SOFT COMPUTING LINE OUTAGE CONTINGENCY RANKING FOR VOLTAGE STABILITY STUDIES

Abstract

Voltage stability is currently one of the most important research areas in the field of electrical power systems. With the increased loading and exploitation of the power transmission system being also due to improved optimized operation the problem of voltage stability and voltage collapse attracts more and more attention. Voltage collapse can take place in systems or subsystems and can appear quite abruptly which requires the improved continuous monitoring of the system state. Researchers have been trying to find out the most effective way for online system status monitoring, so that necessary precautions can be taken prior to voltage collapse. 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 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.