A fast method for determining the voltage stability limit of a power system

The voltage stability problem of a power system is associated with a rapid voltage drop due to heavy system load, and it occurs because of inadequate reactive power support at some critical buses. One of the serious consequences of the voltage stability problem is a system blackout, and this problem has received much attention in recent years. This paper proposes a fast method for finding the maximum load, especially the reactive power demand, at a particular load bus before reaching the voltage stability limit. The method uses the base-case system information to find special two-bus equivalent of the system for analyzing the voltage stability problem. The method was tested on the IEEE 14-, 30-, and 118-bus systems and the results obtained were compared with those found by some other methods.