Abstract-This Paper deals with the problem of voltage
instability that leads in some cases to voltage collapse and
complete blackouts. Voltage instability, being the absence
of voltage stability, results in progressive voltage decrease
(or increase). A power system at a given operating state
and subject to a given disturbance undergoes voltage
collapse if the post-disturbance equilibrium voltage is
below acceptable limits. Voltage collapse may be total or
partial blackout. Many major blackouts throughout the world have been
directly associated to this phenomenon, e.g. in France,
Italy, Japan, Great Britain, USA, etc. The analysis of this
problem shows that the major causes is the system’s
inability to meet the reactive power demands. The main
objective of this work is to find the most favorite methods
to assure the security of the system in terms of voltage
stability.[2]
In most case studies, using of one remedial action is not
enough to solve the voltage instability problem. This
paper declares that the usage of combined remedial
actions, specially during the peak load hours is a must
solution in most cases. Also it is declared that the usage of
normal capacitors to add reactive power together with the
other suggested methods helps much as being a cheap
tool.
It is known that the improvement of voltage levels on a
power system reduces the losses. In the present case,
specially at peak load, it is gained that the same energy
demand could be fulfilled with less power generation. In
addition to securing the voltage levels on a power system,
a feasible return is achieved.