О. V. Vygovskyi
Institute for Safety of Problems of Nuclear Power Plants, NAS of Ukraine,
12, Lysogirska st. Kyiv, 03028, Ukraine
Given statistics of Ukrainian NPP turbogenerators failures for 2011-2017 was shown that machines with a capacity of 1,000 MW have insufficient reliability. This is a significant factor reducing the safety, reliability and efficiency of the power units operation in general. New three-dimensional mathematical model for calculating the temperature field of turbogenerator stator winding that allows to determine diagnostic features of the technical condition of mentioned winding was developed. Discrepancy of experimental and calculated data on non-stationary (for starting) and stationary heating of stator winding bars of turbogenerator type TVV-1000-2U3 with a capacity of 1,000 MW is less than 5 %, that confirms the accuracy of developed techniques, algorithms and mathematical apparatus. With a help of developed mathematical model the theoretical studies of three-dimensional temperature field of stator winding bars for starting the turbogenerators types TVV-1000-2U3 and TVV-1000-4U3 with such defects as stopple of a hollow conductor and increased current in a hollow conductor of stator winding bar are carried out. Studies have shown when stopple of hollow conductor occurs the start time regularization and time constant of the regular mode are increasing significantly for both a copper hollow conductor and resistance thermometer, while the initial derivatives remain unchanged. For high current in a conductor, the start time regularization and time constant of the regular mode remain unchanged and the initial derivatives increase significantly. Thus, according to the results of information processing from devices of staff heat control, it is possible to diagnose these defects, in particular, coil fault, reliably and effectively. At the NPP tests can be conducted at planned startups, load changes or unload of power units.
Keywords: turbogenerator, stator winding, mathematical model, damages, diagnostic features.
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