Abstract: With regard to the single machine infinite bus (SMIB) system with uncertain parameters and uncertain disturbances, the nonlinear robust adaptive control algorithm based on (system) immersion and (manifold) invariant is designed for static VAR compensator (SVC). The proposed algorithm improves transient system performance when the uncertain damping coefficient and uncertain disturbances exist in the controlled system. The adaptive update law for the damping coefficient is based on the I&I adaptive method, and the designing procedure doesnot follow the classical certainty-equivalence principle. Meanwhile, in the design of the control law, L₂ gain restraint is applied to eliminating the effects of the uncertain disturbances on the system transient performance. The simulation result shows that the proposed SVC robust adaptive control algorithm is superior to the classical adaptive backstepping method in terms of the parameter estimation accuracy and the transient performance of the generator rotor angle, which indicates that the proposed algorithm can enhance the system's transient stability.