Details
| Original language | English |
|---|---|
| Article number | 9305210 |
| Pages (from-to) | 2266-2273 |
| Number of pages | 8 |
| Journal | IEEE ACCESS |
| Volume | 9 |
| Early online date | 23 Dec 2020 |
| Publication status | Published - 2021 |
Abstract
The radial and tangential force components acting on each sub-conductor of a Roebel bar in a large generator lead to mechanical vibration of the stator bars in the slot. This double-frequency vibration results in additional mechanical stress on fixation materials in the slot and causes insulation deterioration and looseness of stator bars. Particularly during short circuits, the stator bars are subjected to immense radial forces. Understanding the origin of these vibrations and developing models to anticipate them is essential to increase the reliability and expected life time of large generators. This paper presents an analytical method for the estimation of Roebel bar forces during symmetrical and asymmetrical short circuits. For this purpose, an analytical calculation method is developed to estimate the transient three-phase currents during different short circuits. These currents induce tangential and radial flux density components along the slot width and length, respectively. An analytical approach is introduced to estimate these flux densities as a function of the slot length. Subsequently, an analytical method for calculating the Roebel bar forces considering three-dimensional transpositions is developed and verified with finite element calculations. Beyond the state of the art, the impact of the rotor field on the radial and tangential components of the stray fluxes are analytically estimated. The result is a comprehensive analytical tool for the estimation of Roebel bar forces during different short circuits in large generators.
Keywords
- hydrogenerators, Lorentz force, Roebel bar forces, salient-pole synchronous machines, short circuits, transient model of large generators
ASJC Scopus subject areas
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In: IEEE ACCESS, Vol. 9, 9305210, 2021, p. 2266-2273.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Transient Roebel Bar Force Calculation in Large Salient-Pole Synchronous Machines
AU - Meiswinkel, Marius Wenzel
AU - Ebrahimi, Amir
AU - Wohlers, Constantin
AU - Neschitsch, Tim
PY - 2021
Y1 - 2021
N2 - The radial and tangential force components acting on each sub-conductor of a Roebel bar in a large generator lead to mechanical vibration of the stator bars in the slot. This double-frequency vibration results in additional mechanical stress on fixation materials in the slot and causes insulation deterioration and looseness of stator bars. Particularly during short circuits, the stator bars are subjected to immense radial forces. Understanding the origin of these vibrations and developing models to anticipate them is essential to increase the reliability and expected life time of large generators. This paper presents an analytical method for the estimation of Roebel bar forces during symmetrical and asymmetrical short circuits. For this purpose, an analytical calculation method is developed to estimate the transient three-phase currents during different short circuits. These currents induce tangential and radial flux density components along the slot width and length, respectively. An analytical approach is introduced to estimate these flux densities as a function of the slot length. Subsequently, an analytical method for calculating the Roebel bar forces considering three-dimensional transpositions is developed and verified with finite element calculations. Beyond the state of the art, the impact of the rotor field on the radial and tangential components of the stray fluxes are analytically estimated. The result is a comprehensive analytical tool for the estimation of Roebel bar forces during different short circuits in large generators.
AB - The radial and tangential force components acting on each sub-conductor of a Roebel bar in a large generator lead to mechanical vibration of the stator bars in the slot. This double-frequency vibration results in additional mechanical stress on fixation materials in the slot and causes insulation deterioration and looseness of stator bars. Particularly during short circuits, the stator bars are subjected to immense radial forces. Understanding the origin of these vibrations and developing models to anticipate them is essential to increase the reliability and expected life time of large generators. This paper presents an analytical method for the estimation of Roebel bar forces during symmetrical and asymmetrical short circuits. For this purpose, an analytical calculation method is developed to estimate the transient three-phase currents during different short circuits. These currents induce tangential and radial flux density components along the slot width and length, respectively. An analytical approach is introduced to estimate these flux densities as a function of the slot length. Subsequently, an analytical method for calculating the Roebel bar forces considering three-dimensional transpositions is developed and verified with finite element calculations. Beyond the state of the art, the impact of the rotor field on the radial and tangential components of the stray fluxes are analytically estimated. The result is a comprehensive analytical tool for the estimation of Roebel bar forces during different short circuits in large generators.
KW - hydrogenerators
KW - Lorentz force
KW - Roebel bar forces
KW - salient-pole synchronous machines
KW - short circuits
KW - transient model of large generators
UR - http://www.scopus.com/inward/record.url?scp=85098792168&partnerID=8YFLogxK
U2 - 10.1109/ACCESS.2020.3046789
DO - 10.1109/ACCESS.2020.3046789
M3 - Article
AN - SCOPUS:85098792168
VL - 9
SP - 2266
EP - 2273
JO - IEEE ACCESS
JF - IEEE ACCESS
SN - 2169-3536
M1 - 9305210
ER -