10. Interarea Mode Analysis for Large Power Systems Using Synchrophasor Data

Interarea oscillations are predominantly governed by the slower electromechanical modes which, in turn, are determined by the coherent machine rotor angles and speeds. The issue is that, although these rotor angles and speeds provide the best visibility of such modes, currently they are not available from phasor measurement units (PMU). As such, the aim of this chapter is to demonstrate that interarea oscillations are observable in the network variables, such as voltages and line currents, which are measured by PMU. By analyzing the electromechanical modes in the network variables, we can trace how electromechanical oscillations are spread through the power network following a disturbance. Applying eigenvalue and sensitivity analysis, we provide an analytical framework to understand the nature of these network oscillations through a relationship termed network modeshapes. Using this relationship, a novel concept, “dominant interarea oscillation paths,” is developed to identify the passageways where the interarea modes of concern travel the most. We demonstrate the concept of the dominant path with an equivalent two-area system. We propose an algorithm for identification of the dominant paths and illustrate with a reduced model of a large-scale network. Finally, we end this chapter with an important application of the concept: feedback input signal selection for damping controller design.