Low-order valid models for dynamic studies of multi-machine power systems

A dynamic equivalent of an external electric power system is estimated from locally measured information. A sensitivity method is used to select the most suitable model for the equivalent external system among several hypotheses. Local system responses, due to an intentional disturbance, are used for the parameter identification of external equivalent model. The estimated dynamic equivalent is verified by comparing the dynamic interacting effects of the original external system with those of the equivalent external system. It is further verified by short-circuit tests.