%0 Journal Article %T Application of Firefly Algorithm in Voltage Stability Environment Incorporating Circuit Element Model of SSSC with Variable Susceptance Model of SVC %A Luke Jebaraj %A Charles Christober Asir Rajan %A Kumar Sriram %J Advances in Electrical Engineering %D 2014 %R 10.1155/2014/349787 %X This paper proposes an application of firefly algorithm (FA) based extended voltage stability margin and minimization of active (or) real power loss incorporating Series-Shunt flexible AC transmission system (FACTS) controller named as static synchronous series compensator (SSSC) combined with static var compensator (SVC). A circuit model of SSSC and variable susceptance model of SVC are utilized to control the line power flows and bus voltage magnitudes, respectively, for real power loss minimization and voltage stability limit improvement. The line quality proximity index (LQP) is used to assess the voltage stability of a power system. The values of voltage profile improvement, real power loss minimization, and the location and size of FACTS devices were optimized by FA. The results are obtained from the IEEE 14- and 30-bus test case systems under different operating conditions and compared with other leading evolutionary techniques such as shuffled frog leaping algorithm (SFLA), differential evolution (DE) and particle swarm optimization (PSO). 1. Introduction Voltage stability is concerned with the ability of a power system to maintain acceptable voltage at all buses in the system under normal conditions and after being subjected to a disturbance [1]. The recent day power systems are undergoing numerous changes and becoming more complex from the standpoints of operation, control, and stability maintenance when they meet ever-increasing load demand [2]. A system enters a state of voltage instability when a disturbance, increase in load demand, or change in system condition causes a progressive and uncontrollable decline in voltage. The main factor causing voltage instability is the inability of the power system to meet the demand for reactive power [3, 4]. The authors [5, 6] discuss methods to assess voltage stability of a power system to find possible ways to improve the voltage stability. Abnormal voltages and voltage collapse pose a primary threat to power system stability, security, and reliability. Moreover, with the fast development of restructuring, the problem of voltage stability has become a major concern in deregulated power systems. To maintain security of such systems, it is desirable to plan suitable measures to improve power system security and increase voltage stability margins [7]. Voltage instability is one of the phenomena which have resulted in major blackouts. Recently, several network blackouts have been related to voltage collapse [8]. The only way to counteract this problem is by reducing the reactive power load in the system %U http://www.hindawi.com/journals/aee/2014/349787/