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Development of a 13.2 kV/630 A (8.3 MVA) High Temperature Superconducting Fault Current Limiter
Hyoungku Kang,Chanjoo Lee,Kwanwoo Nam,Yong Soo Yoon,Ho-Myung Chang,Tae Kuk Ko,Bok-Yeol Seok IEEE 2008 IEEE transactions on applied superconductivity Vol.18 No.2
<P>This paper deals with fabrication and development of a high temperature superconducting (HTS) fault current limiter (FCL) based on YBCO coated conductor (CC) wire for distribution systems. The capacity of the developed HTS FCL is 8.3 MVA and its rated voltage is 13.2 kV which corresponds to a three-phase power equipment voltage class of 22.9 kV. Tests of the developed prototype HTS FCL were conducted at Korea Electrotechnology Research Institute (KERI) accredited as a testing laboratory by the Korea Laboratory Accreditation Scheme (KOLAS). A short-circuit test and an AC dielectric withstand voltage test for the HTS FCL were conducted under sub-cooled liquid nitrogen (LN<SUB>2</SUB> ) conditions of 3 bar and 65 K. The magnitude of an asymmetric short- circuit current without FCL reached 30 kA<SUB>peak</SUB> in a short-circuit test. The superconducting coil quenched instantaneously after the fault, and the magnitude of the fault current was limited to 3.6 kA<SUB>peak</SUB> within quarter cycle by the developed resistance of the superconducting coil. An AC dielectric withstand voltage test was performed, and the HTS FCL successfully withstood 143 kV for 1 minute. Also, it was found that there was no electrical or mechanical damage on the superconducting coil after the tests.</P>
Kang, Jong O,Lee, Onyou,Mo, Young Kyu,Kim, Junil,Bang, Seungmin,Lee, Hongseok,Lee, Jae-Hun,Jang, Cheolyeong,Kang, Hyoungku The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.3
Recently, the electrical insulation design for electrical apparatuses is important to cope with the tendency of high voltage. The degradation characteristics of a superconducting coil due to an electrical breakdown should be considered to design a high voltage superconducting coil. In this paper, the degradation characteristics of 2G high temperature superconducting (HTS) wires are studied with respect to electrical breakdown tests. To analyze the dependency of the degradation characteristics of 2G HTS wires, the electrical breakdown tests are performed with AC(alternating current) and DC(direct current) voltage. All tests are performed by applying various magnitudes of AC and DC breakdown voltages. To verify the degradation characteristics of 2G HTS wires, the tests are performed with various 2G HTS wires with respect to stabilizer materials. The degradation characteristics of 2G HTS wires, such as Ic(critical current) and index number are measured by performing electrical breakdown tests. It is found that the characteristics such as Ic and index number can be degraded by an electrical breakdown. Moreover, it is concluded that the degradation characteristics of 2G HTS wires are affected by the stabilizer material and applied voltages. The cross-sectional view of 2G HTS wires is observed by using a scanning electron microscope (SEM). As results, it is found that the degradation characteristics of 2G HTS wires are concerned with hardness and electrical conductivity of stabilizer layers.
Dielectric Tests of Superconducting Coils for Development of High Voltage Superconducting Machines
Hyoungku Kang,Chanjoo Lee,Seong Eun Yang,Tae Kuk Ko,Bok-Yeol Seok Institute of Electrical and Electronics Engineers 2007 IEEE transactions on applied superconductivity Vol.17 No.2
<P>This paper deals with the dielectric breakdown characteristics of superconducting coils for development of high voltage superconducting machines such as superconducting fault current limiter (SFCL) and superconducting transformer. The electrode systems are simulated to investigate the dielectric breakdown characteristics of solenoid and pancake coil. Dielectric breakdown tests are carried out on several basic electrode systems: needle-plane, sphere-plane, rod-plane, cutting bar-plane, and rounded bar-plane electrodes. These results could be applied to design the high voltage superconducting magnet system. Dielectric tests of turn-turn and layer-layer in solenoid coil are performed according to the groove depth, pitch length, and the distance between two layers. Dielectric tests of turn-turn with various insulation materials are also performed in pancake coil. In addition, the deterioration of high temperature superconducting (HTS) tapes and coils due to the electrical breakdown are investigated experimentally. It is proven that the HTS tape and coil could be robust to the electrical breakdown by the laminated metal.</P>
Hyoungku Kang,Jin Bae Na,Yoon Do Chung,Tae Kuk Ko IEEE 2011 IEEE transactions on applied superconductivity Vol.21 No.3
<P>It has been widely established that gaseous helium (GHe) can be injected into a sub-cooled liquid nitrogen (LN<SUB>2</SUB>) cooling system to control the pressure of such a system because of its non-condensing characteristics. A sub-cooled LN<SUB>2</SUB> cooling system is known as one of the most promising method to develop a large scale superconducting machine. Unfortunately, the electrical breakdown voltage of GHe is not good enough for developing a high voltage electric machine such as a superconducting fault current limiter (SFCL). To enhance the dielectric characteristics of current leads placed in GHe, the use of solid barriers is regarded as an efficient method. In this study, experiments are made on the dielectric characteristics of GHe and the barrier effects and results are analyzed in order to improve the dielectric performance of a high voltage SFCL using a sub-cooled LN<SUB>2</SUB> cooling system. The dielectric experiments of the energized sphere and the grounded plane in GHe are examined according to various pressures with a solid insulating barrier. The dielectric experiments are performed by installing barriers made of glass fiber reinforced plastics (GFRP) between two electrodes and the electrical breakdown voltage according to the pressure of GHe and the position of a barrier is observed. As a result, it is found that the position of a solid barrier and the pressure of GHe are important in enhancing the dielectric characteristics of a sphere-to-plane electrode system with quasi-uniform field.</P>
Conceptual Design of the Termination Part for a Transmission Superconducting Fault Current Limiter
Kang Hyoungku,Bella Eliana,Ratri Dewimaruto,O Seunghee,Park Younghun 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.1
One of the critical components for high-voltage superconducting apparatuses, such as superconducting fault current limiters (SFCLs), superconducting cables, and superconducting transformers, is the termination part. The termination part supplies power to superconducting coils without insulating diffi culties, and it is designed considering several conditions, such as temperature and pressure. Generally, the termination part for a high-voltage SFCL is divided by a spacer into SF 6 and gaseous nitrogen (GN 2 ) parts. To design an electrically reliable termination part, dielectric experiments on the sparkover and creepage discharge along the surface of a solid material in GN 2 are performed, and the dielectric characteristics of the electric fi eld intensity at the sparkover of GN 2 and creepage discharge along the surface of a solid material in GN 2 are expressed as an empirical formulae in terms of the fi eld utilization factor ( ξ ). As a result, the electrical and mechanical design of the termination part including a spacer with respect to the material and shape is conducted. Finally, a conceptual design of the termination part for a 220 kV high voltage SFCL is proposed. The experimental results and design method proposed in this paper were applied to the design of the world’s largest commercial 220 kV/300MVA SFCL installed and operating in Moscow
Degradation Characteristics of Superconducting Wires With Respect to Electrical Breakdown Tests
Kang, Jong O.,Onyou Lee,Seungmin Bang,Junil Kim,Hongseok Lee,Jonggi Hong,Seokho Nam,Tae Kuk Ko,Yoon Do Chung,Hyoungku Kang Institute of Electrical and Electronics Engineers 2015 IEEE transactions on applied superconductivity Vol.25 No.3
<P>The electrical insulation design for a superconducting system is important when developing a high-voltage superconducting apparatus as a substitute for a conventional one. In this paper, the degradation characteristics of 2G high temperature superconducting (HTS) wires, with respect to electrical breakdown tests, were studied. It was found that the superconducting materials in 2G HTS wires can be damaged in electrical breakdown, and the damaged structure of 2G HTS wires results in the degradation of the Ic and index number. As a result, it was found that the degradation characteristics of the 2G HTS wires were affected by the stabilizer material and applied breakdown voltage. Thus, the hardness and electrical conductivity of a stabilizer material can be considered as design parameters in developing a high-voltage superconducting coil. Finally, the cross-sectional views of 2G HTS wires were presented using a scanning electron microscope.</P>
Hyoungku Kang,Tae Kuk Ko IEEE 2011 IEEE transactions on applied superconductivity Vol.21 No.3
<P>A sub-cooled liquid nitrogen (LN<SUB>2</SUB>) cooling system is known as an appropriate method for developing a high voltage superconducting fault current limiter (SFCL). The pressure of a sub-cooled LN<SUB>2</SUB> cooling system should be controlled by injecting non-condensable gas such as gaseous helium (GHe) and gaseous neon (GNe) into the cryostat. Therefore, the electrical breakdown voltage of current leads is directly influenced by an injected gaseous medium. In this study, electrical insulation experiments on GHe and GNe are conducted and the results are compared with each other. Also, the dielectric characteristics of GHe and GNe are analyzed by using field utilization factors. It is found that the dielectric characteristics of GHe are superior to those of GNe under the same conditions. The experimental results are applicable for designing the current leads of a high voltage superconducting fault current limiter.</P>
Degradation characteristics of 2G HTS tapes with respect to an electrical breakdown
Kang, Jong O,Lee, Onyou,Mo, Young Kyu,Kim, Junil,Bang, Seungmin,Lee, Hongseok,Lee, Jae-Hun,Jang, Cheolyeong,Kang, Hyoungku The Korea Institute of Applied Superconductivity a 2015 한국초전도저온공학회논문지 Vol.17 No.1
The electrical insulation design for a superconducting coil system is important for developing high voltage superconducting apparatuses. Also, the degraded characteristics of superconducting tapes due to an electrical breakdown should be considered for superconducting coils design. In this study, the degradation characteristics of 2G high temperature superconducting (HTS) tapes were studied with respect to electrical breakdown tests. The degradation tests of 2G HTS tapes were performed with various stabilizer materials. The degradation characteristics of 2G HTS tapes such as critical current(Ic) and index number were observed by performing electrical breakdown tests. It was found that the characteristics such as Ic and index number can be degraded by an electrical breakdown. Moreover, it was concluded that the degradation characteristics of 2G HTS tapes were affected by a stabilizer material and applied breakdown voltage. The cross sectional view of 2G HTS tapes was observed by using a scanning electron microscope (SEM). As results, it is found that the degradation characteristics of 2G HTS tapes are concerned with hardness and electrical resistivity of stabilizer layers.