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In order to prevent the faults caused by the overheating phenomena of gas insulated switchgear (GIS) contacts, it is necessary to monitor and predict the temperature of GIS contacts. In view of the problems that the temperature of contacts is not easy to be directly measured and the temperature is easily affected by the operation conditions and external factors, a prediction method of GIS contact temperature based on multiple parameters is proposed in this work. The temperature distribution law of GIS under different influencing factors is investigated by employing a three-dimensional simulation model. The influencing factors are contact resistance, load current, ambient temperature, wind speed, SF6 pressure and solar radiation intensity. The reliability of the model is validated by use of heat circuit model. The results indicate that the key factors to predict the contact temperature are the shell temperature rise, load current, wind speed, SF6 pressure and solar radiation intensity. At the same time, the influence of ambient temperature can be ignored. Further, the back propagation (BP) neural network is adopted to predict the temperature rise of the contacts with the above factors. The predicted temperature rise is compared with the calculated one of the model, and the error is in the range of -0.70~0.68 ℃. The method comprehensively takes into account the influence of various factors on the GIS temperature field, and it helps to give a reference for the temperature prediction of GIS contacts based on external sensors.

The Ru atomic catalyst-doped GaN (Ru-GaN) model was established by density functional theory (DFT), and the adsorption models of transformer oil dissolved gas (CO, H2, CH4, C2H2, C2H4 and C2H6) by a Ru-GaN monolayer were optimised. From the adsorption energy, differential charge density, electron state density, molecular orbital and desorption properties, the modification mechanism of Ru-GaN and the gas-sensitive response mechanism of Ru-GaN to CO, H2, CH4, C2H2, C2H4 and C2H6 were systematically studied. The introduction of metal Ru increases the defect state of GaN to provide the active site for the adsorption of gas molecules and reduces the adsorption barrier of GaN to gas molecules. The results show that Ru metal-doped GaN can adsorb CO, C2H2 and C2H4 by chemisorption, with Eads of −2.068 eV, −2.422 eV and −1.877 eV and Qt of −0.1696 e, −0.0671 e, −0.1222 e. In addition, charge redistribution leads to changes in the density of states, molecular orbitals and the conductivity of CO, C2H2 and C2H4 adsorption systems, indicating excellent gas sensitivity to the three gases. The desorption time further verified that Ru-GaN is an ideal CO and C2H2 gas scavenger and a recyclable material for C2H4 gas sensors. [ABSTRACT FROM AUTHOR]