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An Effect of HTS Wire Configuration on Quench Recovery Time in a Resistive SFCL
Heesun Kim,Ji-Young Lee,Hye-Rim Kim,Seong-Eun Yang,Seung-Duck Yu,Woo-Seok Kim,Ok-Bae Hyun,Junseok Ko,Hankil Yeom IEEE 2013 IEEE transactions on applied superconductivity Vol.23 No.3
<P>We experimentally investigated the correlation between the high-temperature superconducting (HTS) wires configuration in an HTS element and recovery time after quench in a resistive superconducting fault current limiter. The variables of the configuration are horizontal and vertical gap distances between HTS tapes in an element. Eight samples were made with different gap distances and tested. A SUS-stabilized YBCO tape with 4.4 mm width had been used in the experiment. It was cooled by LN2 in a cryostat under the pressure of 1 bar, saturated state. In the short-circuit test, the temperature of the wire's surface was measured. Recovery time of the HTS sample increased with decreasing horizontal and vertical gap distance due to stagnation of bubbles. When the gap distance was larger than a size of a bubble, the effect of gap distance was ignorable. Considering a volume and recovery time, the sample that has narrower gap distance was favorable.</P>
Development and Test of a Cooling System for a 154 kV Superconducting Fault Current Limiter
Kim, Heesun,Han, Young Hee,Yang, Seong-Eun,Yu, Seung-Duck,Park, Byung Jun,Park, Kijun,Yoo, Jaeun,Kim, Hye-Rim,In, Sehwan,Hong, Yong Joo,Yeom, Hankil Korea Electric Power Corporation 2015 KEPCO Journal on electric power and energy Vol.1 No.1
The superconducting fault current limiter (SFCL) is an electric power device that limits the fault current immediately in a power grid. Korea Electric Power Corporation (KEPCO) has been developing a 154 kV, 2 kA SFCL since 2011 to protect power grids from increasing fault current and improve the stability and quality of electric power. This SFCL adopts 2G YBCO wires and operates at 71 K and 5 bars. In this paper, a cooling system for the 154 kV SFCL and its cooling test results are reported. This cooling system uses a Stirling-type cooler to make sub-cooled liquid nitrogen ($LN_2$), which cools the superconductor modules of the SFCL. The $LN_2$ is circulated between the cooler and the cryostat that contains superconductor modules. The $LN_2$ also plays the role of a high voltage insulator between the modules and the cryostat, so the pressure was maintained at 5 bars for high insulation performance. After installation in a test site, the cooling characteristics of the system were tested. In this operation test, some important data were measured such as temperature distribution in $LN_2$, pressure change, performance of the heat exchanger, and cooling capacity of the total system. Consequently, the results indicate that the cooling system operates well as designed.
Cool-down test of cryogenic cooling system for superconducting fault current limiter
Hong, Yong-Ju,In, Sehwan,Yeom, Han-Kil,Kim, Heesun,Kim, Hye-Rim The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.3
A Superconducting Fault Current Limiter is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of high temperature superconductor modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen, the cryogenic cooling system should be designed well with a cryocooler and coolant circulation devices. The pressure of the cryostat for the SFCL should be pressurized to suppress the generation of nitrogen bubbles in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype 154 kV SFCL, which consist of a Stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat for the SFCL module, to verify the design of the cooling system and the electric performance of the SFCL. The normal operation condition of the main cryostat is 71 K and 500 kPa. This paper presents tests results of the overall cooling system.
홍용주(Yong-Ju Hong),인세환(Sehwan In),염한길(Han-Kil Yeom),김희선(Heesun Kim),김혜림(Hye-Rim Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
The Superconducting Fault Current Limiter (SFCL) is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of HTS(High Temperature Superconductor) modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics of HTS modules. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen should be designed well with a cryocooler and circulation devices. The pressure of the cryostat for the SFCL should be pressurized to reduce the generation of nitrogen vapor in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype SFCL, which consist of a 4 kW stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat, to verify the design of the cooling method and the electric performance of the SFCL. The normal operation condition of the SFCL is 71 K and 500 kPa.