Research of dampher system damage physical processes of synchronous machines rotor

Abstract

The physical processes in the damper system of the rotor with the appearance of a static eccentricity of the rotor for two types of salient-pole synchronous machines - a capsule hydrogenator SGK 538/160-70M with a capacity of 22 MW and a synchronous generator with a capacity of 500 kW were investigated by means of mathematical modeling. A field mathematical model has been developed that takes into account the combined action of three physical fields of different nature: electromagnetic, temperature and field of thermomechanical stresses, and makes it possible to evaluate the heating and three-dimensional distribution of thermomechanical stresses in the structural elements of the rotor damper system of a salient-pole synchronous machine. These physical processes cause gradual destruction of the structure of the rotor damper system. It is proved that the primary cause of degradation and damage of the damping system of the rotor of an open-pole synchronous machine is the uneven distribution of induced currents in the rods at the poles of the rotor, which occurs when the machine works asynchronously or with the appearance of rotor static eccentricity. The largest induced currents and heat occur in the rods located at the edges of the pole pieces, while the central rods at the pole are heated significantly less. This asymmetric heating of the damping system of the rotor leads to significant thermomechanical stresses in the elements of the damping system of the rotor, which significantly depend on the magnitude of the eccentricity and slippery of the rotor in asynchronous mode. The magnitude of the total thermomechanical stresses in the rods is influenced not only by axially directed forces but also by transverse forces in the end short-circuiting elements. At considerable slippery and eccentricities there are inadmissibly big breaking forces which break cores and face short-circuiting elements of a damping system of a rotor. According to the results of the analysis, the heating and thermomechanical stresses of the structural elements were determined and recommendations for its structural improvement were given.