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Transient Stability Analysis of Converter-based Islanded Microgrids Based on Iterative Equal Area Criterion Considering Reactive Power Loop Dynamics and Varying Damping

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Journal of Modern Power systems and Clean Energy 2024年第4期12卷 1170-1182页

作者： Xilin Li Jingyi Zhang Zhen Tian Xiaoming Zha Wei Wang Meng Huang Chong Shao Hubei Key Laboratory of Power Equipment&System Security for Integrated Energy School of Electrical Engineering and AutomationWuhan UniversityWuhanChina NARI Technology Co. Ltd.NanjingChina State Grid Gansu Electric Power Company LanzhouChina

With the rapid increase in the installed capacity of renewable energy in modern power systems,the stable operation of power systems with considerable power electronic equipment requires further *** converter-based islanded microgrid(CIM)systems equipped with grid-following(GFL)and grid-forming(GFM)voltage-source converters(VSCs),it is challenging to maintain stability due to the mutual coupling effects between different VSCs and the loss of voltage and frequency support from the power *** previous studies,quantitative transient stability analysis was primarily used to assess the active power loop of ***,frequency and voltage dynamics are found to be strongly coupled,which strongly affects the estimation result of stability *** addition,the vary-ing damping terms have not been fully *** bridge these gaps,this paper investigates the transient stability of CIM consid-ering reactive power loop dynamics and varying ***,an accuracy-enhanced nonlinear model of the CIM is derived based on the effects of reactive power loop and post-disturbance frequency jump *** these effects will eliminates the risk of *** reactive power loop dynamics make the model coefficients be no longer constant and thus vary with the power *** evaluate quantitatively the effects of re-active power loop and varying damping on the transient stability of CIM,an iterative criterion based on the equal area criterion theory is *** addition,the effects of parameters on the stable boundary of power system are analyzed,and the dynamic interaction mechanisms are *** and experiment results verify the merits of the proposed method.

关键词： Transient stability converter iterative criterion reactive power loop post-disturbance frequency jump

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A multi-channel image-based method for flight delay prediction in terminal area 4

A multi-channel image-based method for flight delay predicti...

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2024 4th International Conference on Intelligent Traffic systems and Smart City, ITSSC 2024

作者： Yang, Yihan Chen, Haiyan Yang, Longwu State Key Laboratory of Air Traffic Management System Nanjing China College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing China

ISBN: (纸本)9781510686304

With the rapid development of civil aviation, flight delays have become increasingly critical. Effectively predicting flight delays has become a research hotspot in recent years. In this paper, we propose a novel flight delay prediction method based on image recognition by applying deep learning techniques. We first rasterize the target terminal area into a grid image of size 25×25. Then, we convert the arrival and departure traffic flow data collected over some time into colors and fill them into the corresponding grids to obtain the arrival and departure traffic flow images. On this basis, we design the prediction model Attention-Complementary Hybrid Network (ACHNet), which can be used for multi-channel image feature fusion. It takes arrival and departure traffic flow images as inputs and fuses the spatial information of these two types of images through the fusion branch. We use the Convolutional Neural Network (CNN)-based prediction model to predict flight delays on arrival and departure traffic flow image sets respectively, and compare the prediction results with those of ACHNet. The experimental results show that the fusion of multi-channel image features can effectively improve the performance of flight delay prediction. © 2025 SPIE.

关键词： Convolutional neural networks

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A Survey of Underwater Multi-Robot systems

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IEEE/CAA Journal of Automatica Sinica 2022年第1期9卷 1-18页

作者： Ziye Zhou Jincun Liu Junzhi Yu State Key Laboratory for Turbulence and Complex System Department of Advanced Manufacturing and RoboticsBeijing Innovation Center for Engineering Science and Advanced TechnologyCollege of EngineeringPeking UniversityBeijing 100871China College of Information and Electrical Engineering China Agricultural UniversityBeijing 100083China

As a cross-cutting field between ocean development and multi-robot system(MRS),the underwater multi-robot system(UMRS)has gained increasing attention from researchers and engineers in recent *** this paper,we present a comprehensive survey of cooperation issues,one of the key components of UMRS,from the perspective of the emergence of new *** specifically,we categorize the cooperation in terms of task-space,motion-space,measurement-space,as well as their ***,we analyze the architecture of UMRS from three aspects,i.e.,the performance of the individual underwater robot,the new functions of underwater robots,and the technical approaches of *** conclude,we have discussed related promising directions for future *** survey provides valuable insight into the reasonable utilization of UMRS to attain diverse underwater tasks in complex ocean application scenarios.

关键词： Cooperation formation control multi-robot systems(MRS) taxonomy underwater robots underwater tasks

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High-efficiency crystalline carbon nitride photocatalysts:Status and perspectives

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Nano Research 2024年第9期17卷 7840-7863页

作者： Wenji Pu Yunqiao Zhou Lingfeng Yang Haifeng Gong Yuhan Li Qingyu Yang Dieqing Zhang Engineering Research Center for Waste Oil Recovery Technology and Equipment Ministry of EducationChongqing Key Laboratory of Catalysis and New Environmental MaterialsChongqing Technology and Business UniversityChongqing 400067China The Education Ministry Key Lab of Resource Chemistry Joint International Research Laboratory of Resource Chemistry of Ministry of EducationShanghai Key Laboratory of Rare Earth Functional Materialsand Shanghai Frontiers Science Center of Biomimetic CatalysisShanghai Normal UniversityShanghai 200234China State Key Laboratory of Tibetan Plateau Earth System Resources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

Crystallinity and crystal structure greatly influence the photocatalytic behavior of *** g-C3N4 produced by traditional thermal-induced polycondensation reaction bears low crystallinity and thus poor photoactivity,which originates from the incomplete polymerization of the precursor containing amine groups,abundant hydrogen bonds,and unreacted amino,as well as cyanide functional groups in the *** photocatalytic process,these residual functional groups often work as electron trap sites,which may hinder the transfer of electrons on the plane,resulting in low ***,crystalline carbon nitride(CCN)was reported as a promising photocatalyst because its increased crystallinity not only reduces the number of carriers recombination centers,but also increases charge conductivity and improves light utilization due to extendedπ-conjugated systems and delocalizedπ-*** such,we summarize the recent studies on CCN-based photocatalysts for the photoactivity ***,the unique structure and properties of CCN materials are ***,the preparation methods and modification strategies are well *** also sum up the applications of CCN-based materials in the environmental purification and energy ***,this review concerning CNN materials ends with prospects and challenges in the obtainment of high crystallinity by effective techniques,and the deep understanding of photocatalytic mechanism.

关键词： crystalline carbon nitride preparation method modification strategy photocatalytic application

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Influence of Repetitive Impulse Waveforms on Surface Discharge Characteristics and Insulation Life for Polyimide Film

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CSEE Journal of Power and Energy systems 2024年第2期10卷 746-755页

作者： Zhiyun Han Qingmin Li Yujin Guo Tao Liu Guojing Dong Hanwen Ren State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China Electric Power Research Institute Beijing 100085China Inner Mongolia Electric Economy and Technology Academy Hohhot 010020China

Accelerated insulation aging problems under high frequency repetitive impulses in power electronic transformers are drawing more and more attention in modern power systems. Partial discharge (PD) characteristics including discharge inception voltage, phase distribution and statistical characteristics on polyimide (PI) surface under different impulse waveforms and the insulation life of PI films are studied in this paper. We carry out experiments based on PD and insulation lifetime test systems, using five different types of repetitive impulses, including three bipolar waves and two unipolar waves. The experimental results show that there is little variation in discharge inception voltage under different waveforms, but great variation in phase distribution and statistical characteristics of PD. In addition, insulation life is approximately the same under different waveforms with the same polarity, and the aging rate under bipolar waveforms is larger than that under unipolar waveforms. We explain the differences between the bipolar and unipolar waveforms on insulation life, which can be concluded that the surface charge under unipolar waveform accumulates more significnatly compared with bipolar waveform and decreases the electric filed strength in discharging the air gap and inhibits surface discharge from occurring.

关键词： Insulation life polyimide film power electronic transformer repetitive impulse surface discharge characteristics

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Study on the influence of oil-gas pressure difference on diaphragm in diaphragm compressor 9

Study on the influence of oil-gas pressure difference on dia...

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2024 9th International Seminar on Computer technology, Mechanical and Electrical Engineering, ISCME 2024

作者： Li, Fengyu Liu, Xiaoming Liu, Zhilong Yu, Yang State Key Laboratory of High-end Compressor and System Technology Hefei General Machinery Research Institute Co. Ltd Hefei230031 China

—As one of the main components of hydrogen refueling stations, the diaphragm hydrogen compressor is an important equipment supporting the development of hydrogen energy in China. Currently, the diaphragm hydrogen compressor is facing a significant demand for improving reliability. The diaphragm is one of the vulnerable parts in diaphragm hydrogen compressors, mainly affected by the difference between hydraulic oil pressure and hydrogen pressure, which deforms and compresses hydrogen gas to achieve the operation of diaphragm hydrogen compressors. This study selected the oil gas pressure difference as the independent variable and conducted simulation research on the variation laws of equivalent stress and axial deformation of the diaphragm. © 2025 Institute of Physics Publishing. All rights reserved.

关键词： Diaphragms

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HabitAction: A Video Dataset for Human Habitual Behavior Recognition

arXiv

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arXiv 2024年

作者： Li, Hongwu Zhang, Zhenliang Wang, Wei The State Key Laboratory of Robotics and System Harbin Institute of Technology Harbin150080 China Beijing100080 China

Human Action Recognition (HAR) is a very crucial task in computer vision. It helps to carry out a series of downstream tasks, like understanding human behaviors. Due to the complexity of human behaviors, many highly valuable behaviors are not yet encompassed within the available datasets for HAR, e.g., human habitual behaviors (HHBs). HHBs hold significant importance for analyzing a person’s personality, habits, and psychological changes. To solve these problems, in this work, we build a novel video dataset to demonstrate various HHBs. These behaviors in the proposed dataset are able to reflect internal mental states and specific emotions of the characters, e.g., crossing arms suggests to shield oneself from perceived threats. The dataset contains 30 categories of habitual behaviors including more than 300,000 frames and 6,899 action instances. Since these behaviors usually appear at small local parts of human action videos, it is difficult for existing action recognition methods to handle these local features. Therefore, we also propose a two-stream model using both human skeletons and RGB appearances. Experimental results demonstrate that our proposed method has much better performance in action recognition than the existing methods on the proposed dataset. All the dataset and codes are available at ***/view/hhb30. Copyright © 2024, The Authors. All rights reserved.

关键词： Video analysis

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Intensified Tropical Cyclones in Global Climate Simulations Employing a High-Wind Drag Relation over Sea Surface

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Journal of Climate 2025年第10期38卷 2205-2223页

作者： Wei, Wei Lu, Yixiong Yang, Shunan Liu, Yiming Wu, Tongwen Song, Zhenya Qiao, Fangli Li, Yubin Wu, Fanghua Rong, Xinyao Li, Jianglong CMA Earth System Modeling and Prediction Centre China Meteorological Administration Beijing China State Key Laboratory of Severe Weather Meteorological Science and Technology CMA Earth System Modeling and Prediction Centre Beijing China National Meteorological Centre China Meteorological Administration Beijing China First Institute of Oceanography Key Laboratory of Marine Science and Numerical Modeling Ministry of Natural Resources Qingdao China School of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing China

Accurate parameterization of momentum fluxes at high winds across the air–sea interface is crucial for realistically simulating the surface wind fields of tropical cyclones (TCs). Climate models often struggle to reproduce observed TC intensities, particularly surface wind speeds. This study evaluates the performance of a revised surface drag scheme with a capping drag coefficient at high wind speeds in global climate models (GCMs). Our results indicate that the revised surface drag scheme significantly improves the representation of TCs in a statistical sense: (i) Not only the mature intensity but also the maximum 10-m wind speeds throughout the TC life cycle are largely enhanced;(ii) biases in the pressure–wind relationship are notably alleviated, exhibiting reasonable agreement with observations;and (iii) other TC statistical features, such as TC number, central sea level pressure, individual lifetime, and intensification rate, show relatively minor sensitivity to the surface drag schemes. The main reason for the superiority of the revised high-wind drag relation is that the lower drag coefficient in high-wind conditions significantly increases the maximum potential intensity (MPI), indicating a higher theoretical limit for TC intensities. These findings are consistent across different model versions and resolutions, highlighting the robustness of the high-wind surface drag parameterization in controlling the simulated surface wind speeds of TCs in GCMs. © 2025 American Meteorological Society.

关键词： Tropical cyclone

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Tuning the ONOOH of plasma-activated water: Effect of the N2/O2 ratio and post-discharge duration 6

Tuning the ONOOH of plasma-activated water: Effect of the N2...

引用

6th IEEE International Electrical and Energy Conference, CIEEC 2023

作者： Ran, Congfu Liu, Kun Chongqing University The State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing China

ISBN: (纸本)9798350346671

Plasma activated water (PAW) contains a variety of reactive oxygen and nitrogen species (RONS). Among them, ONOOH has an impact on the activity and function of cells in the biological system, and also has a pharmacological inhibitory on many human diseases. However, since ONOOH in PAW is a transient species that is difficult to determine, most of the current research is still mainly focused on its determination or basic applications. There is no in-depth study and discussion on its regulation mechanism. Therefore, this research mainly investigates the two aspects mentioned above. In this study, the dielectric barrier discharge (DBD) is used to treat phosphate buffer solution (PBS) for preparing PAW. The effect of different gas ratios of N2 to O2 on the product characteristics and the lifetime of ONOOH with its precursors is studied, and the pH value of the solution is also tested. The result shows that the maximum yield of ONOOH is at a gas ratio of N2:02=6:4. Then, PAW prepared under different conditions is preserved, in which the products are detected on the different periods. The result shows that the concentration of ONOOH rises briefly after the treatment with the gas ratio of N2:02= 9:1, 8:2 and 7:3, which indicates that the generation of ONOOH can be more than the consumption under these conditions at 0-15 minutes. © 2023 IEEE.

关键词： Dielectric materials

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Preparation of Graphene Loaded Cobalt Catalyst and its Oxygen Evolution Performance 4

Preparation of Graphene Loaded Cobalt Catalyst and its Oxyge...

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4th IEEE International Conference on Electrical Materials and Power Equipment, ICEMPE 2023

作者： He, Wenkai Yang, Qing Zhang, Zhaotian Chongqing University State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing China

ISBN: (纸本)9798350334678

The energy crisis is becoming more severe, and energy restructuring is imperative. Hydrogen energy introduction effectively reduces the proportion of fossil energy, and hydrogen production from the water splitting is a core technology to realize low-carbon transition. Transition metal compounds with large reserves and high catalytic activity are considered promising catalysts for oxygen evolution reactions. In this work, CoS2-loaded oxygen evolution catalysts on graphene were prepared by radio frequency plasma treatment. The introduction of two-dimensional structured graphene accelerates the surface electron migration and increases the reaction area. The plasma treatment promotes the loading of nanoparticles on graphene. The plasma etching effect was used to create a large number of carbon structure defects and oxygen vacancy structures on the surface of catalysts, which improve the distribution of CoS2, effectively modulate CoS2 transition state free energy, and improve the oxygen evolution catalytic activity. Electrochemical tests show that the experimentally synthesized CoS2/rGO@30min achieves an overpotential of300 mV at 50 mAc m-2 with excellent OER performance and stability. © 2023 IEEE.

关键词： Graphene

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