Transmission congestion must be managed so that transmission capacity is utilized as efficiently as possible with minimal social welfare loss-usually by system operator. Congestion management must provide incentives for investments in transmission network and generation capacity in the right areas. Minimizing the risks associated with different congestion management methods are important task for every market participant who is trading between different areas. The idea for solving this problem is the use of FACTS devices especially the use of Static Var Compensators (SVC). In this paper the study of SVC with its various modes of operation is investigated. Finally by help of modeling of a power system in MATLAB/PSAT toolbox, and by installing SVC in transmission line, its use as power flow controller and voltage injection is seen. Conclusion is made on different results to see the benefit of SVC in power system.