Page 270 - From Smart Grid to Internet of Energy

Cognitive radio based smart grid communications Chapter 6 241

6.6.5 Wide area monitoring applications
Wide area monitoring system (WAMS) covers the real-time data collection
from several components of SG systems such as IEDs and PMUs. The PMU
that is also referred as synchrophasor is an essential component of a Wide Area
Monitoring Protection and Control (WAMPAC) system. Typically, a PMU
obtains voltage and current waveforms of the power system by employing trans-
formers and produces their phasor by sampling measured data. The PMU is one
of the measurement methods, which is usually established and is swiftly being
utilized in increasing numbers. This system is developed for observing load
sharing, power flows, voltage stability, phasor synchronizations, restoring the
power systems, and estimating the effective algorithms to recover lost power.
It extracts the phasor of the line voltage and line current in power systems in
which entire components of phasor are compared to the period of signal. Fur-
thermore, a PMU can estimate the frequency of the transmission line and han-
dles the correct detection of frequency security [68].
On the other hand, wide area control systems can present several advantages
such as self-repairing, faster response and local control opportunity when com-
pared to the classical control performed by a control center. Wide area protec-
tion is able to preserve the power systems against the power outages and
unforeseen situations completely and autonomously [73, 75]. The WAMS can-
not only observe the all stages of power grids (i.e., power generation, transmis-
sion and distribution), but it can also collect information regarding system
devices such as protection devices, capacitor banks, and transformers. Various
communication technologies operating over licensed or license-free spectrum
bands may be employed for the monitoring applications in the SG systems.
Nonetheless, it is obvious that the utilization of licensed frequency bands leads
to increased costs. The CR technology can be efficiently exploited in the wide
area monitoring applications based on its advantages explained previously.

6.6.6 Advanced metering infrastructure applications

One ofthe mostimportant applicationsofthe SGsystems is the AMI systemthatis
utilized to measure, obtain and analyze power-related data regarding energy con-
sumption and power quality ofeach user. TheAMIsystemcan bealsosupposedas
an advanced version of conventional automated meter reading (AMR) and auto-
matic meter management (AMM) systems because of the fact that it includes var-
ious improved devices and networks types such as the SMs, HANs, WANs, and
NANs [68]. Since the gathered information are very crucial, a communication
backbone that will provide reliability, security, scalability and cost effectiveness
shouldbeestablishedbetweencustomersandservicesproviders.ASMsupporting
the AMI infrastructure has the ability to communicate with measurement devices
on demand. The AMI characteristics of the SMs allow controlling of the two-way
communication that makes the SMs accomplished to execute commands