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Beijing, China

Xia C.,Tongji University | Zhou Y.,Tongji University | Zhou S.,Tongji University | Zhang P.,Tongji University | Wang F.,China Datang Corporation
Renewable Energy | Year: 2015

Temperature and pressure variations in compressed air energy storage (CAES) caverns are important factors that affect the overall performance of CAES systems. However, current air storage cavern models used in the thermodynamic analysis of CAES systems usually ignore the effect of heat exchange between cavern air and the surrounding environment and thus cannot accurately predict temperature and pressure variations. In this study, a diabatic analytical solution in a simple and unified form and that considers heat exchange is proposed for temperature and pressure variations in CAES caverns. The solution is derived on the basis of assumptions that the air density in the cavern can be represented by a constant average value and that the cavern wall temperature remains constant. The proposed solution is validated with the test data of the Huntorf plant trial test and the results calculated with other solutions. Moreover, the errors of the proposed solution caused by the assumptions are analyzed. Results show that in representative ranges, the errors have a significant positive correlation with the ratio of the injected to the initial cavern air mass and the difference between the injected air temperature and the initial air temperature. The errors also have an insignificant negative correlation with the rock thermal effusivity and the heat transfer coefficient. Finally, the condition under which the proposed solution is applicable with an error less than 20% is defined on the basis of the combination of the ratio of the injected to the initial cavern air mass and the difference between the injected air temperature and the initial air temperature. This simplified and unified solution can be a simple yet adequately accurate tool to be used in the thermodynamic analysis of CAES systems. © 2014 Elsevier Ltd. Source


Li F.-G.,China Datang Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

By analyzing the impact of the transition resistance on the distance protection when line outlet fault occurs, this paper compares the advantages and disadvantages among traditional distance protection, adaptive distance protection, and distance protection of neural networks. By the PSASP simulation of double-ended power supply system from Guangdong Shaoguan Power Grid South Hydro Power Plant to Spring Hydro Power Plant, it tests a large number of circuits in order to calculate the angle. The measured data together with the value of the angle are input to BP network to get a well-trained three-layer BP network. When short circuit occurs in the line, through inputting the real-time measurement data into the trained BP networks, ANN can estimate the inclination angle to realize the application of ANN in the self-adaptive distance protection. It is proven that artificial neural network based adaptive distance protection is better to escape the transition resistance. Source


Wang A.-J.,North China University of Water Conservancy and Electric Power | Li H.,China Datang Corporation | Zhang X.-T.,North China University of Water Conservancy and Electric Power
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

In order to realize fast phase selection when fault occurs in EHV transmission line, a scheme of faulted phase selection is proposed based on the features of faulted traveling waves and the singularity detection principle of wavelet transforms. According to the boundary conditions of fault types, the basic relationship meeting the wavelet modulus maxima of each mode component is deduced by the phase-mode transformation formula, and a simplified phase selection criterion is obtained and improved. Simulation results show that this phase selection scheme can detect faulted phase accurately for various fault types at any conditions involving different fault inception angle, fault resistance and fault position. Source


He P.,Xiangtan University | Wang X.,Xiangtan University | Liu Y.,China Datang Corporation | Liu X.,Xiangtan University | Yi L.,Xiangtan University
International Journal of Hydrogen Energy | Year: 2012

The Au-M (M = Fe, Co, Ni, Cu and Zn) bimetallic nanoparticles supported on the Vulcan XC-72R (Au-M/C) were synthesized by a reverse micelle method. The structures and compositions of the carbon supported Au-M catalysts were characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDS). The electrocatalytic activity of the Au-M bimetallic nanoparticles with respect to borohydride electro-oxidation for the application of fuel cell was investigated by voltammetry, chronoamperometry and chronopotentiometry. The results showed that alloying Au with 3d transition metals Fe, Co, Ni, Cu or Zn, a metal that leads to the maximum eight-electron oxidation of BH 4 -, not only improved the electrode kinetics of BH 4 - oxidation but also reduced catalyst cost. Among the various investigated Au-M/C electrocatalysts, the Au-Zn, Au-Fe and Au-Cu catalysts showed no activity of NaBH 4 hydrolysis, and Au-Zn presented an attractive catalytic activity for borohydride oxidation. ©, 2012 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


He P.,Xiangtan University | Wang X.,Xiangtan University | Liu Y.,China Datang Corporation | Yi L.,Xiangtan University | Liu X.,Xiangtan University
International Journal of Hydrogen Energy | Year: 2012

The carbon supported AuNi electrocatalyst (AuNi/C) for electrochemical oxidation of borohydride is prepared in water-in-oil microemulsion of water/AOT/n-heptane. The effects of the molar ratios of water to AOT (Rω) on the particle size and catalytic performance are systemically investigated. It has been found that when the Rω is less than 10, the particle size increases with the increase of Rω value, and the particle size is decreased after Rω > 10 due to two-phase separation of the microemulsion. The morphology and structure of as-prepared AuNi/C electrocatalysts are examined by transmission electron microscopy (TEM) and X-ray diffractometer (XRD). It is confirmed that all AuNi nanoparticles are spherical with average diameters in the range of 3-9 nm and uniformly distributed on the surfaces of carbon. The electrooxidation behaviors of BH4- on the AuNi/C anodic electrocatalyst have been investigated. The results show that the catalytic activity of BH4- oxidation on AuNi/C electrocatalyst is apparently improved and the smaller particle size can get a higher catalytic activity. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source

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