Vibration characteristic analysis of rotor in excitation winding inter‐turn short circuit state of turbo generator

The distribution characteristics of fault electromagnetic field and temperature field and the unbalanced stresses on the rotor could be obtained through establishing a three‐dimensional model of the rotor and two‐dimensional models of the stator and rotor, and respectively solving the electromagnetic field and the temperature field of excitation winding inter‐turn short circuit fault by using the finite element analysis method. Two kinds of unbalanced stresses can be respectively equivalent to the unbalanced masses on the rotor surface. The equivalent centrifugal forces as excitation are added into the rotor dynamic equation, and solving the dynamic equation of the rotor by means of Newmark can finally obtain the rotor vibration response. The results show that the fault will cause the changes of amplitude and phase of rotor fundamental frequency vibration. So the amplitude and phase difference of the rotor fundamental frequency vibration can be used as the fault criterion in order to make an accurate diagnosis of excitation winding inter‐turn short circuit fault. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.