Design of Power System Stabilizers Using Synergetic Control Theory

Power system stabilizers (PSSs) are used to provide damping torque for the synchronous generators to suppress low frequency oscillations present in the power system by generating supplementary control signals for the excitation system. Strong nonlinearity and dynamics exist in the power system. Numerous previous techniques have been proposed to design PSSs but many of them are synthesized based on a linearized model. This paper presents a nonlinear power system stabilizer based on synergetic control theory. Synergetic synthesis of the PSS is based fully on a simplified nonlinear model of the power system. The synergetic control law provides asymptotic stability with respect to the required operating modes, invariance to the load variations, and robustness to variations of the input variables and power system parameters. The dynamic characteristics of the proposed PSS are studied in a typical single-machine infinite-bus power system and compared with the cases with a conventional PSS and without a PSS. Simulation results show the proposed PSS is robust for such nonlinear dynamic system and achieves better performance than the conventional PSS in damping oscillations.