中文摘要：

为揭示水电机组的机电耦联振动规律，研究了发电机转子轴系在电磁激励作用下的扭振特性．考虑凸极磁极分布对气隙磁导的影响，利用能量法推导了电磁转矩和电磁刚度的表达式；建立了电磁激励作用下的系统机电耦联扭转振动模型；通过模态分析揭示了系统存在零频现象，提出了零频的简化计算方法；利用级数解法求解了系统的稳态响应，并分析了稳态响应的敏感度．实例计算结果表明，提出的零频简化计算方法的精度可以满足工程要求；为控制稳态响应，应减小电磁刚度，降低激磁电流，使内功率角避开敏感区域．研究结果为机组的设计与稳定运行提供了理论依据．

英文摘要：

To reveal the rules of electromechanical coupling vibration of hydrogenerating set, torsional vibration characteristic of hydrogenerator rotor system under electromagnetic excitation were investigated. Considering the influence of distribution of salient pole on air-gap permeance, expressions of electromagnetic torque and electromagnetic stiffness were derived using energy method. Model of electromechanical coupling torsional vibration for the rotor system under electromagnetic excitation was established. Results of modal analysis demonstrate that zero frequency exists in the system, and a simplified calculation method of zero frequency was presented. Steady response of the system was solved using Fourier progression solution, and then response sensitivities were analyzed. An example shows the precision of the simplified method of zero frequency calculation can meet engineering requirements. To control steady response, electromagnetic stiffness and excitation current should be reduced with internal active power angle avoiding sensitivity areas. Results in this study provide theoretical foundation for the design of power station and the stable operation.