This paper proposes an application of differential evolution (DE) algorithm based extended voltage stability margin and minimization of real power loss incorporating static synchronous series compensator (SSSC) and static var compensator (SVC) devices. A new circuit element based model of SSSC and variable susceptance model of SVC are utilized to control the line power flows and bus voltage magnitudes for voltage stability limit improvement. The line stability index is used to assess the voltage stability of a power system. Voltage profile improvement values, real power loss minimization values and the location and size of SSSC and SVC devices were optimized by differential evolution algorithm. The results are obtained from the IEEE-30 Bus test case system and were analyzed with the voltage and real power loss under normal loading, critical loading and single line outage contingency conditions.

Key words: Differential evolution algorithm (DEA), voltage stability, static synchronous series   compensator (SSSC), static var compensator (SVC), line stability index, FACTS devices, load flow.