An equivalent of multi-machine power systems and its identification for on-line application to decentralized stabilizers

An analysis of modal oscillations in multimachine power systems is presented. On the basis of the analysis, a power system equivalent representing a coherence mode of oscillations appearing in such a multimachine system is proposed for designing a decentralized control system. The equivalent is represented by an equivalent voltage and an equivalent reactance, which are identified by using measurements on a generator in the multimachine system under a transient condition. The identification is implemented by a sequential estimator based on the Kalman filter algorithm. Performance of the estimator is verified by using actual data on some example power systems