多失效模式水轮发电机组非线性振动可靠性模型

Nonlinear Vibration Reliability of Hydraulic Turbine-generator Units with Multiple Failure Modes

以混流式水轮发电机组主轴系统为研究对象,应用有限元法建立主轴系统非线性动力学方程,分析系统非线性振动特性,得到系统的激励频率和固有频率。针对主轴系统结构尺寸、材料属性、水力参数及电磁参数的随机性,导出系统固有频率对随机参数的梯度关系,依据主轴系统激励频率与固有频率之差在规定范围内的关系准则,将变量空间划分为多个简单区域,推导单失效模式的失效概率和两失效模式的联合失效概率计算公式,并在此基础上建立具有相关失效模式的水轮发电机组主轴系统非线性振动可靠性模型,提出多失效模式水轮发电机组非线性振动可靠性分析方法。通过实例对混流式水轮发电机组主轴系统的振动可靠性进行仿真计算,并运用Monte Carlo法验证模型的正确性。

Taking the main shaft system of hydraulic turbine-generator unit as an object,the nonlinear dynamic equation is established by the finite element method.Based on the equation,the nonlinear vibration characteristics of the system are analyzed and the excitation frequencies of the system are obtained.Considering the randomness of the structure parameters,material parameters,hydraulic parameters and electromagnetic parameters of system,the gradients of natural frequencies to the random parameters are obtained.According to the criterion that the absolute values of difference between the natural frequencies and excitation frequencies of system should be less than specific values,the failure probability with one single failure mode and the combined failure probability with two failure modes are calculated by dividing the variable space into several simple areas.The nonlinear vibration reliability model of the main shaft system of hydraulic turbine-generator units with correlated failure modes is constructed and the method by which the nonlinear vibration reliability of system with multiple failure modes can be analyzed is proposed.An example is presented and the nonlinear vibration reliability model is proved by the Monte Carlo method.