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Protection and Control of Modern Power Systems 2023年第2期8卷 207-217页

作者： Hongchun Shu Shixin Wang shunguang lei Yunnan Key Laboratory of Green Energy Electric Power Measurement DigitalizationControl and ProtectionKunming University of Science and TechnologyKunming 650500Yunnan ProvinceChina School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001Heilongjiang ProvinceChina

Hybrid high-voltage direct current(HVDC)transmission has the characteristic of long transmission distance,complex corridor environment,and rapid fault evolution of direct current(DC)*** high fault current can easily cause irreversible damage to power devices,rapid and reliable line protection and isolation are necessary to improve the security and reliability of hybrid HVDC transmission *** address such requirement,this paper proposes a single-ended protection method based on transient voltage frequency band ***,the frequency characteristics of the smoothing reactor,DC filter,and DC line are analyzed,and the characteristic frequency band is defined.A fault criterion is then constructed based on the voltage characteristic frequency band energy,and faulty pole selection is performed according to the fault voltage characteristic frequency band energy *** proposed protection method is verified by simulation,and the results show that it can rapidly and reliably identify internal and external faults,accurately select faulty poles without data communication synchronization,and has good fault-resist-ance and anti-interference performance.

关键词： Boundary frequency characteristics Characteristic frequency band Hybrid HVDC Single-end protection Transient voltage

基于桥臂功率特征的全-半混合型柔性直流输电线路保护

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电工技术学报 2023年第13期38卷 3563-3575页

作者：雷顺广束洪春李志民哈尔滨工业大学电气工程及自动化学院哈尔滨150001 昆明理工大学电力工程学院昆明650051

全-半混合型柔性直流输电系统具有故障自清除能力,能在一定程度上解决因高压直流断路器技术滞后导致的柔性直流输电容量提升困难问题,是新能源发电大容量远距离输出的解决方案之一。但全-半混合型柔性直流输电对保护时间提出了更高要求... 详细信息

全-半混合型柔性直流输电系统具有故障自清除能力,能在一定程度上解决因高压直流断路器技术滞后导致的柔性直流输电容量提升困难问题,是新能源发电大容量远距离输出的解决方案之一。但全-半混合型柔性直流输电对保护时间提出了更高要求,需要在更短时间内实现故障识别。该文基于能量观点分析了直流线路故障下桥臂功率特征,提出基于桥臂功率特征的全-半混合型柔性直流输电线路保护方法,能够在1 ms内识别直流线路故障,实现故障选极。最后,通过大量实时数字模拟(RTDS)实验验证了该方法的可靠性高、选择性好,且具有较强的耐过渡电阻能力和抗干扰能力。

关键词：全-半混合型柔性直流输电等效电路桥臂功率特性直流线路保护

Metarelation2vec:A Metapath-Free Scalable Representation Learning Model for Heterogeneous Networks

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Tsinghua Science and Technology 2024年第2期29卷 553-575页

作者： lei Chen Yuan Li Yong lei Xingye Deng School of Information and Electrical Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Computer Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China

Metapaths with specific complex semantics are critical to learning diverse semantic and structural information of heterogeneous networks(HNs)for most of the existing representation learning ***,any metapaths consisting of multiple,simple metarelations must be driven by domain *** sensitive,expensive,and limited metapaths severely reduce the flexibility and scalability of the existing models.A metapath-free,scalable representation learning model,called Metarelation2vec,is proposed for HNs with biased joint learning of all metarelations in a bid to address this ***,a metarelation-aware,biased walk strategy is first designed to obtain better training samples by using autogenerating cooperation probabilities for all metarelations rather than using expert-given ***,grouped nodes by the type,a common and shallow skip-gram model is used to separately learn structural proximity for each node ***,grouped links by the type,a novel and shallow model is used to separately learn the semantic proximity for each link ***,supervised by the cooperation probabilities of all meta-words,the biased training samples are thrown into the shallow models to jointly learn the structural and semantic information in the HNs,ensuring the accuracy and scalability of the *** experimental results on three tasks and four open datasets demonstrate the advantages of our proposed model.

关键词： metarelation random walk heterogeneous network metapath representation learning

基于随机矩阵理论的混合三端直流线路非单元式纵联保护

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电力系统自动化 2022年第19期46卷 162-171页

作者：束洪春王广雪田鑫萃代月雷顺广何廷一昆明理工大学电力工程学院云南省昆明市650500 昆明理工大学国土资源工程学院云南省昆明市650032 云南电网有限责任公司电力科学研究院云南省昆明市650011

针对混合三端直流输电线路保护难以兼顾速动性与选择性的问题,提出一种基于随机矩阵理论的非单元式纵联保护。分析发现,混合三端直流线路区内、区外故障时,线路各测点电压、电流突变量方向不同。首先,利用各测点电压、电流突变量复制、... 详细信息

针对混合三端直流输电线路保护难以兼顾速动性与选择性的问题,提出一种基于随机矩阵理论的非单元式纵联保护。分析发现,混合三端直流线路区内、区外故障时,线路各测点电压、电流突变量方向不同。首先,利用各测点电压、电流突变量复制、平移构成随机矩阵并计算各矩阵特征值;其次,结合单环定理与特征根统计量进行区内、区外故障识别以及故障区段定位;最后计算故障区段极波能量比值实现故障选极。基于实时数字仿真器(RTDS)搭建混合三端直流系统进行测试分析。测试结果表明,所提保护判据简单可靠,耐受高阻能力强,在不同故障情况下均能快速准确识别区内外故障、故障区段及故障极,不需要同步时钟且对通信通道要求低。

关键词：高压直流输电纵联保护极波能量比随机矩阵理论

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柔性直流输电系统的桥臂功率解析

电网技术 2023年第4期47卷 1490-1499页

作者：雷顺广束洪春李志民田鑫萃王广雪哈尔滨工业大学电气工程及自动化学院黑龙江省哈尔滨150001 昆明理工大学电力工程学院云南省昆明市650051

该文从能量传递角度对柔性直流输电系统故障进行解析,提出了基于换流阀桥臂功率的柔性直流输电系统故障解析方法与新思路,为柔性直流输电系统交流故障、直流线路故障分析及瞬时能量平衡控制提供了解析基础和实用工具。首先,建立了交流... 详细信息

该文从能量传递角度对柔性直流输电系统故障进行解析,提出了基于换流阀桥臂功率的柔性直流输电系统故障解析方法与新思路,为柔性直流输电系统交流故障、直流线路故障分析及瞬时能量平衡控制提供了解析基础和实用工具。首先,建立了交流系统故障等效电路,利用对称分量法推导在交流单相故障、双相短路故障以及三相短路故障下桥臂功率解析表达式,分析了交流故障下桥臂功率的变化特征;继而,从能量传递角度出发,建立了直流故障等效电路,推导了直流线路故障下桥臂功率解析表达式,分析了直流故障下桥臂功率的变化特征;最后,在PSCAD/EMTDC仿真平台搭建了柔性直流输电系统,把解析结果与仿真结果进行了对比,验证了该文所提解析方法的准确性。

关键词：柔性直流输电故障电路等效故障解析桥臂功率解析桥臂功率特征

Two-Stage Online Debiased Lasso Estimation and Inference for High-Dimensional Quantile Regression with Streaming Data

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Journal of Systems Science & Complexity 2024年第3期37卷 1251-1270页

作者： PENG Yanjin WANG lei School of Statistics and Data Science KLMDASRLEBPS and LPMCNankai UniversityTianjin 300071China

In this paper,the authors propose a two-stage online debiased lasso estimation and statistical inference method for high-dimensional quantile regression(QR)models in the presence of streaming *** the first stage,the authors modify the QR score function based on kernel smoothing and obtain the online lasso smoothed QR estimator through iterative *** estimation process only involves the current data batch and specific historical summary statistics,which perfectly accommodates to the special structure of streaming *** the second stage,an online debiasing procedure is carried out to eliminate biases caused by the lasso penalty as well as the accumulative approximation error so that the asymptotic normality of the resulting estimator can be *** authors conduct extensive numerical experiments to evaluate the performance of the proposed *** experiments demonstrate the effectiveness of the proposed method and support the theoretical *** application to the Beijing PM2.5 Dataset is also presented.

关键词： Adaptive tuning asymptotic normality debiased lasso online updating quantile regres-sion

Structural energy storage composites based on modified carbon fiber electrode with metal-organic frame enhancing layered double hydroxide

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Nano Research 2024年第3期17卷 1552-1563页

作者： Jinrui Ye Zhongbao Wang Qin lei lei Sun Jinfeng Gu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Tangshan Research Institute Beijing Institute of TechnologyTangshan 063000China School of Materials Science and Engineering Shenyang Jianzhu UniversityShenyang 110168China Department of Stomatology PLA Strategic Support Force Characteristic Medical CenterBeijing 100101China Beijing Electromechanical Engineering Research Institute Beijing 100074China

Structural energy storage composites present advantages in simultaneously achieving structural strength and electrochemical *** of carbon fiber electrodes and resin structural electrolytes in energy storage composite poses challenges in maintaining good mechanical and electrochemical properties at reasonable cost and ***,we report a simple method to fabricate structural supercapacitor using carbon fiber electrodes(modified by Ni-layered double hydroxide(Ni-LDH)and in-situ growth of Co-metal-organic framework(Co-MOF)in a two-step process denoted as Co-MOF/Ni-LDH@CF)and bicontinuous-phase epoxy resin-based structural ***-MOF/Ni-LDH@CF as electrode material exhibits improved specific capacity(42.45 F·g^(-1))and cycle performance(93.3%capacity retention after 1000 cycles)in a three-electrode *** bicontinuous-phase epoxy resin-based structural electrolyte exhibits an ionic conductivity of 3.27×10^(-4) S·cm^(-1).The fabricated Co-MOF/Ni-LDH@CF/SPE-50 structural supercapacitor has an energy density of 3.21 Wh·kg^(-1) at a power density of 42.25 W·kg^(-1),whilst maintaining tensile strength and modulus of 334.6 MPa and 25.2 *** results show practical potential of employing modified commercial carbon fiber electrodes and epoxy resin-based structural electrolytes in structural energy storage applications.

关键词： carbon fiber electrode structural electrolyte structural energy storage composites supercapacitor

Terminal-selective C（sp3）–H borylation of unbranched alkanes enabled by intermolecular radical sampling and LMCT photocatalysis

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National Science Review 2024年第5期11卷 96-98页

作者： Zhexuan lei Jie Wu Department of Chemistry National University of Singapore

The selective functionalization of C（sp3）–H bonds with subtle differences in alkanes is highly sought after due to its atom-and step-efficiency. The activation of C（sp3）–H bonds through hydrogen atom transfer （HAT） has been extensively exploited to produce a valueadded product from unfunctionalized material [1,2].

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DCVAE-adv:A Universal Adversarial Example Generation Method for White and Black Box Attacks

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Tsinghua Science and Technology 2024年第2期29卷 430-446页

作者： lei Xu Junhai Zhai College of Mathematics and Information Science Hebei UniversityBaoding 071002China

Deep neural network(DNN)has strong representation learning ability,but it is vulnerable and easy to be fooled by adversarial *** order to handle the vulnerability of DNN,many methods have been *** general idea of existing methods is to reduce the chance of DNN models being fooled by observing some designed adversarial examples,which are generated by adding perturbations to the original *** this paper,we propose a novel adversarial example generation method,called *** from the existing methods,DCVAE-adv constructs adversarial examples by mixing both explicit and implicit perturbations without using original ***,the proposed method can be applied to both white box and black box *** addition,in the inference stage,the adversarial examples can be generated without loading the original images into memory,which greatly reduces the memory *** compared DCVAE-adv with three most advanced adversarial attack algorithms:FGSM,AdvGAN,and AdvGAN++.The experimental results demonstrate that DCVAE-adv is superior to these state-of-the-art methods in terms of attack success rate and transfer ability for targeted *** code is available at https://***/xzforeverlove/DCVAE-adv.

关键词： deep neural network adversarial examples white box attack black box attack robustness

Extended finite element-based cohesive zone method for modeling simultaneous hydraulic fracture height growth in layered reservoirs

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 2960-2981页

作者： lei Yang Baixi Chen Hopkins Extreme Materials Institute Johns Hopkins UniversityBaltimoreMD21218USA School of Civil Engineering The University of SydneyNSW2006Australia Department of Mechanical Engineering University of Wisconsin-Madison1513 University AvenueMadisonWI53706-1572USA Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

In this study,a fully coupled hydromechanical model within the extended finite element method(XFEM)-based cohesive zone method(CZM)is employed to investigate the simultaneous height growth behavior of multi-cluster hydraulic fractures in layered porous reservoirs with modulus *** coupled hydromechanical model is first verified against an analytical solution and a laboratory ***,the fracture geometry(***,aperture,and area)and fluid pressure evolutions of multiple hydraulic fractures placed in a porous reservoir interbedded with alternating stiff and soft layers are investigated using the *** stress and pore pressure distributions within the layered reservoir during fluid injection are also *** simulation results reveal that stress umbrellas are easily to form among multiple hydraulic fractures’tips when propagating in soft layers,which impedes the simultaneous height *** is also observed that the impediment effect of soft layer is much more significant in the fractures suppressed by the preferential growth of adjoining *** that,the combined effect of in situ stress ratio and fracturing spacing on the multi-fracture height growth is presented,and the results elucidate the influence of in situ stress ratio on the height growth behavior depending on the fracture ***,it is found that the inclusion of soft layers changes the aperture distribution of outmost and interior hydraulic *** results obtained from this study may provide some insights on the understanding of hydraulic fracture height containment observed in filed.

关键词： Hydraulic fracturing Layered reservoir Simultaneous height growth In situ stress Fracture spacing Extended finite element method(XFEM) Cohesive zone method(CZM)