Overview of algorithms for estimating swing modes from measured responses

Linear-system formulations are often used to describe power-system small-signal electromechanical dynamic properties. Over the past two decades, many techniques have been developed to conduct modal analysis using only actual-system measurements. Some techniques are appropriate for transient signals, others are for ambient signal conditions, and some are for conditions where a known probing signal is exciting the system. An overview of many of the more successful analysis techniques is presented. The theoretical background for these methods is summarized as well as application properties. Examples include computer simulations and actual system experiments from the western North American power system. Analysis goals center on estimating the modal frequency and damping.