scholarly journals Torsional Vibration of a Shafting System under Electrical Disturbances

2012 ◽  
Vol 19 (6) ◽  
pp. 1223-1233 ◽  
Author(s):  
Ling Xiang ◽  
Shixi Yang ◽  
Chunbiao Gan
Keyword(s):  
Transfer Matrix ◽  
Torsional Vibration ◽  
Simulation Analysis ◽  
Short Circuit ◽  
Lumped Mass ◽  
Concentrated Mass ◽  
Dynamical Equations ◽  
Mass Model ◽  
Two Phase ◽  
Turbo Generator

Torsional vibration responses of a nonlinear shafting system are studied by a modified Riccati torsional transfer matrix combining with the Newmark-βmethod. Firstly, the system is modeled as a chain consisting of an elastic spring with concentrated mass points, from which a multi-segment lumped mass model is established. Secondly, accumulated errors are eliminated from the eigenfrequencies and responses of the system's torsional vibration by this newly developed procedure. The incremental transfer matrix method, combining the modified Riccati torsional transfer matrix with Newmark-βmethod, is further applied to solve the dynamical equations for the torsional vibration of the nonlinear shafting system. Lastly, the shafting system of a turbine-generator is employed as an illustrating example, and simulation analysis has been performed on the transient responses of the shaft's torsional vibrations during typical power network disturbances, such as three-phase short circuit, two-phase short circuit and asynchronous juxtaposition. The results validate the present method and are instructive for the design of a turbo-generator shaft.

An Increment Transfer Matrix Method for the Torsional Vibration Response of Steam Turbo-Generator Shaft System

2010 ◽  
Vol 34-35 ◽  
pp. 1082-1087 ◽  
Author(s):  
Cheng Bing He ◽  
Cheng Xing ◽  
Jian Shen
Keyword(s):  
Transfer Matrix ◽  
Torsional Vibration ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Short Circuit ◽  
Nonlinear Differential Equations ◽  
Mass Model ◽  
Shaft System ◽  
Turbo Generator ◽  
Generator Unit

In order to solve nonlinear system torsion response of turbo-generator unit, an increment transfer matrix method based on step-by-step integration method and traditional transfer matrix method was put forward. The method can be directly used to analyze nonlinear differential equations. Combined with Riccati method, the increment transfer matrix method was used in a multi-mass model. And matrix equations calculating the responses of torsional vibrations were deduced. Torsional vibration resulted from the faults of short circuit and asynchronous synchronization of 600MW steam turbo-generator unit were discussed in this work by using the increment transfer matrix method which can also extend the application of transfer matrix method in nonlinear field.

Study on Dynamic Response of Torsional Vibration of Turbo-Generator Unit Caused by Short Circuit Fault

2012 ◽  
Vol 566 ◽  
pp. 248-252 ◽  
Author(s):  
Cheng Bing He ◽  
Dong Chao Chen ◽  
Yu Jiong Gu
Keyword(s):  
Torsional Vibration ◽  
Short Circuit ◽  
Dynamic Responses ◽  
Stable Operation ◽  
Two Phase ◽  
Time Frequency ◽  
Turbo Generator ◽  
Complex Morlet Wavelet ◽  
Generator Terminal ◽  
Short Circuit Fault

When short circuit faults happen near power plant or generator terminal, severe transient torque shock will act on the shaft system, which seriously affects the safe and stable operation of the unit. Using the increment transfer matrix method, the dynamic responses of torsional vibrations are calculated in this work. Combined with the complex Morlet wavelet and time-frequency contour map, the time-frequency domain characters of dynamic torque are analyzed. The analyzed results show that the torque value caused by three phase short circuit fault is largest. The order of torque value from high to low is two phase short circuit to ground, two phase interphase short circuit and single phase short circuit. The electric distance between short circuit point and generator is more short, and the torsional vibration is more serious.

Coupled Torsional Vibration and Fatigue Damage of Turbine Generator Due to Grid Disturbance

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Chao Liu ◽  
Dongxiang Jiang ◽  
Jingming Chen
Keyword(s):  
Fatigue Damage ◽  
Torsional Vibration ◽  
Coupled System ◽  
Lumped Mass ◽  
Mass Model ◽  
Turbine Generator ◽  
Failure Prevention ◽  
Lumped Mass Model ◽  
Continuous Mass ◽  
Fatigue Evaluation

Crack failures continually occur in shafts of turbine generator, where grid disturbance is an important cause. To estimate influences of grid disturbance, coupled torsional vibration and fatigue damage of turbine generator shafts are analyzed in this work, with a case study in a 600MW steam unit in China. The analysis is the following: (i) coupled system is established with generator model and finite element method (FEM)-based shafts model, where the grid disturbance is signified by fluctuation of generator outputs and the shafts model is formed with lumped mass model (LMM) and continuous mass model (CMM), respectively; (ii) fatigue damage is evaluated in the weak location of the shafts through local torque response computation, stress calculation, and fatigue accumulation; and (iii) failure-prevention approach is formed by solving the inverse problem in fatigue evaluation. The results indicate that the proposed scheme with continuous mass model can acquire more detailed and accurate local responses throughout the shafts compared with the scheme without coupled effects or the scheme using lumped mass model. Using the coupled torsional vibration scheme, fatigue damage caused by grid disturbance is evaluated and failure prevention rule is formed.

Identification of firefly algorithm-based fluctuation coefficient of the exciting torque for vehicle driveline

2018 ◽  
Vol 233 (2) ◽  
pp. 317-326
Author(s):  
Qiaobin Liu ◽  
Wenku Shi ◽  
Zhiyong Chen
Keyword(s):  
Torsional Vibration ◽  
Firefly Algorithm ◽  
Vibration Response ◽  
Theoretical Modelling ◽  
Lumped Mass ◽  
Mass Model ◽  
Engine Torque ◽  
Lumped Mass Model ◽  
Vibration Performance ◽  
Engine Excitation

The unbalanced excitation force and torque generated by an engine that resonate with the natural frequency of drivetrain often causes vibration and noise problems in vehicles. This study aims to comprehensively employ theoretical modelling and experimental identification methods to obtain the fluctuation coefficients of engine excitation torque when a car is in different gear positions. The inherent characteristics of the system are studied on the basis of the four-degree-of-freedom driveline lumped mass model and the longitudinal dynamics model of vehicle. The correctness of the model is verified by torsional vibration test. The second order's engine torque fluctuation coefficients are identified by firefly algorithm according to the curves of flywheel speed in different gears under the acceleration condition of the whole open throttle. The torque obtained by parameter identification is applied to the model, and the torsional vibration response of the system is analysed. The influence of the key parameters on the torsional vibration response of the system is investigated. The study concludes that proper reduction of clutch stiffness can increase clutch damping and half-axle rigidity, which can help improve the torsional vibration performance of the system. This study can provide reference for vehicle drivetrain modelling and torsional vibration control.

scholarly journals Nonlinear Torsional Vibration Analysis and Control of Semidirect Electromechanical Coupling Transmission System in Shearer

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Song Jiang ◽  
Wei Li ◽  
Lianchao Sheng ◽  
Jiajun Chen ◽  
Min Li
Keyword(s):  
Hopf Bifurcation ◽  
Torsional Vibration ◽  
Electromechanical Coupling ◽  
High Reliability ◽  
Permanent Magnet Synchronous Motor ◽  
Nonlinear Damping ◽  
Transmission System ◽  
Concentrated Mass ◽  
Mass Model ◽  
Hurwitz Stability

The nonlinear torsional vibration and instability oscillation caused by nonlinear damping in the shearer electromechanical coupling cutting transmission system in shearer driven by the permanent magnet synchronous motor (PMSM) is investigated in this paper. The electromechanical coupling transmission system in the shearer is equivalent to a concentrated mass model for the purpose of establishing the system dynamic model by the Lagrange–Maxwell equation. Then, the Routh–Hurwitz criterion is used to determine the torsional vibration critical point and stability region for the Hopf bifurcation for the cutting transmission system. According to the Routh–Hurwitz stability criterion, the Hopf bifurcation type and the effect of the supercritical Hopf bifurcation in the torsional vibration of the cutting transmission system are analyzed. Furthermore, based on the washout filter, the Hopf bifurcation controller is designed for suppressing the transmission system’s large vibration amplitude and unstable oscillation. In addition, the influences of the linear gain and nonlinear gain on the bifurcation point and the limit cycle amplitude are discussed. Finally, the numerical simulation results indicate the effectiveness of the designed controller. The research achievements can provide a theoretical basis for design or optimize the cutting transmission system of high-reliability shearer driven by PMSM.

Analysis on Torsional Fatigue Life of Turbo-Generator Shafts

2011 ◽  
Vol 467-469 ◽  
pp. 1858-1863 ◽  
Author(s):  
Yu Jiong Gu ◽  
Tie Zheng Jin
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Circuit Simulation ◽  
Short Circuit ◽  
Cycle Fatigue ◽  
Two Phase ◽  
Torsional Fatigue ◽  
Turbo Generator ◽  
The Impact

Both low-cycle fatigue and high-cycle fatigue exist during torsional vibrations, but the impact of high-cycle fatigue has rarely been considered. In this paper, a torsional fatigue life analyzing method used for torsional vibration of turbo-generator shafts has been developed based on Manson-Coffin equation and high-cycle fatigue theory. The method has been used to estimate the torsional fatigue life in the most dangerous section of the shafts in a power plant. The cumulative torsional fatigue damage under two-phase short circuit simulation has been predicted.

scholarly journals Analysis of pressure wave in gas-liquid two-phase flows by concentrated mass model

2014 ◽  
Vol 80 (814) ◽  
pp. DR0166-DR0166
Author(s):  
Satoshi ISHIKAWA ◽  
Takahiro KONDOU ◽  
Kenichiro MATSUZAKI ◽  
Hiromitsu EMOTO
Keyword(s):  
Pressure Wave ◽  
Two Phase Flows ◽  
Concentrated Mass ◽  
Mass Model ◽  
Two Phase

Study on the Coupled Bending and Torsional Vibrations of Turbo-Generator Unit with Rub-Impact

2012 ◽  
Vol 246-247 ◽  
pp. 1273-1277
Author(s):  
Cheng Bing He ◽  
Shi Chao Wang
Keyword(s):  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Vibration Amplitude ◽  
Critical Speed ◽  
Torsional Vibrations ◽  
Mass Model ◽  
Mass Unbalance ◽  
Turbo Generator ◽  
Generator Unit

An increment transfer matrix equations based on step-by-step integration method and traditional transfer matrix method are deduced Combined with multi-mass model and Riccati method, the increment transfer matrix method is put forward, that can be directly used to analyze the dynamic response of the coupled bending and torsional vibrations of turbo-generator shafts with rub-impact. Taking a turbo-generator unit as example, the vibration character of rub-impact fault is analyzed when unit starts up. The research results show that rubbing will make vibration amplitude increase when the rotational speed is lower than the first critical speed; however, when the speed is higher than the first critical speed, rubbing will make the rotor mass unbalance reduce, thereby vibration amplitude will reduce slightly.

Correction on Parameters in Torsion Vibration Model for Turbine-Generator Shafts

2007 ◽  
Vol 353-358 ◽  
pp. 2505-2508
Author(s):  
Yu Jiong Gu ◽  
Xiao Bo Li ◽  
Cheng Bing He
Keyword(s):  
Vibration Monitoring ◽  
Lumped Mass ◽  
Mass Model ◽  
Turbine Generator ◽  
Torsion Vibration ◽  
Turbo Generator ◽  
Vibration Fatigue ◽  
Lumped Mass Model ◽  
The Difference ◽  
Stiffness And Damping

The accuracy of parameters in model has important influence on torsion vibration analysis of turbo-generator shafts. In this paper, a method for torsion vibration response calculation based on multistage lumped mass model is introduced. A method for identification and correction on stiffness and damping in torsion vibration monitoring is put forward. Pre-revision on shaft stiffness is realized through analytic calculation of the temperature distribution of turbine-generator shafts. The difference of natural frequencies and response of torsion vibration of shafts are calculated and analyzed after parameter correction, which offers the reference for studying torsion vibration fatigue of shafts.

Analysis on Torsional Stresses in Turbo-Generator Shafts due to Two-Phase Short-Circuit Fault

2013 ◽  
Vol 397-400 ◽  
pp. 427-430 ◽  
Author(s):  
Yu Jiong Gu ◽  
Jing Xu
Keyword(s):  
Cross Sections ◽  
Safety Management ◽  
Short Circuit ◽  
Target System ◽  
Fe Method ◽  
Two Phase ◽  
Management Level ◽  
Turbo Generator ◽  
Frequency Components ◽  
Short Circuit Fault

Taking a 660MW turbine generator shaft system as a target system, the torsional stresses responses are calculated under two-phase short-circuit fault by the finite element (FE) method which can obtain torsional stresses in local areas accurately. The results show that torsional stresses threaten the safety of shafts appear at the first several cycles of the vibration. And the amplitude of stress in weak cross sections located between the low pressure cylinder and the generator is much greater. In addition, the proportion of torsional stresses frequency components in different sections is distinct. The results are helpful to improve the safety management level of the unit.

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