Abstract
A suitable dynamic model of rotor system is of great significance not only for supplying knowledge of the fault mechanism, but also for assisting in machine health monitoring research. Many techniques have been developed for properly modeling the radial vibration of large hydro-turbine generator units. However, an applicable dynamic model has not yet been reported in literature due to the complexity of the boundary conditions and exciting forces. In this paper, a finite element (FE) rotor dynamic model of radial vibration taking account of operating conditions is proposed. A brief and practical database method is employed to model the guide bearing. Taking advantage of the method, rotating speed and bearing clearance can be considered in the model. A novel algorithm, which can take account of both transient and steady-state analysis, is proposed to solve the model. Dynamic response for rotor model of 125 MW hydro-turbine generator units in Gezhouba Power Station is simulated. Field data from Optimal Maintenance Information System for Hydro power plants (HOMIS) are analyzed compared with the simulation. Results illustrate the application value of the model in providing knowledge of the fault mechanism and in failure diagnosis.
Highlights
Large hydro-turbine generator units play important roles in power network, special attentions need to be paid to ensure their stability and safety in the process of operation
An applicable simulation model of radial vibration is influential for the following aspects: the comprehension of mechanism to the oscillation phenomenon, the failure diagnosis and condition-based maintenance of units
Numerical methods such as finite element method (FEM) are useful to obtain a numerical solution for the field associated problems, but the time for the calculation is so long that a FE rotordynamic model with such boundary model is too time-consuming for practical application [2]
Summary
Large hydro-turbine generator units play important roles in power network, special attentions need to be paid to ensure their stability and safety in the process of operation. Y. Xu et al / Dynamic model for hydro-turbine generator units based on a database method for guide bearings. Problem is that almost all the boundary conditions and exciting forces are field associated Numerical methods such as finite element method (FEM) are useful to obtain a numerical solution for the field associated problems, but the time for the calculation is so long that a FE rotordynamic model with such boundary model is too time-consuming for practical application [2]. Since there is no stationary position in a vertical machine, the linear dynamic coefficients of guide bearings cannot be used [4] Methods coped with this problem have been presented in previous literature. Either oversimplified or time-consuming method to analyze the guide bearing is not suitable for a simulation model. A brief and practical nonlinear guide bearing model may be prominent for the simulation of shaft system for large hydro-unit
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