Page 131 - From Smart Grid to Internet of Energy

Smart grid network architectures Chapter 3 115

provide users the opportunity to decrease or change their power utilization in
periods of peak demand. The bandwidth requirement of the DR technologies
is significant low since they only transmit commands to control devices such
as switch on/off. On the other hand, latency requirement of these technologies
may change in a broad interval from milliseconds to minutes.
Connection and disconnection circumstances, which have need of various
response times, may occur in several situations. If the users are mobile, long
latencies can be compensated. Nonetheless, if the connection or disconnection
transaction will be employed as a response to grid circumstances, the latency
has to be in the range of milliseconds.
One of the significant measurement technologies for wide-area situa-
tional awareness (WASA) is Synchronized Phasor Measurements (Synchro-
phasor) that is related to technologies developed to enhance the power
system monitoring over wide geographic regions. Data traffic requirement
of this application may change between 20 and 200 ms, and bandwidth
requirement is in several hundreds of Kbps depending on the technical spec-
ifications. Data traffic of a SCADA system is depend on the number of IEDs
located on substations that are systematically polled by the master. The data
rate requirement of SCADA systems is predicted in the range of 10–30 Kbps
while the latency need changes up to 200 ms. On the other hand, inter-
substation communications are managed by Generic Object Oriented Substa-
tion Event (GOOSE) whose latency requirement is quite low. Communica-
tions among multiple substations for new SG applications may be realized by
the GOOSE, and the latency requirement value may vary in the range of 12–
20 ms.
Substation surveillance is the another popular application requiring a spec-
ified QoS. This type application needs relatively high bandwidth in the level of
Mbps since the surveillance is generally realized by video systems. It is worth
noting that the utilized equipment and targeted resolutions directly affect band-
width requirement of this application. The latency characteristics of the surveil-
lance systems is in several seconds.
Fault location, isolation, and restoration (FLIR) systems are utilized for
protecting power systems in the distribution level. These systems should have
low latency characteristics and the value of mentioned latency is in millisec-
onds. On the other hand, bandwidth requirement of this application type
changes between 10 and 30 Kbps. In addition, protection processes are also
ensured for microgrid systems. The latency values between 100 ms and 10 s
should be considered for microgrids. Also, distribution grid optimization is
a vital process which handles optimization transactions such as power quality
optimization, volt/VAR optimization on distribution level of the SG. While the
latency characteristic varies approximately 100 ms, the bandwidth require-
ment of this process is around 2–5 Mbps. In addition to latency and bandwidth
needs, SG communication networks should present superiorities in terms of
stability and security.