Contingency Ranking for Voltage Stability in Power System

Continuous assessment of voltage stability is vital to ensure a secure operation of the power system. Several voltage stability indicators have been developed in an attempt to quantify proximity to voltage collapse. Some of them are computationally expensive, whereas others are reported not to perform as expected under all conditions. This paper deals with the voltage stability index for an outage of a power transmission line. This index indicates that how sensitive the line is to voltage stability after the occurrence of a fault. The voltage stability index of the line becomes low when it gets faulted. The voltage stability index is determined for all possible outage conditions in each line of the system. After that, according to their stability indexing lines are ranked in descending order. This kind of ranking is very helpful in preventing the system from complete blackouts or failure. The effectiveness of the proposed methodology is demonstrated on IEEE 6-bus power system. The approach can be beneficial tool which is less time consuming and accurate security assessment and contingency analysis at energy management center. The simulation results show that the severity of a line outage can be indicated by contingency ranking analysis.