Abstract:
The generator shaft designers usually consider the shaft torques that develop during
short circuit as the most severe case. But, recent studies show that the developed
torques due to faulty synchronisation could be greater than that occur during short
circuit. This thesis describes a method of simulating faulty synchronisation of a generator
with a power system. Previous studies, in almost all cases, neglected the effects of
generator saturation in the process of simulation. Even included, the saturation only
in the mutual paths of a p;enerator was considered. But since the currents involved
during faulty synchronisation become quite large for some synchronising angle, the
leakage paths may also saturate. The simulation of faulty synchronisation described
in this thesis includes saturation both in the mutual and leakap;e path of a p;enerator.
It has been demonstrated that a considerable change in results occur if saturations
in a generator are neglected.
A comparison between the phenomena of faulty synchronisation and that of short
circuit has also been incorporated in the work. For this purpose, the shaft torques
developed during fault throwing test under varying conditions are studied. The results
reveal that the shaft designers should consider the magnitude of torques developed
during faulty synchronisation as one of the design criterion of turbine generator shaft
system.
