The Dynamics Characteristic Analysis For The Shafts Of Large Hydraulic Generator Unit

The hydraulic generator unit is the essential equipment of the hydroelectric power generation, and Shafts are the important part of large hydroelectric machines. Its dynamic characteristic is bound up with the hydroelectric reliability, life-span and economic index of the entire machines. Therefore, it is analysis the large hydroelectric machines from the aspect machines. It is important to analysis the large hydroelectric machines from the aspect of theory.By using concentrated mass method, the author built a mathematic model with thinking of the system boundary of machines affecting the shafts, such as the guide bearings, seal, electrical and hydraulic forces, the water in the runner etc. Taking into account the different support conditions of the shafts that workshop is considered as rigidity or elasticity; the natural characteristic of the shafts are computed by integrating with high stable Riccati Transfer Matrix Method.Riccati transfer matrix and Newmark numerical integral method are adopted to calculate and analyze instantaneous non-linear response of the rotor system of the hydraulic generator sets in the paper. First of all, model of the rotor system is founded. The effect of shear deformation, rotary inertia and gyroscopic moment are considered, and the action of the water additional mass in the hydraulic turbine and electromagnetic induction of instantaneous response of the rotor system under arbitrary forces are obtained. The concept of non-linear oil film force of the bearing is further cleared, and its influencing factor is summarized. The action of non-linear oil film force is considered when calculating. A software system to calculate response of the rotor system is programmed, and the calculation results are analyzed and compared.Based on the computations, following conclusions can be drawn:1)The critical speed of the shafts is influenced obviously by the elastic bearing.2)Disequilibrium magnetic pull reduce the first order critical speed, but has no effects on second order critical speed;3)When the rotor has initial position and initial speed, the shaft's nonlinear node conservation speed is larger than linear conservation speed;4)Underunbalanced condition, nonlinear response will become much more complicated.