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Asymmetrical Fault current calculation Method and Influencing Factors Analysis of Droop-controlled Inverters

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cSEE Journal of Power and Energy Systems 2024年第2期10卷 562-573页

作者： Huimin zhao zhikang Shuai Jun ge An Luo Weimin Wu z.John Shen college of Electrical and Information Engineering Hunan UniversityChangsha 410006China Electrical Engineering Department Shanghai Maritime UniversityShanghai 201306China Department of Electrical and computer Engineering Ilinois Institute of TechnologyChicagoIL 60616 USA

Since the fault dynamic of droop-controlled inverter is different from synchronous generators (SGs), protection devices may become invalid, and the fault overcurrent may damage power electronic devices and threaten the safety of the microgrid. Therefore, it is imperative to conduct a comprehensive fault analysis of the inverter to guide the design of protection schemes. However, due to the complexity of droop control strategy, existing literatures have simplified asymmetric fault analysis of droop-controlled inverters to varying degrees. Therefore, accurate fault analysis of a droop-controlled inverter is needed. In this paper, by analyzing the control system, an accurate fault model is established. Based on this, a calculation method for instantaneous asymmetrical fault current is proposed. In addition, the current components and current characteristics are analyzed. It was determined that fault currents are affected by control loops, fault types, fault distance and nonlinear limiters. In particular, the influences of limiters on the fault model, fault current calculation and fault current characteristics were analyzed. Through detailed analysis, it was found that dynamics of the control loop cannot be ignored, the fault type and fault distance determine fault current level, and part of the limiters will totally change the fault current trend. Finally, calculation and experimental results verify the correctness of the proposed method.

关键词： Asymmetrical fault analysis droop control fault current calculation method limiter transient fault characteristics

AN INVESTIGATION ON（100）MONOEPITAXIAL DIAMOND MONOcRYSTALLINE FILMS

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AN INVESTIGATION ON（100）MONOEPITAXIAL DIAMOND MONOCRYSTALL...

NUcLEATION AND GROWTH OF ＜111＞ ORIENTATION HOMOEPITAXIAL DIAMOND MONOcRYSTAL

Sixteenth congress of the International Union of crystallography

作者： z.M.zhang S.H.Li Q.Y.cai H.M.chen X.c.He D.L.Ling S.J.Wang z.W.Wu S.S.Jiang c.z.ge N.B.Ming Shanghai Jiao Tong Univ. Nanjing Univ.

＜正＞For diamond’s excellent microelectrical properties and the rapid development of cVD techniques, the diamond high temperature semiconductor materials have been received increasing *** our work,we have obtained quite smooth homoepitaxial monocrystalline films deposited on（100） oriented HT-HP synthesized diamond by microwave PcVD *** microwave frequency was 2.45 GHz,internal dimension of the quartz horizontal reaction tube was 35mm the reaction gases were acetone and hydrogen,

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NUCLEATION AND GROWTH OF ＜111＞ ORIENTATION HOMOEPITAXIAL D...

controllability of Semilinear Integrodifferential Degenerate Sobolev Equations

Sixteenth congress of the International Union of crystallography

作者： z.M.zhang S.H.Li Q.Y.cai H.M.chen X.c.He D.L.Ling S.J.Wang z.W.Hu S.S.Jiang c.z.ge N.B.Ming Shanghai Jiao Tong Univ. Nanjing Univ.

＜正＞It has been reported that only polycrystal diamond film could be formed on beteroepitaxial substrate by cVD method,which stimulated great interesting to grow homoepitaxial film,however, few reports concerned the growth on ＜111＞ oriented *** this paper,a successful growth of homoepitaxy on（111） natural diamond substrate is presented by using microwave PcVD method. The experimental process was almost same as that of（100） homoepitaxy reported before.

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Journal of Systems Science & complexity 2024年第5期37卷 1923-1936页

作者： ge zhaoqiang School of Mathematics and Statistics Xi’an Jiaotong University

In this paper, the approximate controllability of semilinear integrodifferential degenerate Sobolev equations with nonlocal conditions is investigated in the sense of integral solution in Hilbert spaces. Some sufficient and necessary conditions are obtained. Firstly, the existence and uniqueness of integral solutions of semilinear integrodifferential degenerate Sobolev equations with nonlocal conditions are considered by ge-evolution operator theory and Sadovskii's fixed point theorem, the existence and uniqueness theorem of solutions is given. Secondly, the approximate controllability of semilinear integrodifferential degenerate Sobolev equations with nonlocal conditions is studied in the sense of integral solution. The criterion for approximate controllability is provided. The obtained results have important theoretical and practical value for the study of controllability of semilinear integrodifferential degenerate Sobolev equations with nonlocal conditions.

关键词： Approximate controllability ge-evolution operator integral solution Sadovskii’s fixed point theorem semilinear integrodifferential degenerate Sobolev equations

The Effect of Heat Treatment Process on Metallic LaNiO3 Films from Metalorganic Precursors

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The Effect of Heat Treatment Process on Metallic LaNiO3 Film...

Polymeric piezoelectric accelerometers with high sensitivity,broad bandwidth,and low noise density for organic electronics and wearable microsystems

1996年中国青年学者物理学讨论会

作者： A.D.Li c.z.ge D.Wu P.Lü N.B.Ming(National Laboratory of Solid State Microstructures,Physics Dept.,Nanjing University,Nanjing 210093) Y.Q.zuo S.z.Yang(Dept.of Electronic Science and Engineering,Nanjing University,Nanjing 210093)

conductive mataUic LaNiO(LNO)films were prepared by metalorganic *** films were obtained by spin-on pyrolysis in air and than annealing at various temperature in air or *** effect of different thermal treatments on erystallinity and conductive behavior of LNO films was studied. The results indicated the pyrolysis process in the critical step to obtain good metaUie LNO films at lower grown *** films with the lowest resitivity(～800μΩ cm)were obtained on Si by annealing in oxygen at 700℃.

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Microsystems & Nanoengineering 2024年第3期10卷 63-74页

作者： chang ge Edmond cretu The Department of Electrical and computer Engineering The University of British ColumbiaVancouverBCCanada

Piezoelectric accelerometers excel in vibration *** the emerging trend of fully organic electronic microsystems,polymeric piezoelectric accelerometers can be used as vital front-end components to capture dynamic signals,such as vocal vibrations in wearable speaking assistants for those with speaking ***,high-performance polymeric piezoelectric accelerometers suitable for such applications are *** organic compounds such as PVDF have inferior properties to their inorganic counterparts such as ***,most existing polymeric piezoelectric accelerometers have very unbalanced performance *** often sacrifice resonance frequency and bandwidth for a flat-band sensitivity comparable to those of PzT-based accelerometers,leading to increased noise density and limited application *** this study,a new polymeric piezoelectric accelerometer design to overcome the material limitations of PVDF is *** new design aims to simultaneously achieve high sensitivity,broad bandwidth,and low *** samples were manufactured and characterized,demonstrating an average sensitivity of 29.45 pc/g within a±10 g input range,a 5%flat band of 160 Hz,and an in-band noise density of 1.4μg/√*** results surpass those of many PzT-based piezoelectric accelerometers,showing the feasibility of achieving comprehensively high performance in polymeric piezoelectric accelerometers to increase their potential in novel applications such as organic microsystems.

关键词： piezoelectric polymeric overcome

Meridional deflection of global eddy propagation derived from tandem altimetry: Mechanism and implication

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Science china Earth Sciences 2024年第3期67卷 811-825页

作者： ge cHEN Xiaoyan cHEN Frontiers Science center for Deep Ocean Multispheres and Earth System School of Marine TechnologyOcean University of ChinaQindao 266100China Laboratory for Regional Oceanography and Numerical Modeling Laoshan LaboratoryQindao 266237China

A common view on meridional deflection of eddy propagation is poleward for cyclones and equatorward for anticyclones. This widely accepted polarity-sensitive pattern has been increasingly undermined given that it is systematically violated on both zonal and regional scales as recently reported. Here, we approach the problem by exploring these violations in terms of eddy effects of spatiotemporal geostrophy, thermal fading, and flow dragging, yielding the following main conclusions.(1) The polarity-dependent deflection discrepancy is a pseudo feature resulting from a biased fit to the normalized eddy tracks which are spatially asymmetric(though azimuthally symmetric) between the two signs;Instead, the primary pattern of eddy deflection appears to be geographically correlated and polarity independent.(2) geostrophic adjustment plays a critical role in defining the meridional movement of an eddy. Specifically, a consistent poleward(equatorward) trajectory bending of spatially(temporally) ageostrophic eddies is observed irrespective of their polarity.(3) The mechanism of eddy deflection is also determined by its zonal propagation direction. Westward propagating eddies are substantially affected by thermal fading, while opposite ones by flow dragging. A realistic and comprehensive understanding of eddy deflection mechanisms serves as a significant contribution to the prediction of eddy trajectory, and the protection of ocean environment.

关键词： Mesoscale eddies Eddy propagation Eddy meridional deflection Satellite observation geostrophic adjustment

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Solid Desiccant Heat Pump Fresh Air Unit using composite Silica gel

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Journal of Thermal Science 2024年第4期33卷 1286-1300页

作者： YANG Tianyu GUO Defang ge Tianshu Institute of Refrigeration and cryogenics Shanghai Jiao Tong UniversityKey Laboratory of Power Mechanical EngineeringMOE ChinaShanghai200240China Qingdao Haier A/c Electronic co. LtdQingdao266101China

The introduction of fresh air into the indoor space leads to a significant increase in cooling or heating *** desiccant heat pump fresh air unit which can handle the latent and sensible load of fresh air efficiently have been proposed *** improve the performance of the solid desiccant heat pump fresh air unit in the fresh air handling process,in this paper,the application of composite silica gel in a heat pump fresh air unit was *** comparison between silica gel coating(SGc)and composite silica gel coating(cSGc)shows that the adsorption rate and water uptake capacity of cSGc are more than two times higher than those of *** experimental setup for the solid desiccant heat pump fresh air unit was *** performance of SGc and cSGc was tested in the setup *** show that under summer conditions,compared with the solid desiccant heat pump fresh air unit using silica gel(SGFU),the average moisture removal and cOP of the one using composite silica gel(cSGFU)increased by 15%and 30%,*** winter conditions,compared with SGFU,the average humidification and cOP of cSGFU increased by 42%and 17%.With optimal operation conditions of 3 min switchover time and 40 r/s compressor frequency,the cOP of cSGFU under summer conditions can reach *** also show that the cSGFU and SGFU have higher cOP and dehumidification rate under higher outdoor temperature and humidity ratio.

关键词： fresh air system desiccant coated heat exchanger humidification dehumidification experimental comparison

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Theoretical study on the stability of nanobubbles and its verification in molecular dynamics simulation

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Particuology 2024年第4期87卷 99-105页

作者： Sheng Mi chaofeng Hou Wei ge School of chemical Engineering and Technology Tianjin UniversityTianjin300072China State Key Laboratory of Multiphase complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing.100190China School of chemical Engineering University of Chinese Academy of SciencesBeijing100049China

The stability of vapor nanobubbles in bulk liquid was investigated theoretically and the critical bubble size was derived from macroscale thermodynamic equations,below which the system destabilizes with sharp drop in *** critical size was quantitatively verified in molecular dynamic simulation using the Lennard-Jones model of argon,where stronger attraction between the molecules at lower density is found to contribute most to the drop of system pressure and,as the Laplace pressure on the curved bubble interface fails to balance the pressure difference across the interface,the bubbles become *** theoretical model could be extended to other systems where reliable equations of state and interfacial tension are available.

关键词： Nanobubble Stability Phase diagram critical size