A System of Calculation and Analysis of Torsional Vibration for Turbine-Generator Shafts

2007 ◽  
Author(s):  
Dongmei Du ◽  
Zhi Zhang ◽  
Qing He
Keyword(s):  
Power System ◽  
Electric Power ◽  
Transfer Matrix ◽  
Torsional Vibration ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Electric Power System ◽  
Torsional Angle ◽  
Good Precision ◽  
Turbine Generator

Due to the disturbance of electric power system or other shock load, the torsional vibration of turbine-generator shafts occurs. Alternative shear stress due to torsional vibration decreases the shafts life, even results in shafts broken. It is significant to calculate and analyze natural properties and the responses of tosional vibration excited by the disturbance of electric power system in order to analyze and prevent catastrophic accident. The calculation and analysis system of torsional vibration of turbine-generator shafts is developed. With multi-mass lumped model, the model of torsional vibration of turbine-generator shafts is obtained. The system calculates the natural frequencies and the modal shapes of torsional vibration with the transfer matrix method, the response of torsional vibration of shafts with the increment transfer matrix method, such as torsional angle, angular velocity, angular acceleration, cross-section torque, and torsional stress. The response spectrum of torsional vibration can be obtained by fast Fourier transform algorithm Take an example of a 200MW turbine-generator, which is in the condition of non-all-phase operation. The responses of torsional vibration of shafts are calculated and analyzed. The bolt broken reasons of the coupling of inter-pressure rotor and low-pressure rotor and the coupling of generator and exciter are discussed. The results are identical with the data recorded in field. It is proved that the system is good precision, convenient using, friendly interfacing, and visual calculating.

Response Calculation and Analysis of Torsional Vibration of Turbine-Generator Shafts

2006 ◽  
Author(s):  
Zhi Zhang ◽  
Dongmei Du ◽  
Qing He
Keyword(s):  
Power System ◽  
Electric Power ◽  
Transfer Matrix ◽  
Cross Sections ◽  
Torsional Vibration ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Electric Power System ◽  
Turbine Generator ◽  
Lumped Model

Due to the disturbance of electric power system or other shock load, the torsional vibration of turbine-generator shafts occurs. It is significant to calculate the response of torsional vibration excited by the disturbance of electric power system in order to analyze and prevent catastrophic accident. The multi-mass lumped model of turbine-generator shafts is used. A new method of response calculation of torsional vibration of turbine-generator shafts, the Increment Transfer Matrix method (ITM), which combines the Riccati transfer matrix method with the Newmark-β step-by-step integral method, is presented. By the ITM method, the transient response of torsional vibration of turbine-generator shafts, especially at the dangerous cross-sections, can be calculated. The responses of torsional vibration of 200MW turbine-generator shafts due to the generator at non-all-phase operation are calculated and analyzed. The cause of bolt broken of the coupling of intermediate-pressure rotor and low-pressure rotor and the coupling of generator and exciter are discussed. The results are identical with the data recorded in field.

Torsional Vibration of Turbine Generator Shafts Under the Disturbance of Electric Power System

2008 ◽  
Author(s):  
Qing He ◽  
Dongmei Du
Keyword(s):  
Power System ◽  
Electric Power ◽  
Torsional Vibration ◽  
Low Pressure ◽  
Electric Power System ◽  
Torsional Stress ◽  
Turbine Generator ◽  
Coupling Interaction ◽  
Intermediate Pressure ◽  
Natural Characteristics

The torsional vibration of turbine-generator shafts can be excited by the disturbance of electric power system. The coupling interaction between the system disturbance and the torsional vibration makes turbine-generator oscillate. Alternate torsional stress due to large torsional vibration shortens the life of shafts, even makes shafts break. The natural characteristics and responses of torsional vibration of shafts of 200MW turbine-generator are simulated and analyzed under the catastrophic accidental condition. The causes for the breaking of bolts between the coupling of intermediate-pressure and low-pressure rotor and the coupling of generator and exciter rotor are discussed. The results are identical with the data recorded in the field.

Sensitivity Analysis and Application of Natural Frequency of Torsional Vibration of Rotor System

2008 ◽  
Author(s):  
Qing He ◽  
Dongmei Du
Keyword(s):  
Sensitivity Analysis ◽  
Electric Power ◽  
Natural Frequency ◽  
Torsional Vibration ◽  
Natural Frequencies ◽  
Electric Power System ◽  
Rotor System ◽  
Analysis Method ◽  
Turbine Generator ◽  
Sensitivity Analysis Method

The disturbance of electric power system makes large-scale turbine-generator shafts generate torsional vibration. A available method to restrain the torsional vibration of turbine-generator shafts is that all the natural frequencies of torsional vibration of turbine-generator shafts must keep away from the working frequency and its harmonic frequencies as well as all the frequencies that possibly bring on interaction between turbine-generator and electric power system so that the torsional resonation of shafts may not occur. A dynamic design method for natural frequencies of torsional vibration of rotor system based on sensitivity analysis is presented. The sensitivities of natural frequency of torsional vibration to structure parameters of rotor system are obtained by means of the theory of sensitivity. After calculated the torsional vibration dynamic characteristics of original shafts of a torsional vibration stand that simulates the real shafts of 300MW turbine-generator, the dynamic modification for the torsional vibration natural frequency is carried out by the sensitivity analysis method, which makes the first-five natural frequencies of torsional vibration of the stand is very close to the design object. It is proved that the sensitivity analysis method can be used to the dynamic adjustment and optimal design of real shafts of turbine-generator.

Dynamic Analysis of an 1150 MW Turbine-Generator

2005 ◽  
Author(s):  
Edgar J. Gunter ◽  
Wen Jeng Chen
Keyword(s):  
Finite Element ◽  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Transient Analysis ◽  
Operating Speed ◽  
Turbine Generator ◽  
Finite Element Program ◽  
Critical Speeds ◽  
Blade Loss

This paper presents the dynamical analysis of an 11-bearing 1,150 MW turbine-generator system. Original studies of this system yielded information on the system critical speeds and mode shapes. These calculations were first generated by the transfer matrix method. It was found that the transfer matrix method is unsuited for the analysis of large turbine-generators for a number of reasons. The first is the problem of convergence of the modes with a large number of mass stations. The second is that the iteration procedure misses modes that are closely spaced. In the study of the dynamical behavior of large T-G sets, it was determined that it was necessary to include the foundation or bearing pedestal effects. This not possible with the transfer matrix method due to the numerical problems associated with branched elements of the supports. The system critical speeds were computed using a structural finite element program. This approach could generate the system modes, but is not capable of computing damped eigenvalues, unbalance response, or to perform accurate time transient analysis to evaluate system motion and bearing forces transmitted due to blade loss. With the recent enhancements to the PC-based finite element program DyRoBeS, it is now possible to perform both linear and nonlinear time transient studies on large turbine-generator systems, as well as damped eigenvalue analysis and unbalance response. In the calculation of the undamped critical speeds, it was observed that there can be as many as 12 undamped modes in the operating speed range. Not all of these modes need to be of concern. A mode is of concern if it has a low log decrement damping and is in the vicinity of the operating speed, or that it has a negative log decrement which indicates that it may be unstable. In order to compute the damped complex 3-dimensional eigenvalues of the system, the 8 bearing stiffness and damping coefficients for the 11 bearings must be known. These values were computed for each bearing and are then used in the calculation of the damped modes. Instead of considering only 12 modes, one must compute the first 30 complex modes to span the frequency range of interest. These modes represent forward, mixed, and backward modes. Only several of these modes are of concern. There are several forward modes that are near the operating speed and have high exciter and LP turbine motion. These modes also have low log decrements which makes them of concern, particularly as regards to a suddenly applied unbalance. A time transient analysis is required in order to assess the TG response at running speed due to a sudden unbalance, such as caused by blade loss. One of the limitations with structural finite element programs is that transient analysis is accomplished by assuming a set of undamped modes. One is then required to assume a percent of modal damping for each mode. This approach may be acceptable for structural systems, but it is not acceptable for a rotor dynamics analysis in which the bearings have high damping in addition to the bearing cross-coupling coefficients which structural FEA programs can not handle. A time transient analysis was performed using DyRoBeS to simulate 6 cycles of shaft motion. In this simulation of LP3 blade loss at running speed, one of the system modes around 1,600 CPM was excited to the extent that exciter damage could occur, leading to system failure. It is concluded that exciters of this class may be insufficiently supported and also have insufficient damping to withstand blade loss.

Torsional Vibration Dynamic Analysis of the Test Rig for Intersecting Axes Gears of Helicopters

2011 ◽  
Vol 42 (11) ◽  
pp. 3-8
Author(s):  
Xiangyang Jin ◽  
Li Gui Xian ◽  
Zhao Yong Qiang
Keyword(s):  
Dynamic Analysis ◽  
Transfer Matrix ◽  
Torsional Vibration ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Test Rig ◽  
Vibration Load ◽  
Beveloid Gears ◽  
Vibration Dynamics ◽  
The Mathematical Model

In this paper, the transfer matrix method has been employed to analyze the torsional vibration dynamics of the test rig for closed intersecting axes beveloid gears of helicopter. The torsional vibration dynamic model has been established through adopting the transfer matrix method. At the same time, the mathematical model of the branch nodes and the dynamic analysis of test rig closed system have been also derived. The dynamic simulation principle of the test rig is studied and the corresponding dynamic load coefficients are also solved. Finally, the simulation curve of the vibration load coefficients of the test gears under different speed is drawn. The results shows that both the dynamic character of test rig and the loading precision can meet the test requirement.

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.

scholarly journals Torsional vibration of suspension bridge with a variable cross section

1981 ◽  
Vol 3 (2) ◽  
pp. 22-26
Author(s):  
Nguyen Van Tinh
Keyword(s):  
Computer Program ◽  
Transfer Matrix ◽  
Cross Section ◽  
Cross Sections ◽  
Torsional Vibration ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Suspension Bridge ◽  
Variable Cross Section ◽  
Variable Cross

The transfer matrix method to torsion’ al vibrations of a suspension bridge with variable cross sections is reported. The method described above is particularly suitable for implementing an efficient computer program. A numerical example is also givens.

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