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Number of results: 3
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Abstract

With the availability of UHV engineering technology, the scale of the power network is expanding, and the level of the short-circuit current is getting higher, which brings hidden trouble to the safe and stable operation of the power network. Further this article issued a method that optimized the configuration of a current limiter based on the reliability of the power network. According to the reliability analysis under the influence of a short circuit, the quantitative evaluation of reliability of the power network is realized by the calculation of the short-circuit current.Aquantitative model is established among reliability evaluation and the short-circuit current as well as load loss, the candidate installation site of a current limiter can be determined according to reliability quantification results. This method uses the particle swarm optimization algorithm to optimize the distribution of the limiter, aiming at the reliability level and the minimum number of current limiters in the short circuit of a power grid. Finally, taking the actual power grid of a province as an example, the result shows that this method can reduce the search space of the optimal solution, optimize the configuration of the current limiter, and effectively limit the short-circuit current and improve the reliability of the power network.

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Authors and Affiliations

Jianjun Zeng
Yonggao Zhang
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Abstract

Electromagnetic forces generated by the short circuit current and leakage flux in low- and high-voltage windings of distribution transformers as well as amorphous core transformers will cause the translation, destruction, and explosion of the windings. Thus, the investigation of these forces plays a significant role for researchers and manufacturers. Many authors have recently used the finite element method to analyze electromagnetic forces. In this paper, an analytic model is first developed for magnetic vector potential formulations to compute the electromagnetic forces (i.e., axial and radial forces) acting on the low- and high-voltage windings of an amorphous core transformer. The finite element technique is then presented to validate the results obtained from the analytical model. The developed model is applied to an actual problem.
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Authors and Affiliations

Bao Doan Thanh
1
ORCID: ORCID
Doan Duc Tung
1
ORCID: ORCID
Tuan-Ho Le
1
ORCID: ORCID

  1. Faculty of Engineering and Technology, Quy Nhon University, Binh Dinh province, Vietnam
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Abstract

This paper presents the results of testing samples of shield-centering elements from medium-voltage surge arresters. The elements were made of TSE glass textolite. The elements have been dismantled from different operated surge arresters, which were subjected to discharge currents (short-circuit currents) of different intensity and duration. The discharge currents led to degradation of the tested elements with various degrees of advancement. The degradation was investigated using microscopic methods and energy-dispersive X-ray spectroscopy (EDS). Changes in the content of elements of the surface of textolite materials – as the degradation progresses – were documented.
It was found that high discharge current flows resulted in melting of the organic binder, epoxy resin, especially its surface layer. Partial charring and even burning of the resin was noticeable. Furthermore, it was found that with increasing degradation on the surface of the TSE laminate, the carbon and oxygen content, which are part of the organic resin, decreases. Simultaneously the amount of silicon, calcium and aluminium, which are present in the glass fibres, increases. The charring effect of the resin and the formation of conductive paths result in a decrease in the performance of surge arresters and their subsequent failure.
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Authors and Affiliations

P. Papliński
1
H. Śmietanka
1
P. Ranachowski
2
Z. Ranachowski
2
ORCID: ORCID
K. Wieczorek
3
S. Kudela Jr
4

  1. Institute of Power Engineering – Research Institute, 8 Mory Str., 01-330 Warsaw, Poland
  2. Institute of Fundamental Technological Research PAS, 5b Pawińskiego Str., 02-106 Warsaw, Poland
  3. Wrocław University of Science And Technology, Faculty of Electrical Engineering, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
  4. Institute of Materials and Machine Mechanics Slovak Academy of Sciences, Dúbravská Cesta 9/6319, 845 13 Bratislava, Slovakia

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