present grid allows only one way communication
only from generating station to downstream points
of distribution. This is clearly insufficient in a
system where a point of consumption can also
become point of generation.
• Slow mechanical switches, lack of automated
analysis
• Inability to detect power outages in most parts of
North America.
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Smart Grid
• Smart Grid characteristics:
– Self healing
– Allow consumer participation
– Resist physical and cyber attacks
– Provide high quality power
• Smart grid must provide two-way communication, along
with sensing and control, among the points of generation
and the end users
• Smart grid has three function al blocks:
– Sensing
– Communication
– Control
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Distribution Network Architecture
• Present Distribution Network
5
Overview of present and future distribution
network
Facts and figures
• Transmission substations: 10,287
• Distribution Substations: 2179
• Electricity Consumers: 131 million
• Distributed Energy facilities: 5600
• Electric utility organizations: 3100
Smart Grid Distribution Network
• Smart Grids will have sensors and point of communication
at almost each and every node of the grid including meters
at customer’s premises, feeders, distribution lines,
Distribution substations, transmission substations, control
centers and distributed energy resources.
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Communication needs of Smart Grid
• Flexibility of adding new devices and Interoperability
Above requirements can be easily and cost effectively handled
by using IP based network.
Constraints:
Latency: - It is one of the most stringent requirements for the
grid. If the control center misses any input then it might
substitute the missing input with inputs from other sensors
which can produce different actions leading to erroneous
results. The latency is in the order of a few milliseconds (­~
10ms)
Large numbers of messages: - As new elements are added
to the network with the evolution of the grid system, the
new network should be able to transport more messages
simultaneously without any major effect on latency.
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Bandwidth Evaluation
Assumptions Based available Data:
• 100,000 Customers
• 10,000 feeders
• Message size 100bits
• Packet flow follows Poisson’s distribution
• M/M/1 Traffic
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Bandwidth Evaluation
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Bandwidth Evaluation
• Message length, 1/μ =100 bits,
• mean latency ,T=10 msec
• number of messages λ = 106 per sec.
1
T=
µc − λ
• Transmission Line bandwidth c ~100.01 Mbps
• If 1/μ =400 bits the c = 400.04 Mbps
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Optical Fiber for Smart Grid Communications
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Supports speeds of several gigabits per second
Low bit error rates
No electromagnetic interference
More secure
Ideal for long distance transmission and distribution lines.
Ability to carry different channel in cable without any
interference
• Right of way along their transmission facilities
• Decreasing cost
• Serves as long term solution
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Conclusion
• Presented the need for a Smart Grid
• Smart Grids build on the technologies of sensing,
communication, and control.
• Postulated a medium size distribution network and
computed the bandwidth requirements of the
communication facilities in the grid.
• Based on the assumptions we have used, we can
already foresee needs for communicating at 100Mbps
and above even for a moderate size distribution system.
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