On the torsional dynamics of the subsynchronous cascade drive

This paper examines the torsional behaviour of the subsynchronous cascade drive. A four-mass model of the mechanical subsystem is considered in order to study the torsional oscillations of the shaft train due to the - characteristic for this drive - pulsation of the electromagnetic torque. A theoretical analysis is carried out and some guidelines are proposed regarding the design of the mechanical subsystem in order to avoid excessive torsional oscillations which may lead to severe mechanical damage in the shaft train. Finally, the torsional dynamics of this system are also investigated via simulation, where the non-linear characteristic of the mechanical coupling is additionally taken into account.