Torsional interaction between nonidentical turbine generators

Torsional interaction between nonidentical generating units with a coincident torsional mode is investigated. The generators are electrically identical but have differences in their mechanical parameters. The mechanical system of each generator in the two-machine model is represented by the modal mode; this permits independent variation of mode damping, inertia, and frequency, which is not possible with the conventional spring-mass representation. It is shown that in a system without series capacitance, differences in mode damping affect the phase deviation but not the relative amplitude of torsional oscillations, the opposite being true for mode inertia and frequency differences. The amplitude and phase characteristics are both greatly affected by series capacitance for a difference in any mechanical parameter