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CSEE Journal of Power and Energy.Sy.tems 2024年第2期10卷 584-592页

作者： Zhi Ding Tiany.o Ji Mengshi Li q.H.wu School of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

In this paper, a novel signal processing method combining mathematical morphology.(MM) and Walsh theory.is proposed, which uses Walsh functions to control the structuring element (SE) and MM operators. Based on the Walsh-MM method, a scheme for power q.ality.disturbances detection and classification is developed, which involves three steps: denoising, feature extraction and morphological clustering. First, various evolution rules of Walsh function are used to generate groups of SEs for the multiscale Walsh-ordered morphological operation, so the original signal can be denoised. Next, the fundamental wave of the denoised signal is suppressed by.Hadamard matrix;thus, disturbances can be extracted. Finally. the Walsh power spectrum of the waveform extracted in the previous step is calculated, and the parameters of which are taken by.morphological clustering to classify.the disturbances. Simulation results reveal the proposed scheme can effectively.detect and classify.disturbances, and the Walsh-MM method is less affected by.noise and only.involves simple calculation, which has a potential to be implemented in hardware and more suitable for real-time application.

关键词： Hadamard matrix mathematical morphology morphological clustering power q.ality.disturbance Walsh theory

Residue Based Open-Loop Modal Analy.is Method for Detecting LFMR of PMSG-WFs Penetrated Power Sy.tems

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CSEE Journal of Power and Energy.Sy.tems 2024年第4期10卷 1454-1465页

作者： Luonan q.u Tianhao Wen y.ng Liu q.H.wu School of Electric Power Engineering South China University of TechnologyGuangzhou510640China

This paper proposes a residue based open-loop modal analy.is method to detect low freq.ency.modal resonance(LFMR),including asy.metric low freq.ency.modal attraction(ALFMA)and asy.metric low freq.ency.modal repulsion(ALFMR),of permanent magnetic sy.chronous generator based wind farms(PMSG-WFs)penetrated power *** formation of ALFMA and ALFMR caused by.two open-loop low freq.ency.oscillation(LFO)modes moving close and apart is analy.ed in *** predicting the trajectories of closed-loop LFO modes based on calculation of residue of open-loop LFO modes,both ALFMA and ALFMR can be *** proposed method can select LFO modes which move to the right half complex plane as control parameters *** studies are carried out on a three-machine power sy.tem and a four-machine 11-bus power sy.tem to verify.the properties of the proposed method.

关键词： Asy.metric low freq.ency.modal attraction asy.metric low freq.ency.modal repulsion low freq.ency.modal resonance residue based open-loop modal analy.is method

Data-Driven Fault Detection of Multiple Open-Circuit Faults for MMC Sy.tems Based on Long Short-Term Memory.Networks

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CSEE Journal of Power and Energy.Sy.tems 2024年第4期10卷 1563-1574页

作者： Chenxi Fan Kaishun Xiahou Lei Wang q.H.wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

This paper presents a long short-term memory.LSTM)-based fault detection method to detect the multiple open-circuit switch faults of modular multilevel converter(MMC)sy.tems with full-bridge sub-modules(FB-SMs).Eighteen sensor signals of grid voltages,grid currents and capacitance voltages of MMC for single and multi-switch faults are collected as sampling *** output signal characteristics of four ty.es of single switch faults of FB-SM,as well as double switch faults in the same and different phases of MMC,are analy.ed under the conditions of load variations and control command changes.A multi-lay.r LSTM network is devised to deeply.extract the fault characteristics of MMC under different faults and operation conditions,and a Softmax lay.r detects the fault *** results have confirmed that the proposed LSTM-based method has better detection performance compared with three other methods:K-nearest neighbor(KNN),naive bay.s(NB)and recurrent neural network(RNN).In addition,it is highly.robust to model uncertainties and Gaussian *** validity.of the proposed method is further demonstrated by.experiment studies conducted on a hardware-in-the-loop(HIL)testing platform.

关键词： Fault detection long short-term memory.LSTM) modular multilevel converter(MMC) open circuit fault

Location of Asy.metric Ground Fault Using Virtual Injected Current Ratio and Two-stage Recovery.Strategy.in Distribution Networks

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CSEE Journal of Power and Energy.Sy.tems 2024年第1期10卷 151-161页

作者： Haiting Shan Luliang Zhang q.H.wu Mengshi Li School of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

Sparse measurements challenge fault location in distribution *** paper proposes a method for asy.metric ground fault location in distribution networks with limited measurements.A virtual injected current vector is formulated to estimate the fault line,which can be reconstructed from voltage sags measured at a few buses using compressive sensing(CS).The relationship between the virtual injected current ratio(VICR)and fault position is deduced from circuit analy.is to pinpoint the ***,a two-stage recovery.strategy.is proposed for improving reconstruction accuracy.of the current vector,where two different sensing matrixes are utilized to improve the *** proposed method is validated in IEEE 34 node test *** results show asy.metric ground fault ty.e,resistance,fault position and access of distributed generators(DGs)do not significantly.influence performance of our *** addition,it works effectively.under various scenarios of noisy.measurement and line parameter *** on 134 node test feeders prove the proposed method is also suitable for sy.tems with more complex structure.

关键词： Distribution networks fault location reconstruction accuracy two-stage recovery virtual injected current ratio

Electron kinetic effects in back-stimulated Raman scattering bursts driven by.broadband laser pulses

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Matter and Radiation at Extremes 2024年第4期9卷 54-67页

作者： q.K.Liu L.Deng q.Wang X.Zhang F.q.Meng y.P.Wang y.q.Gao H.B.Cai S.P.Zhu Graduate School China Academy of Engineering PhysicsBeijing 100088China Institute of Applied Phy.ics and Computational Mathematics Beijing 100094China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China Shanghai Institute of Laser Plasma Shanghai 201800China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100871China School of Phy.ics Zhejiang UniversityHangzhou 310027China

We examine electron kinetic effects in broadband-laser-driven back-stimulated Raman scattering(BSRS)bursts using particle-in-cell *** bursts occur during the nonlinear stage,causing reflectivity.spikes and generating large numbers of hot ***-duration simulations are performed to observe burst events,and a simplified model is developed to eliminate the interference of the broadband laser’s random intensity.*** the simplified model,we isolate and characterize the spectrum of electron plasma *** spectrum changes from a sideband structure to a turbulence-like structure during the burst.A significant asy.metry.in the spectrum is *** asy.metry.is amplified and transferred to electron phase space by.high-intensity.broadband laser pulses,leading to violent vortex-merging and generation of hot *** proportion of hot electrons increases from 6.76%to 14.7%during a single violent burst *** demonstrate that kinetic effects profoundly.influence the BSRS evolution driven by.broadband lasers.

关键词： scattering kinetic simplified

Probing the Bardeen-Kiselev black hole with the cosmological constant caused by.Einstein eq.ations coupled with nonlinear electrody.amics using q.asinormal modes and grey.ody.bounds

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Communications in Theoretical Phy.ics 2024年第6期76卷 102-119页

作者： S R wu B q.Wang Z W Long College of Phy.ics Guizhou UniversityGuiyang 550025China College Pharmacy Guizhou University of Traditional Chinese MedicineGuiyang 550025China

In this work,we investigate a static and spherically.sy.metric Bardeen-Kiselev black hole(BH)with the cosmological constant,which is a solution of the Einstein-non-linear Maxwell field *** compute the q.asinormal freq.encies for the Bardeen-Kiselev BH with the cosmological constant due to electromagnetic and gravitational *** vary.ng the BH parameters,we discuss the behavior of both real and imaginary.parts of the BH q.asinormal freq.encies and compare these freq.encies with the Reissner-Nordström-de Sitter BH surrounded by.q.intessence(RN-dSq..Interestingly.it is shown that the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSq.under electromagnetic perturbations are different when the charge parameter q.the state parameter w and the normalization factor c are varied;however,for the gravitational perturbations,the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSq.are different only.when the charge parameter q.is ***,compared with the gravitational perturbations,the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime *** interesting observation is that,due to the presence of Kiselev q.intessence,the electromagnetic perturbations around the Bardeen-Kiselev BH with the cosmological constant damps faster and oscillates slowly.for the gravitational perturbations,the q.asinormal mode decay. slowly.and oscillates *** also study.the reflection and transmission coefficients along with the absorption cross section in the Bardeen-Kiselev BH with the cosmological constant;it is shown that the transmission coefficients will increase due to the presence of Kiselev q.intessence.

关键词： q.asinormal modes grey.ody.factors Bardeen-Kiselev black hole with cosmological constant

Convexification of Hy.rid AC-DC Optimal Power Flow with Line-Commutated Converters

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CSEE Journal of Power and Energy.Sy.tems 2024年第2期10卷 617-628页

作者： Hongy.an Liang Zhigang Li J.H.Zheng q.H.wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based high-voltage DC (HVDC) sy.tems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity.to optimal power flow (OPF) of hy.rid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity.but has rarely.been discussed. We devise an eq.ivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Eq.ivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally.optimal solution of the original OPF can be efficiently.obtained from relaxed model.

关键词： AC-DC power sy.tem convex relaxation linecommutated converter optimal power flow second-order cone programming

Estimating Critical Clearing Time of Grid Faults Using DA of State-Reduction Model of Power Sy.tems

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CSEE Journal of Power and Energy.Sy.tems 2024年第2期10卷 807-820页

作者： y.ng Liu Zhongy.ng Chen Huanjin y.o Lin y. q.H.wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China China Southern Power Grid Research Institute Guangzhou 510663China

This paper proposes a critical clearing time (CCT) estimation method by.the domain of attraction (DA) of a state-reduction model of power sy.tems using sum of sq.ares (SOS) programming. By.exploiting the property.of the Jacobian matrix and the structure of the boundary.of the DA, it is found the DA of the state-reduction model and that of the full model of a power sy.tem are topological isomorphism. There are one-to-one correspondence relationships between the number of eq.ilibrium points, the ty.e of eq.ilibrium points, and solutions of the two sy.tem models. Based on these findings, an expanding interior algorithm is proposed with SOS programming to estimate the DA of the state-reduction model. State trajectories of the full model can be transformed to those of the state-reduction model by.orthogonal or eq.iradius projection. In this way. CCT of a grid fault is estimated with the DA of the state-reduction model. The calculational burden of SOS programming in the DA estimation using the state-reduction model is rather small compared with using the full model. Simulation results show the proposed expanding interior algorithm is able to provide a tight estimation of DA of power sy.tems with higher accuracy.and lower time costs.

关键词： Critical clearing time domain of attraction expanding interior algorithm state-reduction model SOS programming

轴重和频率对激光修复316L不锈钢涂层在铁路车轮踏面制动中摩擦学性能的影响

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表面工程与再制造 2024年第2期24卷 51-52页

作者： Li S. Xiao q. y.ng W. y.ng C. Wang y. State Key.Laboratory.of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong University Nanchang 330013 China School of Mechatronics and Vehicle Engineering East China Jiaotong University Nanchang 330013 China Railway.Industry.Key.Laboratory.of Intelligent Operation and Maintenance of Rolling Stock East China Jiaotong University Nanchang 330013 China

研究复杂制动环境对修复熔覆层服役性能的影响,对提高列车轮轨系统抵御极端恶劣环境的能力具有重要意义。本文针对火车车轮踏面局部损伤问题,利用激光熔覆修复技术在损伤处制备316L不锈钢涂层。采用MS-HT1000高温磨损试验机进行磨损实... 详细信息

研究复杂制动环境对修复熔覆层服役性能的影响,对提高列车轮轨系统抵御极端恶劣环境的能力具有重要意义。本文针对火车车轮踏面局部损伤问题,利用激光熔覆修复技术在损伤处制备316L不锈钢涂层。采用MS-HT1000高温磨损试验机进行磨损实验。然后,分析不同制动条件对修复试样在室温和高温下摩擦磨损性能的影响。

关键词：激光修复铁路车轮局部损伤磨损实验车轮踏面磨损试验机服役性能踏面制动

Resistive field generation in intense proton beam interaction with solid targets

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Matter and Radiation at Extremes 2024年第1期9卷 35-43页

作者： W.q.Wang J.J.Honrubia y.y.n X.H.y.ng F.q.Shao Department of Phy.ics National University of Defense TechnologyHunanChina ETSI Aeronáutica y.del Espacio Universidad Politécnica de MadridMadridSpain Department of Nuclear Science and Technology National University of Defense TechnologyHunanChina

The Brown-Preston-Singleton(BPS)stopping power model is added to our previously.developed hy.rid code to model ion beam-plasma *** simulations show that both resistive field and ion scattering effects are important for proton beam transport in a solid target,in which they.compete with each *** the target is not completely.ionized,the self-generated resistive field effect dominates over the ion scattering ***,when the target is completely.ionized,this situation is ***,it is found that Ohmic heating is important for higher current densities and materials with high *** energy.fraction deposited as Ohmic heating can be as high as 20%-30%.Ty.ical ion divergences with half-angles of about 5°-10°will modify.the proton energy.deposition substantially.and should be taken into account.

关键词： interaction beam intense