Page 226 - Decision Making Applications in Modern Power Systems

190 Decision Making Applications in Modern Power Systems

a channel can sustain in 1 second. Latency is the time elapsed between time
of data creation and time of data available at the receiving unit or location.
Real-time µPMU applications need a low-latency communication channel.
Commonly used communication channels are switched telephone circuits
(high latency), power line carrier (moderate latency), and fiber optics
(extremely low latency). The most advanced communication network fol-
lowed nowadays is 4G and 5G. The power needed for the operation of the
modules is supplied by the switch mode power supply module (Md0).

7.5 Decision application of microphasor measurement unit
in modern distribution system

A plethora of decision applications of µPMU in modern distribution system
is possible [12,13,17,18]. The decision application can be broadly catego-
rized into noninstantaneous and instantaneous decisions. Noninstantaneous
decisions include nonreal-time decisions such as decisions regarding plan-
ning, modeling, and equipment health, which help the utility to understand
the past and present conditions of the distribution system. Instantaneous deci-
sions include more or less real-time decisions such as topology reconfigura-
tion, island detection, and fault detection. The important applications are
explained in detail as follows:
1. Island: Islanding in distribution system is defined as a condition when a
part of the distribution grid is electrically isolated from the main utility
grid but still gets power from the DGs connected in that part [7]. Fig. 7.7
shows the island concept. Islanded microgrid areas 1, 2, 3, and 4 are
formed when circuit breakers 1, 2, 3, and 4 open, respectively. Islanding
may be intentional or nonintentional. While intentional islanding does
not pose any problem to the isolated grid as it is planned, unintentional
islanding is unplanned (caused by faults, human error, lightning, etc.) and
thus poses adverse problems in the isolated grid. The significant pro-
blems of unintentional island and how µPMUs can resolve those decision
problems are listed below:
a. Information to DG and utility about island: When island occurs, both
the DG and the utility should be made aware about it to prevent
adverse cascading condition. The phase angle measured by µPMUs of
the main grid and the islanded area can be compared to detect island
and broadcast the islanded information, creating a wide-area situa-
tional awareness [19].
b. Active and reactive power balance: An islanded grid is a miniature
form of the main grid that needs for a balance between generated
power and consumed power to maintain voltage and frequency to a
nominal value. However, due to the renewable energy sources, it
becomes difficult. While PV sources have zero inertia and react to