Abstract
Rotor winding inter-turn short circuit a common fault in hydro-generators. This fault would change the temperature, stress, and other thermal fields of a rotor and threaten the safe operation of the generator. In this paper, the Three Gorges hydro-generator is taken as an example. Mathematical models of three-dimensional temperature field and thermal stress field of rotor magnetic poles are established based on heat transfer theory and solved by finite element method. The temperature field, thermal deformation, and thermal stress distribution of magnetic poles in rotor winding inter-turn short circuit are calculated. On the basis of the calculation, the effects of the different turn numbers and positions of short circuit on the temperature, thermal deformation, and thermal stress of rotor magnetic poles are further studied. It is concluded that the thermal stress of the winding adjacent to the shorted turn would decrease, the thermal stress of the winding farther away from the shorted winding would increase, and so on. The results of this paper can provide references for inter-turn short circuit fault diagnosis and lay a foundation for the further studies of related faults.
Highlights
Rotor winding inter-turn short circuit a common fault in hydro-generators
It is of great significance to analyze the temperature field and thermal stress of excitation winding inter-turn short circuit fault of the large hydro-generator, which can provide a theoretical basis for related fault detection and treatment of the hydro-generator
16, itShort can beCircuit seen that the larger tensile stress than that of the surrounding windings would appear in the shorted turn when inter-turn short circuit occurs in the excitation windingpoles, in XIn this section, for different fault positions, the whole thermal stress changes of magnetic direction, that is, inofthe rotation stress would increase with the increasing the thermal stress therotor short circuit direction
Summary
Rotor winding inter-turn short circuit a common fault in hydro-generators. For most hydro-generators, rotor inter-turn short circuit faults have occurred or exist [1,2]. When inter-turn short circuit occurs in the large hydro-generator rotor winding, the effective turns of the excitation winding decrease and the excitation current changes. This paper establishes the calculation models of temperature field and thermal stress field of hydro-generator rotor magnetic poles based on finite element theory, heat transfer theory, and structural mechanics theory. Taking the 778 MW hydro-generator on the right bank of the Three Gorges Hydropower Station as an example, the paper calculates the various fields of the magnetic poles in the excitation winding inter-turn short circuit fault by using ANSYS software, respectively study the effects of different positions and turn numbers of the excitation winding inter-turn short circuit on the temperature field, thermal deformation, and thermal stress of various parts of the fault magnetic poles. Many conclusions of the thermal static structure are obtained under different inter-turn short circuit conditions
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