[국내논문]상용변압기와 결합된 초전도체 및 상전도체 한류기의 고장전류 및 보호기기 동작특성 Characteristics of the Fault Current and the Protection for Superconducting and Normal Conducting Limiter combined with a Transformer원문보기
With increasing demand of power, the equipment of power system is enlarging and the absolute capacity is going up. As a result, when a fault occurs, the fault current is consistently increasing. Therefore, I suggested some solution for limiting the fault current more efficiently. This study shows th...
With increasing demand of power, the equipment of power system is enlarging and the absolute capacity is going up. As a result, when a fault occurs, the fault current is consistently increasing. Therefore, I suggested some solution for limiting the fault current more efficiently. This study shows the characteristics of superconducting limiting elements and normal conducting elements combined with a transformer. We performed a short-circuit test about the fault current by using SCR switching control system operated from a CT. When short circuit accidents happened in the secondary side of a transformer, fault currents flowed and a SCR switching control system was operated. It resulted in a decrease of the fault current in the limited elements of third winding connected in parallel. For this test, we used YBCO thin films and normal conducting elements as the limited elements. Within a cycle, a superconducting fault current limiter with YBCO thin films reduced more than 90% of fault current because the resistance of superconducting elements sustainedly grew. On the other hand, the limiter with normal conductors limited as much as a set value because its resistance characteristic was linear. Consequently, in case of the limiter with superconductor, limiting range of the circuit was wide but the range of protective detection was undefined. In contrast, as for the limiter with normal conductors, limiting range and protection duty were appropriate.
With increasing demand of power, the equipment of power system is enlarging and the absolute capacity is going up. As a result, when a fault occurs, the fault current is consistently increasing. Therefore, I suggested some solution for limiting the fault current more efficiently. This study shows the characteristics of superconducting limiting elements and normal conducting elements combined with a transformer. We performed a short-circuit test about the fault current by using SCR switching control system operated from a CT. When short circuit accidents happened in the secondary side of a transformer, fault currents flowed and a SCR switching control system was operated. It resulted in a decrease of the fault current in the limited elements of third winding connected in parallel. For this test, we used YBCO thin films and normal conducting elements as the limited elements. Within a cycle, a superconducting fault current limiter with YBCO thin films reduced more than 90% of fault current because the resistance of superconducting elements sustainedly grew. On the other hand, the limiter with normal conductors limited as much as a set value because its resistance characteristic was linear. Consequently, in case of the limiter with superconductor, limiting range of the circuit was wide but the range of protective detection was undefined. In contrast, as for the limiter with normal conductors, limiting range and protection duty were appropriate.
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문제 정의
Though superconducting element has economic problems such as composing heat and cooling systems yet, it seems to be developed through steady researches[4-6]. Therefore, this study proposed SFCL as a new alternative for reducing fault currents. For securing work reliability in case of applying it to the distribution system, the study compared and analyzed work characteristics with normal conducting fault current limiter when an fault happened in single line-to-ground.
제안 방법
Therefore, this study proposed SFCL as a new alternative for reducing fault currents. For securing work reliability in case of applying it to the distribution system, the study compared and analyzed work characteristics with normal conducting fault current limiter when an fault happened in single line-to-ground.
1 is the single-phase electric circuits of the simulated distribution system. In the primary coil of the transformer, the study installed a breaker for 15A distribution, and CT detecting the fault current at the secondary coil. Also, the study set up SCR control system that makces the track of fault currents changed by executing switching work in case of fault.
In the primary coil of the transformer, the study installed a breaker for 15A distribution, and CT detecting the fault current at the secondary coil. Also, the study set up SCR control system that makces the track of fault currents changed by executing switching work in case of fault. And the fault current element that limits the fault current was installed in the third coil.
For the fault current element, this study used normal conducting element and superconducting element. Fig.
As a result, the fault current was breaked after flowing for 1/5 of the fault cycle having set up at the first stage. In this experiment, the breaker that was installed for protecting the distribution system in case of not having fault current limiter breaked the track after 23 cycles. Fig.
This experiment analyzed limited volume and time of fault current by the fault current element. Only when installing the breaker, fault current of 213A occurred, and then breaked after 23 cycles.
This study analyzed sizes and time of the fault current limited by types of the fault current element so as to ensure work reliability in case of applying SFCLto the distribution system. The experiment was processed by using the fault current element on normal conducting impedance and superconductors together with the caseof no fault current limiter.
This study analyzed sizes and time of the fault current limited by types of the fault current element so as to ensure work reliability in case of applying SFCLto the distribution system. The experiment was processed by using the fault current element on normal conducting impedance and superconductors together with the caseof no fault current limiter. The study applied voltage of 240V, and operated single line-to-ground fault.
성능/효과
By changes from the point of contact, the fault current was flowed into the third coil after the track waschanged, and then restricted by linked fault current element. As the result of experiment, stable limitation characteristics were appeared after half a cycle after fault current in case of applying normal fault current limiter. In case of applying SFCL, restriction and recovery were repeated owing to critical properties of the superconducting element.
후속연구
However, SFCL showed excellent characteristics in limited scale of fault time and restricted time, and it seems to be improved sufficiently through research development. It is considered that these findings will be a new alternative for solving occurred problems by being connected to current distribution system in case of applying SFCL to the system. Also, comparing SFCL with the fault currentlimiter using normal fault current element to apply the former to the distribution system is expected to be utilized as a basic data for doing protective coordination.
참고문헌 (6)
H. S. Choi, O. B. Hyun, H. R. Kim, K. B. Park, "Switching properties of hybrid type superconducting fault current limiter using YBCO stripes," IEEE Trans. Appl. Supercond, vol. 12, pp. 1833 - 1838, 2002.
H. S. Choi, S. H. Lim, "Operating Performance of the Flux-Lock and the Transformer Type Superconducting Fault Current Limiter Using the YBCO Thin Films," IEEE Trans. Appl, Superconduc, vol. 17, pp. 1823 - 1826, 2007.
K. H. Ha, S. G. Choi, Y. S. Cho, H. S. Choi, "Operational Behaviors of Flux-Coupling Type SFCL Using Integrated Three Phase Transformer Under Transient State," IEEE Trans, Vol.22 No3, pp5601604, 2012.
J. S. Kim, S. H. Lim, J. C. Kim, "Study on Protective coordination of a Flux-Lock Type SFCL with Over-Current Relay," IEEE Trans. Appl. Supercond., vol. 20, no. 3, pp. 1159-1163, 2010.
O. B. Hyun, J. W. Sim, H. R. Kim, K. B. Park, S. W. Yim, I. S. Oh, "Reliability Enhancement of the Fast Switch in a Hybrid Superconducting Fault Current Limiter by Using Power Electronic Switches," IEEE Trans. Appl. Supercond., vol. 19, no. 3, pp. 1843-1846, 2009.
B. W. Lee, K. B. Park, J. Sim, I. S. Oh, H. G. Lee, H. R. Kim, O. B. Hyun, "Design and Experiments of Novel Hybrid Type Superconducting Fault Current Limiters," IEEE Trans. Appl. Supercond., vol. 18, no. 2, pp. 624-627, 2008.
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