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Power generation maximization of distributed photovoltaic systems using dynamic topology reconfiguration

Protection and Control of Modern Power Systems 2022年第1期7卷 508-522页

作者： xiaolun fang Qiang Yang Wenjun Yan College of Electrical Engineering Zhejiang UniversityHangzhou 310027China Zhejiang Lab Hangzhou 310000China

The‘mismatch losses’problem is commonly encountered in distributed photovoltaic(PV)power generation systems.It can directly reduce power generation.Hence,PV array reconfiguration techniques have become highly popular to minimize the mismatch losses.In this paper,a dynamical array reconfiguration method for Total-Cross-Ties(TCT)and Series-Parallel(SP)interconnected PV arrays is proposed.The method aims to improve the maximum power output generation of a distributed PV array in different mismatch conditions through a set of inverters and a switching matrix that is controlled by a dynamic and scalable reconfiguration optimization algorithm.The structures of the switching matrix for both TCT-based and SP-based PV arrays are designed to enable flexible alteration of the electrical connections between PV strings and inverters.Also,the proposed reconfiguration solution is scalable,because the size of the switching matrix deployed in the proposed solution is only determined by the numbers of the PV strings and the inverters,and is not related to the number of PV modules in a string.The performance of the proposed method is assessed for PV arrays with both TCT and SP interconnections in different mismatch conditions,including different partial shading and random PV module failure.The average optimization time for TCT and SP interconnected PV arrays is 0.02 and 3 s,respectively.The effectiveness of the proposed dynamical reconfiguration is confirmed,with the aver-age maximum power generation improved by 8.56%for the TCT-based PV array and 6.43%for the SP-based PV array compared to a fixed topology scheme.

关键词： Dynamical reconfiguration Inverter Switching matrix Mismatch losses

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Photovoltaic array reconfiguration under partial shading conditions based on ant colony optimization

Photovoltaic array reconfiguration under partial shading con...

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第32届中国控制与决策会议

作者： Rui Cao Yifan Ding xiaolun fang Siming Liang Fengyang Qi Qiang Yang Wenjun Yan College of Electrical Engineering Zhejiang University Zhejiang Lab Taizhou Institute of Zhejiang University

The utilization of photovoltaic（PV） array installations to acquire solar energy is one of the most important ways of renewable energy obtain. However, the power output of the PV array installations will decrease greatly under partial shading conditions. This paper proposes a new approach for reconfiguration of PV array to extract maximum power using ant colony optimization（ACO）. To prove the validity of the approach, the simulations are performed in Matlab-Simulink comparing with Total cross tied（TCT） configuration. The simulation results show that the proposed approach can enhance efficiency of power extraction from the PV array under partial shading condition.

关键词： Photovoltaic（PV） Array reconfiguration Partial shading Ant colony optimization（ACO）

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A VGGNet-based correction for satellite altimetry-derived gravity anomalies to improve the accuracy of bathymetry to depths of 6500 m

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Acta Oceanologica Sinica 2024年第1期43卷 112-122页

作者： xiaolun Chen Xiaowen Luo Ziyin Wu Xiaoming Qin Jihong Shang Huajun Xu Bin Li Mingwei Wang Hongyang Wan Key Laboratory of Submarine Geosciences Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Ocean College Zhejiang UniversityZhoushan 316021China Key Laboratory of Ocean Space Resources Management Technology Marine Academy of ZhejiangHangzhou 310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200240China School of Civil Engineering and Architectures Zhejiang University of Science and TechnologyHangzhou 310023China National Center for Archaeology Beijing 100013China

Understanding the topographic patterns of the seafloor is a very important part of understanding our planet.Although the science involved in bathymetric surveying has advanced much over the decades,less than 20%of the seafloor has been precisely modeled to date,and there is an urgent need to improve the accuracy and reduce the uncertainty of underwater survey data.In this study,we introduce a pretrained visual geometry group network(VGGNet)method based on deep learning.To apply this method,we input gravity anomaly data derived from ship measurements and satellite altimetry into the model and correct the latter,which has a larger spatial coverage,based on the former,which is considered the true value and is more accurate.After obtaining the corrected high-precision gravity model,it is inverted to the corresponding bathymetric model by applying the gravity-depth correlation.We choose four data pairs collected from different environments,i.e.,the Southern Ocean,Pacific Ocean,Atlantic Ocean and Caribbean Sea,to evaluate the topographic correction results of the model.The experiments show that the coefficient of determination(R~2)reaches 0.834 among the results of the four experimental groups,signifying a high correlation.The standard deviation and normalized root mean square error are also evaluated,and the accuracy of their performance improved by up to 24.2%compared with similar research done in recent years.The evaluation of the R^(2) values at different water depths shows that our model can achieve performance results above 0.90 at certain water depths and can also significantly improve results from mid-water depths when compared to previous research.Finally,the bathymetry corrected by our model is able to show an accuracy improvement level of more than 21%within 1%of the total water depths,which is sufficient to prove that the VGGNet-based method has the ability to perform a gravity-bathymetry correction and achieve outstanding results.

关键词： gravity anomaly bathymetry inversion VGGNet multibeam sonar satellite altimetry

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Microbe-induced gene silencing explores interspecies RNAi and opens up possibilities of crop protection

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Science China(Life Sciences) 2024年第3期67卷 626-628页

作者： Rongxiang fang State Key Laboratory of Plant Genomics Institute of MicrobiologyChinese Academy of Sciencesand National Plant Gene Research CenterBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

In most eukaryotes, small RNA(sRNA)-mediated RNA silencing(or RNA interference, RNAi) is an evolutionarily conserved mechanism that regulates gene expression in a sequence-specific manner.Generally, s RNAs are produced by the RNase III enzymes Dicers and then incorporated into Argonaute(AGO) proteins to regulate gene expression by mRNA degradation.

关键词： protection conserved manner

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Life forms affect beta-diversity patterns of larch forests in China

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Plant Diversity 2024年第1期46卷 49-58页

作者： Wenjing fang Qiong Cai Chengjun Ji Jiangling Zhu Zhiyao Tang Jingyun fang School of Ecology and Environmental Science Yunnan UniversityKunming 650091China Department of Ecology College of Urban and Environmental Sciencesand Key Laboratory for Earth Surface Processes of the Ministry of EducationPeking UniversityBeijing 100871China

Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components(species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total betadiversity and its components in different life forms(i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total betadiversity of larch forests was mainly dependent on the species turnover component. In all life forms,total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%-25% of total beta-diversity, 18%-27% of species turnover component, and 4%-16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.

关键词： Beta-diversity Species turnover Nestedness-resultant Geographic distance Climatic distance Larch forest

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Pancreatic panniculitis as the first presentation of pancreatic ductaladenocarcinoma

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Hepatobiliary & Pancreatic Diseases International 2024年第1期23卷 106-108页

作者： Wei-fang Zhu Shan fang Jian-Jun Qiao Department of Dermatology the First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003China

To the Editor:Pancreatic panniculitis,also known as pancreatic fat necrosis or enzymatic panniculitis,is a rare type of panniculitis that occurs in 0.3%−3%of patients with pancreatic disease such as acute or chronic pancreatitis and pancreatic carcinoma,especially acinar cell carcinoma[1,2].The clinical manifestations are nonspecific erythema tender nodules.

关键词： Pancreatic acute adenocarcinoma

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Nociceptors and Macrophages in Bacterial Meningitis:Partners in Crime?

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Neuroscience Bulletin 2024年第3期40卷 418-420页

作者： fang Gao Hongzhen Hu The Kimberly and Eric J.Waldman Department of Dermatology Icahn School of Medicine at Mount SinaiNew York NY10029USA The Nash Family Department of Neuroscience Icahn School of Medicine at Mount SinaiNew York NY10029USA The Mark Lebwohl Center for Neuroinfammation and Sensation Icahn School of Medicine at Mount SinaiNew York NY10029USA Friedman Brain Institute Icahn School of Medicine at Mount SinaiNew York NY10029USA

Bacterial meningitis is a serious and potentially life-threatening infection that affects the protective layers surrounding the brain and spinal cord,known as the meninges.Several types of bacteria,including Streptococcus pneumoniae,Neisseria meningitidis,and Haemophilus influenzae,can cause this condition.Certain populations,such as infants,children,immunocompromised adults,and the elderly,are particularly vulnerable to these pathogens.Symptoms of bacterial meningitis can manifest suddenly and may include high fever,severe and persistent headache,stiff neck,vomiting,sensitivity to light,and confusion or changes in mental state[1,2].Identifying these symptoms in infants can be more challenging and may lead to long-term disability or death[3].Despite the effectiveness of vaccines,it is crucial to understand how bacteria invade the brain and how our innate immune system responds to infection(Fig.1).

关键词： protective infection suddenly

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Superior compound coatings prepared by low-temperature vanadium-nitrocarburizing duplex treatment

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Rare Metals 2024年第4期43卷 1828-1835页

作者： Gen Jin fang-fang Xu Xun-Xun Hu Yue Xu School of Chemistry Beihang University Guobiao (Beijing) Testing and Certification Co. Ltd School of Materials Science and Engineering Beihang University

Superior compound coatings were prepared on CK45 steel surface by vanadium-nitrocarburizing duplex treatment in low-temperature salt bath.In this study,the microhardness,the phase constitution and the compositional distribution in the coatings prepared under different conditions were systematically characterized.The results indicated that the reactions among activated vanadium,carbon and nitrogen atoms occurred on the steel surface,leading to the formation of compound coatings composed of outermost and compound layers.The mechanism for the formation of compound layer as well as the growth kinetics of the layer was also discussed.Upon the duplex treatment,the wear and corrosion resistances of steel surface were significantly improved.It was found that the growth kinetics of compound layer obeyed the parabolic law,with the activation energy of 122.82 kJ·mol-1.

关键词： Vanadium-nitrocarburizing duplex treatment Compound coatings Microstructure Formation mechanism Growth kinetics

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AI enhances drug discovery and development

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National Science Review 2024年第3期11卷 52-54页

作者： fang Bai Shiliang Li Honglin Li Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology ShanghaiTech University Lingang Laboratory Innovation Center for AI and Drug Discovery East China Normal University

The advent of the third wave of artificial intelligence(AI) heralds a new era in drug discovery. AI-powered techniques can be characteristic of identifying features that are difficult for humans to interpret from big ...

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Control of Virtual Synchronous Generator for Frequency Regulation Using a Coordinated Self-adaptive Method

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 175-184页

作者： Hongwei fang Zhiwei Yu School of Electrical and Information Engineering and Key Laboratory of Tianjin Electric Power System Simulation and Control Tianjin UniversityTianjin 300072China

Power inverter adopting virtual synchronous generator(VSG)control can provide inertia support for distributed generation systems.However,it cannot take into account the dynamic regulation characteristics of frequency.Thus,when the system encounters a sudden change in load or disturbance,the dynamic process of frequency regulation will be greatly influenced.In view of this issue,an improved VSG control strategy based on a coordinated self-adaptive(CSA)method is proposed.The time domain analysis method is used to study the influences of virtual inertia and damping parameter perturbation on the system steady and dynamic performances.Furthermore,in order to make the control strategy suitable for large load changes and suppress frequency variations beyond the limit,the secondary frequency modulation is introduced into the control loop.Through the coordinated adaptive control of virtual inertia,virtual damping and frequency modulation,the dynamic performance of vSG frequency regulation can be obviously improved.Simulation and experiment results have verified the effectiveness of the proposed CSA control strategy.

关键词： Coordinated self-adaptive method frequency regulation time domain analysis virtual synchronous generator

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