Design Of Resistive Superconducting Fault Current Limiting Element And Study On AC Loss Characteristics

With the development of superconducting tape technology,superconducting technology provides great help for the problem of short-circuit faults in power grids.When the SFCL(Superconducing Fault Current Limiter)is used in the power grid,the short-circuit current is quickly limited to the critical current,and the resulting AC loss is small.Therefore,the application of superconducting fault current limiter brings huge economic benefits.However,the AC loss generated when the superconducting fault current limiter is used in the power grid leads to a decrease in the overall efficiency of the power equipment,an increase in operating costs,and an increase in the total volume.Therefore,we need to study the AC loss characteristics of the important current-limiting component of the resistive SFCL-the superconducting fault current-limiting component,and find a design scheme to minimize the AC loss.First of all,three different types of large-capacity superconducting fault current-limiting elements(double-line superconducting current-limiting element,single-line superconducting current-limiting element and cylindrical superconducting current-limiting element)are fabricated based on Bi-2212 bulk superconductor material through Nexans.The measurement method measures the AC loss.Calculate the AC loss generated by these three large-capacity superconducting fault current limiters in the 22.9k V/25 MVA superconducting fault current limiter,and find the current limiting element that achieves the best results in terms of AC loss and total volume..Secondly,based on Bi-2223 superconducting tape,three solenoids with different structures(monofilar solenoid,ETE bifilar solenoid and FTF bifilar solenoid)are made,study the influence of cylindrical structure diameter,gap,strip position and current direction on its AC loss,and find the solenoid model with the least loss.Finally,in order to reduce the total volume of the current-limiting element,a FTF bifilar solenoid(reverse current model)is applied to the pancake coil,pancake coils with different spacer thicknesses are made,and measure the AC loss to find the thickness of the pancake coil spacer that achieves the best effect in terms of AC loss and recovery time..The experimental results show that,AC loss results of the three large-capacity superconducting fault current-limiting elements are that the cylindrical SFCL element has the smallest loss,and the single-line SFCL element has the smallest total volume.Therefore,in the design of the large-capacity superconducting current-limiting element,proper combination of the cylindrical SFCL element and the single-line SFCL element can reduce the loss and appropriately reduce the total volume.The AC loss results of three solenoids and pancake coils show that the use of FTF bifilar solenoid(reverse current model)to reduce the loss,the selection of pancake coils to reduce the total volume,when choosing a pancake coil with a thickness of 2mm spacer,the AC loss and recovery time achieve the best results.