Research on High Sensitive D-Shaped FBG Hydrogen Sensors in Power Transformer Oil

Abstract

Dissolved hydrogen is a symbol gas decomposed by power transformer oil for electrical faults such as overheat or partial discharges. A novel D-shaped fiber Bragg grating (D-FBG) sensor is herein proposed and was fabricated with magnetron sputtering to measure the dissolved hydrogen concentration in power transformer oil in this paper. Different from the RI (refractive index)-based effect, D-FBG in this case is sensitive to curvature caused by stress from sensing coating, leading to Bragg wavelength shifts accordingly. The relationship between the D-FBG wavelength shift and dissolved hydrogen concentration in oil was measured experimentally in the laboratory. The detected sensitivity could be as high as 1.96 μL/L at every 1-pm wavelength shift. The results proved that a simple, polished FBG-based hydrogen sensor provides a linear measuring characteristic in the range of low hydrogen concentrations in transformer oil. Moreover, the stable hydrogen sensing performance was investigated by X-ray diffraction analysis.

Optical Fiber Grating Hydrogen Sensors: A Review

“…Some obvious improvements of this field were proposed in the last few years. For example, the sensitivity of Pd-based hydrogen sensors [28,32,33,34] was greatly increased, and some of them [32,33] have great potential application in transformer oil. Moreover, the threshold of WO 3 -based fiber grating hydrogen sensor can be reduced to 50 ppm in air at room temperature [47].…”

“…In power transformer oil, SPFBG (with residual thickness of 20-μm cladding) coated with 560 nm of Pd/Ag composite film exhibited a sensitivity of 0.477 pm/(μL/L), which was 11.4 times higher than that of the common FBG hydrogen sensor. Subsequent improvements were reported in 2016 [33], and the hydrogen sensor showed a linear response when exposed to different concentrations of hydrogen at room temperature. All these results prove the FBG hydrogen sensor has great potential to monitor hydrogen concentration in a power transformer.…”

“…Optical fiber hydrogen sensors can be intrinsically safe as they employ optical signals as a sensing medium, and as such they have attracted much research interest. Several kinds of optical fiber hydrogen sensors, such as evanescent sensors [4,5,6], micro-mirror sensors [7,8], interference sensors [9], surface plasmon resonance (SPR) sensors [10], acoustic resonator sensors [11], and fiber grating sensors [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35], have been proposed in recent years. Compared to other optical fiber hydrogen sensors, hydrogen sensors based on fiber grating are more suitable for distributed measurement and temperature compensation because of their wavelength multiplexing capability.…”

Perspectives of surface plasmon resonance sensors for optimized biogas methanation

“…More recently, various optical sensor principles have been proposed for H 2 monitoring [44][45][46][47][48][49][50][51][52][53][54][55][56]. Sensors based on the H 2 uptake in palladium appear particularly promising.…”

Femtosecond Laser Ablated FBG with Composite Microstructure for Hydrogen Sensor Application

“…Therefore, improving the sensitivity would be a key issue for the development of a FBG hydrogen sensor. A number of researchers have reported chemical etching and side-polishing methods as a way to enhance the sensitivity [2,18,19], but the FBG becomes fragile after etching, and the thickness of side-polish is hard to control. Femtosecond lasers have high micromachining accuracy and small thermal deformation on the surface of materials [20,21,22].…”