Numeric calculation of current distribution in the damper cylinder of a large superconducting generator

The calculation of the subtransient reactance, winding forces, and surface losses in large superconducting turbogenerators with an air-gap stator winding must start from the three-dimensional magnetic stator winding field. A calculation method for the damper current distribution is presented that approximates the damper cylinder by a grid of short-circuited loops with an infinite conductivity. The magnetic field of the stator winding and the field of the damper cylinder are calculated by the Biot-Savart law. The loop currents are calculated by iteration. As a sample result, damper current distribution plots are shown for a generator with a special type of high-voltage stator winding called the coaxial turn winding