Analyzing Rotor Vibrations Caused by Exposing Synchronous Package Generator of Power Plant to Geomagnetic Disturbances

The research team has modeled a synchronous package generator-a transformer supplying power to an electric power system over a long overhead power line while exposed to geomagnetic disturbances. We selected a mathematical geoelectric-field model with linear intensity buildup, as such models are most informative for finding the intensity threshold, exceeding which affects the unit transformer. The harmonics of the stator current were found for the case of unilateral saturation of the package-transformer magnetic system at various potentials of the earthing device. It is shown herein that the second stator-current harmonic is the most significant one, as its current can reach 53% of the rated stator current. It is also proven that the rotor may begin to vibrate at 300 Hz due to exposure to a forward magnetomotive-force wave excited by the main stator-current harmonic; and to the backward magnetomotive-force wave of the second stator-current harmonic.