Superconducting Materials, Power Apparatus and Systems

（1）超导体电磁现象的理论和数值分析：在脉冲磁场磁化过程中，随着外加脉冲磁场的增加，高温超导体（HTS）的俘获磁通出现一个峰值。考虑了局部发热降低屏蔽电流密度。在脉冲磁场磁化分析中，采用磁通流-蠕变模型，考虑了屏蔽电流对动态磁场的非线性依赖关系。在分析中还评估了流动阻力。由于HTS的导热率小，所以在磁化期间几乎没有热扩散到周围的液体N2。我们可以看到，在边缘区域的局部发热降低了屏蔽电流密度和捕获场。磁体可以悬浮在块状HTS上。另一方面，有一个玩具带有磁悬浮旋转陀螺。从恩肖定理出发，讨论了陀螺和高温超导体的悬浮问题。Horizont ...更多信息 通过涡流分析评价陀螺的稳定性，通过磁通钉扎评价高温超导陀螺的稳定性。临界态模型和冻结场模型都被应用于高温超导体的分析中，它们对高温超导体的评估是有用的。（2）超导悬浮系统中超导导线稳定性的改善和控制方法：提出了一种由低温超导体和高温超导体组成的混合导体。建立了导体暂态稳定性的仿真模型，分析了在低温超导体中加入高温超导体后，稳定电流的增加。还提出了一种抑制磁悬浮体中由于某些瞬态扰动而产生的振动的主动控制方法，并且该方法被证明对于抑制振动是有效的。（3）超导故障限流器：提出了一种磁屏蔽型有源触发线圈超导故障限流器（MSFCL）。分析表明，该方法可显著改善限流性能。研制了由Bi_（2223）块材、YBCO薄膜、Nb_（3Sn）丝等组成磁屏蔽体的MSFCL。对它们的限流特性、超导恢复特性等进行了研究，并建立了设计超导限流器的数据库。还提出了MSFCL的“多功能”和/或“免维护”的概念，并显示了具有这种概念的概念。（4）储能系统：储能系统因其快速响应和灵活性而被认为是未来电力系统的关键技术。许多研究机构正在研究和开发几种新型的储能系统。考虑到电力系统中小型储能系统的分散性，研究了分散储能系统的电压无功控制特性。此外，本研究讨论了分散储能系统的几个特点，考虑真实的和无功功率控制在一天。（5）系统控制：利用最优控制系统的渐近特性，提出了一种同时设计控制系统和被控对象的新方法。最优控制系统在渐近情形下逼近解耦控制系统。在解耦控制系统的设计中，参考信号与被控量之间的时间常数与被控对象参数的选取无关。由于在响应速度一定的情况下，被控对象的参数可以仅通过控制输入的大小进行比较，因此这些特性有助于简化过程，减少同时设计中的试验和误差。此外，该方法被应用于感应电动机驱动器的矢量控制系统，其中参考信号和/或干扰的预览信息可以被用来改善控制系统的性能。少

(1)Theoretical and numerical analysis of electromagnetic phenomena of superconductor : In pulsed field magnetization of a melt processed bulk high Tc superconductor (HTS), there exists a peak of the trapped flux as applied pulsed field was increased. Local heat generation is considered reducing the shielding current density. Nonlinear dependence of shielding current on dynamic magnetic field is considered by using the flux flow - creep model in the analysis of the pulsed field magnetization. Flow resistivity is also evaluated in the analysis. Since heat conductivity of the HTS is small, little heat diffuses to the surrounding liquid N2 during the magnetization. We can see that local heat generation at the edge region reduces the shielding current density and the trapped field.A magnet can be levitated on a bulk HTS.On the other hand, there is a toy with a magnetically levitated spinning top. Both levitations with spinning top and with HTS are discussed from Earnshaw's theorem. Horizont … More al stability of the spinning top is evaluate from eddy current analysis, and that of HTS is evaluate from pinning of fluxoid. Both critical state model and frozen field mode are applied to the analysis of the HTS, and they are useful for the evaluation.(2)Improvement on Stability in Superconducting Wire and Control Method for Superconducting Levitation System : A hybrid conductor consisting of both low and high temperature superconductors was proposed. A simukation model on the transient stabilities in the conductor was developed and the stabilized current was analyzed and shown to be fairly increased by adding a high temperature superconductor to a low temperature one. An active control method suppressing a vibration in the magnetically levitated body due to some transient perturbation was also proposed and was shown to be effective for suppressing a vibration.(3)Superconducting Fault Current Limiter : A magnetic shield type superconducting fault current limiter(named MSFCL) with active trigger coil was proposed. The current limiting performances were analyzed and shown to be considerably improved by its method. The MSFCL's with the magnetic shielding bodies composed with Bi2223 bulk, YBCO thin film, Nb3Sn wire etc. were also developed. Their current limiting characteristics, superconducting recovery ones and so on were investigated and a data base for designing a MSFCL was developed. The concepts of "multifunction" and / or "maintenance free" for the MSFCL was also proposed and the one with such a concept was shown.(4)Energy Storage System : The energy storage systems are considered to be a dispensable technology for future power systems because of their fast response and flexibility. Several new types of energy storage systems are researched and developed in many institutes. Considering that small-scale energy storage systems will be installed dispersively in power system, this study investigates the characteristics of voltage and reactive power control using dispersed energy storage systems. Further, this study discusses several characteristics of dispersed energy storage systems considering real and reactive power control during a day.(5)System Control : A new method is developed on simultaneous design of a control system and a controlled object utilizing an asymptotic characteristics of optimal control systems. The optimal control system approaches the decoupled control system in asymptotic situation. In the design of the decoupled control system, the time constant between the reference signal and the controlled variable is independent on the selection of the parameters of the controlled object. The characteristics are helpful for simplifying the procedure and reducing trial and error in the simultaneous design because the parameters of the controlled object can be compared by only the magnitude of the control input while the response speed is fixed. Further, the method is applied to the vector control system for an induction motor drive where the preview information of the reference signal and/or disturbance can be utilized to improve the control system performance. Less