Calculation and Analysis of Torsional Vibration of Turbine Generator Shafts

摘要

The torsional vibration of turbine-generator shafts occurs due to the disturbance of electric power system. The coupling interaction between disturbance of electric power system and torsional vibration of shafts makes turbine-generator oscillate. Alternating torsional stress due to large torsional vibration decreases the life of shafts, even results in shafts broken. It is significant to calculate and analyze the natural properties and response of torsional vibration excited by the disturbance of electric power system in order to analyze and prevent catastrophic accident. A new method of response calculation of torsional vibration of turbine-generator shafts, the Increment Transfer Matrix method (ITM), which combines the Riccati transfer matrix method with the Newmark-β step-by-step integral method, is presented. By the ITM method, the transient response of torsional vibration of turbine-generator shafts, especially at the dangerous cross-sections, can be calculated. A system of calculation and analysis of torsional vibration of turbine-generator shafts is developed. With multi-mass lumped model, the model of torsional vibration of turbine-generator shafts is obtained. The system calculates the natural frequencies and the modal shapes of torsional vibration with the transfer matrix method, the response of torsional vibration of shafts with the increment transfer matrix method, such as torsional angle, angular velocity, angular acceleration, cross-section torque, torsional stress, and so on. The response spectrum of torsional vibration can be obtained by fast Fourier transform algorithm. It is proved that the system is good precision, convenient use, friendly interface, and visual calculation. The responses of torsional vibration of 200MW turbine-generator shafts due to the generator at non-all-phase operation are calculated and analyzed. The natural characteristics and responses of torsional vibration of shafts of 200MW turbine-generator are simulated and analyzed under the catastrophic accident condition. The cause of bolt broken of the coupling of intermediate-pressure rotor and low-pressure rotor and the coupling of generator rotor and exciter rotor are discussed. The results are identical with the data recorded in field.