Estimation of the damper winding pole-to-pole impedance in hydro generators

The damper winding of a synchronous machine plays an important role in its transient behavior. In the case of hydro generators, the electrical connection between the damper bars of the neighboring poles can be implemented in different ways. Typical design options include the conventional copper ring connection, the indirect connection through the pole end plate, and the open connection with no electrical contact at all. The goal of this paper is to experimentally determine the local impedance of each of these connections, as this influences the inductances of the complete damper winding system, especially along the quadrature axis. In addition to that, simplified calculation methods are developed for estimating this impedance. The findings of this research are relevant for providing the input parameters necessary to build a 2D transient model of the complete machine in future works.