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![Ratio of [S¹⁸O¹⁶OF2] to [S¹⁶O2F2] with the content of H2¹⁸O](publication/355650944/figure/fig5/AS:11431281179416745@1691185636412/Ratio-of-SOOF2-to-SO2F2-with-the-content-of-H2O_Q320.jpg)
Abstract The statistics of the Conference International des Grands Reseaux Electriques (CIGRE) indicate that the operational reliability of SF6 gas‐insulated equipment (GIE) is very high; however, the failure rate of the GIE in operation is much higher than that of the IEC standard, and the fault occurs frequently in the GIE at a high voltage level...
Citations
... insulated electrical equipment has been widely used in power system because of its excellent insulation performance, high stability, small size and easy maintenance. However, in the long-term operation, there are inevitably various insulation defects inside the equipment [1][2][3][4]. Partial discharge or abnormal overheating inside the equipment caused by these defects can lead to the decomposition of SF 6 [5][6][7][8][9], which can generate characteristic decomposition components such as sulphur dioxide (SO 2 ) and thionyl fluoride (SOF 2 ) [10][11][12]. Many studies have shown that by detecting SF 6 decomposition components, the insulation defects of the equipment can be diagnosed, the operating state of the equipment can be understood, and the efficiency of the equipment maintenance can be improved [13][14][15][16][17]. ...
In the detection of multi‐component gas based on tunable diode laser absorption spectroscopy (TDLAS), the problem of overlapping interference between the absorption lines of each gas is often encountered. For example, when detecting a gas mixture of sulphur dioxide (SO2) and thionyl fluoride (SOF2), the characteristic decomposition components of SF6, there is overlapping interference in the absorption lines of the two gases, which makes it difficult to detect the concentration of gases accurately. In view of this problem, a novel method based on support vector regression model used for TDLAS is proposed to detect two gases simultaneously. The detection results show that the correlation coefficients between the concentration of SO2 and SOF2 and the average value of the second harmonic peak reached 0.992 and 0.993. In addition, through model testing, different concentrations of SO2 and SOF2 gas mixture are simultaneously detected, and the resulting maximum errors for measuring SO2 and SOF2 concentrations are less than 7.13 × 10⁻⁵ and 0.26 × 10⁻². The maximum errors of the measurement results in the verification test are not more than 6.4 × 10⁻³ and 4.6 × 10⁻². Therefore, with assistance of the novel method, the detection of multiple gases by using a single laser is achieved.
... However, it is partially decomposed by high-voltage arcs, causing its decomposition products to be highly corrosive and toxic with electrical equipment severely affected. [40][41][42] Therefore, the addition of more active centres allows the BPN to act as a sensor to detect these gases to ensure proper operation of the device. Since the transition metal atom (TMA) has unfilled d valence orbitals with relatively active valence electrons, it is easy to electronically hybridize with gas molecules, while the properties can be improved with less doping or adsorption. ...
... SF 6 , widely used in the power industry, has been identified as a limiting gas by the Kyoto Protocol due to its strong greenhouse effect, whose global warming potential is 23 900 times that of CO 2 [1][2][3]. At present, the annual use of SF 6 worldwide has 4 The authors contributed equally to this work. ...
... SF 6 , widely used in the power industry, has been identified as a limiting gas by the Kyoto Protocol due to its strong greenhouse effect, whose global warming potential is 23 900 times that of CO 2 [1][2][3]. At present, the annual use of SF 6 worldwide has 4 The authors contributed equally to this work. * Author to whom any correspondence should be addressed. ...
... * Author to whom any correspondence should be addressed. exceeded 10 000 tons, and fluorinated greenhouse gases like SF 6 are the category with the fastest annual emission growth [4][5][6]. EU Regulation (EU 517/2014) stipulates that SF 6 is forbidden in electrical equipment of 52 kV and below starting from 2030 [7][8][9]. ...
The harmless treatment of SF6 waste gas is currently a highly concerned focus in the power industry. This article used a new supported catalyst, TiO2/SiC, to study the thermocatalytic conversion of SF6 waste gas. Firstly, the catalytic activity of TiO2/SiC was tested, and it was found that the catalytic efficiency of TiO2/SiC was 3.73 times that of TiO2 at 700 ℃; Subsequently, the optimal catalytic conditions for TiO2/SiC were figured out by experiments, which were conducted under different initial pressures and oxygen concentrations. It was found that the catalytic efficiency of TiO2/SiC was highest when the initial pressure was 0.16MPa and the concentration rate of SF6 and O2 was 1:4. Under these conditions, the total conversion of SF6 by TiO2/SiC reached 288mL in 6 hours, and the average catalytic conversion efficiency reached 33mL/g·h. It was also found that when the conversion of SF6 reached 110-130mL, the catalytic activity of TiO2/SiC decreased; The oxygen concentration has a significant influence on the products: The higher the oxygen concentration is, the higher the production of SO2F2 rate in the product, while the lower that of SO2 rate. Finally, in order to know the catalytic mechanism of TiO2/SiC, XPS tests were conducted on the catalysts before and after the experiment. According to the XPS spectrum, gaseous products would react with TiO2 and generate TiF4 and Ti(SO4)2. According to the test results, the catalytic mechanism of TiO2/SiC was summarized in this article. It explained the catalytic effect of TiO2/SiC from two aspects: promoting the defluorination of SF6 and consuming low-fluorinated sulfides. The empirical conclusions of this article provide a theoretical reference for the harmless treatment of SF6 waste gas.
... 4,5,7,8 In HVDC, gas-insulated switchgear (GIS) and gasinsulated line (GIL) are low-volume-consumption equipment that not only connect to DC submarine cables under the sea but also adapt to some harsh natural environments. 9,10 and it was listed as one of the six greenhouse gases in the Kyoto Protocol in 1997; the carbon consumption of SF6 in GIS/GIL is 0.3%-0.4% of the total global carbon emissions. [17][18][19][20] To reduce carbon emissions, instead of pure SF6, SF6 mixed with buffer gases (e.g., N2 and CO2) is employed in modern GIS/GIL. ...
The determination of the low-temperature plasma propagation of SF6/N2 in gas discharge will accelerate the application of SF6/N2 in advanced electrical equipment. This study investigates the positive streamer propagation characteristics of SF6/N2 by establishing a plasma discharge model and discusses the effects of SF6 ratio on the electron density, electric field, chemical reaction rates, ion concentrations, and streamer thickness and velocity. As the streamer propagates, the shapes of the electron density and electric field become “narrower and taller.” Moreover, the ionization and attachment reaction rates increase, and the streamer thickness and velocity decrease with increasing SF6 mixing ratio and propagation time. As the SF6 ratio increases, the electric field distortion degree and particle mobility near the high-voltage electrode decrease due to the increase in the ionization and attachment rates. Consequently, the streamer velocity remains nearly unchanged, but the streamer thickness obviously decreases in the corona discharge process. In the streamer propagation process, the decrease in the streamer thickness and velocity with increasing SF6 ratio is attributed to the reduction in the electric field distortion and particle mobility, which stems from the increase in the DC breakdown voltage with the SF6 mixing ratio. The study results clarify the influence mechanisms of the SF6 mixing ratio on the particles’ spatiotemporal evolution during streamer propagation.
... On the other hand, when local overheating and discharge faults occur in electrical equipment, it will inevitably cause SF6 decomposition and generate primary decomposition products such as SF4 、 SF3 、 SF2, etc. The primary decomposition products further react chemically with O2、H2O to generate SO2、H2S、HF, and other toxic products [3], [4]. These toxic products not only endanger human health but also cause bad effects on the ecological environment. ...
The effective trapping of leaking SF
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and its decomposition products is of great significance to protect the ecological environment. This paper focuses on the trapping and adsorption characteristics of the porous metal-organic framework ZIF-8 for SF
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and its decomposition products. Grand canonical Monte Carlo (GCMC) was applied to study the gas adsorption at GPa pressure, compare the density distribution of different gas molecules in the framework, plot the adsorption isotherms and analyze the effect of temperature and pressure changes on the adsorption. Using the adsorption sites provided by GCMC, the adsorption sites were divided into three categories, and the energy change law of ZIF-8 when adsorbing SF
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and its main decomposition products was revealed by the analysis of adsorption energy, energy band structure, and density of states based on density functional theory (DFT). The results show that SF
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and its typical decomposition products tend to adsorb near the adjacent C atoms on mIm, and the adsorption amount shows an increasing trend with decreasing temperature and increasing pressure. The results of the study provide new ideas and a theoretical basis for the treatment of waste SF
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.
... What's more, the gases will react with H 2 O to produce acidic substances that further corrode and damage the equipment. Therefore, the monitoring of its decomposition characteristic products can detect the internal insulation defects of the equipment in time to avoid generating larger insulation failures, which is vital for the safe operation of electrical equipment [4][5][6][7]. ...
SF6/N2 mixture is an alternative gas of SF6, which is already used in electrical equipment. When a malfunction occurs , SF6/N2 will decompose and further react with trace water and oxygen to produce nitrogen-containing gases such as NO, NO2, N2O and NF3. It’s necessary to monitor these gases to ensure the safe operation of the equipment. This paper is based on density functional theory (DFT), the nanomaterial Ti3C2Tx doped with Au atom was selected as sensing material. The result shows that Au/Ti3C2Tx has larger adsorption energy when NO and NO2 adsorbed on the surface, the stable structures were conformed more easily with NO and NO2 compared with N2O and NF3. The density of states (DOS) analysis and the frontier molecule orbital analysis reveal more change of the system before and after NO and NO2 adsorption, suggesting the material showed good sensitivity performance to NO and NO2. Thus, Au/Ti3C2Tx is considered to have the potential for sensing NO and NO2.
... Characteristics of these gaseous byproducts (components, concentrations, and variations) are highly valued in the fault diagnosis of GIS due to the fact that they can provide a wealth of valuable information on the fault properties, for example, the generation mechanism, development, and evolution process. Hence, the analysis of the SF 6 decomposed product (DPA) has been one of the research hotspots in the power industry [4,5]. ...
Sulphur hexafluoride (SF6) decomposed products analysis is highly critical in the early‐stage fault diagnosis of gas‐insulated switchgear (GIS). Spectrum technology outperforms traditional methods on non‐invasiveness, no sample preparation, and no consumption. Here, the authors present an improved fibre‐enhanced Raman spectroscopy (FERS) as a comprehensive analytical tool to detect a suite of SF6 decomposed products (SO2F2, SOF2, SO2, H2S, CF4, OCS, CO2, and CO). The FERS approach is combined with two iris diaphragms for spatial filtering and a rear‐end reflector for additional Raman signal enhancement. Limits of detection down to 1×10⁻⁶–8 × 10⁻⁶ are achieved for different SF6 decompositions, and quantification of an undefined multigas, sampled from an 800 kV GIS in service, is realised utilising SF6 as the internal standard gas and with a maximum error of 5.5 %. The GIS is diagnosed according to the results and confirmed by an on‐site check. The authors foresee that this technique will provide a route for trace gas analysis in the power industry.
... used in modern power systems [1,2]. It has obvious application advantages, such as small footprint, low failure rate and low environmental impact, but its fully enclosed structure also makes it difficult to detect the potential insulation faults caused by internal defects [3,4]. Operating experience shows the defects such as poor contact will inevitably occur inside the chamber of SF 6 gas-insulated equipment [5], resulting in an increase in contact resistance at the defect. ...
There are occasionally partial over-thermal faults in gas-insulated equipment inducing SF 6 insulating medium to dissociate. It remains unclear at the atomic scale how this chemically stable gas pyrolyzes at high temperatures. Up to now, there is a lack of micro-level investigations on the molecular behavior of SF 6 at high temperatures. Especially, it needs an effective force field to characterize the evolution of the reactions involving SF 6 and low-fluorine sulfides. The paper aims to fill the gap in this field by performing reactive molecular dynamics (MD) simulations. In this work, MD simulations were carried out on a system consisting of more than 100 SF 6 molecules using a new developed reactive force field (ReaxFF). The dissociation of SF 6 and the subsequent reactions involving low-fluorine sulfides at high temperatures were simulated. The variation of all species in the system were recorded to investigate the effects of the temperature and pressure on the pyrolysis process. The obtained data was then used to establish the relationship between the reaction rate and temperature, thereby formulating Arrhenius law. Moreover, the trajectories of SF 6 and other species were observed at the atomic level. Snapshots of key frames during the reaction helped us to explore the interaction mechanism of free F atoms with SF 6 molecules and SF 5 fragments. It was found that the early dissociation of SF 6 mainly comes from the thermal vibrations of the molecule itself, while the later decomposition of SF 6 , SF 5 and others is related to high-speed collisions by F atoms. This work contributes to the understanding of the mechanism of SF 6 pyrolysis and lays a foundation for more MD investigations.
... CMD is applied to many power system components like generators, transformers, switchgear, transmission lines, cables etc. Up to now, researchers have put forward many developments and much progress in CMD of electrical power equipment and components by using different ways with different measured quantities [107][108][109][110]. Generally, CMD of electrical power components is carried out to achieve one or more of the following: ...
This paper reviews the applications of Internet of Things (IoT) and digital twin technology in electrical power systems. It begins by discussing the generalized IoT value chain, followed by the terminology of smart grid, with clarifying the role of IoT‐systems and the digital twin structure within the Smart Grid. A comparison between different short‐range and long‐range transports is presented. The paper then discusses the use of IoT and digital twin technology for effective energy management with applications in smart homes, smart buildings, smart grids, smart industries (Industry 4.0), smart transportation and smart cities. Additionally, the paper explores the use of IoT and digital twin technology for condition monitoring and diagnosis (CMD) in electrical power systems. Three different cases are presented for CMD, that is, CMD of power transformers, CMD of electrical grids and CMD of substations. IoT and digital twin applications are also highlighted in power electronic systems. Finally, the paper discusses the challenges and opportunities of applying IoT and digital twin technology to electrical power systems and provides recommendations for future research.
... SF 6 is a widely used insulating medium in gas-insulated switchgears (GISs) because of its great insulation strength [1]. However, since it is a strong greenhouse gas with a global warming potential (GWP) of 23,500, the application of SF 6 has been restricted in past decades [2,3]. ...
C5F10O is a promising insulating medium in the manufacturing of environmentally friendly gas-insulated switchgears (GISs). The fact that it is not known whether it is compatible with sealing materials used in GISs limits its application. In this paper, the deterioration behaviors and mechanism of nitrile butadiene rubber (NBR) after prolonged exposure to C5F10O are studied. The influence of C5F10O/N2 mixture on the deterioration process of NBR is analyzed through a thermal accelerated ageing experiment. The interaction mechanism between C5F10O and NBR is considered based on microscopic detection and density functional theory. Subsequently, the effect of this interaction on the elasticity of NBR is calculated through molecular dynamics simulations. According to the results, the polymer chain of NBR can slowly react with C5F10O, leading to deterioration of its surface elasticity and loss of inside additives, mainly ZnO and CaCO3. This consequently reduces the compression modulus of NBR. The interaction is related to CF3 radicals formed by the primary decomposition of C5F10O. The molecular structure of NBR will be changed in the molecular dynamics simulations due to the addition reaction with CF3 on NBR’s backbone or branched chains, resulting in changes in Lame constants and a decrease in elastic parameters.
