AC Loss of a Conductor with Multilayer, Spiral Structure for High-Tc Superconducting Power Cable
AC Loss of a Conductor with Multilayer, Spiral Structure for High-Tc Superconducting Power Cable
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高温超导电力电缆多层螺旋结构导体的交流损耗
DOI：
10.2221/jcsj.33.114
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
T. Hara
中科院分区：
文献类型：
--
作者：
H. Noji;T. Shibata;S. Isojima;J. Fujikami;Ken;H. Ishii;T. Hara
本文应用电路模型计算了四层夹层绝缘高温超导电力电缆导体的交流损耗。该模型由每一层的阻抗组成，阻抗由电阻部分和感应部分组成。利用多芯Bi2223丝的电阻电压随传输电流的近似值，计算了各层的电阻。每一层的电感被认为是两种类型之一：一种取决于沿导体轴向的自场，另一种取决于沿导体圆周方向的自场。从电路模型的计算结果可以看出，交流损耗随导体传输电流的变化规律与实验值基本一致，该模型较好地解释了导体的电磁特性。在计算导体的电流分布时，还发现当传输电流低于导体的IC值时，会发生漂移，即几乎所有的电流都通过外层。在每一层的阻抗中，取决于沿导体圆周方向定向的自场的电感占主导地位。此值随层半径的增加而减小。因此，外层的阻抗降低，因此，流经外层的传输电流增加。漂移增加了导体的交流损耗。为了控制各层之间阻抗的不平衡，必须增加电感，该电感取决于沿导体轴向定向的电感，该自磁场在外层增加。这个电感值随着构成导体的高T_c超导导线的螺旋节距长度的减小而增加。对导线交流损耗随螺距长度变化的计算结果表明，当螺距长度小于0.5m时，交流损耗显著降低。
We applied an electric-circuit model for the calculation of AC loss of a high-Tc superconducting power-cable conductor with four layers and interlayer insulation. This model is composed of the impedance of each layer, which has a resistive part and an inductive part. The resistance of each layer was calculated using the approximate value of the resistive voltage as a function of transport current of multifilamentary Bi-2223 wire. The inductance of each layer was considered to be one of two kinds: one depending on the self-field directed along the axis of the conductor, and one depending on the self-field directed along the circumferential direction of the conductor. From the results of the calculation using the electric-circuit model, it was found that both the calculated and experimental values of AC loss, as a function of transport current of the conductor, are nearly equal, and that the model explains the electromagnetic property of the conductor well. In calculating the current distribution of the conductor, it was also found that drift, in which almost all the current passes through the outer layer, occurs when the transport current is lower than the Ic-value of the conductor. The inductance that depends on the self-field directed along the circumferential direction of the conductor is dominant in the impedance of each layer. This value decreases with the increase in layer radius. Therefore, the impedance of the outer layer is decreased, and hence, the transport current passing through the outer layer is increased. The drift increases the AC loss of the conductor. In order to control the lack of balance of impedance amongst the layers, the inductance that depends on the self-field directed along the axial direction of the conductor, which is increased in the outer layer, must be increased. This value of inductance increases as the length of the spiral pitch of the high-Tc superconducting wires which make up the conductor decreases. The results of calculations of conductor AC loss as a function of the length of the spiral pitch of the wire showed that AC loss is markedly decreased when the length of the spiral pitch is less than 0.5m.