Abstract
Based on the physical phenomena of optical effects produced by the partial discharge (PD) and on the characteristics of fluorescent fiber sensing of weak fluorescent signals, a PD measurement system using a fluorescent fiber sensor was designed. The main parameters of the sensing system were calculated, an experimental testing platform for PD simulation in the lab was established, and PD signals were then detected through ultra-high frequency (UHF) and optical methods under a needle-plate discharge model. PD optical pulses in transformer oil contained signal-peak and multi-peak pulse waveforms. Compared with UHF detection results, the number of PD pulses and the elapsed PD pulse phase time revealed a good corresponding relationship. However, PD signal amplitudes presented the opposite, thus indicating that PD UHF signals reflected pulse amplitude value, whereas PD optical signals reflected pulse energy magnitude. The n-u-φ three-dimensional distributions indicated that most of the PD signals concentrated in the nearby industrial frequency voltage peak value. Overall, the proposed fluorescent fiber sensing system design can be used successfully in transformer PD signal detection.
Highlights
In power transformer insulation monitoring and fault diagnosis, partial discharge (PD) is an important parameter of and technology for reflection of insulation status
The results show that the optical fiber sensor with the highest sensitivity can detect PD signals under a 5 kV test voltage and 2 μA current
PD Signals Tested by Optical Method and ultra-high frequency (UHF) Method
Summary
In power transformer insulation monitoring and fault diagnosis, partial discharge (PD) is an important parameter of and technology for reflection of insulation status. In [8], the attenuation characteristics and absorption and emission spectra of six different doped fluorescent fibers were studied, and sensitivity tests were conducted in a GIS simulation device filled with SF6. In 2005, Austrian scholars used the optical method to study corona discharge in transformer oil [9] They found that fluorescent optical fiber sensors can be used for PD detection in a transparent insulating medium. Most fluorescent optical fiber sensors continue to be used for the detection of air-dielectric partial discharge signals, but the use of such sensors in transformer internal defects has rarely been reported. Based on the experimental platform, PD light effect testing was performed on the typical needle-plate insulation fault model in transformer oil. The designed measurement system was proven capable of accurately detecting PD signals compared with the UHF method
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