Page 222 - From Smart Grid to Internet of Energy

196 From smart grid to internet of energy

prevented by using the RTS and CTS mechanism. If the Station 1 intends to
convey data, it transmits an RTS message to Station 2, and the Station 2
approves transmission by transmitting a CTS message that is sent to all stations
within the coverage areas of the Station 2. After this, the stations except Station
1 and 2 avoid data transmission.

5.4.2 Application perspective of WLAN systems

From the concept of SG applications, Wi-Fi is an important technology for SEP
2.0. It is able to provide efficient performance in both shared spectrum and noisy
channels. In addition, this technology can support many application scenarios
and IP based protocols as mentioned before. It is worth noting that the Wi-Fi
Alliance has characterized several specifications for certified devices that
can fulfill requirements of the SEP 2.0. Since the Wi-Fi connectivity has been
already covered all over the world, it can play a considerable role in popular
application scenarios such as smart metering, smart energy management and
smart home automation. This technology aims to provide services in home area
networks (HANs), neighborhood area networks (NANs) and field area networks
(FANs) of the SG systems. Using the Wi-Fi in these networks may also develop
interoperability. On the other hand, there are some drawbacks of the Wi-Fi tech-
nology. Its high-power consumption has been considered as a disadvantage over
a long time. The development of novel Wi-Fi chips with lower power consump-
tion has presented new solutions to overcome this problem. In addition, these
developed Wi-Fi chips are able to operate many years like ZigBee chips.
Ethernet based communication infrastructure for substation automation sys-
tems has been proposed by IEC 61850 standard. This standard based WLAN
system is able to improve protection of distribution substations thanks to smart
monitoring and control systems [42–44]. In addition, Wi-Fi systems including
smart sensing and control devices can be employed in protection applications.
Moreover, the combination of WLAN and wireless mesh concepts may provide
robust systems with self-organizing and self-healing features. Wireless mesh
exploits multi-hop routing techniques to extend coverage range with low trans-
mission power [45]. Wi-Fi enabled SMs can be utilized for repeating informa-
tion signals, and thus coverage area and network capacity may be improved
[46]. It is also important to note that WLAN systems can also support these ser-
vices for both distribution substations and Distributed Energy Resources
(DERs). On the other hand, there exist several important problems for WLAN
systems as follows [47].
l Interference is very crucial issue for communication signals. Electrical
equipment of power systems may adversely affect communication signals
or even may wipe out communication signals completely. In addition, other
wireless devices may also generate interference effects, which will cause
negative influences on communication signals.