Adaptive Vibration Control Of Hydropower Unit Shafting System And Foundation

The vibration problem of large-scale rotating machinery has been paid attention to for many years.As a kind of large-scale rotating machinery,the hydro-generator unit has the influence of water-machine-electric coupling caused by the particularity of its own operating environment,making its dynamic response complex nonlinearity.With the trend for hydro-generator unit is moving toward large-scale and complicated,the nonlinear vibration problems and operational stability of the shaft system have become increasingly prominent.At the same time,the concrete foundation structure will generate complex uncertain vibration under various loads such as hydraulic pulsation,and the radial load will be transmitted to the unit through the guide bearing and the frame,which will affect the stable operation of the unit shafting.Therefore,it is of great theoretical significance and engineering to further study and reveal the inherent mechanism of the complex nonlinear dynamic characteristics of the hydropower unit shaft system and apply corresponding control measures for its different vibration states or fault phenomena to achieve safe and reliable operation value.In this paper,the hydro-generator shafting system is taken as the research object.The rotor dynamics theory and nonlinear numerical analysis method are used.The modeling and simulation analysis is carried out by MATLAB and Simulink program.The main work and research results are as follows(1)Aiming at the vibration time-dependent of hydro-generator unit shafting,the shape vibration alloy(SMA)is used to study the vibration control of the system and the nonlinear vibration model and control method of the hydro-generator shaft system with SMA damper are established.The effects of SMA dampers on the shafting vibration of hydro-generator units are studied by considering the corresponding bifurcation diagram and Poincare map respectively under the action of single and coupled excitation.The results show that the SMA damper has obvious damping effect on the shafting system of the hydro-generator unit,which can effectively reduce the vibration amplitude of the turbine shafting and improve the stability of the hydro-generator unit.(2)Taking the hydro-generator set and the foundation coupled power system as the research object,and considering the nonlinear effects such as rotor imbalance and runner sealing force,the nonlinear dynamic differential of the hydro-motor shaft system with basic random external excitation is established equation.The effects of basic random excitation on the vibration of the spindle system under different frequencies,intensities and spectral widths are studied.The results show that the change of the fundamental excitation frequency and the variation of the intensity and spectral width will affect the stability of the unit operation,resulting in complex nonlinear vibration phenomena such as multi-cycle motion and chaotic motion in the spindle system.(3)In order to solve the vibration problem caused by the basic excitation of the hydro-generator unit,a MRD damper-PID composite control method is proposed.Based on the vibration control of the conventional unit shafting of the MRD damper,according to the influence of the foundation random excitation on the unit shafting,the PID control is added in a targeted manner,and the damping force is adaptively adjusted through the feedback parameters to suppress the vibration of the unit shafting.Through the comparative analysis of the dynamic response of the hydro-generator shafting under control,it is shown that the MRD-PID control system can effectively target the vibration amplification of the unit shaft system due to faults,effectively reduce the impact of foundation excitation and improve the unit The stability of the axis system operation.