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Research on discharge phenomenon caused by cross‐adsorption of linear insulating fibre and metal dust under DC voltage

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high voltage 2022年第2期7卷 269-278页

作者： Ruixue Liang Qi Hu Heng Liu Jian Wang Qingmin Li state key laboratory of alternate electrical power system with renewable energy sources North China Electric Power UniversityBeijingChina

A large amount of metal dust is often generated during production and operation of Gas Insulated Switchgear/Gas‐Insulated Transmission Line,and insulating fibres are very easy to mix in during *** discharge phenomenon induced by these two impurities remains *** setting up a test rig with parallel electrodes,the discharge characteristics of metal dust and linear insulating fibres under the negative DC voltage were studied separately and *** obtained research results indicate some interesting phenomena that the metal dust may render‘sand storm’motion characteristics under the action of the electric field,and the linear insulating fibres appear to show‘standing’,‘jumping’,‘flying fire’and other phenomena.A small amount of dust and fibres alone present little effect on the breakdown voltage of the air ***,while the insulating fibres and metal dust coexist,the metal dust will be adsorbed on the surface of the insulating fibres,then the surface charge of the fibres is reallocated,and the discharge phenomenon at both ends of the fibres is enhanced,so that the insulating fibre exhibits similar movement and discharge characteristics to the linear metal *** the same time,the fibres with dust absorbed on will result in an air gap breakdown voltage drop of approximately 25%-40%.What's more,if the discharge of fibres and the‘sand storm’movement of the dust coexist,it may directly lead to‘explosion’of the moving dust,causing severely ablation of the plate surfaces,and thereby the degree of destruction increases dramatically.

关键词： jointly fibre fibres

Flexible ion-conducting membranes with 3D continuous nanohybrid networks for high-performance solid-state metallic lithium batteries

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Journal of energy Chemistry 2022年第12期75卷 360-368,I0009页

作者： Lehao Liu Dongmei Zhang Tianrong Yang Weihao Hu Xianglong Meng Jinshan Mo Wenyan Hou Qianxiao Fan Kai Liu Bing Jiang Lihua Chu Meicheng Li state key laboratory of alternate electrical power system with renewable energy sources School of New EnergyNorth China Electric Power UniversityBeijing 102206China

Polyethylene oxide(PEO)-based electrolytes are considered as one of the most promising solid-state electrolytes for next-generation lithium batteries with high safety and energy density;however,the drawbacks such as insufficient ion conductance,mechanical strength and electrochemical stability hinder their applications in metallic lithium *** enhance their overall properties,flexible and thin composite polymer electrolyte(CPE)membranes with 3D continuous aramid nanofiber(ANF)–Li_(1.4)Al_(0.4)Ti_(1.6)(PO_(4))_(3)(LATP)nanoparticle hybrid frameworks are facilely prepared by filling PEO–Li TFSI in the 3D nanohybrid scaffolds via a solution infusion *** construction of the 3D continuous nanohybrid networks can effectively inhibit the PEO crystallization,facilitate the lithium salt dissociation and meanwhile increase the fast-ion transport in the continuous LATP electrolyte phase,and thus greatly improving the ionic conductivity(~3 times that of the pristine one).With the integration of the 3D continuity and flexibility of the 3D ANF networks and the thermostability of the LATP phase,the CPE membranes also show a wider electrochemical window(~5.0 V vs.4.3 V),higher tensile strength(~4–10times that of the pristine one)and thermostability,and better lithium dendrite resistance ***,the CPE-based Li FePO_(4)/Li cells exhibit superior cycling stability(133 m Ah/g after 100 cycles at 0.3 C)and rate performance(100 m Ah/g at 1 C)than the pristine electrolyte-based cell(79 and 29m Ah/g,respectively).This work offers an important CPE design criteria to achieve comprehensivelyupgraded solid-state electrolytes for safe and high-energy metal battery applications.

关键词： Composite polymer electrolyte Aramid nanofiber Ceramic electrolyte nanoparticle Ion conductivity Mechanical strength Solid-state battery

Universal generating function based probabilistic production simulation for wind power integrated power systems

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Journal of Modern power systems and Clean energy 2017年第1期5卷 134-141页

作者： Tingchao JIN Ming ZHOU Gengyin LI state key laboratory for alternate electrical power system with renewable energy sources North China Electric Power UniversityBeijingChina

According to the demand of sustainable development and low-carbon electricity, it is important to develop clean resources and optimize scheduling generation mix. Firstly, a novel method for probabilistic production simulation for wind power integrated power systems is proposed based on universal generating function(UGF), which completes the production simulation with the chronological wind power and load demand. Secondly,multiple-period multiple-state wind power model and multiple-state thermal unit power model are adopted, and both thermal power and wind power are coordinately scheduled by the comprehensive cost including economic cost and environmental cost. Furthermore, the accommodation and curtailment of wind power is synergistically considered according to the available regulation capability of conventional generators in operation. Finally, the proposed method is verified and compared with conventional convolution method in the improved IEEE-RTS 79 system.

关键词： Universal generating function(UGF) Chronological characteristics Environment cost Multiple-period multiple-state wind power model Wind power accommodation

Transient electric field of the combined insulation structure under positive periodic square waveform voltage:Analytical analysis and application

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high voltage 2022年第5期7卷 877-889页

作者： Teng Wen Xiang Cui Xuebao Li Sijia Liu Zhibin Zhao state key laboratory of alternate electrical power system with renewable energy sources North China Electric Power UniversityBeijingChina

The working voltage of the high-voltage high-power electronic devices is the positive periodic square waveform(PPSW)voltage,which is much different from the conventional AC or DC *** the composite insulation structure of devices,it is important to analyse the transient electric field under the PPSW ***,the existing investigations are often conducted under the electrostatic field due to the high frequency of the PPSW ***,the transient characteristics of the electric field are *** obtain some qualitative conclusions,this paper focusses on the theoretical analysis of the transient characteristics of electric field for the composite insulation structure under the PPSW ***,the formula of the electric field intensity and the interfacial charge density are derived ***,the influence of the cycle and the duty cycle on the transient characteristics are ***,the maximum of the electric field intensity and the interfacial charge density in the positive square waveform steady-state are discussed in ***,the engineering calculation methods for obtaining these maximum values are also ***,an actual model is employed to testify the validity of the analytical *** work is significant for the numerical calculation of the transient electric field of composite insulation structure under the PPSW voltage in engineering.

关键词： composite insulation field

Review of Charge Accumulation on Spacers of Gas Insulated Equipment at DC Stress

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CSEE Journal of power and energy systems 2020年第3期6卷 496-517页

作者： Hongyang Zhou Guoming Ma Cong Wang Jue Wang Guixin Zhang Youping Tu Chengrong Li state key laboratory of alternate electrical power system with renewable energy sources and the beijing key laboratory of high voltage and emc North China Electric Power UniversityBeijing 102206China Institute of electrical Engineering Chinese Academy of SciencesBeijingChina Department of electrical Engineering Tsinghua UniversityBeijing 100084China

Charge accumulation on the spacer surface in gas insulated equipment is very severe in the DC field,leading to easy flashover,which restricts the application of DC GIS/***,knowledge about the charge accumulation characteristics of gas insulated equipment at DC stress is *** this paper,we reviewed the research methods and the characteristics of charge accumulation on spacers.A summary of charge measurement methods and setups are *** the surface charge inversion algorithms are *** the simulation model for charge accumulation in the DC field is ***,the charge accumulation mechanisms and phenomenon,the influence factor of surface charge accumulation and the influence of accumulated charge on spacer insulation characteristics are *** addition,some suppression methods of surface charge accumulation are ***,based on the understanding of charge accumulation on spacers,some suggestions on further studies are presented to aid in the design of a better spacer free from surface charges.

关键词： Charge accumulation DC gas insulated equipment review spacer

SSO Risk Evaluation for a Grid-connected PMSG-based Wind Farm Based on Sequential Monte Carlo Simulation

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CSEE Journal of power and energy systems 2023年第4期9卷 1348-1358页

作者： Shun Tao Yunbo Liu Yanan Yan Lei Zhao the state key laboratory of alternate electrical power system with renewable energy sources North China Electric Power UniversityBeijing102206China.

In a grid-connected wind farm based on permanent magnet synchronous generators(PMSGs),the wind speed and the number of operating PMSGs are the two most important influencing factors along with the stochastic nature of sub-synchronous oscillation(SSO)from the point view of the *** paper proposes a method of unstable SSO risk evaluation for grid-connected PMSG-based wind farms based on the sequential Monte Carlo simulation(SMCS).The determination of critical wind speed(CWS)of SSO and the sequential simulation strategy of wind speed states and PMSG states in a wind farm at the same wind speed(S-WF),as well as in a wind farm at different wind speeds(D-WF),are *** indices evaluating the expectation,duration,frequency and energy loss of SsO risk are ***,a strategy to reduce SsO risk by adjusting the cut-in wind speed is *** effectiveness of the discussed issues in this paper are proved by the case studies of a 750-PMSG wind farm based on the actual wind speed data collected.

关键词： PMSG-based wind farm subsynchronous oscillation(SSO) Sequential Monte Carlo simulation(SMCS) risk evaluation

Enhanced voltage distribution and breakdown strength performances of oil‐paper composite insulation by adding TiO_(2)nanoparticles

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high voltage 2021年第1期6卷 42-50页

作者： Meng Huang Yupeng Ying Baixin Liu Yuzhen Lv Bo Qi Chengrong Li state key laboratory of alternate electrical power system with renewable energy sources North China Electric Power UniversityBeijingChina beijing key laboratory of high voltage&emc North China Electric Power UniversityBeijingChina School of energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijingChina

Oil-paper composite insulation(OPCI)is used as the main insulation material in the converter ***,the dielectric properties of insulating oil and oil‐impregnated paper are markedly mismatched under direct current(DC)voltage,resulting in an unbalanced distribution of voltage,which is considered to be a major cause of large insulation margin but frequent ***,it is necessary to adjust the voltage distribution in OPCI to enhance its breakdown *** this work,surface‐treated TiO_(2) nanoparticles were employed to modify *** polarisation current tests revealed that by changing the additive amount of nano-particles,the polarisation intensities of both oil and oil‐impregnated paper could be *** on this,a model taking relaxation polarisations into full consideration was established to analyse the voltage distribution in OPCI and predict the optimal *** prepared OPCI with the concentration of 0.02 g/L has desired balanced voltage distribution due to the influence of nanoparticles on interface charge,and therefore high breakdown strengths under both DC voltage and polarity reversal voltage,which can be increased by 22.6%at *** work puts forward a novel idea to improve insulation property of OPCI and provides a reference for broader application of nanomaterial in power equipment.

关键词： insulation distribution breakdown

Assessment Method of Offshore Wind Resource Based on Multi-dimenssiional Indexes system

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CSEE Journal of power and energy systems 2024年第1期10卷 76-87页

作者： Xiaomei Ma Yongqian Liu Jie Yan Shuang Han Li Li Hang Meng Muhammet Deveci Konstanze Kolle Umit Cali the state key laboratory of alternate electrical power system with renewable energy sources(NCEPU) School of New EnergyNorth China Electric Power UniversityBeijing 102206China School of Physical and Electronic Information Engineering Qinghai Normal UniversityXiningQinghai 810016China state key laboratory of alternate electrical power system with renewable energy sources(NCEPU) School of New EnergyNorth China Electric Power UniversityBeijing 102206China the Royal School of Mines Imperial College London.London SW72AZUKand also with Department of Industrial EngineeringTurkish Naval AcademyNational Defence University34940IstanbulTurkey Department of energy systems SINTEF Energy ResearchTrondheimNO-7034 Norway Department of Electric power Engineering Norwegian University of Science and TechnologyTrondheimNO-7491 Norway

Traditional assessment indexes could not fully describe offshore wind resources,for the meteorological properties of offshore are more complex than *** a result,the uncertainty of offshore wind power projects would be increased and final economic benefits would be ***,a study on offshore wind resource assessment is carried out,including three processes of“studying data sources,conducting multidimensional indexes system and proposing an offshore wind resource assessment method based on analytic hierarchy process(AHP).First,measured wind data and two kinds of reanalysis data are used to analyze the characteristics and reliability of data ***,indexes such as effective wind speed occurrence,affluent level occurrence,coefficient of variation,neutral state occurrence have been proposed to depict availability,richness,and stability of offshore wind resources,*** with existing parameters(wind power density,dominant wind direction occurrence,water depth,distance to coast),a multidimensional indexes system has been built and on this basis,an offshore wind energy potential assessment method has been ***,the proposed method is verified by the annual energy production of five offshore wind turbines and practical operating data of four offshore wind farms in *** study also compares the ranking results of the AHP model to two multi-criteria decision making(MCDM)models including weighted aggregated sum product assessment(WASPAS)and multi-attribute ideal real comparative analysis(MAIRCA).Results show the proposed method gains well in practical engineering applications,where the economic score values have been considered based on the offshore reasonable utilization hours of the whole life cycle in China.

关键词： Annual energyproduction aatmospheric stability data sources offshore wind resource wind power density

In-situ Observation of Crack Growth and Domain Switching Around Vickers Indentation on BaTiO_3 Single Crystal Under Sustained Electric Field

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Acta Metallurgica Sinica(English Letters) 2013年第6期26卷 772-776页

作者： Bing JIANG Yusong LIU Meicheng LI state key laboratory of alternate electrical power system with renewable energy sources School of Renewable EnergyNorth China Electric Power University beijing Sustainable Development Center

The crack propagation and domain switching process around the indentation on the surface of barium titanate single crystal under the external electric field was investigated by atomic force microscope and polarized light microscope. The evolutions of domain switching and crack propagation were in-situ observed when a 90°a- c domain wall moved across the indentation which was driven by external electric field. The results show that the incompatible strain induced by domain switching in the residual stress zone around the indentation is the driving force of the anisotropic crack propagation. The crack propagation results in the changes of the fine domain stripes around the crack tip.

关键词： Domain switching Indentation Crack propagation BaTiO3 AFM