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Yu Z.,China Datang Corporation | Wang J.,Peking University
ISA Transactions | Year: 2016

This paper assesses the performance of feedforward controllers for disturbance rejection in univariate feedback plus feedforward control loops. The structures of feedback and feedforward controllers are confined to proportional-integral-derivative and static-lead-lag forms, respectively, and the effects of feedback controllers are not considered. The integral squared error (ISE) and total squared variation (TSV) are used as performance metrics. A performance index is formulated by comparing the current ISE and TSV metrics to their own lower bounds as performance benchmarks. A controller performance assessment (CPA) method is proposed to calculate the performance index from measurements. The proposed CPA method resolves two critical limitations in the existing CPA methods, in order to be consistent with industrial scenarios. Numerical and experimental examples illustrate the effectiveness of the obtained results. © 2016 ISA.

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.

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.

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.

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.

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.

Liang S.,University of North Dakota | Liang S.,China Datang Corporation | Shephard K.,University of North Dakota | Pierce D.T.,University of North Dakota | Zhao J.X.,University of North Dakota
Nanoscale | Year: 2013

The effects that nanometer-sized matrices have on the properties of molecules encapsulated within the nanomatrix are not fully understood. In this work, dye-doped silica nanoparticles were employed as a model for studying the effects of a nanomatrix on the fluorescence quantum yield of encapsulated dye molecules. Two types of dye molecules were selected based on their different responses to the surrounding media. Several factors that affect fluorescence quantum yields were investigated, including aggregation of dye molecules, diffusion of atmospheric oxygen, concentration of dye molecules, and size of the nanomatrix. The results showed that the silica nanomatrix has a varied effect on the fluorescence quantum yield of encapsulated dye molecules, including enhancement, quenching and insignificant changes. Both the properties of dye molecules and the conditions of the nanomatrix played important roles in these effects. Finally, a physical model was proposed to explain the varied nanomatrix effects on the fluorescence quantum yield of encapsulated dye molecules. © The Royal Society of Chemistry 2013.

He Y.,China Datang Corporation | Liu T.,China Datang Corporation
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2010

The dominant mode during power grid low-frequency oscillating process is analyzed based on reliable data and results show that: along with the capacity increase of individual generating unit, power grid is easily influenced by its power fluctuating. As the fast excitation system is widely adopted in large-capacity generating units, while the static stability and transient stability of power system are enhanced, the dynamic instability is also increased because of the decreased system damping. Aiming at the existing unsafe coordination of generator and grid in China, the main solution is to apply the power system stabilizer with rational parameter settings in large-capacity generating units and to properly set the parameters of primary frequency control for DEH control system and DCS in order to meet the requirements of the quick power grid frequency response and the safety and stability of power units. The adoption of DC stability-control networking system among large-capacity regional power grids is the most safe and economic networking mode.

Wang J.,China Datang Corporation
Applied Mechanics and Materials | Year: 2014

For the capacity and the location of the photovoltaic power generation in the urban distribution network, this paper adopts LSI(Loss sensitivity index) to determine the access to the location of photovoltaic power generation system. At the same time, we put forward a kind of multi-objective programming methods for the distribution network, which adopts three sorts of indices including LOI(Loss optimization index), EOI(Environmental optimization index) and VQI (Voltage quality index) as a multi-objective function. Therefore, an auxiliary search space is built in this paper to improve BPSO(binary particle swarm algorithm), in order to solve the complicated nonlinear optimization problem. And through the simulation verification IEEE-30, the simulation results show that this method can realize the optimization of distribution network system configuration. © (2014) Trans Tech Publications, Switzerland.

Wang R.,China Datang Corporation
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics | Year: 2013

In order to study on the reaction mechanism of HCl with CaO, The HCl removal capability by CaO dry process with humidification and the influence of several factors on the removal efficiency of HCl have been investigated in the temperature range from 160°C to 750°C in a fluidized-bed incinerator. The results show that the removal efficiency decreases firstly and then increases as the steam concentration range from 1.5% to 20%. The effect of steam on the reaction acts as both-sides function: promoting and inhibiting. Through XRD analysis, the reaction can be divided into two steps, at first, it produces CaClOH, then the reaction enters into the second step, which produces the final production of CaCl2·2H2O.

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