Mechanical countermeasures to subsynchronous torsional instability [in turbogenerators]

A mechanical countermeasure is presented that uses a fluid coupling to drive a flywheel at the end of a turbogenerator shaft, resulting in increased torsional damping for the shaft. The effect of varying the flywheel inertia and the fluid coupling´s characteristics on the mechanical damping is presented. The application of such a countermeasure to subsynchronous resonance requires studies to determine the size of the coupling and flywheel that would be required to offset any negative electrical damping that may exist due to series compensation on the transmission system