Transcript Technologies, Systems and Future Trends

Smart Grid Research Consortium Conference
Communications:
Technologies
Systems
Future Trends
Dr Rick Russell
Systems and supporting Technologies
• Old processes beginning with the phone system
• The normal connection would be a modem attached to phone lines with automated dialup within each
modem creating a point to point serial data link. This basic communication link was not very reliable and at
times hard to synchronize the modems for consistent data integrity.
• Order wire & ISDN Leased Line
•Order wire and ISDN modem systems used a dedicated phone line provided by the local phone company to
create a continuous link between two stations. This allowed for higher bandwidth and increased reliability
needed to monitor realtime equipment such as SCADA devices. Some of the issues related to this
communication channel was expense, modem data synchronization and this service could only be used
where existing phone line equipment was present or cost would allow for a buildout.
• Licensed UHF/VHF modulated to serial
•UHF/VHF serial modulated systems provided a new way to connect Utility Office Monitoring systems to
Substation and Feeder equipment creating a backbone for SCADA in places phone lines were not available.
Issues with this PTT or Push To Talk system came from less than desirable radio network design or circuit
overload with too many endpoint devices transmitting at the same time. A PTT system not only required an
excellent radio connection but a special modem on each end to convert ascii data into the voice radio
protocol for transmission over the airwaves. Push to Talk systems ran in simplex mode only and carried a
good deal of latency because of this
Systems and supporting Technologies
• Licensed Digital Radio with serial transfer protocol
• Licensed Digital Radio's with serial protocol services built in became the evolution upgrade to the PTT
systems and introduced a new communication technology called multiplexing. With this system you could
insert a multiplexer or "MUX" on either end of the radio link and provide multiple serial interface connections
for substation equipment to take advantage of. This system usually had a relative slow baud rate associated
with the radio itself and adding the MUX with its multi-channel overhead created a slow, high latency serial
network that consumed considerable time in tweaking and tuning in order to maintain reliability.
• Unlicensed Digital Radio with serial transfer protocol
• Unlicensed Digital Radio’s with serial transfer protocol provided the same service as the licensed version
but at a reduced power level. These radios would not transmit the same distance as the licensed version
and was susceptible to noise interference from local systems.
Systems and supporting Technologies
• Licensed and Unlicensed Digital Radios with Ethernet protocol capabilities
• These radio networks combined new RF technologies with networking TCP/IP services to produce an IP
addressable radio network that could be an extension to the office control network. This system would allow
a large number of IP networkable devices and serial devices to communicate over the same RF channel.
This type of network requires a more detailed radio path study and understanding of noise interference
before a high speed reliable system can be realized.
• Hi-Capacity Microwave Systems providing Ethernet service
• Older systems usually were in excess of 6GHz had six foot or larger dishes and were very expensive to
install. Typically these units consisted of the microwave RF section and an external card rack that provided
options such as ethernet and other protocols. In many cases you would find a multiplexer installed into the
system to provide multi communication channels as well.
Technologies
•
Point to Multipoint Hi-Capacity Microwave Systems
• Point to multipoint Hi-bandwidth microwave is a relative new technology, a typical system would involve a
sectored antenna at the master station or repeater site.
• This system is mostly used in a high traffic data backbone between a master station and multiple remote
sites needing high speed bi-directional simultaneous connectivity.
• Satellite backbone providing Ethernet technologies
• A satellite receiver networked thru a router and serial port server provides both ethernet and serial traffic at
remote locations when conventional radio and land line technologies are not accessible.
• This type of network is prone to high latency and upper atmospheric interference and should not be used
for SCADA applications without careful consideration.
Technologies
• Cellular Data backhaul
• This technology parallels the same techniques used for remote satellite networks except it only works
where a reliable cellular signal is present.
• Some of the issues known with this form of connectivity is high latency and excessive charges when
cellular data plans run in overages.
• Fiber Optics
• Fiber networks are the newest of technologies being used in Electric Cooperatives where high speed and
large data rates are desired. Fiber systems are expensive to implement and can be very challenging in
remote areas. A properly designed fiber network will provide reliable connectivity, transmission speed in
excess of one Gigabit and multiple VLAN’s.
Future Trends
•
With the continuing development of WiFi, WiMax, Fiber technologies and
constant demand for tighter security:
•
Electric Utilities are implementing hybrid systems to facilitate their
communication needs.
•
These designs generally incorporate two or more of the technologies previously
described to form a communication network extending from the control center
to the most remote sub-stations. Some new systems include Hub and Spoke
designs so the most important components of the backbone can utilize
redundant Ring technology and provide connectivity to the most remote substations and feeder equipment.
•
The current trend is to build these systems in a modular progression minimizing
cost and spare parts inventory.