Detection Methods Of Superconducting Electromagnetic Properties In Application Of High Temperature Superconducting Power

Development of high temperature superconducting tape over the past 20 years has played an important promoting role in the extensive application of superconducting technology.High temperature superconducting tape has complicated electromagnetic properties,and parameters such as critical current and AC loss are related to the performance of superconducting magnet.Therefore,electromagnetic properties of tapes should be accurately understood when designing the superconducting power device.Performance of superconducting coil should be tested during manufacturing process;meanwhile,monitoring and protection technology is required during operation of superconducting device.However,all these steps are associated with technical difficulties.Life evaluation of superconducting power device is one of the problems to be solved before the extensive application of superconducting power device in power system.Currently,research examining performance degradation of superconducting wire under the action of bearing multiple overcurrent shocks and repeated stress is lacking.This paper proposed to carry out research on the multiple overcurrent shocks properties of high temperature superconducting tape and drew relevant conclusions.Research in this paper would establish foundation for evaluating the attenuation characteristics and life evaluation theoretical system of superconducting power device after long-term operation.Superconducting coil has great inductance,which will produce great inductive voltage in the time of current fluctuation.Inductive voltage is larger than voltage of resistance and increases the complexity of detection circuit in alternating current loss measurement,which leads to difficulty in extracting quench voltage in quench detection.This paper had designed the analogue integrated circuit-based inductive voltage compensation scheme aiming at the inductive voltage compensation during alternating current loss measurement of superconducting coil.Such scheme possessed advantages in terms of compensation range and degree of automation,which could also enhance the measuring efficiency of alternating current loss measurement of superconducting coil.Analog circuit-based inductive voltage compensation scheme was a new thinking,which was promising to be applied in high temperature superconducting alternating current loss measurement,quench detection and real-time loss measurement after design improvement.In some experiments,superconducting coil operates under the state of alternating current flow passage.However,determination of safe working current in the event of alternating current flow passage of superconducting coil is a problem due to the lack of alternating current quench criterion.Furthermore,quench state of superconducting coil in alternating current flow passage remains unknown as a result of lack of technological means.This paper had carried out experimental research on quench detection method of quench coil under alternating current flow passage state.Quench detection method that could be applied in high temperature coil flow passage was designed,which guaranteed the safety of superconducting coil in alternating current flow passage during experimental research and laid foundation for research on alternating current quench criterion.Quench detection based on electrical method is subject to noise interference during quench detection.Quench signal interfered by noise will give rise to quench misjudgment,which thereby leads to quench protection malfunction,affecting the stable operation of superconducting power device.Based on the problem that electrical method-based quench detection signal was subject to noise interference,this paper had proposed the solution of adopting wavelet analysis theory that was honored as mathematical microscope to filter the quench detection signal.Besides,filtering algorithm based on wavelet analysis theory was successfully transplanted into the embedded hardware platform.Applying such technique in quench detection of superconducting magnet contributed to inhibiting the influence of noise and lowering the probability of quench protection malfunction resulted from voltage fluctuation,which was of great significance to guarantee the long-term stable operation of superconducting power device.State of superconducting magnet as well as all auxiliary equipments should be monitored during on-line operation of superconducting power device,so as to guarantee that all devices operate under normal state.Treating quench detection as the only state monitoring means of superconducting magnet can hardly satisfy the demands,while structure should be taken into consideration when integrating multiple detection methods.Fault messages obtained through detecting various physical quantity analyses should be defined logically and classified in level.Only through designing different protection strategies can one cope with the occurrence of faults of various types and under different emergency conditions.Superconducting magnet state monitoring and protection system was designed in this paper aiming at the problem of safe and stable operation of superconducting power device.Optimal design of structure had solved the problem of hardware integration for multiple quantities of state.Fault messages obtained through detecting various physical quantity analyses were defined logically and classified in level,and the protection strategy of fault classification was formulated.Finally,the paper summarizes the significance of the research work,puts forward the innovation points,and offers the following steps of the research plan.