Study On Vibration Of Water Turbogenerator Stator System

As the turbogenerator are developing towards the large scale, especially with it's voltage and electric current enhancing even more than before, inevitable results are that electromagnetism field intensity and electromagnetism stress of turbogenerator are increased, and that the magnetism and solid coupling in the turbogenerator become more and more apparent. Hence it becomes more important to study the magnetism and solid coupling dynamics of turbogenerator stator system. The engineering background of the thesis is based on the 777.8MW water turbogenerator produced by ABB Corporations. Magnetism and soldid coupling vibration of water turbogenerator stator system is studied systematically when three-phase symmetric steady state. Through establishing a double-shell model of the water turbogenerator stator system, and the natural characteristic of the double-shell stator system is derived by means of the combination method of beam function. Magnetism and soldid coupling dynamic equation of the stator system is proposed. By using the method of multiple scales for nonlinear oscillation, nonlinear oscillation of magnetism and soldid coupling of stator system is investigated.The main work can be outlined as follows:(1) To establish the double-shell from the water turbogenerator stator system, the water turbogenerator stator system is simplified as double cylinder shells which contact with springs each other. The spring stiffness of cold state is considered as zero,and the spring stiffness of hot state is regarded as infinity.(2) In three-phase symmetric steady state the electromagnetic forces acting on the inner surface of the water turbogenerator stator core are obtained in consideration of the radial vibration displacements with the magnetic field in air gap coupling of the stator core. While calculating the electromagnetic forces, the effect of the radial vibration displacements of stator core on the electromagnetic forces is taked into account.(3) By means of the combination method of beam function, the analytic expressions formula of the inherent vibration modes of the stator system double-shell model are derived, and the inherent frequency of the stator system double-shell model is obtained.(4) The stator system vibration differential equation is established. Through using the method of multiple scales, the nonlinear dynamic characteristics of the forced resonances of the stator system double-shell model excited by electromagnetic forces are analyzed.(5) The effect of electromagnetism stiffness upon the inherent frequency of the stator system is analysed.