Damping Shaft Torsional Oscillations Using a Dynamically Controlled Resistor Bank

The technical feasibility of using a dynamically controlled, three phase resistor bank to damp shaft torsional oscillations in large steam turbo-generators is examined. Torsional damping is achieved using a straightforward control strategy based on generator speed. A study system is defined and the shaft torques following various electrical system disturbances are computed and analyzed. It is shown that substantial damping can be achieved with a relatively small resistor bank, thus reducing the risk of significant shaft damage due to electrical disturbances.