Damping shaft Torsional Oscillations with Application to High Speed Reclosure

A method of damping torsional oscillations in large steam turbine generators is presented. The method utilizes a small AC-DC converter connected to the high voltage side of the generator step up transformer. The DC side of the converter is connected to a large inductor which is used to store energy. By modulating the inductor energy appropriately, damping can be added to the torsional modes of a turbo-generator. It is shown that this added damping significantly reduces the shaft torques occurring as a result of unsuccessful high speed reclosure thus reducing the possibility of shaft damage