Placement of PMUs for tracking inter-area modes in the Mexican system

Identification of suitable signals in a power system for monitoring critical inter-area modes is a very important issue when using wide area measurement systems (WAMS). This paper reports on the application of modal analysis to identify the critical inter-area modes in the Mexican system and to determine a set of appropriate signals of the system for extracting both the frequency and damping associated with the inter-area modes. Identification and characterization of the inter-area modes were based on modal analysis. Participation factors and mode shape associated to the inter-area modes were also used for choosing suitable system signals that would allow a good tracking of those modes. Tracking of the inter-area mode was performed through the application of the Prony method to the time response of the selected signals. Finally, the study results served as a guide to the choice of an appropriate set of signals as well as suitable locations for Phasor Measurement Unit (PMU) placement for online monitoring of the inter-area modes.