Abstract
In recent years, extensive research has been conducted on the ultrahigh-frequency (UHF) method. Considering that acquiring a partial discharge UHF signal is the first step in a series of tasks, such as fault diagnosis and defect location, the UHF sensor plays an important role in the UHF method. An antipodal Vivaldi antenna installed at a transformer’s joint is designed in this study according to the structural features of 750 kV transformers in China. Several effective structures, such as linear gradient microstrip and slot edge, are employed to improve the return loss and radiation characteristics. A metal box is designed after analyzing the influence of the metal around the antenna. The metal box can effectively shield against electromagnetic interference and does not deteriorate the performance of the antenna significantly. Experimental data show that this antenna is much more sensitive than the rectangular plane spiral antenna. The proposed antipodal Vivaldi antenna is suitable for detecting partial discharge in large transformers.
Highlights
Several local defects, such as bubbles, cracks, burr on the electrode, and suspended conductive particles, are difficult to avoid in the manufacture process of transformers [1]
We reduced the deterioration in antenna performance as much as possible by designing a metal box
Through simulation calculation and laboratory experiments, several conclusions were obtained: (1) A linear gradient microstrip can effectively improve the performance of the antipodal Vivaldi antenna
Summary
Several local defects, such as bubbles, cracks, burr on the electrode, and suspended conductive particles, are difficult to avoid in the manufacture process of transformers [1]. Several Chinese scholars have conducted preliminary studies on utilizing this joint to detect partial discharge They used Archimedes and planar equiangular spiral antennas to receive the signals in a laboratory [14,15,16,17,18,19]. Considering that these scholars merely wished to prove that signals can leak out of the joint, many factors, such as electromagnetic interference, influence of metal around the antenna, and installation, were not considered. The laboratory experiment showed that the antenna can meet the requirements of partial discharge detection for subsequent UHF signal analysis
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