Disturbance analysis of hydropower station vertical vibration dynamic characteristics: the effect of dual disturbances

2015 ◽  
Vol 53 (2) ◽  
pp. 297-309 ◽  
Author(s):  
Baoping Zhi ◽  
Zhenyue Ma
Keyword(s):  
Dynamic Characteristics ◽  
Vertical Vibration ◽  
Hydropower Station ◽  
Disturbance Analysis

scholarly journals Study on Vibration Transmission among Units in Underground Powerhouse of a Hydropower Station

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3015 ◽  
Author(s):  
Jijian Lian ◽  
Hongzhen Wang ◽  
Haijun Wang
Keyword(s):  
Low Frequency ◽  
Field Tests ◽  
Vertical Vibration ◽  
Transmission Mechanism ◽  
Structural Vibration ◽  
Hydropower Station ◽  
Fe Model ◽  
Vibration Transmission ◽  
Underground Powerhouse ◽  
Mechanical Models

Research on the safety of powerhouse in a hydropower station is mostly concentrated on the vibration of machinery structure and concrete structure within a single unit. However, few studies have been focused on the vibration transmission among units. Due to the integrity of the powerhouse and the interaction, it is necessary to study the vibration transmission mechanism of powerhouse structure among units. In this paper, field structural vibration tests are conducted in an underground powerhouse of a hydropower station on Yalong River. Additionally, the simplified mechanical models are established to explain the transmission mechanism theoretically. Moreover, a complementary finite element (FE) model is built to replicate the testing conditions for comprehensive analysis. The field tests results show that: (1) the transmission of lateral-river vibration is greater than those of longitude-river vibration and vertical vibration; (2) the vibration transmission of the vibrations that is caused by the low frequency tail fluctuation is basically equal to that of the vibrations caused by rotation of hydraulic generator. The transmission mechanism is demonstrated by the simplified mechanical models and is verified by the FE results. This study can provide guidance for further research on the vibration of underground powerhouse structure.

Switched Model and Dynamic Analysis of a Hydroturbine Governing System in the Process of Load Rejection Transient

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Huanhuan Li ◽  
Diyi Chen ◽  
Feifei Wang ◽  
Hao Zhang
Keyword(s):  
Mathematical Model ◽  
Dynamic Analysis ◽  
Numerical Simulations ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Hydropower Station ◽  
Transfer Coefficients ◽  
Operational Conditions ◽  
Governing System ◽  
Hammer Impact

In this paper, we pay attention to studying the switched model of the hydroturbine governing system (HTGS) by introducing the concept of the switching of operational conditions. More specifically, utilizing the data of an existent hydropower station in China, we propose six nonlinear dynamic transfer coefficients of the hydroturbine, which can better describe the dynamic characteristics of the HTGS in the process of load rejection transient. Moreover, the elastic water hammer-impact of the penstock system and the nonlinearity of the generator for the process of load rejection transient are considered. Based on the combination of the different regulation modes of the governor and the corresponding running conditions of the hydroelectric generating unit, a novel nonlinear dynamic switched mathematical model of the HTGS is finally established. Meanwhile, the nonlinear dynamic behaviors of the governing system are exhaustively investigated using numerical simulations. These methods and analytical results will provide some theory bases for running a hydropower station.

Computation of Dynamic Characteristics of Deepwater Group Pile Foundation for Bridges

2011 ◽  
Vol 261-263 ◽  
pp. 1510-1514
Author(s):  
Can Xu ◽  
Wan Cheng Yuan ◽  
Kai Wei ◽  
Pak Chiu Cheung
Keyword(s):  
Dynamic Characteristics ◽  
Pile Foundation ◽  
Pile Group ◽  
Vertical Vibration ◽  
Lateral Bending ◽  
Approximate Analytical Solutions ◽  
Simplified Method ◽  
Pile Cap ◽  
Bending Modes ◽  
The Impact

In the design of deepwater foundation for bridges, the interaction between water and the structure especially under earthquake motions should be addressed. This paper presents a practical simplified method to analyze deepwater pile group foundation to determine its dynamic characteristics by combining approximate analytical solutions with the finite element method. The applicability of this proposed method is shown in a case study of a nine-pile foundation. Compared with those from complete numerical method, the analysis results from this simplified method are in agreement when the pile cap is not submerged in water. Furthermore when ignoring the vertical hydrodynamic added mass of the pile cap, the vertical vibration mode results are greatly affected, but not for other non-vertical vibration modes. This simplified method is also used in the study of the influence of water on the dynamic characteristics. The deeper the water is, the more obvious the impact of water is, particularly for the pile cap lateral bending modes, and there appears no evident difference for the pile lateral bending modes, on which water effect is stronger than that on pile cap lateral bending mode.

Dynamic Characteristics Research in Frame Structures Subjected to Vertical Vibration

2010 ◽  
Vol 163-167 ◽  
pp. 3935-3938 ◽  
Author(s):  
Zhi Hua Nie ◽  
Hong Bing Liu ◽  
Kai Liu
Keyword(s):  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Vertical Vibration ◽  
Frame Structures ◽  
Analysis Method ◽  
Parallel Connection ◽  
Joint Rotation

The traditional analysis method about dynamic characteristics with frame structures was building story models instead of structures. In this paper, the series-parallel-connection models with considering joint rotation on frame structures subjected to vertical vibration were presented, and the result what’s computed between the two models was compared, a notion called “natural frequency zone” was advanced. At last, some conclusions on the frame structures subjected to vertical vibration were obtained.

scholarly journals Design Optimization of a Mecanum Wheel to Reduce Vertical Vibrations by the Consideration of Equivalent Stiffness

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Jong-Jin Bae ◽  
Namcheol Kang
Keyword(s):  
Design Optimization ◽  
Dynamic Characteristics ◽  
Vertical Vibration ◽  
Equivalent Stiffness ◽  
Dynamic Simulations ◽  
Vibration Signals ◽  
Average Value ◽  
Vertical Accelerations ◽  
Vertical Vibrations ◽  
Mecanum Wheel

Mecanum wheels are capable of moving a vehicle to any direction instantaneously by the combination of independent wheel rotations. Because the mecanum wheel is composed of a hub and rollers, however, it has unavoidable drawbacks such as vertical and horizontal vibrations due to the sequential contacts between rollers and ground. In order to investigate the dynamic characteristics of a mecanum wheel, we made a prototype and performed experiments to measure the vertical vibrations. Interestingly, it was observed that the vertical accelerations were asymmetric with respect to the average value of signals; the vibration signals of upward and downward directions show quite different shape. This asymmetric phenomenon was confirmed through the dynamic simulations performed by RecurDyn. In addition, the peak-to-peak and RMS values of the displacements and accelerations were calculated to investigate the effects of the curvature of rollers on the vertical vibrations of the vehicle. Furthermore, we proposed a mecanum wheel having a spring to attenuate the vibrations. It was also noted that the significant reduction of the vertical accelerations was observed due to the absence of the spring. Finally, considering the equivalent stiffness of the mecanum wheel for several different fillet radii, we found the optimal geometric design which minimizes the vertical vibration of a mecanum wheel.

scholarly journals Dynamic Behavior of a Suspended Steel Space Frame-Glass Composite Floor

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhihao Wang ◽  
Xin Qi ◽  
Youkun Huang ◽  
Buqiao Fan ◽  
Xiaoke Li
Keyword(s):  
Dynamic Characteristics ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Vertical Vibration ◽  
Ambient Vibration ◽  
Fe Model ◽  
Glass Composite ◽  
Space Frame ◽  
Vertical Stiffness ◽  
Steel Space Frame

This study investigates the dynamic performance of a large-span suspended steel space frame-glass composite floor (SSSF-GCF). Both the ambient vibration and the human-induced vibration of the floor were experimentally measured to identify vertical dynamic characteristics and evaluate vibration serviceability of the floor. Although vertical dynamic characteristics of the floor based on the global simplified finite element (FE) model of the structure agree well with those identified via experimental modal analysis, the global simplified FE model significantly underestimates vertical vibration amplitudes of the floor due to the coupled effect between two layers. Accordingly, an equivalent local FE model of the floor system was proposed and updated via adjusting the vertical stiffness of the interstory hanging pillars. It is shown that the equivalent local FE model can well predict both the dynamic characteristics and human-induced vibration response of the floor. Finally, the effect of the damping ratio on the acceleration response of the floor was numerically demonstrated with the verified local FE model.

Vibration Control Analysis of High-Rise Cantilevered Floors under Pedestrian Walking Loads

2011 ◽  
Vol 94-96 ◽  
pp. 1110-1114
Author(s):  
Man Yi Qi ◽  
Zhi Qiang Zhang ◽  
Fei Ma ◽  
Ai Qun Li
Keyword(s):  
Dynamic Response ◽  
Vibration Control ◽  
Dynamic Characteristics ◽  
Human Activities ◽  
Vertical Vibration ◽  
Control Analysis ◽  
Tuned Mass Dampers ◽  
Human Comfort ◽  
High Rise ◽  
Normal Human

Aimed at the human comfort problem with cantilevered floors arising from normal human activities, the Tuned Mass Dampers are used to control the vibration of the steel cantilevered floors which span 16.3m. Based on studies on the dynamic characteristics of the overall structure, with the position of TMDs optimized and the parameters set reasonably, the vertical vibration response of the cantilevered floors under different cases of pedestrian walking loads is calculated. The results show that the TMD system can effectively reduce the dynamic response of the cantilevered floors, in order to meet the requirements of human comfort.

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