Abstract: The robust control problem was studied for the single machine-infinite bus containing thyristor controlled series compensation (TCSC) power system with parameter uncertainties and external disturbances. Based on a nonlinear third-order model for a single machine-infinite bus system, two kinds of nonlinear controller were designed using backstepping methods. With backstepping, the origin nonlinear system does not need to be linearized and the closed-loop error system is guaranteed to be asymptotically stable. When damping coefficients is measured inaccurately, a dynamic feedback controller can be designed using adaptive backstepping containing the real-time estimation of uncertainty parameter. The design procedure revealed that the controller designed by backstepping possessed good performances.