Real-time power system dynamic equivalencing to preserve system center of oscillations via PMU-based dynamic state estimator

This paper presents a novel scheme for real-time dynamic equivalencing of a power system to preserve the system center of oscillations. It is based on real-time dynamic monitoring of the system achieved through the implementation of a distributed, substation based, dynamic state estimator. The dynamic state estimator utilizes local (substation) synchronized and non-synchronized measurements and provides the evolution of the dynamic state of the system (real-time dynamic model) at rates of 60 times per second. The information provided by the dynamic state estimator, is used for the identification of the center of oscillations of the oscillating system. The center of oscillations is utilized as a reference physical point in the system in order to derive a dynamic simplified equivalent of the original system on the other side of the center of oscillations. The derived equivalent system mimics the dynamics of the original system and can be used for online dynamic security assessment of the system. The theoretical background and the methodology for the derivation of the dynamic equivalent system are provided. The accuracy of the derived dynamic equivalent model is also demonstrated.