Effect of damper windings' parameters on subsynchronous oscillation

Skin effect, magnetic saturation and temperature will have an impact on the equivalent resistance and leakage reactance of damper windings, and thus have an impact on the dynamic characteristics of the power system. Methods of data translation for synchronous generators will lead to different parameter errors. Moreover, the structures of damping system including damper bars and slot wedge have effect on the equivalent parameters of damper windings. The errors of classic generator design formula will also affect the equivalent parameters of damper windings. Previous studies mainly focused on the effects of whether to consider damper windings and the numbers of the equivalent damper windings on subsynchronous oscillations. By use of eigenvalue analysis, the influences of the damper windings' equivalent resistance and leakage reactance on the damping of subsynchronous oscillation modes are analyzed. The results show that, in a certain range, the damping of mode 0 to mode 4 increases with the increasing of damper winding's resistance, and vice versa. The effects of damper winding's leakage reactance on the damping of mode 0 to mode 4 have no obvious regularity, but the errors of damper winding's leakage reactance may have great influence on the damping. The damping of mode 5 is almost not affected by the damper windings' resistance and leakage reactance.