Soft Computing for Voltage Stability Analysis and Contingency Ranking in Power System

Voltage stability has recently become a challenging problem for many power systems. Voltage instability is one phenomenon that could happen in power system due to its stressed condition. The result would be the occurrence of voltage collapse which leads to total blackout to the whole system Investigation and online monitoring of power system stability have become vital factors to electric utility suppliers. Suitable preventive control actions can be implemented considering contingencies that are likely to affect the power system performance. An effective method for contingency ranking is proposed in this paper. This method calculates the voltage stability margin considering branch outages. The basic methodology implied in this technique is the investigation of each line of the system through calculating line stability indices. The point at which Voltage Stability Index (VSI) close to unity indicates the maximum possible connected load termed as maximum loadability at the point of bifurcation. This technique is tested on the IEEE system and results proved that the contingency ranking indicates the severity of the voltage stability condition in a power system due to line outage.