Abstract

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.

Highlights

  • Rotor dynamics plays an important role in many engineering fields,such as gas turbine, steam turbine, reciprocating and centrifugal compressors, the spindle of machine tools, and so on

  • The finite element method (FEM) formulates rotor systems by second-order differential equations directly utilized for control design and estimation, while the transfer matrix method (TMM) solves dynamical problems in the frequency domain [2]

  • A highly complex shafting system is analyzed by a modified Riccati torsional transfer matrix combining with the Newmark-β method

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Summary

Introduction

Rotor dynamics plays an important role in many engineering fields,such as gas turbine, steam turbine, reciprocating and centrifugal compressors, the spindle of machine tools, and so on. The finite element method (FEM) formulates rotor systems by second-order differential equations directly utilized for control design and estimation, while the transfer matrix method (TMM) solves dynamical problems in the frequency domain [2]. Combining with the Newmark-β method, it is applied to study the characteristic frequencies and responses of the torsional vibrations in the turbogenerator shaft during power network faults or disturbance. The results of this work are summarized and discussed

Shafting system model
Riccati torsional transfer matrix
Improved riccati torsional transfer matrix
Incremental equation
Incremental transfer equations of torsional vibration
Natural frequencies of torsional vibration
Responses of torsional vibration under electrical disturbances
Conclusions and discussions
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