In this paper, through AC and DC overcurrent tests on second generation high temperature superconducting tape (2G HTS tape), we respectively summarize the typical types of quenching resistance and corresponding quenching degree, in which there are three types under AC overcurrent and two types under DC overcurrent. According to experimental results, a rule was found that, when 2G HTS tape quenches to normal state, the relationship between quenching resistance and joule heat generated from 2G HTS tape presents a fixed trend line, and the influence of liquid nitrogen can be ignored. Then, the characteristics and rules of quenching resistance found in experiments are well explained and confirmed by a detailed 3D finite element model of 2G HTS tape including electromagnetic field and thermal field. Finally, based on above works, our group proposes a new equivalent method to estimate the quenching resistance, where the results of AC and DC overcurrent experiments can be equivalent to each other within a certain range. Compared with FEM, the method has the following advantages: (i) The method is simple and easy to implement. (ii) This method combines precision and computational efficiency. (iii) With superconducting tape quenching to normal state, this method presents a good consistency with experimental results.

AbstractWith regard to the state-of-the-art technologies in the fields of applied superconductivity and electromagnetic devices, research and development highlights are presented. The recent progress and achievement described with principle and technical details include mainly i) applied superconducting materials; ii) superconducting magnets and their applications such as in ITER and Tokamaks; iii) high Tc superconducting (HTS) magnetic levitation and applications; iv) HTS smart grids; v) superconducting and electromagnetic material modelling and characteristics; vi) advanced electromagnetic devices. The applied superconductivity technology and availability are especially focused and verified with the trend of its development prospection.

With the rapid development of the integrated power system (IPS) on shipboard, the medium voltage DC (MVDC) power distribution system has received widely attention. At present, one of the bottlenecks restricting the development of MVDC IPS for ships is the occurrence of short circuit faults. Short circuit faults not only cause extensive damage to the line hardware, but also cause a lot of losses. Therefore, how to protect system from high-amplitude short circuit fault current has become a hot research topic. In order to ensure that the MVDC IPS of the ship can still operate safely in the event of typical faults, a flux-coupling-type superconducting fault current limiter (SFCL) is applied to shipboard MVDC IPS under two typical short circuit faults. In this paper, a flux-coupling-type SFCL is conceptual and electromagnetic designed, with working principle analyzed and mathematical model established. Two typical types of short-circuit fault are selected in the shipboard MVDC IPS, and the flux-coupling-type SFCL is installed at different positions on two fault short platforms to evaluate its performance. The results show that the flux-coupling-type SFCL has effective current limiting performance on protection of shipboard MVDC IPS.

High-temperature superconducting (HTS) cables have significant advantages in large-capacity and long-distance transmission. In order to analyze the operation characteristics of HTS cables in AC power system, this paper develops a numerical model to research its electric and thermal properties in transient process of power system. Different from the model built by FEM method in COMSOL, this model is built in MATLAB/SIMULINK for faster calculation and simpler model-ing process. Besides, it is compatible with the power system simulation. Based on the structure of HTS cables, the model is built by an equivalent circuit and an electrical-analog method, to study the electric and transient thermal properties. The author tested the model by comparing it with a model built in COMSOL, to verify the effectiveness and advantages. The simulation result illustrates that, the proposed model helps analyze the electric and thermal property of cables during transient process in power system quickly and efficiently.