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Analysis and suppression of operational overvoltage and inrush current for high-speed trains by automatic phase-switching technique

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High Voltage 2024年第3期9卷 733-748页

作者： Ye Cao Song Xiao Zhizong Ye Guangning Wu Yujun Guo Guoqiang Gao Chuanming Sun Jiancheng Liu Zheng Chen Hao Hou Zijing Wang Puyang Liu Yuhui Zhang Jie Yu School of Electrical engineering Southwest Jiaotong UniversityChengduChina Guangdong power Grid Limited Liability co.pany China Southern Power GridGuangzhouChina CRRC Qingdao Sifang co. Ltd.QingdaoChina State Grid Chongqing Electric power co.pany ChongqingChina

When a high-speed train approaches the insulated phase-splitting section embedded between neighbouring power supply arms,the vacuum circuit breaker(VCB)installed on trains must be disco.nected to maintain the traction power supply system as a no-load co.dition for co.pleting phase-switching action,as the train passes through the phase-splitting section depending on its ***,when operating VCBs,the arc is easily triggered between the mobile co.tacts inside,acco.panied by an overvoltage ***,to explore the generating mechanism of inrush current and operational overvoltage,a model describing the‘substation-catenary-train’traction power supply system is launched based on an equivalent circuit modelling *** the analysis of the transient VCB operational process,the phase of catenary voltage is directly related to the characteristics of the VCB switching-on overvoltage,as the traction cur-rent's phase angle is relevant to the amplitude-frequency characteristics of the VCB switching-off *** current as a noteworthy element is related to the traction transformer's *** automatic phase-switching technique is utilised to suppress both operational overvoltage and inrush current,as the optimal co.bination of VCB switching-on and switching-off phases co.sidering the balance between overvoltage and inrush current is achieved based on the particle swarm algorithm.

关键词： traction phase inrush

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Spatio-temporal evolution analysis of landscape pattern and habitat quality in the Qinghai Province section of the Yellow River Basin from 2000 to 2022 based on InVEST model

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Journal of Arid Land 2024年第9期16卷 1183-1196页

作者： ZHENG Guoqiang Li Cunxiu LI Runjie LUO Jing FAN Chunxia ZHU Hailing co.lege of Geography Qinghai Normal UniversityXining 810008China Qinghai engineering consulting Center co. Ltd.Xining 810001China Qinghai University Xining 810016China

Habitat quality is an important indicator for evaluating the quality of *** Qinghai Province section of the Yellow River Basin plays an important role in the eco.ogical protection of the upper reaches of the Yellow River *** co.prehensively analysis the alterations of habitat quality in the Qinghai Province section of the Yellow River Basin,this study utilized the Integrated Valuation of Eco.ystem Services and Tradeoffs(InVEST)model to calculate the habitat quality index and analyze the spatio-temporal variation characteristics of habitat quality in the study area from 2000 to 2022,and calculated seven landscape pattern indices(number of patches,patch density,largest patch index(LPI),landscape shape index(LSI),co.tagion index(co.TAG),Shannon diversity index,and Shannon evenness index)to research the variation of landscape pattern in the study *** results showed that the number of patches,patch density,LPI,LSI,Shannon diversity index,and Shannon evenness index increased from 2000 to 2022,while the co.TAG decreased,indicating that the landscape pattern in the Qinghai Province section of the Yellow River Basin changed in the direction of distribution fragmentation,shape co.plexity,and *** average value of the habitat quality index in the Qinghai Province section of the Yellow River Basin from 2000 to 2022 was *** on the value of habitat quality index,we divided the level of habitat quality into five categories:lower(0.00-0.20),low(0.20-0.40),moderate(0.40-0.60),high(0.60-0.80),and higher(0.80-1.00).Most areas were at the higher habitat quality *** lower habitat quality patches were mainly distributed in Longyang Gorge and Yellow River-Huangshui River *** 2000 to 2022,the habitat quality in most areas was stable;the increase areas were mainly distributed in Guinan co.nty,while the decrease areas were mainly distributed in Xining City,Maqen co.nty,Xinghai co.nty,Qumarleb co.nty,and Darlag *** show the extent of

关键词： InVEST model landscape pattern index habitat quality largest patch index landscape shape index Shannon evenness index

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A Cascading Fault Path Prediction Method for Integrated Energy Distribution Networks Based on the Improved OPA Model under Typhoon Disasters

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Energy engineering 2024年第10期121卷 2825-2849页

作者： Yue He YaxiongYou ZhianHe Haiying Lu Lei Chen Yuqi Jiang Hongkun Chen Guangzhou power Supply Bureau Guangdong Power Grid Co.Ltd.CSGGuangzhou510000China School of Electrical engineering and Automation Wuhan UniversityWuhan430072China

In recent times,the impact of typhoon disasters on integrated energy active distribution networks(IEADNs)has received increasing attention,particularly,in terms of effective cascading fault path prediction and enhanced fault reco.ery *** this study,we propose a modified ORNL-PSerc-Alaska(OPA)model based on optimal power flow(OPF)calculation to forecast IEADN cascading fault *** first established the topology and operational model of the IEADNs,and the typical fault scenario was chosen acco.ding to the co.ponent fault probability and information *** modified OPA model co.sisted of two layers:An upper-layer model to determine the cascading fault location and a lower-layer model to calculate the OPF by using Yalmip and CPLEX and provide the data to update the upper-layer *** approach was validated via the modified IEEE 33-node distribution system and two real *** results showed that the fault trend forecasted by the novel OPA model co.responded well with the development and movement of the typhoon above the *** proposed model also increased the load reco.ery rate by>24%co.pared to the traditional OPA model.

关键词： IEADNs OPA model cascading fault path prediction fault probability optimal power flow typical fault scenario

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Analysis of Calcined Red Mud Properties and Related Mortar Performances

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Fluid Dynamics & Materials Processing 2024年第5期20卷 901-913页

作者： Zhengfan Lyu Yulin Li Mengmeng Fan Yan Huang Chenguang Li Technical Center Office Guangxi Jiaojian Engineering Inspection Consulting Co.Ltd.Nanning530001China Technical Center Office Guangxi Road Construction Engineering Group Co.Ltd.Nanning530001China Nanning Road co.struction Technology and Road co.struction Materials engineering Technology Research Centre Guangxi Road Construction Engineering Group Co.Ltd.Nanning530001China

Red mud(RM)is a low-activity industrial solid waste,and its utilization as a resource is currently a hot *** this study,the micro characteristics of red mud at different calcination temperatures were analyzed using X-ray diffraction and scanning electron *** performance of calcined red mud was determined through mortar strength *** indicate that high-temperature calcination can change the mineral co.position and microstructure of red mud,and increase the surface roughness and specific surface *** the optimal temperature of 700°C,the addition of calcined red mud still leads to a decrease in mortar strength,but its activity index and flexural co.fficient increase by 16.2%and 11.9%with respect to uncalcined red mud,reaching values of 0.826 and 0.974,*** with the co.trol group,the synergistic activation of calcined red mud with slag can increase the co.pressive and flexural strength of the mortar by 12.9%and 1.5%,reaching 8.7 and 62.4 MPa,***,the activity index and flexural co.fficient of the calcined RM and GGBS(Ground Granulated Blast furnace Slag)mixtures also increase to 1.015 and 1.130,respectively.

关键词： Red mud slag thermal activation synergistic activation mortar test microsco.ic properties

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Desired Dynamic Equation for Primary Frequency Modulation co.trol of Gas Turbines

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Energy engineering 2024年第5期121卷 1347-1361页

作者： Aimin Gao Xiaobo Cui Guoqiang Yu Jianjun Shu Tianhai Zhang Thermal power Center Jiangsu Frontier Electric Technology Co.Ltd.Nanjing211102China School of Energy and power engineering Nanjing Institute of TechnologyNanjing211167China

Gas turbines play co.e roles in clean energy supply and the co.struction of co.prehensive energy *** co.trol performance of primary frequency modulation of gas turbines has a great impact on the frequency co.trol of the power ***,there are some co.trol difficulties in the primary frequency modulation co.trol of gas turbines,such as the co.pling effect of the fuel co.trol loop and speed co.trol loop,slow tracking speed,and so *** relieve the abovementioned difficulties,a co.trol strategy based on the desired dynamic equation proportional integral(DDE-PI)is proposed in this *** on the parameter stability region,a parameter tuning procedure is *** is carried out to address the ease of use and simplicity of the proposed tuning ***,DDE-PI is applied to the primary frequency modulation system of an MS6001B heavy-duty gas *** simulation results indicate that the gas turbine with the proposed strategy can obtain the best co.trol performance with a strong ability to deal with system *** proposed method shows good engineering application potential.

关键词： Gas turbine primary frequency modulation(PFM) desired dynamic equation(DDE) proportion-integral(PI)

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Unco.fined co.pressive strength and failure behaviour of co.pletely weathered granite from a fault zone

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Journal of Mountain Science 2024年第6期21卷 2140-2158页

作者： DU Shaohua MA Jinyin MA Liyao ZHAO Yaqian School of Civil engineering and Architecture Henan University of Science and TechnologyLuoyang 471023China School of Resources and Safety engineering Central South UniversityChangsha 410083China China Railway 18th Bureau Group co. LtdTianjin 300222 China China General Nuclear power co.poration Shenzhen 518031China

Understanding the strength characteristics and deformation behaviour of the tunnel surrounding rock in a fault zone is significant for tunnel stability *** this study,a series of unco.fined co.pression tests were co.ducted to investigate the mechanical characteristics and failure behaviour of co.pletely weathered granite(CWG)from a fault zone,co.sidering with height-diameter(h/d)ratio,dry densities(ρd)and moisture co.tents(ω).Based on the experimental results,a regression mathematical model of unco.fined co.pressive strength(UCS)for CWG was developed using the Multiple Nonlinear Regression method(MNLR).The research results indicated that the UCS of the specimen with a h/d ratio of 0.6 decreased with the increase ofω.When the h/d ratio increased to 1.0,the UCS increasedωwith up to 10.5%and then ***ρd is co.ducive to the improvement of the UCS at anyω.The deformation and rupture process as well as final failure modes of the specimen are co.trolled by h/d ratio,ρd andω,and the h/d ratio is the dominant factor affecting the final failure mode,followed byωandρ*** specimens with different h/d ratio exhibited co.pletely different fracture mode,i.e.,typical splitting failure(h/d=0.6)and shear failure(h/d=1.0).By co.paring the experimental results,this regression model for predicting UCS is accurate and reliable,and the h/d ratio is the dominant factor affecting the UCS of CWG,followed byρd and thenω.These findings provide important references for maintenance of the tunnel crossing other fault fractured zones,especially at low co.fining pressure or unco.fined co.dition.

关键词： Fault fracture zone co.pletely weathered granite(CWG) Unco.fined co.pression strength(UCS) Multiple nonlinear regression model

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Two-Stage Optimal Scheduling of co.munity Integrated Energy System

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Energy engineering 2024年第2期121卷 405-424页

作者： Ming Li Rifucairen Fu Tuerhong Yaxiaer Yunping Zheng Abiao Huang Ronghui Liu Shunfu Lin New power System Technology Research Institute The Electric Power Research Institute of State Grid Xinjiang Electric Power Co.Ltd.Urumqi830000China The co.lege of Electrical engineering Shanghai University of Electric PowerShanghai200090China

From the perspective of a co.munity energy operator,a two-stage optimal scheduling model of a co.munity integrated energy system is proposed by integrating information on co.trollable *** day-ahead scheduling analyzes whether various co.trollable loads participate in the optimization and investigates the impact of their responses on the operating eco.omy of the co.munity integrated energy system(IES)before and after;the intra-day scheduling proposes a two-stage rolling optimization model based on the day-ahead scheduling scheme,taking into acco.nt the fluctuation of wind turbine output and load within a short period of time and acco.ding to the different response rates of heat and co.ling power,and solves the adjusted output of each co.trollable *** simulation results show that the optimal scheduling of co.trollable loads effectively reduces the co.prehensive operating co.ts of co.munity IES;the two-stage optimal scheduling model can meet the energy demand of customers while effectively and timely suppressing the random fluctuations on both sides of the source and load during the intra-day stage,realizing the eco.omic and smooth operation of IES.

关键词： Integrated energy system two-stage optimal scheduling co.trollable loads rolling optimization

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Dynamic Modeling of Key Operating Parameters for Supercritical Circulating Fluidized Bed Units based on Data-Knowledge-Driven Method

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Journal of Thermal Science 2024年第3期33卷 1216-1230页

作者： YU Haoyang GAO Mingming ZHANG Hongfu CHEN Jiyu LIU Jizhen YUE Guangxi The State Key Laboratory of Alternate Electrical power System with Renewable Energy Sources School of Control and Computer EngineeringNorth China Electric Power UniversityBeijing102206China CHN Energy New Energy Technology Research Institute co. Ltd.Beijing102209China Department of Energy and power engineering Tsinghua UniversityBeijing100084China

To address the pressing need for intelligent and efficient co.trol of circulating fluidized bed(CFB)units,it is crucial to develop a dynamic model for the key operating parameters of supercritical circulating fluidized bed(SCFB)***,data-knowledge-driven dynamic model of bed temperature,load,and main steam pressure of the SCFB unit has been ***,a knowledge-driven method is employed to develop a dynamic model for key operating parameters of SCFB *** model parameters are determined based on the operating data of the unit and co.tinuously optimized in real ***,Bidirectional Long Short-Term Memory co.bined with co.volutional Neural Network and Attention Mechanism is utilized to build the dynamic model of bed temperature,load,and main steam ***,a co.laboration and integration method based on the critic weight method and the variation co.fficient method is proposed to establish data-knowledge-driven model of key operating parameters for SCFB *** model displays great accuracy and fitting ability co.pared with other methods and effectively captures the dynamic characteristics,which can provide a research basis for the design of intelligent flexible co.trol mode of SCFB unit.

关键词： circulating fluidized bed dynamic model data-knowledge-driven method deep learning power plant

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A Novel Defender-Attacker-Defender Model for Resilient Distributed Generator Planning with Network Reco.figuration and Demand Response

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Energy engineering 2024年第5期121卷 1223-1243页

作者： Wenlu Ji Teng Tu Nan Ma Nanjing power Supply co.pany State Grid Jiangsu Electric Power Co.Ltd.Nanjing210019China

To improve the resilience of a distribution system against extreme weather,a fuel-based distributed generator(DG)allocation model is proposed in this *** this model,the DGs are placed at the planning *** an extreme event occurs,the co.trollable generators form temporary microgrids(MGs)to restore the load ***,a demand response program(DRP)mitigates the imbalance between the power supply and demand during extreme *** co.e with the fault uncertainty,a robust optimization(RO)method is applied to reduce the long-term investment and short-term operation *** optimization is formulated as a tri-level defenderattacker-defender(DAD)*** the first level,decision-makers work out the DG allocation scheme;at the seco.d level,the attacker finds the optimal attack strategy with maximum damage;and at the third level,restoration measures,namely distribution network reco.figuration(DNR)and demand response are *** problem is solved by the nested co.umn and co.straint generation(NC&CG)method and the model is validated using an IEEE 33-node *** studies validate the effectiveness and superiority of the proposed model acco.ding to the enhanced resilience and reduced co.t.

关键词： Distribution system resilience defender-attacker-defender distributed generator demand response microgrids formation

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co.position characterization and transformation mechanism of dissolved organic phosphorus in wastewater treatment using 31P NMR spectrosco.y

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Frontiers of Environmental Science & engineering 2024年第3期18卷 103-113页

作者： Yuting Zhang Wei Shang SoonThiam Khu Xingcan Zheng Yongli Sun Pengfeng Li Miao Gu Wen-an Zhang Huanmei Ma National engineering Research Center For Urban water&Wastewater North China Municipal Engineering Design&Research Institute Co.Ltd.Tianjin 300381China School of Environment Science&engineering Tianjin UniversityTianjin 300350China

The migration and transformation of phosphorus co.ponents in wastewater treatment plants(WWTPs)play a crucial role in the co.vergence and circulation of ***,the co.position and variation of dissolved organic phosphorus(DOP)in WWTPs were unclear because of its co.plex nature,hindering its efficient *** this study,the DOP species and their transformation during the treatment process in WWTP were co.prehensively ***,two enrichment methods were assessed for their effectiveness at facilitating wastewater analysis:lyophilization and aluminum salt *** salt precipitation was found to be better because its application allowed 31P nuclear magnetic resonance(31P NMR)spectrosco.y to identify more species in the seco.dary effluent:orthophosphate(Ortho-P)(81.1%–89.3%of the dissolved total phosphorus),pyrophosphates(Pyro-P)(0%–2.3%),orthophosphate monoesters(Mono-P)(7.0%–10.77%),orthophosphate diesters(Di-P)(1.0%–2.96%),and phosphonate(Phos-P)(1.7%–5.16%).Furthermore,the variation and transformation mechanism of phosphorus,particularly those of DOP,during the entire sewage-treatment process were *** the treatment steps,biological treatment co.bined tertiary treatment achieved better DOP removal ***,biological treatment mainly removed Mono-P and Di-P with removal efficiencies of 33.3%and 41.7%co.pared with the effluent of the grit ***-P has higher bioavailability and is more easily co.verted and utilized by microorganisms than ***,Phos-P,with low bioavailability,was hardly utilized by microorganisms,which showed only 18.4%removal efficiency in biological *** tertiary treatment,co.gulation process exhibited higher removal ability of Ortho-P(69.1%)and partial removal efficiencies of DOP,resulting in an increase in the DOP proportion in *** addition,Phos-P co.ld not be effectively removed through the biological treatment and was only partially reduced via the adsorption pro

关键词： Municipal wastewater Dissolved organic phosphorus co.position Transformation 31P nuclear magnetic resonance

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