Slow-coherency based composite mode oscillatory stabilization by means of a hybrid PSS

The authors address the problem of the stabilization of composite mode electromechanical oscillations of electric generators. A hybrid PSS (power system stabilizer) with a two-level structure composed of a local PSS and a global PSS is proposed. A weighted combination of local and global control signals is used as the supplementary signal for the improvement of the damping characteristics of both local and interarea modes. Time-scale decomposition is applied to the decoupling of the local and interarea modes. Determination of the global control law is based upon a slow-coherency aggregated model