Yingang Gui

Mechanism and Application of Carbon Nanotube Sensors in SF6 Decomposed Production Detection: a Review

Carbon nanotubes (CNTs) have aroused extensive attentions as a new category of gas sensor materials owing to their outstanding performance for detecting specific gas among a variety of ones through diverse gas responses. This review summarizes the adsorption mechanism of CNTs and their properties related to the detection of sulfur hexafluoride (SF6) decomposed gases that generated in gas insulation switchgear (GIS) of power system. Their performances as sensors of both experimental analysis and theoretical calculation for various kinds of decomposed gases are summarized, and the further research trend on CNTs in the detection of SF6 decomposition components is also put forward.

Preparation and Application of TiO2 Nanotube Array Gas Sensor for SF6-Insulated Equipment Detection: a Review

Since Zwilling and co-workers first introduced the electrochemical anodization method to prepare TiO2 nanotubes in 1999, it has attracted a lot of researches due to its outstanding gas response and selectivity, making it widely used in gas detection field. This review presents an introduction to the sensor applications of TiO2 nanotube arrays (TNTAs) in sulfur hexafluoride (SF6)-insulated equipment, which is used to evaluate and diagnose the insulation status of SF6-insulated equipment by detecting their typical decomposition products of SF6: sulfur dioxide (SO2), thionyl fluoride (SOF2), and sulfuryl fluoride (SO2F2). The synthesis and sensing properties of TiO2 nanotubes are discussed first. Then, it is followed by discussing the theoretical sensing to the typical SF6 decomposition products, SO2, SOF2, and SO2F2, which analyzes the sensing mechanism at the molecular level. Finally, the gas response of pure and modified TiO2 nanotubes sensor to SO2, SOF2, and SO2F2 is provided according to the change of resistance in experimental observation.

Effects of background gas on sulfur hexafluoride removal by atmospheric dielectric barrier discharge plasma

The effects of background gases (He, Ar, N2 and air) on SF6 removal in a dielectric barrier reactor were investigated at atmospheric pressure. A comparison among these background gases was performed in terms of discharge voltage, discharge power, mean electron energy, electron density, removal efficiency and energy yield for the destruction of SF6. Results showed that the discharge voltage of He and Ar was lower than that of N2 and air, but the difference of their discharge power was small. Compared with three other background gases, Ar had a relatively superior destruction and removal rate and energy yield since the mean electron energy and electron density in SF6/H2O/Ar plasma were both maintained at a high level. Complete removal of 2% SF6 could be achieved at a discharge power of 48.86 W with Ar and the corresponding energy yield can reach 4.8 g/kWh.

Synthesis of Graphene-Based Sensors and Application on Detecting SF6 Decomposing Products: A Review

Graphene-based materials have aroused enormous focus on a wide range of engineering fields because of their unique structure. One of the most promising applications is gas adsorption and sensing. In electrical engineering, graphene-based sensors are also employed as detecting devices to estimate the operation status of gas insulated switchgear (GIS). This paper reviews the main synthesis methods of graphene, gas adsorption, and sensing mechanism of its based sensors, as well as their applications in detecting SF6 decomposing products, such as SO2, H2S, SO2F2, and SOF2, in GIS. Both theoretical and experimental researches on gas response of graphene-based sensors to these typical gases are summarized. Finally, the future research trend about graphene synthesis technique and relevant perspective are also given.

Study on the characteristic decomposition components of air-insulated switchgear cabinet under partial discharge

Air-insulated switchgear cabinet plays a critical role in entire power transmission and distribution system. Its stability directly affects the operational reliability of the power system. And the on-line gas detection method, which evaluates the insulation status of insulation equipment by detecting the decomposition components of filled air in cabinet, becomes an innovative way to ensure the running stability of air-insulated switchgear cabinet. In order to study the characteristic gas types and production regularity of decomposition components under partial discharge, three insulation defects: needle-plate, air-gap and impurity defect are proposed to simulate the insulation defects under partial discharge in air-insulated switchgear cabinet. Firstly, the generation pathways and mechanism of composition components are discussed. Then CO and NO2 are selected as the characteristic decomposition components to characterize the partial discharge due to their high concentration and chemical stability. Based o...

Influence of humidity and voltage on characteristic decomposition components under needle-plate discharge model

Detecting the decomposition components in air-insulated switchgear is an effective method to evaluate the discharge severity of air-insulated switchgear. Experimental and theoretical studies are conducted to investigate the types of decomposition components and generation mechanism under the partial and disruptive discharge conditions. The discharge experiments use a needle-plate discharge tank, and the effect of relative humidity (50, 70 and 90%) and voltage (6, 6.5, 7 and 7.5 kV) are studied in detail. Considering the partial discharge process, the concentrations of CO and NO2 increase with the applied voltage and partial discharge time. The CO concentration increases with the increase of humidity, while NO2 concentration shows the reverse change trend. During the disruptive discharge process, the decomposition component NO increases with humidity. The dissipation of these decomposition components is also investigated using experiment. The small part of CO dissipation is from the adsorption with H2O molecules and onto the surface of discharge tank. The reaction between NO and O free radical, O2 and O3 consumes the concentration of NO and produces NO2. And the reaction between NO2 and H2O consumes most of the generated NO2 in the discharge tank. In the theoretical research, the reaction energy of CO, NO and NO2 generation is computed to analyze the generation and dissipation mechanism of decomposition components using Materials Studio.