II. VOLTAGE STABILITY
The ability of a power system to maintain steady state voltages
at all the buses after being subjected to a disturbance is known
as voltage stability [4]. There are many reasons leading to
voltage instability causing system voltage collapse ie, a
phenomenon which makes the grid voltage to decrease to a
level that is unacceptable and is unable to recover leading to
interruption of the power supply in the system. Slow
variations in the power system eventually lead to voltage
collapse which can be analyzed in the steady state voltage
study. This can be seen from the "PV" curve or "nose" curve
which is the plot of the power with the voltage at the bus.
Figure 1 is a typical P-V curve plot obtained from the equation
1 shown.