水力发电机组轴系不确定性量化及参数敏感性分析

Uncertainty quantification and parametric sensitivity analysis of hydroelectric generating unit shafting

当前关于水力发电机组轴系的研究主要基于确定性的框架,但在实际工程中,不确定性因素对机组轴系的影响不容忽视。鉴此,将在不确定性框架下对水力发电机组轴系结构固有特性和动态响应开展不确定性量化和参数的全局敏感性分析。首先,建立一个包含不确定参数的水力发电机组轴系动力学模型。然后,基于广义多项式混沌方法构建不确定结构参数与输出变量之间的关系,并结合最大熵原理,求得系统随机输出的具体概率分布表达式。另外,通过对多项式混沌展开系数的简单后处理获得了不确定输入参数对轴系结构固有频率和振动响应不确定性贡献的量化指标。同时,不确定性量化及敏感性分析的可靠性也用暴力Monte-Carlo模拟进行验证。在所提出的不确定性框架下水力发电机组轴系不确定性及参数敏感性研究对水力发电机组的设计、优化和运行具有重要指导意义。

At present,studying hydroelectric generating unit shafting is mainly based on deterministic framework,but in practical engineering,effects of uncertain factors on the shafting can’t be ignored.Here,uncertainty quantification and global sensitivity analysis of parameters for natural characteristics and dynamic responses of hydroelectric generating unit shafting structure were studied under uncertainty framework.Firstly,a dynamic model of a hydroelectric generating unit shafting with uncertain parameters was established.Then,based on the generalized polynomial chaos method,relations among uncertain structural parameters and output variables were constructed,and combined with the maximum entropy principle,the specific probability distribution expressions of random outputs of the system were obtained.In addition,through the simple post-processing of polynomial chaotic expansion coefficients,quantitative indexes for uncertain input parameters’contributions to uncertainty of natural frequencies and vibration response of the shafting structure were obtained.Meanwhile,the reliability of uncertainty quantification and sensitivity analysis was also verified by using Monte-Carlo simulation.It was shown that studying uncertainty and parametric sensitivity of hydroelectric generating unit shafting under uncertainty framework here has important guiding significance for design,optimization and operation of hydroelectric generating unit.