Nonlinear response of the generator rotor under the unbalanced electromagnetic force

The vibration response characteristics based on the unbalanced electromagnetic force and the oil film force coupling model for the generator rotor are calculated and analyzed. The nonlinear vibration for the 300 MW turbo-generator rotor under the different situation and different level (normal turns points) excitation winding inter-turn short circuit cases are carried out, and the typical parameters of the vibration response (such as the amplitude, frequency, and vibration component) are obtained. Meanwhile, as a comparative study, the linear and nonlinear dynamics results under the normal working condition are also studied. The results show that the fault of inter-turn short circuit may easily excite the low-frequency vibration, and the frequency is close to the rotor’s first critical speed; and the inter-turn short circuit fault located at the certain situation may induce the rotor’s 1/3 order subharmonic resonance or synchronous whirl.