Grid-following voltage source converter(GFLVSC)and grid-forming voltage source converter(GFM-VSC)have different dynamic characteristics for active power-frequency and reactive power-voltage supports of the power *** p...
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Grid-following voltage source converter(GFLVSC)and grid-forming voltage source converter(GFM-VSC)have different dynamic characteristics for active power-frequency and reactive power-voltage supports of the power *** paper aims to clarify and recognize the difference between gridfollowing(GFL)and grid-forming(GFM)frequency-voltage support more intuitively and ***,the phasor model considering circuit constraints is established based on the port circuit equations of the *** is revealed that the voltage and active power linearly correspond to the horizontal and vertical axes in the phasor space referenced to the grid voltage ***,based on topological homology,GFL and GFM controls are transformed and mapped into different *** topological similarity of the characteristic curves for GFL and GFM controls is the essential cause of their *** on the above model,it is indicated that GFL-VSC and GFM-VSC possess uniformity with regard to active power response,type of coupling,and phasor *** differ in synchronization,power coupling mechanisms,dynamics,and active power-voltage operation domain in the quasi-steady *** studies are undertaken on GFL-VSC and GFM-VSC integrated into a four-machine two-area *** results verify that the dynamic uniformity and difference of GFL-VSC and GFM-VSC are intuitively and comprehensively revealed.
Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam *** opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scann...
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Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam *** opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and ***,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread *** study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation *** corrections were explored through a combination of data processing analysis and numerical ***,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction *** experimental validations were performed at the Huazhong University of Science and technology injector to verify the effectiveness of the proposed compensation *** the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common *** the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.
Efficient and accurate insulator defect detection is essential for maintaining the safe and stable operation of transmission ***,the detection effectiveness is adversely impacted by complex and changeable environmenta...
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Efficient and accurate insulator defect detection is essential for maintaining the safe and stable operation of transmission ***,the detection effectiveness is adversely impacted by complex and changeable environmental backgrounds,particularly under extreme weather that elevates accident ***,this research proposes a high-precision intelligent strategy based on the synthetic weather algorithm and improved YOLOv7 for detecting insulator defects under extreme *** proposed meth-odology involves augmenting the dataset with synthetic rain,snow,and fog algorithm ***,the original dataset undergoes augmentation through affine and colour transformations to improve model's generalisation performance under complex power inspection *** achieve higher recognition accuracy in severe weather,an improved YOLOv7 algorithm for insulator defect detection is proposed,integrating focal loss with SIoU loss function and incorporating an optimised decoupled head *** results indicate that the synthetic weather algorithm processing significantly improves the insulator defect detection accuracy under extreme weather,increasing the mean average precision by 2.4%.Furthermore,the authors’improved YOLOv7 model achieves 91.8%for the mean average precision,outperforming the benchmark model by 2.3%.With a detection speed of 46.5 frames per second,the model meets the requirement of real-time detection of insulators and their defects during power inspection.
The traditional power system dominated by synchronous generators is gradually evolving into a power system with high penetration of inverter-based resources(IBRs).In this paper,the new characteristics that arise from ...
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The traditional power system dominated by synchronous generators is gradually evolving into a power system with high penetration of inverter-based resources(IBRs).In this paper,the new characteristics that arise from the high penetration of IBRs in power systems are *** light of these characteristics,current simulation technologies are inadequate and new requirements for the simulation platforms have been *** response,this paper introduces the rapid system prototype(RSP)-based physical simu-lation platforms,which include the digital simulator,the rapid prototype controller,and the rapid object-controlled *** addresses the time-consuming and labour-intensive shortcomings of traditional simulation techniques and meets the rapid evolu-tion needs of the power system with high penetration of *** with existing simulation platforms,RSP is a more suitable platform for the physical simulation of power systems with high penetration of *** the modular multilevel converter-based high-voltage direct current as a case study,a novel physical simulation platform for power systems based on RSP is *** results demonstrate that the RSP concept and technology can establish an enterprise-level simulation environment and engineering practice ***,it can provide realistic and flexible simu-lations of various characteristics of power systems with high penetration of IBRs.
In-situ polymerized solid-state lithium metal batteries have garnered significant attention due to their conformal interface contact and continuous pathways for lithium ion(Li+) ***,their electrochemical performance...
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In-situ polymerized solid-state lithium metal batteries have garnered significant attention due to their conformal interface contact and continuous pathways for lithium ion(Li+) ***,their electrochemical performance is often hindered by slow Li+transport within high-area-loading *** study presents an in-situ poly(ε-caprolactone) electrolyte with gradient molar mass(iGPCE) through lithium metal anode(LMA)-induced anionic ring-opening *** electrochemical and kinetic analyses reveal that the iGPCE,characterized by low molar mass(M),significantly enhances Li+diffusion within high-area-loading cathodes and bulk electrolytes,thereby reducing concentration polarization and promoting uniform electrochemical ***,the high M region on LMA side acts as artificial solid electrolyte interphases,stabilizing the stripping and plating of ***,Li//LFP(20 mg cm-2) and Li//NCM622(7.4 mg cm-2) utilizing iGPCE exhibit stable charge/discharge *** study offers a fresh approach to accelerate Li+diffusion kinetics of high-area-loading batteries and suggests broad applicability in other systems.
The GFL-GFM hybrid wind farm (HWF) combines the voltage source control advantages of grid-forming (GFM) wind turbines (WTs) with the current source control advantages of grid-following (GFL) wind turbines. It becomes ...
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The GFL-GFM hybrid wind farm (HWF) combines the voltage source control advantages of grid-forming (GFM) wind turbines (WTs) with the current source control advantages of grid-following (GFL) wind turbines. It becomes a new type of large-scale grid-connected wind power generation. In this paper, we propose an HWF frequency-voltage active support based on GFL and GFM hierarchical subgroup control. It aims to realize the support of active power and reactive power under the premise of ensuring system stability. The strategy consists of the determination of the control objectives of the GFM-GFL subgroups, the distributed control (DC) of the GFM-GFL subgroups, and the adaptive control and switching of each unit of the GFM and GFL groups. The GFM-group maintains the grid-connected voltage stability and the GFL-group exhausts the active support. DC at the group level and adaptive control at the unit level are included under the hierarchy of the respective objectives. Finally, a GFL-GFM HWF model is established on the MATLAB/Simulink platform, and the simulation verifies that the proposed strategy can realize the enhancement of the frequency-voltage support capability of the HWF under the premise of grid-connected stability.
The core-shell structure formed by coating can enhance the uniformity of particles within ZnO varistors, which is conducive to the improvement of their microstructure and comprehensive performance. In this study, the ...
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ZnO varistors prepared by surface coating technology show certain potential in reducing grain size, refining microstructure, and improving electrical properties. The sintering process after powder preparation also has...
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The precise localization of insulators in visible images is crucial for ensuring the integrity of power systems. In UVAs inspections, challenges such as arbitrary angles, dense distributions, and complex backgrounds o...
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Solid-state lithium batteries(SSLBs)are regarded as an essential growth path in energy storage systems due to their excellent safety and high energy *** particular,SSLBs using conversion-type cathode materials have re...
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Solid-state lithium batteries(SSLBs)are regarded as an essential growth path in energy storage systems due to their excellent safety and high energy *** particular,SSLBs using conversion-type cathode materials have received widespread attention because of their high theoretical energy densities,low cost,and *** the great progress in research and development of SSLBs based on conversiontype cathodes,their practical applications still face challenges such as blocked ionic-electronic migration pathways,huge volume change,interfacial incompatibility,and expensive processing *** review focuses on the advantages and critical issues of coupling conversion-type cathodes with solid-state electrolytes(SSEs),as well as state-of-the-art progress in various promising cathodes(e.g.,FeS_(2),CuS,FeF_(3),FeF_(2),and S)in ***,representative research on conversion-type solid-state full cells is discussed to offer enlightenment for their practical ***,the energy density exhibited by the S cathode stands out impressively,while sulfide SSEs and halide SSEs have demonstrated immense potential for coupling with conversion-type ***,perspectives on conversion-type cathodes are provided at the material,interface,composite electrode,and battery levels,with a view to accelerating the development of conversion-type cathodes for high-energy–density SSLBs.
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