engleski

Influence of the Turbine Generator Rotor Slot Wedges on the Unstable Vibrations

This paper is concerned with the influence of the microslip in turbine generator rotor slot wedges on the dynamic instability close to the first critical rotational speed. A simple microslip model, i.e., discrete numerical microslip model, has been used. On the assumption that the vibration shape of the turbine generator is the first mode shape, energy input to the vibrations due to internal damping caused by microslip is anlysed during one vibration period. The influence of wedge parameters, such as, length the force in the spring between the wedges and the rotor windings and coefficient of friction, on the energy input to the vibrations has been studied. It has been shown that the energy input grows almost lineary with the wedge cross-section area increase. The wedge length increase causes the energy input to grow asymptotically toward a certain definitevalue. The increase of both coefficient of friction and the force in the spring between the wedges and the rotor windings causes the energy input to decrease asymptotically toward zero. The energy input decreases to zero in cases of high rotational speed. It has been stated that the correct choice of the wedge parameters may have significant influence on the dynamic stability of the turbine generator rotating close to the first critical rotational speed.

vibrations; turbine generator slot wedges; microslip

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