8. Measurement-Based Methods for Model Reduction of Power Systems Using Synchrophasors

Wide-area analysis and control of large-scale electric power systems are highly dependent on the idea of aggregation. For example, one often hears power system operators mentioning how “Northern Washington” oscillates against “Southern California” in response to various disturbance events. The main question here is whether we can analytically construct dynamic electromechanical models for these conceptual, aggregated generators representing Washington and California, which in reality are some hypothetical combinations of hundreds of actual generators. In this chapter we present an overview of several new results on how to construct such simplified interarea models of large power systems by using dynamic measurements available from phasor measurement units (PMUs) installed at limited points on the transmission lines. Our examples of study are motivated by widely encountered power transfer paths in the Western Electricity Coordinating Council (WECC), namely a two-area radial system representing the WA-MT flow, a star-connected three-area system resembling the Pacific AC Intertie, and a generic multi-area system with more than one dominant slow mode of oscillation.