Calculation and analysis on eddy current loss of damping bar under asymmetrical operation of 1000 MW hydro-generator

Aiming at the phenomenon that the damping bars would easily fuse under the asymmetrical operation of large hydro-generator, the eddy current loss of damping bars under the asymmetrical operation of a 1000 MW hydro-generator was further studied on the basis of establishing two-dimensional electromagnetic field-circuit-motion coupled time-stepping finite element model. The influence of such factors as the stator slotting, magnetic pole rotation and stator current on the eddy current loss of damping bars were comprehensively considered. The eddy current loss of each damping bar in one magnetic pole under different operating conditions was accurately calculated, and the change rule of eddy current loss was analyzed. And thus, the influence of the connection mode of damping system as well as the radius and material of damping bar on the eddy current loss of damping bars was discussed. The results indicate that the eddy current loss of last damping bar along the rotation direction is the largest, and the structure parameters of damping system have greater influence on the distribution of eddy current loss of damping bars.