Vibration analysis of coupled bending-torsional rotor-bearing system for hydraulic generating set with rub-impact under electromagnetic excitation

Abstract

Based on Jeffcott rotor model, the coupled bending-torsional rotor-bearing system with rub-impact under electromagnetic excitation for hydraulic generating set is established and the corresponding equation is given. The influence of excitation current, mass eccentricity and electromagnetic torque in the system is investigated by taking use of numerical method. The simulation results show that eccentricity is the crucial factor causing the changes of system dynamic characteristics, compared to the effect of torsional degree of freedom. And the larger the eccentricity is, the more obviously it affects the system responses. While the complicated dynamic behavior of bending vibration response can be restrained, due to the introduction of torsion motion, which has the property to suppress complex dynamic response of system, particularly, the inhibited and improved effect is more evident, as the eccentricity turns to be smaller. In addition, the unstable jumping phenomena of torsional response can be motivated by electromagnetic torque, which has to be taken seriously during the process of model establishment and dynamic analysis of system. From the global view of electromechanical coupling characteristics, the coupled bending-torsional vibration model with rub-impact under electromagnetic excitation can supply a more comprehensive reflection about the dynamic characteristics of system and provide useful reference with system state recognition and fault diagnosis.

Bending fault evaluation for the HP-IP rotor system of the nuclear steam turbine based on the dynamic model

“…The undetermined coefficients in Eq. (13) show that the steady-state solution of the different nodes in the rotor system is the oval orbit; and the axis of rotor bends to a spatial curve. The period is 2 /Ω.…”

“…So, the bending phenomenon has been paid more attention to research its mode of origin, disadvantage and maintenance methods. In these existed studies, for obtaining the influence of the rub-impact faults from the rotor bending on the vibration response of the bearing-rotor system, the rotor dynamic model was established, including the linear model [5][6][7][8][9] and nonlinear model [10][11][12][13]. For example, Ren Z. et al presented a finite element model for a complex rotor-bearing system with coupled faults, such as the rub-impact and crack, and the results show that the responses of the rotor-bearing system increase due to the presence of the coupled fault [5].…”

“…Zhang X. et al proposed a comprehensive dynamic model and the dynamic behaviors (frequencies stiffness and dampness matrix, stability) of the ball bearing-rotor system were analyzed [12]. Zhang L. et al established a coupled bending-torsional rotor-bearing system with rub-impact under electromagnetic excitation for hydraulic generating set and the influence of excitation current, mass eccentricity and electromagnetic torque in the system is investigated by taking use of numerical method [13].…”

Dynamic safety assessment of a nonlinear pumped-storage generating system in a transient process

“…Pumped-storage generating system with a reversible Francis turbine (PSGS) performs as a nonlinear multi-purpose engineering equipment for power production and power consumption, enhancing the efficiency and reliability of electrical power systems [1][2]. Today, the average estimated growth rate of PSGS increases 10% annually in the world, with a total installed capacity of more than 100 GW [3][4][5][6]. Pumped-storage power stations are built to improve the maximum usage of thermal and nuclear power as well as to guarantee a high quality of power supply [7].…”

Dynamic Analyses of the Hydro-Turbine Generator Shafting System Considering the Hydraulic Instability

“…Modesto et al [3] presented the state of the art of hydraulic power generation in drinking and irrigation water networks through an extensive review and how hydraulic power can be applied in water distribution networks (drinking and irrigation) where energy recovery is not the main objective. Therefore, hydropower stations have become an important part of public utilities and infrastructure [4][5][6][7][8][9][10]. Recently, with the rapid development of manufacturing and energy industry, the hydropower stations have been developing towards higher rotational speeds, larger capacity and more complex operation conditions [11][12][13][14].…”