10 MVA thyristor converters for the active damping of generator shaft oscillations at ASDEX Upgrade

Over the last years, ASDEX Upgrade (AUG) improved its fast plasma feedback control. This had a direct implication on the magnetic coils power supplies. During a discharge, very fast changes of the active power occur. This results in torsional oscillations in the flywheel generators shaft lines that feed the power supplies. These oscillations speed up the aging of the generator assemblies. Therefore an active control system providing electromagnetic damping for the generator shaft oscillations has been set up. To optimize this system, two new thyristor converters have been installed and commissioned. ally the new “design features” of the thyristor converter Groups 8 and 9 with generator torque reference processing and protection will be explained in the paper. Further on, the paper will present the various modes of operation, analyses the results of measurements obtained during commissioning, compares them to the calculated (design) values and reports on the performance achieved during AUG plasma experiments.