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.
The application of superconducting(SC)technology enables magnets to excite strong fields with small footprints,which has great potential for miniaturizing proton therapy ***,the slow ramping rate of SC magnets results...
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The application of superconducting(SC)technology enables magnets to excite strong fields with small footprints,which has great potential for miniaturizing proton therapy ***,the slow ramping rate of SC magnets results in a low treatment efficiency compared with normal-conducting(NC)*** address this problem,this study proposes a compact proton therapy gantry design with a large momentum acceptance utilizing alternating-gradient canted-cosine-theta(AG-CCT)SC *** our design,a high-transmission degrader is mounted in the middle of the gantry,and the upstream beamline employs NC magnets with small *** of the degrader,large-bore AG-CCT magnets with strong alternating focusing gradients are set symmetrically as a local achromat,which realizes a momentum acceptance of 20%(or 40%in the energy domain).Therefore,only three magnetic working points are required to cover a treatment energy of 70-230 Me *** to the large momentum acceptance,the proton beam after the degrader can be directly delivered to the isocenter without truncating its energy spectrum,which can significantly increase the treatment efficiency but causes severe dispersion effects during pencil beam ***,a compensation method was introduced by tuning the normal and skewed quadrupoles during the scanning *** a result,the new gantry not only presents a remarkable reduction in the size and weight of the facility but also shows good potential for fast treatment.
Base station(BS)backup batteries(BSBBs),with their dispatchable capacity,are potential demand-side resources for future power *** enhance the power supply reliability and post-contingency frequency security of power s...
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Base station(BS)backup batteries(BSBBs),with their dispatchable capacity,are potential demand-side resources for future power *** enhance the power supply reliability and post-contingency frequency security of power systems,we propose a two-stage stochastic unit commitment(UC)model incorporating operational reserve and post-contingency frequency support provisions from massive BSBBs in cellular networks,in which the minimum backup energy demand is considered to ensure BS power supply *** energy,operational reserve,and frequency support ancillary services are co-optimized to handle the power balance and post-contingency frequency security in both forecasted and stochastic variable renewable energy(VRE)***,we propose a dedicated and scalable distributed optimization framework to enable autonomous optimizations for both dispatching center(DC)and *** BS model parameters are stored and processed locally,while only the values of BS decision variables are required to upload to DC under the proposed distributed optimization framework,which safeguards BS privacy *** studies on a modified IEEE 14-bus system demonstrate the effectiveness of the proposed method in promoting VRE accommodation,ensuring post-contingency frequency security,enhancing operational economics,and fully utilizing BSBBs'energy and power ***,the proposed distributed optimization framework has been validated to converge to a feasible solution with near-optimal performance within limited ***,numerical results on the Guangdong 500 kV provincial power system in China verify the scalability and practicality of the proposed distributed optimization framework.
The process that, the equipment regulates internal voltage's amplitude and frequency (A\F) to generate changes in the electric network terminal power, plays a critical role in determining a power system's dyna...
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OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma ***,experimental studies on how ...
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OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma ***,experimental studies on how the gas content affects the postdischarge temporal evolutions of OH and O in the noble gas ns-NAPP are very *** this work,the effect of the percentages of O_(2),N_(2),and H_(2)O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence(LIF)*** results show that the productions of OH and O increase and then decrease with the increase of O_(2)*** OH and O densities reach their maximum when about 0.8%O_(2)is *** increase of the O_(2)concentration results in a decrease of the initial densities of both OH and O,and leads to their faster *** increase of N_(2)percentage also results in the increase and then decrease of the OH and O densities,but the change is ***,when the H_(2)O concentration is increased from 100 to 3000 ppm,the initial OH density increases slightly,but the OH density decays much faster,while the initial density of O decreases with the increase of the H_(2)O *** analysis,it is found that OH and O are mainly produced through electron collisional dissociation.O(^(1)D)is critical for OH generation.O_(3)accelerates the consumption processes of OH and O at high O_(2)*** addition of H_(2)O in the NAPP considerably enhances the electronegativity,while it decreases the overall plasma reactivity,accelerates the decay of OH,and reduces the O atom density.
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.
In this paper,the bi-layer scheduling method for microgrids,based on deep reinforcement learning,is proposed to achieve economic and environmentally friendly ***,considering the uncertainty of renewable energy,the fra...
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In this paper,the bi-layer scheduling method for microgrids,based on deep reinforcement learning,is proposed to achieve economic and environmentally friendly ***,considering the uncertainty of renewable energy,the framework of day-ahead and intra-day scheduling is established,and the implementation scheme for both price-based and incentive-based demand response(DR)for the flexible load is ***,comprehensively considering the operating characteristics of the microgrid in the day-ahead and intra-day time scales,a bi-layer scheduling model of the microgrid is *** terms of algorithms,since day-ahead scheduling has no strict requirement for dispatching time,the particle swarm optimization(PSO)algorithm is used to optimize the time-of-use electricity price and distributed power output for the next *** the environmental fluctuations and requirements for rapidity of intra-day online scheduling,the deep reinforcement learning(DRL)algorithm is adopted for ***,based on the data from the actual microgrid,the rationality and effectiveness of the proposed scheduling method is *** results show that the proposed bi-layer scheduling based on the PSO and DRL algorithms achieves the optimization of scheduling cost and calculation speed,and is suitable for microgrid online scheduling.
A structural optimization design method of DD orthogonal coil in the seawater environment is introduced in this paper, which is suitable for underwater AUV equipment. The electromagnetic field model considering the ef...
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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 ...
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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.
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