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Erosion Characteristics of Oil-immersed On-load Tap Changer Contacts Under Varying Contact Speeds and Pressures

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Chinese Journal of electrical Engineering 2024年第1期10卷 21-34页

作者： Zongying Li Shuaibing Li Yongqiang Kang Zheng Li Hongwei Li school of new energy and Power Engineering Lanzhou Jiaotong UniversityLanzhou 730070China school of electrical Engineering Southwest Jiaotong UniversityChengdu 611756China school of Automation and electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070China

With the growing demand for precise voltage adjustment and reactive regulation,the frequent operation of on-load tap changers(OLTCs)in oil-immersed systems has led to increased erosion of switch contacts by arcs during the switching *** erosion causes significant wear on the contacts,thereby reducing their ***,the present study aims to investigate the behavior and mechanism of arc erosion on contact surfaces in oil-immersed *** achieve this,a self-designed friction and wear test device for OLTC contacts was utilized to conduct experiments at various sliding speeds and contact ***,finite element analysis was employed to validate the experimental results regarding the influence of sliding speed on arc *** surface morphology of the contacts was observed using an optical *** findings revealed that as the sliding speed increased,the arc energy,arc initiation rate,and contact resistance initially exhibited an upward trend,then decreased,and eventually increased *** minimum values were observed at a sliding speed of 90 mm/***,the arc energy,arc initiation rate,and contact resistance decreased gradually as the contact pressure *** reaching a contact pressure of 1.5 N,the variation in the arc energy *** lower contact pressures,arc erosion dominated the wear on the contact ***,at higher contact pressures,the wear transitioned from predominantly arc erosion to a combination of mechanical wear and arc *** summary,experimental and analytical investigations provided insights into the effects of sliding speed and contact pressure on the behavior of arc erosion,contact resistance,and surface damage of OLTC contacts in oil-immersed systems.

关键词： Oil-immersed on-load tap changer arc energy contact resistance friction and wear arc erosion

Nanostructured AlFeO_(3) thin films as a novel photoanode for photoelectrochemical water splitting

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Nano Research 2024年第3期17卷 1075-1085页

作者： Xin Sun Min Wang Qi Geng Shuailin Chen Xiaojun Lv Xunlei Ding Meicheng Li State Key Laboratory of Alternate electrical Power System with Renewable energy Sources School of New EnergyNorth China Electric Power UniversityBeijing 102206China school of Mathematics and Physics North China Electric Power UniversityBeijing 102206China

The earth-abundant and robust aluminum ferrite,AlFeO_(3)(AFO),is mainly studied in the context of ***,we demonstrate that AFO can be used as a stable solar absorber in photoelectrochemical cells for solar water splitting,exhibiting attractive *** is the first report on the photoelectrochemical activity of *** thin-film photoelectrodes prepared by solution-processing methods are composed of vertically oriented thin nanosheets,featuring the rhombohedral symmetry(R3c)and n-type *** as-prepared AFO photoanodes generate a photocurrent density of+0.78 mA·cm^(-2) at 1.23 V *** hydrogen electrode(RHE)with the photocurrent _(onset) potential(U_(onset))close to the flat band potential of 0.5 V *** in the presence of hole ***,the U_(onset) of AFO for solar water splitting coincides with the flat band potential as well,which is rare in n-type inorganic *** also report other properties of AFO associated with photoelectrochemical *** films exhibit a band gap energy of 2.31 eV and positive band edges with low ***,the carrier lifetimes in AFO films are up to millisecond timescales under the mediation of defect *** on the photoelectrochemical behavior and optoelectronic properties,we believe that AFO has great potential for application in photoelectrochemical cells.

关键词： AlFeO_(3) photoanode nanosheets photoelectrochemistry onset potential

Analytical Verification of Performance of Deep Neural Network Based Time-synchronized Distribution System State Estimation

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Journal of Modern Power Systems and Clean energy 2024年第4期12卷 1126-1134页

作者： Behrouz Azimian Shiva Moshtagh Anamitra Pal Shanshan Ma school of electrical Computer and Energy EngineeringArizona State UniversityTempeAZ 85281USA the school of electrical Computer and Energy EngineeringArizona State UniversityTempeAZ 85281USA Quanta Technology RaleighNC 27607USA

Recently,we demonstrated the success of a time-synchronized state estimator using deep neural networks(DNNs)for real-time unobservable distribution *** this paper,we provide analytical bounds on the performance of the state estimator as a function of perturbations in the input *** has already been shown that evaluating perfor-mance based only on the test dataset might not effectively indi-cate the ability of a trained DNN to handle input *** such,we analytically verify the robustness and trustworthi-ness of DNNs to input perturbations by treating them as mixed-integer linear programming(MILP)*** ability of batch normalization in addressing the scalability limitations of the MILP formulation is also *** framework is val-idated by performing time-synchronized distribution system state estimation for a modified IEEE 34-node system and a real-world large distribution system,both of which are incompletely observed by micro-phasor measurement units.

关键词： Deep neural network(DNN) distribution system state estimation(DSSE) mixed-integer linear programming(MILP) robustness trustworthiness

Regulating solid electrolyte interphase film on fluorinedoped hard carbon anode for sodium-ion battery

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Carbon energy 2024年第6期6卷 200-215页

作者： Cuiyun Yang Wentao Zhong Yuqiao Liu Qiang Deng Qian Cheng Xiaozhao Liu Chenghao Yang Guangzhou Key Laboratory for Surface Chemistry of energy Materials New Energy Research InstituteSchool of Environment and EnergySouth China University of TechnologyGuangzhouChina

For the performance optimization strategies of hard carbon,heteroatom doping is an effective way to enhance the intrinsic transfer properties of sodium ions and electrons for accelerating the reaction ***,the previous work focuses mainly on the intrinsic physicochemical property changes of the material,but little attention has been paid to the resulting interfacial regulation of the electrode surface,namely the formation of solid electrolyte interphase(SEI)*** this work,element F,which has the highest electronegativity,was chosen as the doping source to,more effectively,tune the electronic structure of the hard *** effect of F-doping on the physicochemical properties of hard carbon was not only systematically analyzed but also investigated with spectroscopy,optics,and in situ characterization techniques to further verify that appropriate F-doping plays a positive role in constructing a homogenous and inorganic-rich SEI *** experimentally demonstrated link between the electronic structure of the electrode and the SEI film properties can reframe the doping optimization strategy as well as provide a new idea for the design of electrode materials with low reduction kinetics to the *** a result,the optimized sample with the appropriate F-doping content exhibits the best electrochemical performance with high capacity(434.53 mA h g^(-1)at 20mA g^(-1))and excellent rate capability(141 mAh g^(-1)at 400 mA g^(-1)).

关键词： F-doping hard carbon reduction kinetics sodium-ion batteries solid electrolyte interphase film

Adsorption and sensing characteristics of insulating gas C4F7N on 3d late transition metal-phthalocyanine:Theoretical and experimental study

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High Voltage 2024年第4期9卷 870-878页

作者： Dachang Chen Ziang Zheng Cong Zhang Yi Luo Song Xiao Qing Miao Ke Liu Beibei Xiao school of electrical and Electronic Engineering Wuhan Polytechnic UniversityWuhanChina Beijing International S&T Cooperation Base for Plasma Science and energy Conversion Institute of Electrical EngineeringChinese Academy of SciencesBeijingChina school of electrical Engineering and Automation Wuhan UniversityWuhanChina school of energy and Power Engineering Jiangsu University of Science and TechnologyZhenjiangChina

Heptafluoroisobutyronitrile(C_(4)F_(7)N)is being considered as a promising alternative to the greenhouse gas SF6 in the electrical ***,its biotoxicity necessitates the development of gas sensing technology to detect leaked C_(4)F_(7)N.A combination of density functional theory and experiments was employed to evaluate the adsorption and sensing performance of different metal-phthalocyanines as potential sensing materials for C_(4)F_(7)N *** study included exploring adsorption configurations with adsorption energies,electron transfer,and adsorption distance,as well as comparisons of electronic properties,electron distribution,and density of states(DOS)among the ***,gas sensing experiments were conducted using different MPcs to detect 25-100 ppm C_(4)F_(7)*** results revealed that Mn-Pc,Fe-Pc,Co-Pc,and Zn-Pc exhibited considerable chemical interactions,while Ni-Pc and Cu-Pc showed weaker adsorption *** findings were further elucidated based on the electron density and DOS of atomic ***,gas sensing experiments indicated that Co-Pc demonstrated a higher response compared to Fe-Pc at the same concentration of C_(4)F_(7)***,the theoretical and experimental insights offer valuable guidance for C_(4)F_(7)N detection and provide a systematic approach to screen and explore organometallic polymer-based gas sensors applicable in various fields.

关键词： adsorption phthalocyanine Adsorption

Model reduction of fractional impedance spectra for time–frequency analysis of batteries, fuel cells, and supercapacitors

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Carbon energy 2024年第1期6卷 108-141页

作者： Weiheng Li Qiu-An Huang Yuxuan Bai Jia Wang Linlin Wang Yuyu Liu Yufeng Zhao Xifei Li Jiujun Zhang Institute for Sustainable energy/College of Sciences Shanghai UniversityShanghaiChina Shanxi Key Laboratory of Nanomaterials and Nanotechnology School of Mechanical and Electrical EngineeringXi'an University of Architecture and TechnologyXi'anShaanxiChina Xi'an Key Laboratory of new energy Materials and Devices School of Materials Science and EngineeringInstitute of Advanced Electrochemical EnergyXi'an University of TechnologyXi'anShaanxiChina

Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and *** increase the reliability of time–frequency analysis,a theoretical correlation between frequency-domain stationary analysis and time-domain transient analysis is urgently *** present work formularizes a thorough model reduction of fractional impedance spectra for electrochemical energy devices involving not only the model reduction from fractional-order models to integer-order models and from high-to low-order RC circuits but also insight into the evolution of the characteristic time constants during the whole reduction *** following work has been carried out:(i)the model-reduction theory is addressed for typical Warburg elements and RC circuits based on the continued fraction expansion theory and the response error minimization technique,respectively;(ii)the order effect on the model reduction of typical Warburg elements is quantitatively evaluated by time–frequency analysis;(iii)the results of time–frequency analysis are confirmed to be useful to determine the reduction order in terms of the kinetic information needed to be captured;and(iv)the results of time–frequency analysis are validated for the model reduction of fractional impedance spectra for lithium-ion batteries,supercapacitors,and solid oxide fuel *** turn,the numerical validation has demonstrated the powerful function of the joint time–frequency *** thorough model reduction of fractional impedance spectra addressed in the present work not only clarifies the relationship between time-domain transient analysis and frequency-domain stationary analysis but also enhances the reliability of the joint time–frequency analysis for electrochemical energy devices.

关键词： battery,fuel cell,supercapacitor fractional impedance spectroscopy model reduction time-frequency analysis

Surface plasmon-coupled radiative heat transfer between graphene-covered magnetic Weyl semimetals

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Science China Technological Sciences 2024年第11期67卷 3405-3412页

作者： SONG JinLin YAO XinJie JIN Lin CHEN Lei ZHAO HaiLong CHENG Qiang school of electrical and Information Engineering Wuhan Institute of Technology State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and Technology

Weyl semimetals(WSMs) have recently attracted considerable research attention because of their remarkable optical and electrical properties. In this study, we investigate the near-field radiative heat transfer(NFRHT) between graphene-covered Weyl slabs, particularly focusing on the supported coupled surface plasmon polaritons(SPPs). Unlike bare Weyl slabs where the epsilon-near-zero(ENZ) effect contributes the most to the NFRHT, adding a monolayer graphene sheet yields coupled SPPs, i.e.,the coupling of graphene SPPs(GSPPs) and Weyl SPPs(WSPPs), which dominates the NFRHT. The graphene sheet greatly suppresses the ENZ effect by compressing the parallel wavevector, thereby enabling the heat transfer coefficient(HTC) to be significantly changed. Further, for the graphene-covered magnetic Weyl slab configuration, an increase in the number of Weyl nodes suppresses the SPP coupling and ENZ effect, thereby weakening the NFRHT with a regulation ratio of 4.4 whereas an increase in the Fermi level slightly influences the NFRHT. Several typical heterostructures are also proposed for comparison, and results show that a mono-cell structure has the largest total HTC. Our findings will facilitate the understanding of surface plasmon-coupled radiative heat transfer and enable opportunities in energy harvesting and thermal management at the nanoscale based on WSM-based systems.

关键词： near-field radiative heat transfer Weyl semimetal surface plasmon polariton epsilon-near-zero graphene

Challenges and prospects for room temperature solid-state sodiumsulfur batteries

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Nano Research 2024年第3期17卷 1402-1426页

作者： Yashuang Qiu Jing Xu Research Center of Grid energy Storage and Battery Application School of Electrical and Information EngineeringZhengzhou UniversityZhengzhou 450001China

Room temperature sodium-sulfur(Na-S)batteries,known for their high energy density and low cost,are one of the most promising next-generation energy storage ***,the polysulfide shuttling and uncontrollable Na dendrite growth as well as safety issues caused by the use of organic liquid electrolytes in Na-S cells,have severely hindered their ***-state electrolytes instead of liquid electrolytes are considered to be the most direct and effective solution to solve the above ***,its practical application is still greatly challenged due to the poor interfacial compatibility between the all-solid-state electrolytes and the anode/cathode,ionic conductivity,and the shuttle effect caused by the presence of liquid phase in the quasi-solid-state *** paper presents a comprehensive review of solid-state Na-S batteries from the perspective of regulating interfacial compatibility and improving ionic conductivity as well as suppressing polysulfide *** to different components,solid-state electrolytes were divided into five categories:solid inorganic electrolytes,solid polymer electrolytes,polymer/inorganic solid hybrid electrolytes,gel polymer electrolytes,and liquid–solid inorganic hybrid ***,the prospect of developing high performance solid-state electrolytes to improve the cycling stability of room temperature Na-S cells is envisaged.

关键词： sodium-sulfur batteries solid-state electrolytes ionic conductivity polysulfide shuttling interfacial compatibility

Dynamic Modeling of Key Operating Parameters for Supercritical Circulating Fluidized Bed Units based on Data-Knowledge-Driven Method

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Journal of Thermal Science 2024年第3期33卷 1216-1230页

作者： YU Haoyang GAO Mingming ZHANG Hongfu CHEN Jiyu LIU Jizhen YUE Guangxi The State Key Laboratory of Alternate electrical Power System with Renewable energy Sources School of Control and Computer EngineeringNorth China Electric Power UniversityBeijing102206China CHN energy new energy Technology Research Institute Co. Ltd.Beijing102209China Department of energy and Power Engineering Tsinghua UniversityBeijing100084China

To address the pressing need for intelligent and efficient control of circulating fluidized bed(CFB)units,it is crucial to develop a dynamic model for the key operating parameters of supercritical circulating fluidized bed(SCFB)***,data-knowledge-driven dynamic model of bed temperature,load,and main steam pressure of the SCFB unit has been ***,a knowledge-driven method is employed to develop a dynamic model for key operating parameters of SCFB *** model parameters are determined based on the operating data of the unit and continuously optimized in real ***,Bidirectional Long Short-Term Memory combined with Convolutional Neural Network and Attention Mechanism is utilized to build the dynamic model of bed temperature,load,and main steam ***,a collaboration and integration method based on the critic weight method and the variation coefficient method is proposed to establish data-knowledge-driven model of key operating parameters for SCFB *** model displays great accuracy and fitting ability compared with other methods and effectively captures the dynamic characteristics,which can provide a research basis for the design of intelligent flexible control mode of SCFB unit.

关键词： circulating fluidized bed dynamic model data-knowledge-driven method deep learning power plant