On the coupling measures between modes and state variables and subsynchronous resonance

Abstract

Abstract In a previous paper we related the participation factors of the selective modal analysis approach to MacFarlane's modal energies and we called them coupling measures between modes and state variables. In this paper we relate them to newly suggested measures of modal controllability and observability. We use the coupling measures to select an easily measurable signal, which is the line current, to feed back through the excitation loop to stabilize a single-machine system with subsynchronous resonance. We also show that a dynamic controller designed by classical frequency response methods changes the eigenstructure of the closed-loop system, so as to decouple the mechanical mode from the electrical variables. This links the work to some recent results on eigenstructure assignment by dynamic output feedback.