Results 21 to 30 of about 26,852 (162)
直流输电系统以单极大地方式运行时,地中流散的直流电流流入极址附近交流变压器中性点,导致变压器产生直流偏磁现象。研究土壤结构对流入变压器的直流电流的影响是分析变压器直流偏磁现象的基础。建立考虑山川、海洋、湖泊等复杂土壤结构的直流接地极特性电磁场有限元模型,计算直流接地极散流产生的地中电位;结合变电站电路模型计算流入相应变压器的直流电流;在此模型基础上分析极址附近交流变电站接地网位置对流入变压器直流电流的影响。结果表明:当两交流变电站之间连线与山川、海洋平行时,流入变压器的直流电流量最小 ...
李景丽, 栗超超, 冯鹏
doaj
分析直流偏磁对变压器造成的异常振动噪音规律是预防变压器故障的前提。为此,针对E型电力变压器,根据"铁心—绕组"模型分析了直流偏磁下变压器的振动噪音机理并利用Comsol搭建了电磁—振动—声场多物理场耦合模型,研究直流量大小、直流量从初级绕组流入和直流量从次级绕组流入两种情况下,直流偏磁对不同运行状况变压器的振动噪音规律和对绕组电压电流波形的影响。研究表明:直流量从初级绕组流入对空载变压器的影响最大,随直流量的增加铁心绕组上的振动噪音加剧且振动噪音最大值分布在铁心上 ...
吴静 +6 more
doaj
ABSTRACT Two‐dimensional (2D) nonlayered niobium nitrides have attracted considerable interest for electrochemical energy storage. However, the synthesis of these materials is hampered by their nonlayered crystal structures, which are characterized by strong three‐dimensional chemical bonding.
Rui Huo +7 more
wiley +1 more source
ABSTRACT The realization of bifunctional perovskite devices integrating photovoltaic (PV) and light‐emitting diode (LED) capabilities requires precisely controlled grain architectures to facilitate dual carrier transport pathways. In this work, sulfaguanidine (SG) molecules were introduced into the perovskite solution to reconstruct the crystallization
Jiong Li +7 more
wiley +1 more source
架空线柔性直流电网是实现大规模可再生能源广域协调互补和可靠送出的有效解决方案,是未来高压大容量柔性直流输电的重要应用方向。直流线路短路电流是柔性直流电网中换流阀、直流断路器及电抗器等关键主设备参数选取的重要依据之一。通过建立双极柔性直流电网单个换流站在直流线路不同短路故障类型下的等效电路数学模型,构建了故障时刻双极柔性直流电网等效电路网络模型,提出了一种适用于双极柔性直流电网的单极接地、单极接中性线及双极短路的暂态短路电流定量分析方法,实现了双极柔性直流电网直流线路任意故障类型 ...
裴翔羽 +5 more
doaj +1 more source
ABSTRACT Chemically self‐charging aqueous zinc‐ion batteries (AZIBs) have emerged as promising candidates for energy storage technologies owing to their environmental autonomy and structural simplicity. Nonetheless, the self‐charging performance is significantly compromised by the limited potential difference between cathodes and oxygen, as well as the
Yan Wang +5 more
wiley +1 more source
Driving of the Squirrel-cage Three Phase Induction Motor with Mc Murray-type Three-phase Inverter [PDF]
The output wave form of Mc Murray type three phase inverter is rectangular and it involves many harmonics. The squirrel-cage three phase induction motor (750W, 200V, 50/60 c/s, 4 poles) was drived by the inverter, then efficiendes and temperature rises ...
岡田 粂ニ
core +1 more source
ABSTRACT Objective To investigate whether combining abnormal morphological features observed on ultrasound in live pregnancies that ended in a first‐trimester miscarriage can predict an abnormal karyotype. Methods This retrospective observational cohort study was conducted at the early‐pregnancy assessment unit at University College London Hospital ...
T. Setty +5 more
wiley +1 more source
Application of transistorized CR oscillator [PDF]
In the experiment of character of Wien Bridge transistorized CR ocillator, we found that the output voltage of the oscillator, immediately after the amplitude of oscillation had built up, changed rapidly with its negative feed back ratio. By this result,
井上 浩, 北川 泰郎, 若林 重興
core +1 more source
ABSTRACT In the post‐pandemic period, intensified energy price fluctuations, supply disruptions, and geopolitical tensions have tested national institutional capacities. This study examines the dynamic interaction between energy risks and government effectiveness using annual data from 25 European Union member states over 2008–2023, employing a Panel ...
Tufan Sarıtaş +3 more
wiley +1 more source

