Current Protection Characteristics And Application Research Of High Temperature Superconducting Thin Film Device

High temperature superconducting thin film current limiters(HTS-TFCLs)are regareded as one of the most ideal current limiting devices with the advantages of lower losses,shorter response time,less effect on the system,etc.Their research and application are the important branch of exploration and application of the HTS electric power equipment.Currently,the research of HTS-TFCLs is mainly focused on power system application,and their function is only the single current limiting function.If we can explore the new application fields of HTSTFCL and other electromagnetic functions of HTS thin film device,then,this work will be also meaningful to expand the application fields and electromagnetic functions of traditional superconducting thin film devices,furtherly.Due to the unique structural characteristics of the HTS thin film(eapecially the double sided HTS thin film),the different unit structure can be designed flexibly in one thin film,then,the different functions(such as current limiting,transformer,current compensation,etc.)can also be integrated in the thin film.Accordingly,it has important and far-reaching significance for realizing the miniaturization,multi-function integration and economic index of the HTS devices.Based on the mentioned considerations,this thesis proposes and researches the current protection characteristics of HTS thin film device and its application in SMES-battery hybrid energy storage system(HESS),power electronics planar transformer and current compensation fields,by means of theoretical analysis,simulation calculation,and experimental test.The principal work of this thesis can be summarized as follows:(1)The applied superconducting technology is introduced firstly in this thesis,including the introduction of superconducting materials and superconducting devices.After that,this thesis summarizes the development direction and research status of the HTS-TFCL.The major research content and the arrangement of the following chapters are described at the end.(2)The basic theory and design basis of the HTS-thin film device are introduced.The critical parameters analysis of superconductor,the explanation of superconductivity,the current protection principle analysis of HTS thin film and the fabrication and process introduction of HTS thin film are included in this section.(3)The new application field research of single piece HTS-TFCL in SMES-battery HESS is proposed and carried out by the experimental test in this thesis.The fabrication and design of HTS thin film device,the construction of experimental platform,and the analysis of the experimental results are included in this part.It can be found from the test results that the HTSTFCL can limit the fault current in the battery circuit as expected,and the whole system can operate normally by the protection of the HTS-TFCL.(4)The current limiting characteristic and application of HTS thin film transformer(HTSTFT)are proposed and analyzed in this thesis.Based on the double sided HTS thin film,we propose the HTS-TFT and analyze its operation principle.In this part of the work,four different types of HTS material based TFT and Cu material based TFT are designed and fabricated,besides,a group of comparative experiment was also carried in our laboratory to measure and analyze their operating parameters.It can be found from the experimental results that the HTSTFT has the lower winding resistance,the higher winding self inductance,the higher quality factor and the better operating efficiency than that of the Cu-TFT.Based on this work,the current limiting behavior of HTS-TFT is also carried out by the theoretical analysis and experimental verification.It can be found form the experimental results that the HTS-TFT has the better voltage conversion performance than the Cu-TFT,furthermore,it can also limit the fault current in the circuit effectively.From the research work in this part,the proposed HTS-TFT in this thesis can work as the roles of transformer and current limiter,it has the wide application prospects in power electronics system and wireless power transfer system,to provide the current limiting function and better operating performance.(5)In this thesis,the HTS thin film inductor is proposed and designed,then,its current compensation characteristic and application field is also discussed.Through the theoretical analysis and experimental verification,we can find that the proposed HTS thin film inductor can compensate the current vacancy in the system effectively.In other word,the HTS thin film current compensation characteristic research is an expansion of the traditional “current protection” concept,it can be integrated into superconducting systems to compensate the current vacancy,and enrich the application of HTS thin film current protection characteristics.The research work and related conclusions in this thesis can offer the beneficial development ideas and technical approaches for making full use of the characteristics of HTS thin film devices,expanding the multi-function integration and the new application fields of thin film based electromagnetic device.