Study on High Temperature Superconducting Power Device Due to Dynamic Control of Magnetic Shield Functions

从动态控制的角度研究了高温超导故障限流器和超导电力装置的磁屏蔽功能，在磁屏蔽型超导故障限流器的研究中，一种主动控制方法，其中用于控制的励磁绕组以环形方式缠绕在超导屏蔽管上，并且通过施加交流磁场的频率约为几千赫的一个已提出。研制了具有这种主动控制线圈的故障电流限制器，并对其各种特性进行了实验和计算机模拟研究，结果表明，施加频率在几kHz左右的交流磁场后，磁通流动电阻率将大大增加，相应地，限流阻抗也将变得相当大。这一事实表明，虽然磁通流电阻率被认为是由磁场和/或温度控制到目前为止，它也将取决于交流磁场的频率的大小。磁通流阻率受交流磁场频率影响的原因尚不清楚，但这一现象对于改善故障电流限制器的性能是非常有用的。对于超导电力装置，利用由薄膜超导圆盘和闭合回路铁芯组成的装置，研究了铁芯中磁通的动态行为。阐明了铁芯中的磁通量将由薄膜的超导到正常导电的转变来控制。

The high Tc superconducting fault current limiter and the superconducting power device were studied from a view point of dynamic control in the magnetic shielding functions.In the research on the magnetic shield type superconducting fault current limiter, an active control method in which the field winding for control is wound on the superconducting shield tube in a toroidal fashion and the superconducting properties will be controlled dynamically by applying the ac magnetic field of frequencies of around a few kHz to the one has been proposed. The fault corrent limiters with such an active control coil were fabricated and the various characteristics were studied experimentally and by computer simulation.It was made clear that the flux flow resistivity would be considerably increased by applying the ac magnetic fields of frequencies of around a few kHz and accordingly the current limiting impedance would become fairly large as compared with the case without an active control. This fact indicates that although the flux flow resistivity was thought to be controlled only by magnetic field and/or temperature so far, it will also depend on the magnitude of the frequency of ac magnetic field. The reason why the flux flow resistivity will be affected by the frequency of ac field is not clarified yet, but the phenomenon will be very useful for the improvement in performances of the fault corrent limiters.As for the superconducting power devices, the dynamic behaviors of magnetic flux in the iron core were investigated by using the device consisted of the thin film superconducting discs and the closed circuit iron core. It was clarified that the magnetic flux in the iron core would be controlled by the superconducting to normal conducting transition of the thin film.