水电站水机电-结构系统动力耦联模型研究及数值模拟

Model analysis and numerical simulation of a dynamic coupled hydraulic-mechanical-electric-structural system for a hydropower station

建立了包括引水系统、水轮机、调速器、发电机电磁系统、电网、水电机组轴系及厂房耦联结构等子模型在内全新的水电站系统非线性动力耦联模型。基于水力、电机、结构等学科理论构建了涉及水力、机械和电磁等因素的联立微分方程组,并采用有限元法建立机组轴系和厂房结构模型。结合Ansys的二次开发功能提出了水-机-电多因素影响下机组和厂房耦联结构模型不同工况动力特性的研究方法。采用差分法及特征线法等数值计算方法,利用该模型对水电站系统的开机工况进行了数值模拟计算和分析,同时对模型的合理性给予了验证。计算结果表明,该模型可以模拟计算水电站系统的开机工况运行过程,并能够较好反映水电站运行时的各种非线性动力特性。针对水电站系统较为复杂的特点,该模型的建立可对电站发电系统进行全面的数值模拟以评价和预测其运行安全性和结构可靠性,从而为水电站在极限工况和过渡工况的运行动态控制提供有益参考。

A novel nonlinear dynamic coupled model for a hydropower station system, which contains the model ofa water-carriage system, a water turbine system, a speed governor system, a generator s electromagnetic system as well as grid, a structural system with shaft of hydroelectric generating unit and powerhouse, was established. Firstly, the simultaneous differential equations for coupled hydraulic-mechanical-electric transient process were set up based upon the theories of hydraulics, electric machinery, etc. , while the coupled structural models of shaft for unit and powerhouse were built by means of the finite element method. Secondly, a new method for investigating nonlinear dynamic properties of structures, which was influenced by coupled hydraulic-mechanical-electric factors in different conditions, was introduced with the help of user programmable features of Ansys software. Finally, in order to verify the rationality, several numerical calculation methods were used to simulate and study the start-up process. The results indicate that the model presented in this paper can be adopted to simulate the start-up condition and reflect the nonlinear dynamic characteristics of hydroelectric station comprehensively. It is meaningful to supply an overall numerical result with assessing the operation safety and structures reliability. Furthermore, some references for dynamic regulation during limited and transient conditions of hydroelectric station can also be provided.