Finite-Element-investigations of the transient behaviour of salient pole synchronous machines with different damper end connections

The transient behaviour of synchronous machines is largely determined by the configuration of their damper windings. In this paper, the influence of damper end connections on the induced voltage in the open phase of a machine during a two-phase sudden short circuit is investigated using a commercial Finite Element package. It can be shown that a substantial increase of the resistance between the damper grids of successive poles leads to a significantly higher voltage in the open phase. Moreover, the ratio of the subtransient reactances in the direct and quadrature axes can be estimated from the magnitude of the induced voltage. This method is compared against other approaches known from literature.