水电机组轴系电磁振动特性实测与仿真分析

采用水电机组实测振动数据分析与轴系模型仿真验证相结合的方法,研究了某半伞式两导轴承轴流转桨式水电机组轴系在电磁力影响下的电磁振动特性。通过分析水电机组现场变励磁试验过程中的实测振动数据,总结出机组的实测电磁振动特性规律;利用机组轴系的有限元分析模型和不平衡磁拉力简化计算方法,对机组轴系在电磁力作用下的电磁振动响应进行了仿真验证。结果表明:该水电机组加励磁电流后,机组轴线发生显著偏移,同时上导轴承处的摆度明显增大,而水导轴承处的摆度反而有所减小;仿真验证结果与实测分析结果相吻合,较好地揭示了水电机组轴系电磁振动现象产生的原因。

Investigation on vibration characteristics for shaft system of hydro-turbine generator units under electromagnetic forces by field data analysis and simulation

A combined method of field data analysis and shaft system simulation is utilized in this paper to investigate the vibration characteristics of a Kaplan type hydro-turbine and a semi-umbrella type generator unit with two guide bearings under electromagnetic forces. Vibration data of variable excitation test was analyzed to summarize the vibration characteristics due to electromagnetic forces in the field test. A computational model combined with finite element method(FEM)model for the shaft system and a simplified analytical method for the unbalanced magnetic pull was then established to simulate and validate the dynamic response of the shaft system under the effect of electromagnetic forces. The results show that, for generator units of such type, a significant shift on the axis center can happen after excitation. Meanwhile, the vibration amplitude is increased significantly at the upper guide bearing but slightly reduced at the turbine guide bearing. The simulated results agree well with the field test results, indicating that the simulation analysis is reasonable and the reason of the vibration phenomenon can be well revealed.