A stabilizer for oscillating torques in synchronous machines

A novel torque stabilizer was developed and has been continuously applied at the Max-Planck-Institut fur Plasmaphysik (IPP), Garching, Germany, as a countermeasure to torsional oscillation and resonance problems in large synchronous machines. Such problems are most frequently encountered in rotor systems with long shafts and large inertias constituting a weakly damped mechanical resonator which exhibits a low resonance frequency, e.g., 10-30 Hz. This paper presents examples for the successful suppression of torsional resonances in synchronous machines of the IPP experimental power supply, an isolated power system based on flywheel generators. The novel torque stabilizer is a power electronic device which is connected to the stator winding of the synchronous machine. It produces the same effect as an increased natural damping for oscillation modes in the rotating shaft assembly. It is, therefore, universally applicable to torsional oscillation problems in generators and electrical drive systems.