Concepts on Field Excitation Control of Subsynchronous Resonance in Synchronous Machines

Saito, Mukae and Murotani [1] have showni, theoretically and experimentally, that the negatively damped subsynclironous resonance (SSR) in capacitor compensated transmission lines can be suppressed by feedback field excitation control of the synchronous machine. This paper presents concepts which explain that thie positive dampping is achieved by ensuring that the motoring process ldominates the induction generdtion process at the SSR frequency. Irequency criterion, phase shift guideline and controllable sectors are derived for design purposes. The concepts are supported by numerical results confirming the existence. of the predicted controllable sector and by diagrams from eigenvector analysis.