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RISS 인기검색어
- 검색키워드
- 저자 : Chengrong Li (검색결과 4 건)
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Muhammad Rafq,Yuzhen Lv,Chengrong Li 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1
The Al2O3 nanoparticles (NPs) with favorable features were prepared in our lab to develop transformer oil/paper insulation system with better insulation performance. The nanofuids (NFs) were prepared with diferent shapes (nanorods, nanoplates), surface modifcations (oleic acid, C2, C18) and concentrations (0.6 g/L, 0.8 g/L, 1.2 g/L) of Al2O3 NPs. The positive lightning impulse (LI) breakdown voltages (VBDs) of mineral oil were improved by 1.11 times with nanorod shape, oleic acid surface modifcation and 0.8 g/L concentration of NPs. The efects of Al2O3 NPs with diferent gap distances on insulating properties of NFs under LI voltage were examined. It was noted that after Al2O3 NPs suspension, the positive LI VBDs of transformer oil (TO/MO) were enhanced but the negative LI VBDs of were decreased. The signifcant improvement in insulating performance of NFs is interpreted in light of electron traps theory. It was found that suspended NPs can enhance the shallow trap desity. The generated electrons would lose their kinetic energy through repeatedly trapping and de-trapping process, leading to decline in elcetron mobility. The higher trap density of NPs will lower average energy, and lower mobility of electrons are obtained. The electrons with lower energy are easy to be captured by those molecules with high electron afnity, and be converted into negative space charges. These negative space charge decreases the electrical feld strength at the front of positive streamer and therefore reduce the propagating velocity of positive streamer.
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On-line Temperature Monitoring of the GIS Contacts Based on Infrared Sensing Technology
Li, Qingmin,Cong, Haoxi,Xing, Jinyuan,Qi, Bo,Li, Chengrong The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.4
Gas insulated switchgear (GIS) is widely used in the power systems, however, the contacts overheating of the inside circuit breaker or disconnector may be a potential cause of developing accidents. As the temperature of the contacts cannot be directly acquired due to existence of the metallic shield, an infrared sensor is adopted to directly measure the temperature of the shield and then the contacts temperature can be indirectly obtained by data fitting, based on which the on-line temperature monitoring technology specifically for GIS contacts based on infrared sensing is proposed in this paper. A real GIS test platform is constructed and experimental studies are carried out to account for the influential factors that affect the accuracy of the infrared temperature measurement. A heat transfer model of the GIS module is also developed, together with experimental studies, the nonlinear temperature relationship among the contacts, the metallic shield and the environment based on a neural network algorithm is established. Finally, an integrated on-line temperature monitoring system for the GIS contacts is developed for on-site applications.
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On-line Temperature Monitoring of the GIS Contacts Based on Infrared Sensing Technology
Qingmin Li,Haoxi Cong,Jinyuan Xing,Bo Qi,Chengrong Li 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.4
Gas insulated switchgear (GIS) is widely used in the power systems, however, the contacts overheating of the inside circuit breaker or disconnector may be a potential cause of developing accidents. As the temperature of the contacts cannot be directly acquired due to existence of the metallic shield, an infrared sensor is adopted to directly measure the temperature of the shield and then the contacts temperature can be indirectly obtained by data fitting, based on which the on-line temperature monitoring technology specifically for GIS contacts based on infrared sensing is proposed in this paper. A real GIS test platform is constructed and experimental studies are carried out to account for the influential factors that affect the accuracy of the infrared temperature measurement. A heat transfer model of the GIS module is also developed, together with experimental studies, the nonlinear temperature relationship among the contacts, the metallic shield and the environment based on a neural network algorithm is established. Finally, an integrated on-line temperature monitoring system for the GIS contacts is developed for on-site applications.
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Study of PD Location in Generators by PD Pulses Propagation
YangChun Cheng,ChengRong Li,Wei Wang 한국전기전자재료학회 2006 Transactions on Electrical and Electronic Material Vol.7 No.5
When a partial discharge takes place at the stator of a generator, the electrical pulse will propagate along the stator bars and the capacitor chains formed by the end part of the stator winds. On the first path, the pulse propagates as a travel wave at slow speed. On the second path, the pulse propagates at quick speed. Based on the data of the experiments on a real 50 MW steam generator, the author has found the pulses can propagate by magnetic field of the stator winding. It was studied that how to locating the partial discharge by signals coming from the different paths, including the features of signals on the two paths at time domain and frequency domain, the measurement frequency rang of the signals, the blind area, the advantage and disadvantage of this method.
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