Transient Stability Assessment Using Individual Machine Equal Area Criterion PART I: Unity Principle

Analyzing the system trajectory from the perspective of individual machines provides a distinctive approach for the analysis of the transient stability of power systems. These two-paper series propose a direct-time-domain method that is based on the individual-machine equal area criterion. In the first paper, by examining the mapping between the trajectory and power-vs-angle curve of an individual machine, the stability property that characterizes a critical machine is elucidated. The mapping between the system trajectory and the individual-machine equal area criterion is established. Furthermore, a unity principle between the individual-machine stability and system stability is proposed. It is proved that the instability of the system can be confirmed by finding any one unstable critical machine, enabling the monitoring of the transient stability of a multimachine system in an individual-machine manner in transient stability assessment.