The Static Synchronous Compensator STATCOM is a shunt controller, which is a member of FACTS devices. In this paper, an effective and robust controller for STATCOM device on transmission lines, a Single Machine Infinite Bus SMIB system is modeled. A state space mathematical model is constructed which considers both electromechanical oscillations and reactive current of the STATCOM at the installation site. Based the obtained third order model, state feedback linearization and linear quadratic regulation LQR approach are applied to obtain a nonlinear control law. The controllers are simulated and tested under different operating conditions comparing with the conventional PI controller. Yadana Aung | Phyu Phyu Win | Moe Phyu Thel "Nonlinear Control of Static Synchronous Compensator (STATCOM) for Transmission System" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd28002.pdf