Simplified Analytical Circuital Model of Damper Windings Exploiting Symmetries

The damper windings of salient-pole, wound-field synchronous generators are currently attracting a renewed interest due to their impact on the machine efficiency and power quality, which was somewhat overlooked in the past. This paper focuses on the equivalent circuital modeling of damper windings. After recalling its main physical features, the general approach is first presented, permitting to define an equivalent circuit and to derive the related resistance and inductance matrixes whatever is the pattern of the cage bars. Further assumptions deriving from common or advanced features of damper windings are then analyzed, such as symmetrical, antisymmetrical, shifted and modulated position patterns. It is then shown how such assumptions can be exploited to simplify and shrink the equivalent circuital model of damper windings when analyzing realistic operating conditions.