Dynamic Security Assessment of Bulk Transmission Using PMUs

This paper investigates the use of PMU-based voltage angle differences as indicators of interregional power transfer behavior, with application to the Brazilian Interconnected Power

System. A K-Means clustering-based methodology is employed to dynamically identify representative nodal pairs within each subsystem, accounting for changing operating conditions and the distributed nature of real power systems.

Results obtained with one-hour clustering windows consistently show high correlation levels for both energy-exporting and energy-importing operating scenarios on the Northeast subsystem, indicating that angular differences reliably capture inter-regional power transfer behavior. Analyses using shorter monitoring windows reveal lower correlation, primarily associated with limited power-flow variations and SCADA measurement characteristics, rather than changes in the representativeness of the selected nodal pairs.

The spatial recurrence of representative PMU located in electrically well-connected regions further confirms the physical consistency of the proposed approach. Overall, the results show that PMU-based angular difference monitoring offers a practical and transferable complement to SCADA-based supervision, supporting inter-area monitoring and Dynamic Security

Assessment applications in large-scale power systems.