Page 41 - From Smart Grid to Internet of Energy

30 From smart grid to internet of energy

utility grid due to its synchronization and power control capabilities while
interconnecting to grid. The efficient integration of microgrids and RESs to
high-voltage transmission networks and low-voltage distribution networks
are dependent to efficiency of grid-tie inverters. Furthermore, these inverter
types provide presuming options to low voltage consumers by feeding gener-
ated power of their own microgrid. One of the major contributions of grid-tie
inverters to transmission and distribution networks are their synchronization
and phasor measurement features that ensure synchronized operation with grid
or safely disconnecting from grid to operate the microgrid in island mode. Thus,
it provides self-healing and restoration capability to power network during fault
conditions. These capabilities of inverters are involved with monitoring and
EMS integration to control power flow throughout the smart grid.
EMS is a software-based control system that provides management, moni-
toring, optimization and operating generation, transmission and distribution
networks. A widely known component of EMS is SCADA system that is based
on centralized control to monitor and to control numerous generation plants and
transmission networks in long distances. The integration of EMS and SCADA
enables smart communication and CPS installation along the smart grid with
automatic control processes. Outage management system (OMS) is another sig-
nificant component of EMS that are developed to detect and to solve outages
occurred in the power network. Most of transmission and distribution networks
include special OMS to identify outages instantly, and to store historical data of
outages in databases. The improvement of smart grid communication systems
has developed traditional technologies of transmission network such as flexible
AC transmission systems (FACTS) and static var compensation (SVC). FACTS
is essential to stable voltage and reactive power of networks while voltage and
current are out of phase. On the other hand, SVC is required to compensate reac-
tive power in an AC power network to facilitate stabilizing grid voltage and
frequency. Thus, grid voltage deficiencies such as sags, swell, fluctuation, dips,
and curtailments are efficiently prevented. The substation automation is another
important contribution of smart grid to transmission and distribution networks
to resolve synchronization and fault situations [4, 22].
A comprehensive list of devices and technologies used in smart grid trans-
formation of transmission and distribution networks has been presented in
Table 1.4. The substation automation is required in transmission and distribu-
tion networks to provide several automation applications for voltage control,
synchronization, load transfer, curtailment prevention and fault detection con-
trols. The relays and circuit breakers are major protection devices brought by
smart grid transformation. Although these devices also exist in conventional
power grid, the communication infrastructure enabled by smart grid architec-
ture facilitates the integration of more sophisticated relays and breakers to be
used in transmission and distribution networks.
The relays are controlled by CTs to indicate any fault occurred along the
system and trip signals are transmitted by the controller to prevent damages