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在高压直流输电系统中,高温超导直流电缆具有高功率密度特点被广泛使用.然而,电网中的直流以及开关器件和环境产生的交流纹波,都造成交流损耗.由第二代(2G)带材组成的五边形单层导体在交流和直流作用下,进行了交流损耗特性研究.该次实验从电压引线高度,接触位置和频率等不同角度测量分析了五边形单层导体的交流损耗.结果表明,尽管电... 相似文献
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《低温与超导》2017,(8)
为了研究在HTS电缆导体层和屏蔽层的交流损耗,我们准备了5米长22.9KV/50MVA的BSCCO HTS电缆,在导体层和屏蔽层都附上电压引线,并在几毫秒到几分钟内给导体层和屏蔽层通大小相等、方向相反的电流,以测试通电时间对于交流损耗的影响。实验表明,从屏蔽层引线上测出的交流损耗和通电时间无关,但从导体层引线上测量出的损耗值却很大程度依赖于通电时间,这是因为导体层周围很厚的绝缘层导致热传输很难到达周围的冷却剂。当通电周期变长时,导体层的温度升高,通过导体引线测出的交流损耗增加,尤其在通电若干周期后,导体层引线测出的损耗值比在屏蔽层引线测出的损耗值大1.5倍。 相似文献
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高温超导电缆由于其较低的交流损耗和高传输电流密度的特点,随着地下电缆容量的不断提升在人口密集城区具有潜在的应用前景.交流损耗是是高温超导电缆的一个重要参数,对其运行稳定性和运行成本具有重要影响.为了研究高温超导电缆的交流损耗,用YBCO涂层导体绕制了一根长1.5米的冷绝缘电缆导体,此电缆导体包括一层导体层,绝缘层,和一层屏蔽层.基于Bean临界态模型对电缆导体的交流损耗进行了分析并在工频77K条件下用电测法对交流损耗进行了测量.结果在计算值与试验结果之间有难以置信的差异.本文基于电缆导体两端的几何与机械结构对产生这种现象的原因进行了定性分析. 相似文献
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三相同轴超导电缆具有节约高温超导带材用量、减小电缆体积和降低制冷功率等优点,是目前配电网应用的热点。受超导电缆短路热稳定性、载流能力及交流损耗的影响,三相同轴超导电缆结构设计难度较大。本文通过研究铜稳定层截面、超导层带材排布方式来设计三相同轴超导电缆,获得超导电缆的载流能力及交流损耗特性。建立故障电流下超导电缆热传导模型,提出了三相同轴冷绝缘高温超导电缆结构设计流程,并以10 kV/2.3 kA的高温超导电缆为例进行了优化设计。结果表明,在故障电流下,合理设计结构可有效减小电缆产生的焦耳热,增大超导电缆对故障电流的承受能力。 相似文献
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在无限长堆叠带材模型的基础上对高温超导电流引线的交流损耗建立了新的计算模型,即正十二边形骨架计算模型.由于正十二边形对称性,通过建立合适的坐标系,对坐标进行旋转即可求出每堆带材处的磁场.使用matlab编程计算并得出一系列电流下的交流损耗值,通过将所得数据绘成图形,比较了不同电流下穿透深度及交流损耗的大小.然后搭建实验平台,测量了不同频率下电流引线的交流损耗,并将理论与实验对比,得到较好的一致性. 相似文献
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讨论了银道面内的引力场强分布和太阳在银河系中所受引力与到银心距离r的关系,指出引力场强g并不是与r的平方成反比,这是由于银河系的大小和形状不能忽略造成的.强调了万有引力定律的适用条件. 相似文献
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R. A. Vadov 《Acoustical Physics》2005,51(3):265-270
The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized. 相似文献
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J. Šlechta 《Czechoslovak Journal of Physics》1968,18(10):1299-1308
On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given. 相似文献
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The investigation was made of the dependence of the intensity of Tl, Ga, Mo, Mg, Mn, Sn, Bi, Ni, Zn, Pt and Au spectral lines and the plasma parameters (temperature T, electron concentration ne, degree of 6 ionnization α) from concentration of lithium additive. 相似文献
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We consider associated production of squarks and gluinos with the lightest supersymmetric particle (LSP), or states nearly degenerate in mass with it. Though sub-dominant to pair production of color SU(3)-charged superpartners, these processes are directly sensitive to the wavefunction composition of the lightest neutralinos. Exploiting event-shape variables - including some introduced here for the first time - we are able to identify the composition of the LSP by selecting events involving a single high-pT jet recoiling against missing transverse energy. We illustrate the proposed technique on a set of benchmark cases and propose methods for applying these results in more realistic experimental environments. 相似文献
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SJ Rose 《Contemporary Physics》2013,54(2):109-121
In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required. 相似文献
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Technical Physics - The object of this work is the apokamp—a new type of plasma jet, which is formed from a bright offshoot emerging at the bending point of a channel of a high-voltage... 相似文献