Design And Analysis Of Control Circuit For TCSC FACTS Controller Chiranjit Sain Siliguri Institute of Technology, Electrical Engineering Department Dr. Soumitra Kumar Mandal National Institute of Technical Teacher‟s Training And Research, Kolkata, Electrical Engineering Department Sanjukta Dey Siliguri Institute of Technology, Electrical Engineering Department Abstract Power system engineers are currently facing challenges to enhance the power transfer capabilities of existing transmission system. This is where the Flexible AC Transmission Systems (FACTS) technology comes into effect. Thyristor Controlled Series Capacitor (TCSC) is one of the important member of FACTS family, is an impedance compensation which is used in series reactance on an AC transmission system to provide smooth control of series reactance by controlling thyristor firing angle (α) to increase the capability of the reactive power compensation of the transmission line. This paper presents design of control system by MATLAB/PSCAD which is used to implement the performance of the proposed control circuit in case of peak load and half load of the transmission line where the simulation shows a good result where the reactive power is compensated and transmission line capacity is extended. Key-words: FACTS, TCSC, Reactive power compensator, static VAR compensator. 1. Introduction Present power systems are highly complicated, sometimes made of the thousand buses and hundreds of generators. Basically new power generating stations are primarily determined based on environmental and economic reasons, and are somewhat inexpensive, easy to build and operate. With the lack of new generation and transmission facilities and over exploitation of existing facilities geared by increase in load demand makes system instability. On the other hand new transmission systems are expensive and take considerable amount of time to build. Hence, in order to meet increasing power demands, utilities must rely on power export, important arrangements through existing transmission systems. While the power flows in some of these transmissions line is well below their thermal limits, certain lines are overloaded, which has the effect of fluctuating voltage profiles and decreasing power system stability. Flexible AC Transmission Systems (FACTS) is a new approach to a more efficient use of existing power system resources based on the utilization of 1353 International Journal of Engineering Research & Technology (IJERT) Vol. 2 Issue 5, May - 2013 ISSN: 2278-0181 www.ijert.org