A Dynamic Model Establishment And Numerical Simulation Of Hydraulic-Mechanical-Electric-Structural System For Hydropower Station

The operation safety of hydropower station is the most important focus of water conservancy and hydropower project.The increasing of installed capacity for hydroelectric generating set leads to the trend of large scale unit and complicated powerstation structure,with the continuous development of social economy and the progress of science and technology.The problem of the structural vibration in the process of operation is more and more obvious.According to the operation safety of the unit and powerhouse structure caused by vibration in the transition process,then,in order to fully understand dynamic characteristics of the unit and powerhouse structure in the actual operation process of hydropower,and further to monitor and forecast the dynamic response characteristics of the unit and powerhouse structure during the operation process,this paper takes the hydroelectric power system of hydropower station as the research object.A dynamic hydraulic-mechanical-electric-structural system model is established through Fortran programming language and Ansys software with its UPFs function of development.The system model is roughly comprised of the submodels including penstock,water turbine,speed governor,generator,exciter,structures(hydroelectric generating set and powerhouse)and tilting pad guide bearings.And several numerical calculation methods are adopted to study the vibration charactersitics of unit and building structure under the transient process.The main research contents and results are as follows,(1)In order to realize the reasonable application of hydraulic turbine characteristic curve in hydraulic transition process and provide data support for modeling and solving the coupled hydraulic-mechanical-electric transient process,the full characteristic curve of the reconstructed turbine is obtained by the combination of artificial expansion and neural network fitting.Based on the practical engineering experience,the radial basis function method is used to develop and fit the characteristic curves of the water turbine.The numerical results show that,without significantly increasing the computational time,the extended curves in this paper can cover the shortage of the inadequate learning sample points with only using the neural network fitting existence,and can make the reconstructed curve is more reliable.(2)By summarizing and analyzing the previous research results of each subsystem model,and then based on Ansys software and Fortran language program,a dynamic coupled hydraulic-mechanical-electric-structure-structure system model is established with the relationship between key parameters of each subsystems.The system model can simulate the operation process,such as the start-up,load increased,load rejection and so on,then can analyze the regularity of hydraulics,mechanical as well as electric parmeters and vibration characteristics of structure under the multi system coupling.Finally,it can lay a solid foundation of theory and methodology for the safety evaluation and control of hydropower station.(3)On the basis of achievement(1)and(2),a numerical calculation of start-up condition of hydropower station is carried out by Finite Difference Method and Finite Element Method etc.The results show the change laws of parameters in each system and the dynamic charactersitics of unit structure during the lager fluctuation transient process,which verifying the rationality and effectiveness of the model proposed in job(1).(4)Based on the same above model,the numerical simulation of the transient process of the sudden load increased(5%-10%)of the hydropower station is carried out.The simulation studies the regularities of hydraulic,mechanical and electric parameters during the transient process and the dynamic behaviors of unit and building structure under the loads,especially the water pressure fluctuation of draft tube,which effected by these parameters.The vibration characteristics of the shaft structure and the floor structure of powerhouse in the transient process of small fluctuation are analyzed,and some regularity rules and some useful conclusions are obtained.