Identification and Predictive Analysis of a Multi-Area WECC Power System Model Using Synchrophasors

Abstract

This paper describes the construction of a reduced-order five-machine dynamic equivalent electro-mechanical model of the Western Electricity Coordinating Council (WECC) 500 kV power system network using slow mode oscillations of power flows derived from phasor measurement unit data. We first extract the slow oscillations using modal decomposition, and use them to estimate four key parameters of the reduced-order system, namely, the inter-area transmission line impedances, intra-area Thevenin reactances, rotational inertia, and damping of the aggregated synchronous generators. The resulting five-machine equivalent model is validated using different ranges of contingencies such as generation loss and line loss, and thereafter used for accurate prediction of oscillation mode frequencies and their damping factors. Finally, we present an algorithm by which this reduced-order model can be used to determine the criticality of line loss events within any area based on the divergence of load flow. The conclusions are drawn with the possible applications of the model for transient stability assessment, and prediction of stability limits needed to sustain increasing wind power penetration in the WECC.