Sensitivity Analysis And Vibration Characteristics Of Shaft System Parameters Of Hydro-generator Set

With the national strategic goals of carbon neutrality and carbon peaking,the proportion of clean energy in the power energy structure is increasing.In addition to traditional power generation tasks,hydropower stations also need to provide services for the consumption of new energy such as wind power and photovoltaics.As the core equipment of hydropower stations,hydro-generator units need to face more complex coupling effects of external factors such as hydraulics,machinery,and electromagnetics in the context of the development of the new era.The vibration problem of units is becoming increasingly prominent.The resulting nonlinear dynamics phenomenon has attracted wide attention from the engineering and academic circles,and has become one of the hot research topics in the hydropower industry.This paper takes the shaft system of the hydro-generator unit as the research object,taking into account the universality of the vibration problem in the operation of the unit,the nonlinear dynamics of the rotor bearing system under the combined action of unbalanced magnetic tension,rubbing force and oil film force Systematic research has been carried out on the behavior,the sensitivity of the shaft system parameters of the unit,the evolution of the dynamic characteristics of the shaft system caused by random changes in external excitation,the correlation between the shaft system and the plant vibration,and the prediction and analysis of the shaft stability.The main research contents and results are as follows:(1)On the basis of analyzing the unit kinematics model under external excitation from a single aspect in the past,a unit shafting system model considering the unbalanced magnetic pull,rub-impact force and oil film force is established.This mechanical model better reflects the nonlinear dynamic behavior of the system.(2)Using the extended Fourier sensitivity analysis method,the sensitivity of the shafting system parameters to its output response is obtained,combined with the unit shafting operating parameters and the value range of the structural parameters,and bifurcation diagrams and time-domain diagrams are used to further It reveals the generation and development of its dynamic characteristics,measures to reduce or even avoid unit vibration,and provide theoretical support for the design,installation and operation stability control of the unit’s shafting system.(3)Considering the random changes of external excitation that may occur during the operation of the unit’s shafting system,the vibration characteristics of the unit’s shafting system due to the random changes of electromagnetic force,rub-impact force and oil film force are analyzed in terms of the intensity and scope of the random change.For example,the influence of unbalanced magnetic tension on the lateral vibration characteristics of the system under different random average values and variances.In addition,based on the previous research results of the coupling vibration between the unit and the powerhouse,the correlation mechanism of the coupling vibration between the unit shaft system and the powerhouse is analyzed,which provides a reference for the vibration fault diagnosis of the unit and the vibration and vibration reduction design of the unit powerhouse.(4)Aiming at the stability problem of the unit shaft system under different operating conditions,based on the established non-linear dynamic model of the unit shaft system,numerical simulation is used to obtain the stability type of the shaft system under different operating parameters and structural parameter combinations.The numerical simulation data is used as the training sample data of the stability prediction model of the unit shaft system.A neural network algorithm model suitable for multi-output and multi-output of the shafting system is proposed and trained based on sample data,and the machine learning model of the group shafting system is optimized,and the performance of the learning model is analyzed through the test set data.This model can better predict and analyze the vibration phenomena and stability types of the system under the external excitation coupling,and provide a useful reference for improving the accuracy of vibration fault diagnosis and active vibration control of the unit.