Torsional Vibration Analysis of Hydro-Generator Set Considered Electromagnetic and Hydraulic Vibration Resources Coupling

Abstract

The torsional vibration characteristics of the hydro-generator set considering the electromagnetic and hydraulic vibration resources coupling are studied. The moment of rotation consists of water flow driving and magnetic torques caused by the air gap magnetic field in the generator rotor in the case of ignoring the mechanical friction. A coupling torque vibration model of hydro-generator shaft system was established. The model considered the coupling action of hydraulic and electromagnetic excitations, as well as the elastic effect of rotor spiders. The influences of the rotor moment inertia, rotor stiffness, and mass of turbine water added into the torsional natural vibration of the unit shaft system were studied. The effect of hydraulic excitation frequency on torsional vibration response was also investigated. The frequency response curves of shaft torque, torsional vibration angle, and electromagnetic torque were presented. The electromagnetic and hydraulic coupling resonance was studied when hydraulic excitation frequency was equal to zero and first-order frequencies. The excitation electric current and internal active power angle on torsional vibration was further analyzed. This study provides an analysis model and method considering the coupling of electromagnetic and hydraulic vibration resources for design and stable operation of water turbine generator sets.