OICC Press Majlesi Journal of Electrical Engineering 2345-3796 9 2 2024 02 20 Thyristor Controlled Series Capacitor for Generation reallocation Using Firefly algorithm to avoid Voltage instability EN Venkata Gundavarapu GITAM University Venkateswara Bathina GITAM University Journal Article 2024 02 20 Modern electric power utilities are facing many challenges due to increasing complexity in their operation and structure. In the recent times, one of the problems that got wide attention is the power system instabilities due to lack of new transmission facilities. Existing transmission facilities can be better utilized by installing Flexible AC Transmission System (FACTS) devices. The TCSC is the most effective FACTS device used to increase the power transferable capabilities of the transmission line. This paper presents a Sensitivity analysis based Complex Power Flow Sensitivity Index (CPSI) calculated for placing the TCSC at an appropriate location. Once the location to install the TCSC is determined, the optimal tuning of the TCSC and the impact of TCSC on Generation reallocation is determined through Firefly Algorithm. This Algorithm is implemented on multi objective function to obtain the Optimal Power Flow. The multi objective function consists of total real power loss, total voltage magnitude deviations, the fuel cost of total real power generation and the branch loading. Simulations have been carried out in MATLAB environment for the IEEE 57-bus system. The results have been taken for Firefly Algorithm based Optimal Power Flow without and with TCSC. The results obtained with Firefly Algorithm were compared with Genetic Algorithm (GA).