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Chinese Journal of Electrical Engineering 2024年第1期10卷 35-47页

作者： dongxin he Dechao Yang Xinhua Guo Jiefeng Liu Haoxin Guo Qingquan Li Gilbert Teyssedre School of Electrical Engineering Shandong UniversityJinan 250061China School of Mechanical and Electronic Engineering Wuhan University of TechnologyWuhan 430070China School of Electrical Engineering Guangxi UniversityGuangxi 530004China UPS INPTCNRSLAPLACE(Laboratoire Plasma et Conversion d’Energie)University of ToulouseToulouse 31100France

Hot-spot temperature of transformer windings is a crucial indicator of internal ***,current methods for measuring the hot-spot temperature of transformers do not apply to those already in operation and suffer from data *** study introduces a novel inversion method that combines ultrasonic sensing technology,multiphysics simulation,and the K-nearest neighbors *** the penetrative ability and temperature sensitivity of ultrasonic sensing,a detailed physical field simulation model was *** study extensively investigates the characteristics of ultrasonic wave signals inside *** investigation includes different temperature fields,ranging from 40℃ to 110℃ at 10℃ intervals,and various ultrasonic wave emitter *** extracting the key features of the acoustic signals,such as the peak time,propagation time,and peak amplitude,an accurate inversion of the winding hot-spot temperature is successfully *** results demonstrate that this method achieves a high accuracy rate(98.57%)in inverting the internal winding hot-spot temperatures of transformers,offering an efficient and reliable new approach for measuring winding hot-spot temperatures.

关键词： Ultrasonic temperature measurement non-destructive testing oil-immersed transformers machine learning

A method for detecting two-dimensional plane stress distribution in basin-type insulator based on critically refracted longitudinal wave

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High Voltage 2024年第1期9卷 105-116页

作者： Zhaoyang Kang Fuqiang Ren Hongru Zhang Jingjing Yang Kaining Hou Qingquan Li dongxin he Hongshun Liu Yongzhi Zhao Huaxin Wen Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical EngineeringShandong UniversityJinanChina Shandong Electrical Engineering&Equipment Group Co.Ltd JinanChina SDEE Hitachi High-voltage Switchgear Co. LtdJinanChina

Basin-type insulator often has small cracks due to stress *** current method cannot accurately reflect the stress condition of the insulator to find the stress concentration *** solve these problems,a method for detecting two-dimensional plane stress(δ_(1) andδ_(2))within different depth ranges in a basin-type insulator is proposed based on critically refracted longitudinal(LCR)***,the acoustoelastic equation characterising the relationship between the variation of LCR wave propagation time and the plane stress was ***,the propagation characteristics of LCR wave in epoxy resin samples were ***,the stress distribution within different depth ranges of the insulator subjected to hydraulic load was measured using the proposed method,including direction(θ),δ_(1) andδ_(2).The results show that the magnitude of the stress alone cannot accurately characterise the stress *** with equal distances to the centre have similar stress magnitudes,but their directions are not the *** increasing depth,θremains essentially unchanged at the same location,whileδ1 andδ2 decrease,and the rate of decrease varies at different *** the measured and simulated data,the results showed that they were in good agreement,and the maximum errors of stress value andθwere 0.69 MPa and 2.97°,respectively,which confirmed the feasibility and accuracy of the stress detection in the proposed method.

关键词： stress insulator wave

Mixed-ownership Reform:Private Firms’Role in Targeted Poverty Alleviation-A Perspective on Resource Complementarity and Check&Balance

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China Economist 2024年第5期19卷 25-47页

作者： Ding Hui he dongxin Jiang Fuwei Zhang Zhining School of Finance the Central University of Finance and Economics(CUFE)BeijingChina School of Economics Xiamen UniversityXiamenChina Wang Yanan Institute for Studies in Economics(WISE) Xiamen University

Targeted poverty alleviation(TPA)serves as a winning formula for fighting poverty and has generated valuable experiences for achieving common *** mixed-ownership reform has enhanced corporate economic ***,further testing is required to assess whether enterprises contribute to the improvement of distribution by participating in *** A-share-listed private enterprises between 2016 and 2021 as research samples,we conducted an investigation into the extent and manner in which the mixed-ownership reform contributes to *** research reveals that a higher proportion of state capital equity participation is correlated with a greater level of private enterprises’contribution to *** indicates that the mixed-ownership reform is beneficial for prompting private enterprises to shoulder responsibilities for building a society of common *** shown by the mechanism test,state capital equity participation encourages private enterprises to contribute to TPA primarily by alleviating corporate financing constraints through the resource complementarity *** contrast,the check&balance effect of promoting corporate poverty alleviation by mitigating the principal-agent problem has not yet been significantly *** the poverty alleviation model,state capital equity participation prompts private enterprises to contribute to TPA through industrial development,educational investment,and environmental protection,emphasizing a combination of providing external assistance and cultivating endogenous development *** terms of TPA regions,state capital equity participation plays a significant role in supporting economically less-developed regions,regions with high unemployment rates,and central and western *** paper provides new empirical evidence for deepening mixed-ownership reforms and advancing common prosperity.

关键词： Mixed ownership TPA state capital resource complementarity check&balance

网络安全治理与股价崩盘风险——基于上市公司年报文本分析的证据

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金融评论 2024年第1期16卷 86-106,155,156页

作者：王辉何冬昕陈旭姜富伟中央财经大学金融学院中国财政科学研究院金融研究中心

网络安全治理是维护国家数据安全和保障金融体系稳定运行的必要措施。本文基于2006~2019年中国A股上市公司数据,使用深度学习方法分析上市公司年报文本,构建了企业网络安全治理指标体系,研究企业网络安全治理对其股价崩盘风险的影响。... 详细信息

网络安全治理是维护国家数据安全和保障金融体系稳定运行的必要措施。本文基于2006~2019年中国A股上市公司数据,使用深度学习方法分析上市公司年报文本,构建了企业网络安全治理指标体系,研究企业网络安全治理对其股价崩盘风险的影响。实证分析结果表明,上市公司重视网络安全治理可以显著降低股价崩盘风险。该结论在更换解释变量、增加额外控制变量和以《中华人民共和国网络安全法》颁布作为准自然实验等稳健性检验后仍然成立。机制研究发现,企业加强网络安全治理显著降低了外界的信息不对称、提高了企业声誉,进而降低了股价崩盘风险。进一步研究发现,国有企业和规模较大、成长性较好、有形资产比例较低的公司更重视网络安全治理。本文结论为企业网络安全治理对金融风险的影响提供了经验证据,为企业网络安全治理相关政策制定提供了建议参考。

关键词：股价崩盘风险网络安全治理文本分析信息不对称企业声誉

A comparative analysis of dielectric properties of oil-paper insulation and polymer materials before and after thermal aging

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Science China(Technological Sciences) 2014年第4期57卷 738-746页

作者： WANG Wei YUE CaiPeng he dongxin YANG Kai CheN ShengKe Beijing Key Laboratory of High Voltage & Electromagnetic Compatibility State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Shandong Liaocheng Power Supply Company

The shortcomings of oil-immersed transformer solid insulation like low high-temperature resistance of the insulation paper and the uneven distribution of electric field caused by the large difference of dielectric constants between insulation paper and transformer oil,restricted the development of transformer with smaller size and larger *** view of this situation and the transformer’s demand for the dielectric physicochemical and mechanical property of insulation material,polycarbonate,polyester film and polyphenylene sulfide with high high-temperature resistance were chosen for the comparison analysis in this paper We did the 300-day thermal aging experiment on four samples in transformer oil under different aging temperatures of90°C,110°C and 130°C,then analyzed the changes of their dielectric *** experiment results are as follows;the permittivity and dielectric dissipation factor of the three polymer materials are apparently smaller than those of the paper both before and after 300-day aging;the volume resistivity and partial discharge inception voltage of the three materials are higher than those of the paper both before and after aging;and the breakdown field strength of polycarbonate is higher than that of the paper both before and after aging,while that of polyester film and polyphenylene sulfide are slightly lower than that of the paper.

关键词： oil-immersed transformer solid insulation polymer materials thermal aging dielectric properties

热历史对二氨基二苯甲烷型苯并恶嗪热性能的影响

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工程塑料应用 2024年第9期52卷 86-91页

作者：何东新张震刘承杰李浩宇李仲伟高生齐鲁工业大学(山东省科学院)材料科学与工程学院济南250353

苯并恶嗪树脂是具有独特化学结构和优异性能的类酚醛热固性材料,在不同特殊场景具有很大发展和应用潜力。设定3种不同温度和时间模式的热处理工艺参数以获得不同热历史,用高温烘箱对含质量分数1%固化剂的4,4′-二氨基二苯甲烷型苯并恶嗪... 详细信息

苯并恶嗪树脂是具有独特化学结构和优异性能的类酚醛热固性材料,在不同特殊场景具有很大发展和应用潜力。设定3种不同温度和时间模式的热处理工艺参数以获得不同热历史,用高温烘箱对含质量分数1%固化剂的4,4′-二氨基二苯甲烷型苯并恶嗪(MDA-BZ)和无固化剂MDA-BZ对比物进行同批次处理,分别比较同类型不同热历史和相同热历史不同类型固化物试样的热性能,达成方案以优化复合材料基体用MDA-BZ的固化工艺参数。用综合热分析仪在相同测试条件下测试不同试样的热性能。结果表明,热历史中温度增加和时间延长使无固化剂MDA-BZ的固化反应峰温升高,聚苯并恶嗪在600℃质量损失率增加,热稳定性降低。温度增加和时间延长对含质量分数1%固化剂MDA-BZ产生不同影响,发现质量分数1%固化剂在185℃(1 h)+205℃(1 h)处理条件下可促进MDA-BZ的开环固化反应,使失重起始温度提高,600℃质量损失率降低,热稳定性提高。加入质量分数1%固化剂与未加入固化剂的MDA-BZ具有不同降解机制。优选出MDA-BZ用于复合材料基体的固化工艺方案,即加入质量分数1%固化剂和185℃(1 h)+205℃(1 h)两段处理的组合工艺。

关键词：苯并恶嗪热历史固化剂 4,4′-二氨基二苯甲烷热性能

Study on partial discharge and charge accumulation characteristics of oil‐pressboard insulation under DC superimposed harmonic voltage

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High Voltage 2023年第6期8卷 1215-1224页

作者： Shuqi Li Qiang Wang dongxin he Liangkai Wang Qingquan Li Wen Si Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical EngineeringShandong UniversityJinanChina Zibo City Product Quality Inspection Institute ZiboChina School of Information and Electrical Engineering Shandong Jianzhu UniversityJinanChina

The oil‐pressboard insulation on the valve side of the converter transformer withstands pulsating square wave *** voltage contains lots of DC components and high‐order harmonics,which is likely to cause insulation *** partial discharge and space charge experiments of oil‐impregnated pressboard under DC superimposed har-monic voltage are conducted to study the effects of harmonic frequency and DC com-ponents on the discharge and charge accumulation and to explore the correlation mechanism of charge dynamic behaviour and ***,it is found that high‐order harmonic voltage promotes the partial discharge generation,but DC component sup-presses the ***,the charge inside the pressboard is mainly injected in the same polarity and accumulates over *** space charge density near the electrode increases with the increase of harmonic frequency,and the large amount of charge in-jection leads to electric field ***,the electric field direction changes faster,and the frequent charge injection and extraction behaviours make the charge recombination intensify,which promotes the *** the above analysis,the influence law of harmonic voltage on the failure of oil‐pressboard insulation is obtained,providing a theoretical basis for the structural optimisation and condition assessment of the converter transformer insulation.

关键词： harmonic insulation charge

Behaviour and mechanisms of molecular vibrations induced by a pulsed voltage in a silicone elastomer used for device encapsulation

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High Voltage 2023年第5期8卷 1020-1029页

作者： Junyu Wei dongxin he Teng Gao Lin Zhu Haochen Wang Qingquan Li Gilbert Teyssedre Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical Engineering Shandong UniversityJinanChina School of Materials Science and Engineering Shandong UniversityJinanChina UPS INPTCNRSLAPLACE(Laboratoire Plasma et Conversion d’Energie)University of ToulouseToulouseFrance

Silicone elastomers are widely used to encapsulate power electronic ***,such devices may be subjected to square‐wave pulsed voltages with a high rate of change,which can create significant challenges for encapsulation *** this article,the molecular vibration of silicon elastomer at the edge of pulsed electric field is ***,the relationship between the intensity of molecular vibration and the parameters of pulsed electric field is *** experimental results show that the amplitude of the vibrations decreases as the pulse‐edge time increases,and it increases linearly as the pulseedge slope ***,the amplitude of the vibrations is proportional to the square of the amplitude of the pulsed electric field,and it increases as the space charge density ***,the force analysis of charged molecule at the pulse edges is calculated,and the theoretical change law of molecular vibration intensity with pulse edge slope is *** the theoretical results with the experimental results,it is found that they are highly ***,electrically induced mechanical stress caused by molecular vibration was shown to be an important factor in insulation failure.

关键词： pulsed insulation vibrations

Charge vibration behaviour in polyimide under the pulse voltage with different rise and fall times

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High Voltage 2022年第1期7卷 64-74页

作者： Tao Zhang dongxin he Junyu Wei Hongshun Liu Qingquan Li Gilbert Teyssedre Shandong Provincial Key Laboratory of UHV Transmission Technology and Equipment School of Electrical Engineering Shandong UniversityJinanChina UPS INPTCNRSLAPLACE(Laboratoire Plasma et Conversion d’Energie)University of ToulouseToulouseFrance

High‐voltage electronic equipment is widely used in power systems,which normally operate under the pulse voltage ***,compared to DC or AC stress,the electrical insulation suffers a more severe ageing process under a pulse voltage with steep edges and so may cause electrical equipments to fail *** charge behaviour in polyimide under the pulse voltage with different edge times was investigated in this *** experimental results show that charges vibrate at the pulse edge,while the amplitude of charge vibration increases with decreasing edge ***,the detected vibration signal is strong within the nanosecond edge times,while being negligible in the microsecond ***,the amplitude of charge vibration at the falling edge is larger than that at the rising edge in the presence of the column‐plate *** is believed that the resultant force acting on the charge increases drasti-cally at the pulse edges,leading to the charge movement and the generation of ultra-sonic waves,with the resultant force becoming larger when the edge times *** vibration behaviour is harmful to the microstructure of insulation materials,and so it may be concluded that the rise and fall times of the pulse voltage play an important role in insulation failure.

关键词： pulse behaviour insulation

Multi-variable Dependent Forecast Algorithm for Predicting Secondary Arc

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CSEE Journal of Power and Energy Systems 2020年第2期6卷 469-478页

作者： Hongshun Liu Jian Guo dongxin he Mingming Han Ying Sun Jingjing Yang Qingquan Li School of Electrical Engineering Shandong UniversityJinan 250000China

Hybrid reactive power compensation(HRPC)combines step-controlled shunt reactors and series compensation,and will be employed in ultra-high-voltage(UHV)power *** single-phase auto-reclosure characteristics of secondary arcs in systems with HRPC require further *** this paper,both the arc-recalling voltage and subsidiary variations in arc current are investigated with and without *** frequency components of the secondary arc current and variations in arcing time are analyzed for various influential factors,such as the neutral reactor,arc resistance,fault location,degrees of compensation of HRPC,and the length of the transmission *** non-dominated sorting genetic algorithm II(NSGA-II)and support vector machine regression are combined to create a multi-variable dependent forecasting algorithm to predict the characteristics of the secondary arc in UHV systems with *** paper provides a theoretical reference for optimizing the parameters of HRPC,and for developing adaptive auto-reclosure schemes and protection equipment.

关键词： Forecasting algorithm hybrid reactive power compensation low-frequency component secondary arc characteristics support vector machine regression