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

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

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Aging Mechanism and Life Estimation of Photovoltaic Inverter DC-link Capacitors in Alternating Humid and Thermal Environment

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Chinese Journal of Electrical Engineering 2024年第1期10卷 48-62页

作者： Quanyi Gao Shuaibing Li Yi Cui yongqiang kang Haiying Dong School of New Energy and Power Engineering Lanzhou Jiaotong UniversityLanzhou 730070China State Key Laboratory of Large Electric Drive System and Equipment Technology Tianshui 741000China School of Engineering University of Southern QueenslandSpringfield 4300Australia

DC-link capacitors play a vital role in managing ripple voltage and current in converters and various *** study focuses on exploring the aging characteristics of DC-link capacitors in alternating humid and thermal environments aligned with the operational conditions in photovoltaic and wind power *** to relevant power equipment standards,we designed a 24-h alternating humid and thermal aging environment tailored to the requirements of DC-link *** aging test platform is established,and 20 widely used metallized polypropylene film capacitors are selected for *** such as the capacitance,equivalent series resistance(ESR),and phase angle are assessed during aging,as well as the onset time and extent of aging at various *** study focuses on the aging mechanisms,analyzing electrode corrosion,the self-healing process,and dielectric *** the aging characteristics enabled us to calculate the lifespan of the capacitor and predict it under different degrees of capacitance *** results show that under alternating humid and thermal conditions,capacitance attenuation and ESR increase exhibit exponential nonlinearity,influenced by factors such as the oxidation and self-healing of capacitive metal electrodes,dielectric main-chain fracture,and crystal *** study underscores the pivotal role of encapsulation in determining the aging decay time.

关键词： DC-link capacitors aging mechanism life prediction metallized film capacitors

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双柱体系统局部电场计算的互偶极子模型

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电工技术学报 2024年第12期39卷 3869-3883页

作者：张嘉琳康永强蒲绪宏李帅兵兰州交通大学新能源与动力工程学院兰州730070 大型电气传动系统与装备技术国家重点实验室天水741020

两相体局部电场计算模型是研究两相体电场分布、相互作用机制等重要课题的关键,而线电偶极子模型是当前双柱体系统电场计算的经典模型,但当柱体间距较近且介电常数较大时,其计算误差显著增大。针对该问题,该文考虑双柱体系统在均匀电场... 详细信息

两相体局部电场计算模型是研究两相体电场分布、相互作用机制等重要课题的关键,而线电偶极子模型是当前双柱体系统电场计算的经典模型,但当柱体间距较近且介电常数较大时,其计算误差显著增大。针对该问题,该文考虑双柱体系统在均匀电场中的相互作用与极化过程,将处于电场环境中的柱体极化过程分解为外电场极化与相互作用极化两个过程,其中外电场极化结果通过位于柱体轴心的自偶极矩表征,而柱体间极化结果通过一个偏离柱体轴心的互偶极矩表征,并由此构建了双柱体系统互偶极子模型。通过与经典线电偶极子模型及有限元模型计算结果的对比发现,所提的双柱体系统互偶极子模型即使在柱体间距D=0.1R且介电常数之比εi/εe=100时,其计算误差仍小于5%,该结果表明互偶极子模型能够在柱体间距较小且介电常数之比较大时,对双柱体系统的电场分布得到较为精确的计算结果。

关键词：双柱体系统柱体间相互作用电场分布互偶极子模型

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电气设备复合绝缘结构的太赫兹无损检测综述

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高电压技术 2024年第1期50卷 194-209页

作者：李帅兵李天耕淡嘉豪康永强董海鹰兰州交通大学新能源与动力工程学院兰州730070

在电气设备复合绝缘结构检测方面,基于声、光、电、磁等物理量、化学组分和微观特征的检测方法得到广泛应用,但难以实现无损可视化表征。相比之下,太赫兹检测技术利用太赫兹波的光学和电磁学特性可以有效反演出被测物的结构特征和介电特... 详细信息

在电气设备复合绝缘结构检测方面,基于声、光、电、磁等物理量、化学组分和微观特征的检测方法得到广泛应用,但难以实现无损可视化表征。相比之下,太赫兹检测技术利用太赫兹波的光学和电磁学特性可以有效反演出被测物的结构特征和介电特性,较传统检测方法具有无损可在线测量的明显优势。为此,该文总结了当前太赫兹无损检测技术在电气设备复合绝缘结构检测方面的研究现状。首先,系统介绍了太赫兹检测方法的原理及系统,并与传统检测手段进行了比较;其次,重点总结了太赫兹时域和频域光谱及其成像技术在复合绝缘材料老化和缺陷检测中的实际应用,包括缺陷的识别和定位、组分鉴定及老化状态评估等;最后,对太赫兹无损检测技术在该领域的发展前景进行了展望。希冀该综述可帮助相关研究人员快速了解太赫兹无损检测技术在电气设备状态诊断方面的研究和应用情况,并对同类问题提供解决思路。

关键词：电气设备复合绝缘结构太赫兹无损检测太赫兹时域光谱太赫兹频域光谱太赫兹成像

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户外拓展训练对初中生身体素质的影响研究

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冰雪体育创新研究 2024年第13期 95-97页

作者：康永强马晓聊城大学山东聊城252000

该文旨在探究户外拓展训练对初中生身体素质的影响。通过对实验班和对照班的身体素质进行比较分析,发现经过15周的户外拓展训练后,实验班学生在体能、柔韧性和力量等方面取得显著提高,相较于对照班表现更为优异。研究结果表明,户外拓展... 详细信息

该文旨在探究户外拓展训练对初中生身体素质的影响。通过对实验班和对照班的身体素质进行比较分析,发现经过15周的户外拓展训练后,实验班学生在体能、柔韧性和力量等方面取得显著提高,相较于对照班表现更为优异。研究结果表明,户外拓展训练在初中体育课程中具有积极的影响,为教育实践提供了有益的参考。

关键词：户外拓展训练初中生身体素质

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Fractal Dimension Analysis Based Aging State Assessment of Insulating Paper with Surface Microscopic Images

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Computer Modeling in Engineering & Sciences 2022年第5期131卷 1083-1099页

作者： Shuaibing Li Jiaqi Cui yongqiang kang School of New Energy&Power Engineering Lanzhou Jiaotong UniversityLanzhou730070China School of Automatic&Electrical Engineering Lanzhou Jiaotong UniversityLanzhou730070China

The insulating paper of the transformer is affected by many factors during the operation,meanwhile,the surface texture of the paper is easy to *** explore the relationship between the aging state and surface texture change of insulating paper,firstly,the thermal aging experiment of insulating paper is carried out,and the insulating paper samples with different aging times are *** then,the images of the aged insulating paper samples are collected and *** pre-processing effect is verified by constructing and calculating the gray surface of the ***,the texture features of the insulating paper image are extracted by box dimension and multifractal *** on that,the extreme learning machine(ELM)is taken as the classification tool with texture features and aging time as the input and output,to train the algorithm and construct the corresponding relationship between the texture feature and the aging *** then,the insulating paper with unknown aging time is predicted with a trained *** numerical test results show that the texture features extracted from the fractal dimension of the micro image can effectively characterize the aging state of insulating paper,the average accuracy can reach 91.6%.It proves that the fractal dimension theory can be utilized for assessing the aging state of insulating paper for onsite applications.

关键词： Insulating paper aging state fractal dimension box dimension multifractal spectrum

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Review of condition monitoring and defect inspection methods for composited cable terminals

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High Voltage 2023年第3期8卷 431-444页

作者： Shuaibing Li Binglei Cao Jin Li Yi Cui yongqiang kang Guangning Wu School of New Energy and Power Engineering Lanzhou Jiaotong UniversityLanzhouChina School of Electrical Engineering and Automation Tianjin UniversityTianjinChina School of Engineering University of Southern QueenslandBrisbaneAustralia School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

Composited cable terminals are critical for reliable power delivery of traditional and traction power supply *** its operation,the cable terminal continually undergoes complex circumstances where humidity,temperature,field strength,mechanical stress and other factors continuously change at different *** extreme cases,defects or even failures may occur in the cable terminals,leading to catastrophic *** makes the condition monitoring and defect detection of composited cable terminals become an imperative need for the power ***“state-of-the-art”technology of cable terminal condition assessment is focussed and a systematic review of the current research progress of cable terminal condition assessment from the operation circumstances to failure mechanisms is *** covers both online/offline condition monitoring methods and defects detection *** addition,challenges and future research directions for cable terminal condition assessment are also *** is concluded that the non-destructive and non-intrusive methods like terahertz imaging and ultrasonic testing,and multi-source information fusion methods as well as the digital twin technology have been gaining popularity for cable terminal defect *** is expected the presented work can provide a global field of vision for further advancement of both scholars and industrial engineers in this field.

关键词： defect condition composite

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Engineering nanoporous and solid core-shell architectures of lowplatinum alloy catalysts for high power density PEM fuel cells

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Nano Research 2022年第7期15卷 6148-6155页

作者： yongqiang kang Jiaqi Wang Yinping Wei Yongle Wu Dongsheng Xia Lin Gan Institute of Materials Research Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China

Low-platinum(Pt)alloy catalysts hold promising application in oxygen reduction reaction(ORR)electrocatalysis of protonexchange-membrane fuel cells(PEMFCs).Although significant progress has been made to boost the kinetic ORR mass activity at low current densities in liquid half-cells,little attention was paid to the performance of Pt-based catalysts in realistic PEMFCs particularly at high current densities for high power density,which remains poorly *** this paper,we show that,regardless of the kinetic mass activity at the low current density region,the high current density performance of the low-Pt alloy catalysts is dominantly controlled by the total Pt surface area,particularly in low-Pt-loading H_(2)–air *** this end,we propose two different strategies to boost the specific Pt surface area,the post-15-nm dealloyed nanoporous architecture and the sub-5-nm solid core–shell nanoparticles(NPs)through fluidic-bed synthesis,both of which bring in comparably high mass activity and high Pt surface area for large-current-density *** medium current density,the dealloyed porous NPs provide substantially higher H_(2)–air PEMFC performance compared to solid core–shell catalysts,despite their similar mass activity in liquid *** transmission electron microscopy images combined with electron energy loss spectroscopic imaging evidence a previously unreported“semi-immersed nanoporous-Pt/ionomer”structure in contrast to a“fully-immersed core–shellPt/ionomer”structure,thus favoring O_(2) transport and improving the fuel cell *** results provide new insights into the role of Pt nanostructures in concurrently optimizing the mass activity,Pt surface area and Pt/Nafion interface for high power density fuel cells.

关键词： low-platinum alloy catalyst nanoporosity proton-exchange-membrane fuel cells power density triple-phase boundary

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复方地黄颗粒通过泛素-蛋白酶体系统治疗PD阴虚动风证大鼠的分子机制研究

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南京中医药大学学报 2024年第6期40卷 608-617页

作者：吕子微梁建庆王行玲孙光洁何建成康永强甘肃中医药大学基础医学院甘肃兰州730050 甘肃省中医方药挖掘与创新转化重点实验室甘肃兰州730050 敦煌医学与转化教育部重点实验室甘肃兰州730050 上海中医药大学中医学院上海201203 兰州市第二人民医院神经内科甘肃兰州730050

目的探讨复方地黄颗粒通过调节泛素-蛋白酶体系统相关蛋白变化治疗帕金森病(PD)阴虚动风证的分子机制。方法随机选取26只SPF级雄性SD大鼠作为正常对照组、假手术组,每组13只,其余大鼠采用6-羟基多巴胺(6-OHDA)脑部偏侧注射损毁黑质法制... 详细信息

目的探讨复方地黄颗粒通过调节泛素-蛋白酶体系统相关蛋白变化治疗帕金森病(PD)阴虚动风证的分子机制。方法随机选取26只SPF级雄性SD大鼠作为正常对照组、假手术组,每组13只,其余大鼠采用6-羟基多巴胺(6-OHDA)脑部偏侧注射损毁黑质法制备PD阴虚动风证大鼠模型,将成模大鼠随机分为模型组,美多芭组(150 mg·kg^(-1)),复方地黄颗粒低、中、高剂量组(1.75、3.5、7 g·kg^(-1)),每组13只。各组连续灌胃给药28 d。观察各组大鼠一般情况及神经行为学表现;免疫组化法、Western blot及qPCR法检测各组大鼠脑部损毁侧纹状体组织中泛素(UB)、泛素激活酶(UBE1)、泛素结合酶(UBE2A)、泛素羧基末端水解酶(UCH-L1)阳性细胞表达、蛋白及mRNA表达水平;ELISA法检测各组大鼠脑部损毁侧纹状体中多巴胺(DA)含量变化。结果正常对照组与假手术组一般情况无明显差异,旋转圈数、悬挂时间及移动格数差异无统计学意义,与假手术组比较,模型组大鼠精神差,易激惹,肢体震颤,行动迟缓,毛色黯黄,饮食少,体质量减轻,旋转圈数增加、悬挂时间及移动格数减少(P0.05)。结论复方地黄颗粒可能通过调控泛素-蛋白酶体系统相关蛋白的表达,减少异常蛋白聚集,从而减轻DA含量缺失,发挥治疗PD阴虚动风证的作用,并以复方地黄颗粒高剂量效果最佳。

关键词：帕金森病阴虚动风证复方地黄颗粒泛素-蛋白酶体系统分子机制

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Abnormal State Detection of OLTC Based on Improved Fuzzy C-means Clustering

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Chinese Journal of Electrical Engineering 2023年第1期9卷 129-141页

作者： Hongwei Li Lilong Dou Shuaibing Li yongqiang kang Xingzu Yang Haiying Dong School of Automation and Electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070China School of New Energy and Power Engineering Lanzhou Jiaotong UniversityLanzhou 730070China

An accurate extraction of vibration signal characteristics of an on-load tap changer(OLTC)during contact switching can effectively help detect its abnormal ***,an improved fuzzy C-means clustering method for abnormal state detection of the OLTC contact is ***,the wavelet packet and singular spectrum analysis are used to denoise the vibration signal generated by the moving and static contacts of the ***,the Hilbert-Huang transform that is optimized by the ensemble empirical mode decomposition(EEMD)is used to decompose the vibration signal and extract the boundary spectrum ***,the gray wolf algorithm-based fuzzy C-means clustering is used to denoise the signal and determine the abnormal states of the OLTC *** analysis of the experimental data shows that the proposed secondary denoising method has a better denoising effect compared to the single denoising *** EEMD can improve the modal aliasing effect,and the improved fuzzy C-means clustering can effectively identify the abnormal state of the OLTC *** analysis results of field measured data further verify the effectiveness of the proposed method and provide a reference for the abnormal state detection of the OLTC.

关键词： On-load tap changer singular spectrum analysis Hilbert-Huang transform gray wolf optimization algorithm fuzzy C-means clustering

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