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  5. Determination of mechanical stresses in the fastening elements of the stator cores of turbogenerators

Determination of mechanical stresses in the fastening elements of the stator cores of turbogenerators

A. Strokous
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Description: The article analyzes the vibration state of turbogenerators with a power of 200-300 MW, which for a long time worked in non-nominal modes at thermal power plants in Ukraine and Russia. The state of Ukraine's electrical networks and the uneven electricity consumption during the day and month led to the need to reduce the load of turbogenerators to 70%, 50% or less in comparison with their nominal capacity. Operation in such non-nominal modes increases the wear of all turbogenerator elements. The core of the stator, which is made of thin plates, and the system of its attachment to the body are destroyed especially intensively. The author specified the standard values of the stator core vibration and the system of its attachment to the housing, which are used in the service and repair of power plants. Comparison of the experimentally obtained results on power plant units with regulatory vibration standards for such generators was carried out. The results of the conducted researches showed that turbogenerators that operate more than the service life established by the manufacturing plants have a greater wear of the stator core attachment points to the hull (frame, clamping prisms, legs) than turbogenerators that operated only in rated conditions. It is indicated that such turbogenerators require additional repair and restoration work in order to extend their life. Practical recommendations for reducing the vibration of stators of turbogenerators are proposed. Installation of dynamic vibration dampers, reinforcement of the core suspension design refers to such solutions. The need to restore the isolating properties of tie prisms from vibration, increase the tightness of the weakened upper prisms was noted. Power batteries on the turbogenerators stopped in repair are proposed to be installed to ensure a constant state of compression of the extreme and central packets. The new design of improved stopping devices, which is currently used for repairs, is proposed to strengthen the fixation of the clamp prisms, which are weakened. Such a design is developed and implemented when creating new turbogenerators and carrying out repairs at the State Enterprise "Plant" Electrotyazhmash ", (Ukraine, Kharkov). The proposed measures were successfully implemented at domestic and foreign thermal power plants during repairs and modernization of turbogenerators. Applications of the proposed solutions are checked only on turbogenerators with a capacity of 200 and 300 MW, which are called "maneuverable", because the reduction in the power generation capacity during periods of reduced consumption (night consumption dips) is possible only for such machines. The use of larger turbogenerators (500, 800 or 1000 MW) is unacceptable to solve these problems, because the amplification of vibration and destruction of the fastening system, which was noted for generators with a capacity of 200300 MW, will be greater. This conclusion was drawn on the basis of experimental data collected by the author. In conclusion, it was concluded that it is impossible to completely exclude the increase in the vibration of the stators of turbogenerators and the destruction of the stator suspension system to the body when the machine is in operation more than the rated service life of the specified technical solutions. It is recommended to perform a complete replacement of these units with economic feasibility.


Keywords: turbogenerator, coupling pin, frequency, electromagnetic force, mechanical stress, 3D model, software package

References

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Reference:
Strokous, A.V. (2018), “Opredelenie mekhanicheskikh napriazhenii v elementakh krepleniia serdechnikov statorov turbogeneratorov” [Determination of mechanical stresses in the fastening elements of the stator cores of turbogenerators], Information Processing Systems, Vol. 4(155), pp. 35-40. https://doi.org/10.30748/soi.2018.155.05.