Experimental Research On AC Loss Of High Temperature Superconducting Coil

When HTS power equipment runs on AC lines,such as superconducting fault current limiter,superconducting transformer,etc.,their components will produce AC losses.AC loss will increase the power loss of HTS power equipment,reduce the operating efficiency,increase the workload and operating cost of the refrigeration system.Therefore,studying AC loss of the superconducting coil and analyzing its variation with the transmission current are of great significance for the development of HTS power equipment.In this thesis,the AC loss characteristics of high-temperature superconducting coil were mainly studied by experimental measurements.Firstly,the fabrication process of a non-inductive superconducting coil was presented.The influence of different insulation methods on the critical current attenuation of the superconducting tapes was studied.Based on the Solidworks software,a runway-type skeleton of the non-inductive superconducting coil was designed and the winding method of the solenoid coil was given.A calculation method was proposed which combined the Norris model with the characteristics of the superconducting coil.A critical current test platform was built to measure the critical current of the superconducting coil.Moreover,an experimental method for measuring AC loss of the superconducting coil by weight measured was proposed.The measurement principle and calculation formulas of the method were introduced.The design and optimization process of each component in the measurement device was described in detail.The three measurement steps of this method were introduced,and AC loss of the superconducting coil under the current of different values and frequencies was measured in this way.Based on the measurement results,the characteristics of AC loss with the transmission current were analyzed.To verify the effectiveness of the proposed weighing method,the lock-in amplifier method was used to the measure AC loss of the superconducting coil.The measurement principle and process were introduced,and the results measured by the lock-in method were given.A comparative experiment between the lock-in amplifier method and the weighing method was designed.By comparing the measurement results of these two methods under the same current conditions,the effectiveness and reliability of the weighing method was verified.The characteristics of these two methods in measuring AC loss of the superconducting coil were also analyzed.