Power System Stabilizer Design

With the development of national economy, the number of transmission lines with heavy load is increasing day by day. Accordingly , this induced the problem of low-frequency oscillations which have a very bad effect on stability of power system. PSS is an effective way to solve this problem, conventional PSS is designed at a normal operation point of power system which have been linearized. However, the real-life power system is nonlinear. So the effect of the PSS may be reduced when the operation point is changed and even can't prevent the oscillations when there exists big disturbance in the system.In order to solve the deficiency of conventional PSS ,this paper selects H_∞ control theory to design new power system stabilizer after comparing with artificial neural network, fuzzy control, adaptive control ,and combines the model of power system low-frequency oscillations with the model of H_∞ theory after analyzing the principle of them, in design the disturbance are considered together with the uncertainty of system, and the aim of design is transferred into mix-sensitivity problem ,the nominal model of power system and proper weight which is got by considering the disturbance of power system and the character of frequency compose the augmented plant, then the optimal power system stabilizer is obtained, the matlab simulation results under four operation points of single-machine infinite-bus system show that compared with conventional PSS ,H_∞ PSS provides better damping to the oscillation of the system than the conventional PSS under a wide range of operating conditions .