BENDING-TORSION COUPLING VIBRATION OF A HYDROGENERATOR RUB-IMPACT ROTOR SYSTEM

摘要

The rub impact between the stator and the rotor of a hydro-turbine generator results from electromechanical coupling oscillation and excites bending-torsion coupling vibration, which can lead to serious work accidents. A dynamic bending-torsion coupling model of a rub-impact rotor system for a hydro-turbine generator was established, and a novel simulation method of unbalanced magnetic pull was proposed. With this method, the magnetic stiffness in the bending and torsion directions was obtained by deducing the gap magnetic field energy equation. The bending-torsion coupling vibration of the system was characterized through magnetic stiffness analysis. The effects of electromagnetic stiffness, eccentricity, and damping ratio on the vibration were investigated in the time and frequency domains. Simulation results showed that the bending and torsion electromagnetic stiffness exerted mutual excitation and amplification. The influence of the electromagnetic stiffness decreased with increasing eccentricity. Damping played an important role when the mass eccentricity was large because of the strong bending-torsion coupling effect. The increase in the stator radial stiffness weakened bending vibration but strengthened torsion vibration.