Results 11 to 20 of about 10,256 (170)
全球能源互联网, 2021 随着风电和光伏等新能源发电系统渗透率的不断提高，电网呈现出弱电网甚至极弱电网特性，给新能源并网发电系统稳定和高效运行带来了严峻挑战。通过回顾现有典型的新能源并网逆变稳定控制策略等方面的成果，总结了电流源模式、电压源模式以及双模式控制的基本原理和研究现状，并指出基于锁相环控制的电流源模式并网虽然能够保证强电网下的系统稳定性和功率控制快速性等，但是此类控制方式在稳定性、系统电压和频率调整等方面有诸多局限，难以适应新能源发电单元高比例接入的场景。基于功率自同步控制的电压源模式控制能够为电压和频率提供支撑 ...
张兴 +5 more
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Urban Green Network Design: Defining green network from an urban planning perspective [PDF]
, 2017 From the theoretical context of Smart City various studies have emerged that adopt an analytical approach and description of urban phenomena based on the principles of “network design”; this line of research uses the network systems theory to define ...
Tulisi, Andrea
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Research on Protection Scheme of DC Microgrid Integrated with Fault Current Limiting Control Technology [PDF]
, 2023 [Introduction] With the development of new loads, such as distributed power sources and electric vehicles, DC(Direct Current) microgrids have the advantages of fewer commutation links and lower system losses than AC(Alternating Current) microgrids, and ...
Bingyao ZHENG +6 more
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Dianci bileiqi, 2023 由于雷电流冲击接地网时，造成地网将产生较高的地电位抬升，强大的过电压会将线路或装置的绝缘材料击穿损坏。基于人工引雷实验，观测两个相距10 m的雷击地网和邻近地网的地电位抬升电压特征，提出一种采用有限元法建立仿真模型，求解接地网三维瞬间变化，以此分析雷电流在接地网中的分布规律的研究方法。采用有限元仿真软件构建电磁暂态模型，将试验数据和仿真数据进行对比，得出结论，1)雷电流回击引起雷击地网和邻近地网电压瞬间都有明显的抬升，邻近地网GPR电压幅值上出现较大的衰减。2)雷电流是导致雷击地网GPR的主要因素 ...
冉冉 +5 more
doaj
Dianci bileiqi, 2021 合理的变电站地网设计对于降低地网跨步电压、确保人身安全至关重要,有必要详细研究地网接地导体网格布置。通过EMTP软件输电线路和变电站地网模型,考虑接地体雷击暂态特性和人体高频电路模型,计算地网跨步电压。利用自适应遗传算法确定地网采用不等间距等比布置时中心网孔最佳尺寸,分析不等间距布置对于降低跨步电压效果。最后讨论满足人体容许跨步电压安全标准前提下地网所需最少接地导体数量。研究结果表明:输电线路遭受雷击后,临近变电站地网会产生幅值相对较高的暂态过电压,且过电压波形呈现明显振荡衰减 ...
李鑫, 朱俊澎, 刘立平, 胡婷
doaj
Dianci bileiqi, 2023 为研究雷击电力杆塔时杆塔接地网降低接地电阻的效果，建立近水源平原和山区的单桩塔接地网和四桩塔接地网模型，计算不同土壤电阻率、电流频率下接地网形式对近水源区杆塔接地电阻的影响，并对比分析平原和山区地势条件下杆塔接地网形式的最优方案。仿真结果表明：接地网的接地电阻随着土壤电阻率和电流频率增大而升高。对于近水源的平原地区，单桩塔“米”字型接地网在单桩塔中降阻效果最显著，以单边外延接地网为比较基准，在工频和高频条件下的平均降阻效率分别为64.49%和76.15 ...
董贯雷 +5 more
doaj
Functional Ecology, EarlyView.Read the free Plain Language Summary for this article on the Journal blog. Abstract Ecological communities are stressed by rapid and complex anthropogenic changes, threatening the persistence of biotic interactions and ecosystem functioning. Plant–pollinator communities, for instance, undergo structural transformations as a result of land‐use change ...
Erliang Gao +8 more
wiley +1 more source
Methods in Ecology and Evolution, EarlyView.Abstract Molecular identification of insect food webs can accurately reveal complex trophic interactions and serve as a foundation for understanding ecosystem functioning and advancing biodiversity conservation. This process typically involves DNA library construction, high‐throughput sequencing and subsequent steps, including data assembly, annotation,
Xiao‐man Zhang +9 more
wiley +1 more source
Design and Implementation of Mobile Resource Management System for a Mobile Communication Company [PDF]
, 2016 随着全球移动通信技术的日新月异，中国电信运营商在移动业务上展开激烈的竞争。部署高品质的网络、不断压缩网络的建设与故障处理历时是移动网络品牌的核心。合理利用网络资源，科学动态的管理资源是提高核心竞争力的根本方法，也是三大运营商共同面临的问题。建立移动资源管理系统将基站建设环节与移动网络基站所需资源相结合，使某移动通信公司基站资源、核心网设备资源、建设进度管理以及基站调度开通环节等需求融入到移动资源管理系统的设计过程中，并根据基站建设过程中容易出现的问题，给出合理的、有效的系统解决方案 ...
丁钰钊
core