Study On Tosional Vibration Damage For Shaft System Of A 600MW Steam Turbogenerator

The problem of torsional vibration of shaft system is a long time, but with the development of power system and the complexity of power grid operation mode, shaft torsional vibration problem in the large thermal power unit has become more and more prominent. Torsional vibration has a great influence on generating units, once an accident happens, it will not only cause harm to personal safety, but also cause serious economic loss. So it is very necessary to analyze its security. In large thermal power steam turbine, shaft system is a part of the unit which has been in a bad environment for a long time, it's life can basically reflect the life of unit.Torsional vibration damage will consume the shaft life, so we need to focus on the shafting torsional vibration damage during operation. The torsional vibration test of a 600 MW steam turbine generator set in a domestic power plant and its measured data are studied in this paper, the fatigue life damage and its safety of large scale thermal power units are analyzed. Research ideas is to analysis the torsional vibration test data, select the specific operating conditions of the torsion vibration, detailed analysis of torsion vibration and the attenuation process, based on the S-N curve, modal analysis and the torsional stress spectrum of the key parts of the shaft, use the method of rain flow to analyze the fatigue life of the shaft.First according to the actual structure parameters, the full size of the shafting is modeled, the modal analysis is carried out, and we verified the actual situation of the power plant. The result of modal analysis is the basis of the analysis for theigue loss to the key parts of the shaft system. According to the material parameters, the S-N curve of the rotor material is obtained, which must be corrected by the stress concentration, the size of the structure, the surface quality and other factors to obtain the S-N curve of the shaft system with practical significa nce.We are directly involved in the torsional vibration test of a unit 1 in China to collect a large number of data, which is needed to be processed deeply combined with the modal analysis of the shaft system, the torsional angular velocity curves of the key parts of the shaft are obtained under certain conditions, and the variation of the twist angle is obtained.For these special cases, the torsional angle and the stress change of the dangerous position of the shaft torsional vibration before or after the shaft torsional vibration system are analyzed respectively, the fatigue life damage is calculated and evaluated, which provides reference for the operation of power plant and equipment management.