From few decades, the growth in electricity demand and increase in nonlinear loads increase the requirement of high Voltage stability for electrical power system. The voltage of the power system can be monitored and controlled continuously using voltage stability indices. In this paper firstly contingencies are ranked based on their voltage stability margin, then line stability index (Lmn), fast voltage stability index (FVSI) as well as line stability factor (Lqp) methods are employed to find the most critical line of the IEEE 14-bus system. These three voltage stability indices have been analyzed under top five different contingencies to detect the most critical bus of the system. Static Synchronous Series compensator (SSSC) has placed in top five critical lines and voltage stability indices are observed for optimal location of SSSC.