Impact of short circuit factors on end winding vibrations in generators considering air-gap eccentricity

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Journal of Vibration and Shock ›› 2024, Vol. 43 ›› Issue (14) : 112-121.

XU Mingxing1,2，HE Yuling1,2,3，ZHANG Wen1,2，DAI Derui1,2，LIU Xiang’ao1,2，TANG Guiji1,2

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Abstract

End winding vibration is one of the key factors that lead to the insulation wearing and degrading. This paper presents a comprehensive study on the end winding vibration properties in synchronous generators under rotor interturn short circuit cases. Different from other studies, this work investigates not only the influence of rotor interturn short circuit degrees, but also the rotor interturn short circuit positions and the air-gap eccentricity on the end winding vibrations. Firstly, the expression of the end winding electromagnetic force is obtained through theoretical derivation. Then, the winding electromagnetic forces and response characteristics, such as deformation, strain and stress, are based on a coupled electromagnetic-structural model. Finally, experimental verification at the CS-5 fault simulator generator. The experimental results are basically consistent with the theoretical analyses and finite element calculations. It is shown that the rotor interturn short circuit will bring in extra 50Hz (fundamental frequency), 150Hz and 200Hz harmonics to the electromagnetic force. Moreover, with the increment of either the air-gap eccentricity/rotor interturn short circuit degree or the distance between the short circuit position and the big tooth, the end winding electromagnetic force/vibrations will be increased. In addition, compound faults have a more severe effect on the end winding vibration. Due to the electromagnetic force of the stator winding, the nose part is the location of maximum deformation, while the joint to connect the end part and the linear sections is prone to insulation wear, which should be a key concern in the manufacture and later maintenance.

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synchronous generators / rotor interturn short circuit / air-gap eccentricity / electromagnetic force / winding vibration

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XU Mingxing1, 2, HE Yuling1, 2, 3, ZHANG Wen1, 2, DAI Derui1, 2, LIU Xiang’ao1, 2, TANG Guiji1, 2. Impact of short circuit factors on end winding vibrations in generators considering air-gap eccentricity[J]. Journal of Vibration and Shock, 2024, 43(14): 112-121

References

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