DYNAMIC ANALYSIS OF A HYDRAULIC TURBINE UNIT1*

Abstract

Dynamic analysis is of great importance not only for understanding the natural characteristics and dynamic response of a rotor-bearing system, but also for supplying knowledge of the fault mechanism. The dynamic analysis of a large-scale waterturbine generator set has rarely been investigated. This article establishes a model of a large water-turbine generator set and presents some research results. This article provides a detailed calculation of the critical speed and vibration modes by the Riccati transfer matrix method (RTMM) to study the influence of stiffness of the guide bearings on the characteristics of the shaft. A detailed dynamic model is presented of the No. 1 unit of the Guangzhou Pumped Storage Power Station (GPSPS) in southern China, including nonlinear characteristics of the guide bearing, the thrust bearing, and the magnetic force. An efficient simulation method, referred to as the transient Riccati transfer matrix method (TRTMM), is used to calculate the transient response of the rotor-bearing shaft system. Some simulation results are also presented for responses to other types of forces such as unbalance inertial forces and nonlinear magnetic forces. Results show that, for large vertical water-turbine generator sets, there exists a common characteristic in the first three vibration modes, that is, the maximum amplitude is at the generator rotor in the first vibration mode, while in the third vibration mode, the maximum amplitude is near the turbine runner. Simulation results show that the method and program are correct and can be used expediently. The response of the rotor-bearing system with different values of preload coefficients of the tilting-pad journal bearing reflects the influence of the bearing clearance on the vibration amplitude and the time required for the vibration from transient state to steady state. The effect of hydraulic forces acting on the runner shows that the vibration amplitude and the time required for the vibration at the three guide bearings to reach steady state are different. The analysis of the lateral shaft vibration caused by nonlinear magnetic forces shows that it will produce a new frequency component of 150 Hz. *Communicated by B. Heimann.