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Transient stability Analysis of Grid-connected Converters in wind Turbine systems Based on Linear Lyapunov Function and Reverse-time Trajectory

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Journal of Modern power systems and Clean Energy 2024年第3期12卷 782-790页

作者： Mohammad Kazem Bakhshizadeh sujay Ghosh Guangya Yang Łukasz Kocewiak ørsted wind power a/s Nesa Allé12820Denmark Technical University of Denmark Anker Engelunds Vej 12800Denmark

As the proportion of converter-interfaced renewable energy resources in the power system is increasing,the strength of the power grid at the connection point of wind turbine generators(WTGs)is gradually *** research has shown that when connected with the weak grid,the stability of the traditional grid-following controlled converters will deteriorate,and they are prone to unstable phenomena such as *** to the limitations of linear analysis that cannot sufficiently capture the stability phenomena,transient stability must be *** far,standalone time-domain simulations or analytical Lyapunov stability criteria have been used to investigate transient ***,the time-domain simulations have proven to be computationally too heavy,while analytical methods are difficult to formulate for larger systems,require many modelling assumptions,and are often conservative in estimating the stability *** paper proposes and demonstrates an innovative approach to estimating the transient stability boundary via combining the linear Lyapunov function and the reverse-time trajectory *** proposed methodology eliminates the need of time-consuming simulations and the conservative nature of Lyapunov *** study brings out the clear distinction between the stability boundaries with different post-fault active current ramp rate *** the same time,it provides a new perspective on critical clearing time for wind turbine *** stability boundary is verified using time-domain simulation studies.

关键词： Lyapunov direct method non-autonomous system phase-locked loop(PLL) time trajectory reversal transient stability assessment wind turbine converter system

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Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

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Plasma science and Technology 2024年第1期26卷 42-49页

作者：耿江海林果王平丁玉剑丁杨俞华 Department of Electric power Engineering North China Electric Power UniversityBaoding 071003People’s Republic of China China Electric power Research Institute Beijing 100192People’s Republic of China Xinjiang Electric power Company Research Institute Urumchi 830000People’s Republic of China shanxi Electric power Company Research Institute Taiyuan 030001People’s Republic of China

Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude *** this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 *** experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical *** duration of the dark period and the critical charge of streamer-toleader transition were obtained at high *** on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader *** with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified *** the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

关键词： streamer-to-leader transition model high altitude streamer stem convective diffusion radial thermal expansion

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Dynamic propagation velocity of a positive streamer in a 3 m air gap under lightning impulse voltage

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Plasma science and Technology 2024年第4期26卷 114-121页

作者：李志伟雷挺苏宇姚修远杨冰雪刘德龙律方成丁玉剑 North China Electric power University Beijing 102206People’s Republic of China China Electric power Research Institute Beijing 100192People’s Republic of China

streamers represent an important stage in the initiation of gap discharge. In this work, we used an eight-frame intensified charge-coupled device camera to capture the streamer development process when a lightning impulse voltage of 95%–100% U50% was applied in a 3 m rod–plate gap and the streamer velocity was analyzed. Analysis of the observations shows that streamer velocity can be defined by three stages: rapid velocity decline(stage 1), rapid velocity rise(stage 2)and slow velocity decline(stage 3). The effects of electrode shape, applied voltage and gap breakdown or withstanding on streamer velocity were analyzed. The electrode with a larger radius of curvature will result in a higher initial velocity, and a higher voltage amplitude will cause the streamer to propagate faster at stage 3. Gap withstanding or breakdown has no obvious effect on streamer velocity. In addition, the experimental results are compared with previous results and the statistical characteristics of the primary streamer discharge are discussed.

关键词： lightning impulse 3 m air gap development process streamer velocity

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The characteristics of negative corona discharge and radio interference at different altitudes based on coaxial wire-cylinder gap

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Plasma science and Technology 2024年第2期26卷 77-85页

作者：何旺龄魏宏宇张胤禄刘永聪刘云鹏万保权周阳王延召干喆渊 Hebei Key Laboratory of Green and Efficient New Electrical Materials and Equipment North China Electric Power UniversityBaoding 071000People's Republic of China state Grid suzhou power supply Company Suzhou 215000People's Republic of China state Key Laboratory of power Grid Environmental Protection(China Electric power Research Institute) Wuhan 430000People's Republic of China

The corona discharge from transmission lines in high-altitude areas is more severe than at lower altitudes. The radio interference caused thereby is a key factor to be considered when designing transmission lines. To study the influence of altitude on negative corona characteristics, an experimental platform comprising a movable small corona cage was established: experiments were conducted at four altitudes in the range of 1120-4320 m, and data on the corona current pulse and radio interference level of 0.8-mm diameter fine copper wire under different negative voltages were collected. The experimental results show that the average amplitude, repetition frequency and average current of the corona current pulse increase with increasing altitude. The dispersion of pulse amplitude increases with increase in altitude, while the randomness of the pulse interval decreases continuously. Taking the average current as an intermediate variable,the relationship between radio interference level and altitude is obtained. The result of this research has some significance for understanding the corona discharge characteristics of ultra-highvoltage lines.

关键词： altitude negative corona corona current pulse radio interference level

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Discovering Cathodic Biocompatibility for Aqueous Zn–MnO_(2) Battery:An Integrating Biomass Carbon strategy

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Nano-Micro Letters 2024年第6期16卷 111-126页

作者： Wei Lv Zilei shen Xudong Li Jingwen Meng Weijie Yang Fang Ding Xing Ju Feng Ye Yiming Li Xuefeng Lyu Miaomiao Wang Yonglan Tian Chao Xu Institute of Energy power Innovation North China Electric Power UniversityBeijing 102206People’s Republic of China Department of power Engineering School of EnergyPower and Mechanical EngineeringNorth China Electric Power UniversityBaoding 071003People’s Republic of China Key Laboratory of RNA Biology Institute of BiophysicsChinese Academy of SciencesBeijing 100101People’s Republic of China Collaborative Innovation Center of Integrated Exploitation of Bayan Obo Multi‑Metal Resources Inner Mongolia University of Science and TechnologyBaotou 014010People’s Republic of China

Developing high-performance aqueous Zn-ion batteries from sustainable biomass becomes increasingly vital for large-scale energy storage in the foreseeable ***,γ-MnO_(2) uniformly loaded on N-doped carbon derived from grapefruit peel is successfully fabricated in this work,and particularly the composite cathode with carbon carrier quality percentage of 20 wt%delivers the specific capacity of 391.2 mAh g^(−1)at 0.1 A g^(−1),outstanding cyclic stability of 92.17%after 3000 cycles at 5 A g^(−1),and remarkable energy density of 553.12 Wh kg^(−1) together with superior coulombic efficiency of~100%.Additionally,the cathodic biosafety is further explored specifically through in vitro cell toxicity experiments,which verifies its tremendous potential in the application of clinical ***,Zinc ion energy storage mechanism of the cathode is mainly discussed from the aspects of Jahn–Teller effect and Mn domains distribution combined with theoretical analysis and experimental ***,a novel perspective of the conversion from biomass waste to biocompatible Mn-based cathode is successfully developed.

关键词： Aqueous Zn-ion batteries Biocompatibility Jahn-Teller effect Mn domains γ-MnO_(2)

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A spatiotemporal evolution model of a short-circuit arc to a secondary arc based on the improved charge simulation method

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Plasma science and Technology 2024年第1期26卷 62-73页

作者：丛浩熹王宇轩乔力盼苏文晶李庆民 state Key Laboratory of Alternate Electrical power system with Renewable Energy sources North China Electric Power UniversityBeijing 102206People’s Republic of China

The initial shape of the secondary arc considerably influences its subsequent *** establish the model for the arcing time of the secondary arc and modify the single-phase reclosing sequence,theoretical and experimental analysis of the evolution process of the short-circuit arc to the secondary arc is *** this study,an improved charge simulation method was used to develop the internal-space electric-field model of the short-circuit *** intensity of the electric field was used as an independent variable to describe the initial shape of the secondary arc.A secondary arc evolution model was developed based on this ***,the accuracy of the model was evaluated by comparison with physical experimental *** the secondary arc current increased,the arcing time and dispersion *** is an overall trend of increasing arc length with increasing arcing ***,there is a reduction in arc length during arc ignition due to short circuits between the arc ***,the arcing time decreased in the range of 0°-90°as the angle between the wind direction and the x-axis *** work investigated the method by which short-circuit arcs evolve into secondary *** results can be used to develop the secondary arc evolution model and to provide both a technical and theoretical basis for secondary arc suppression.

关键词： short-circuit arc secondary arc stochasticity improved charge simulation method arc time

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Phase field model for electric-thermal coupled discharge breakdown of polyimide nanocomposites under high frequency electrical stress

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Plasma science and Technology 2024年第2期26卷 114-124页

作者：韩智云李庆民李俊科王梦溪任瀚文邹亮 state Key Lab of Alternate Electrical power system with Renewable Energy sources North China Electric Power UniversityBeijing 102206People's Republic of China school of Electrical Engineering Shandong UniversityJinan 250061People's Republic of China

In contrast to conventional transformers, power electronic transformers, as an integral component of new energy power system, are often subjected to high-frequency and transient electrical stresses, leading to heightened concerns regarding insulation failures. Meanwhile, the underlying mechanism behind discharge breakdown failure and nanofiller enhancement under high-frequency electrical stress remains unclear. An electric-thermal coupled discharge breakdown phase field model was constructed to study the evolution of the breakdown path in polyimide nanocomposite insulation subjected to high-frequency stress. The investigation focused on analyzing the effect of various factors, including frequency, temperature, and nanofiller shape, on the breakdown path of Polyimide(PI) composites. Additionally, it elucidated the enhancement mechanism of nano-modified composite insulation at the mesoscopic scale. The results indicated that with increasing frequency and temperature, the discharge breakdown path demonstrates accelerated development, accompanied by a gradual dominance of Joule heat energy. This enhancement is attributed to the dispersed electric field distribution and the hindering effect of the nanosheets. The research findings offer a theoretical foundation and methodological framework to inform the optimal design and performance management of new insulating materials utilized in high-frequency power equipment.

关键词： dielectric discharge breakdown high frequency power electronic transformer polyimide nanocomposites phase field model

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seismic effectiveness evaluation and optimized design of tie up method for securing museum collections

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 741-763页

作者： Wang Meng Yan Yi Yang Weiguo Liu Pei Ge Jiaqi Ma Botao school of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China Beijing’s Key Laboratory of structural wind Engineering and Urban wind Environment Beijing 100044China Beijing General Municipal Engineering Design&Research Institute Co. LtdBeijing 100082China China Aviation Planning and Design Institute(Group)Co.Ltd. Beijing 100120China

To quantify the seismic effectiveness of the most commonly used fishing line tie up method for securing museum collections and optimize fixed strategies for exhibitions,shaking table tests of the seismic systems used for typical museum collection replicas have been carried *** influence of body shape and fixed measure parameters on the seismic responses of replicas and the interaction behavior between replicas and fixed measures have been *** on the results,seismic effectiveness evaluation indexes of the tie up method are *** suggestions for fixed strategies are given,which provide a basis for the exhibition of delicate museum collections considering the principle of minimizing seismic responses and *** analysis results show that a larger ratio of height of mass center to bottom diameter led to more intense rocking *** the initial pretension of fishing lines was conducive to reducing the seismic responses and stress variation of the *** comprehensive consideration of the interaction forces and effective securement,it is recommended to apply 20%of breaking stress as the initial *** specific museum collections that cannot be effectively protected by the independent tie up method,an optimized strategy of a combination of fishing lines and fasteners is recommended.

关键词： tie up method museum collections shaking table test seismic effectiveness optimized design

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Plasma nitrogen fixation system with dual-loop enhancement for improved energy efficiency and its efficacy for lettuce cultivation

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Plasma science and Technology 2024年第1期26卷 82-92页

作者：韩泽阳张梦雪张頔何欣井天军葛知轩李玉鸽朱童任云鸿仲崇山季方 College of Information and Electrical Engineering China Agricultural UniversityBeijing 100083People’s Republic of China College of Water Resources and Civil Engineering China Agricultural UniversityBeijing 100083People’s Republic of China Electric power Research Institute state Grid Gansu Electric Power Company GansuLanzhou 730030People’s Republic of China

Plasma nitrogen fixation(PNF)has been emerging as a promising technology for greenhouse gasfree and renewable energy-based ***,most PNF studies seldom address practical application-specific *** this work,we present the development of a compact and automatic PNF system for on-site agricultural *** system utilized a gliding-arc discharge as the plasma source and employed a dual-loop design to generate NO_(x)from air and water under atmospheric *** results showed that the system with a dualloop design performs well in terms of energy costs and production *** operational parameters for the system were determined through experimentation,resulting in an energy cost of 13.9 MJ mol^(-1)and an energy efficiency of 16 g kWh^(-1)for NO_(3)^(-)production,***,the concentration of exhausted NO_(x)was below the emission *** lettuce cultivation experiments demonstrated that NO_(x)^(-)produced by the PNF system could serve as liquid nitrate nitrogen ***,our work demonstrates the potential of the developed PNF system for on-site application in the production of green-leaf vegetables.

关键词： plasma nitrogen fixation gliding arc soilless cultivation lettuce

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Ecological network analysis reveals complex responses of tree species life stage interactions to stand variables

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Journal of Forestry Research 2024年第1期35卷 29-43页

作者： Hengchao Zou Huayong Zhang Tousheng Huang Research Center for Engineering Ecology and Nonlinear science North China Electric Power UniversityBeijing 102206People’s Republic of China

Tree interactions are essential for the structure,dynamics,and function of forest ecosystems,but variations in the architecture of life-stage interaction networks(LsINs)across forests is ***,we constructed 16 LsINs in the mountainous forests of northwest Hebei,China based on crown overlap from four mixed forests with two dominant tree *** results show that LsINs decrease the complexity of stand densities and basal areas due to the interaction cluster *** addition,we found that mature trees and saplings play different roles,the first acting as“hub”life stages with high connectivity and the second,as“bridges”controlling information flow with high *** the forests,life stages with higher importance showed better parameter stability within *** results reveal that the structure of tree interactions among life stages is highly related to stand *** efforts contribute to the understanding of LsIN complexity and provide a basis for further research on tree interactions in complex forest communities.

关键词： Tree interactions Life stages Interaction networks Ecological complexity

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