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마용호,이주영,류경우,손송호,황시돌,Ma, Yong-Hu,Li, Zhu-Yong,Ryu, Kyung-Woo,Sohn, Song-Ho,Hwang, Si-Dol 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.7
The AC loss is an important issue in the design of the high temperature superconductor (HTS) power cables and fault current limiters. In these applications, a cylindrical HTS conductor is often used. In commercialization of these apparatuses, AC loss is a critical factor but not elucidated completely because of complexities in its measurement, e.g. non-uniform current distribution and phase difference between currents flowing in an individual HTS tape. We have prepared two cylindrical conductors composed of a Bi-2223 tape with different critical current density. In this paper, the AC loss characteristics of the conductors have been experimentally investigated and numerically analyzed. The result show that the measured losses for two conductors are not dependent on both arrangements and contact positions of a voltage lead. This implies that most of loss flux is only in the conductors. The loss for the Bi-2223 conductor with low critical current density is in good agreement with the calculated loss from Monoblock model, whereas the loss measured for the Bi-2223 conductor with high critical current density doesn't coincide with the loss calculated from the Monoblock model. The measured loss is also different from numerically calculated one based on the polygon model especially in low transport current.
마용호(Y.H. Ma),이주영(Z.Y. Li),진홍범(H.B. Jin),류경우(K. Ryu),임지현(J.H. Lim),손송호(S.H. Sohn),황시돌(S.D Hwang) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7
다층구조의conductor와 shield로 구성되는 HTS-cable의 교류손실 특성 연구를 위하여 2005년부터 실증시험 중에 있는 22.9㎸, 50㎹A, 100m급 KEPCO HTS-cable system에 사용된 케이블과 동일한 두개의 short-sample에 대하여DC 및 AC 특성을 실험적으로 조사하였다. KEPCO HTS-cable system에서 처럼 shield전류를 conductor와 크기는 같게 하고 방향을 반대로하여 수주기동안 AC pulse전류를 인가했을 때, shield의 임계전류가 conductor보다 작음에도 불구하고 conductor-lead에 대하여 측정된 AC loss가 shield의 것과 비교하여 약 1.5배 큰 것을 알 수 있었다.
경사 외부자장에 대한 600 kJ급 SMES용 HTS도체의 DC V-I 특성
이주영,마용호,류경우,최세용,김해종,Li, Zhu-Yong,Ma, Yong-Hu,Ryu, Kyung-Woo,Choi, Se-Yong,Kim, Hae-Jong 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.1
We are developing a small-sized high temperature superconducting magnetic energy storage (HTS-SMES) magnet with the nominal storage capacity of 600 kJ, which provides electric power with high quality to sensitive electric loads. Critical current and N-value of a high temperature superconductor with large current, which was selected for the development of the 600 kJ HTS-SMES magnet, were investigated in various oblique external magnetic fields. Based on the critical current and N-value measured for the short sample conductor, we discussed the DC V - I characteristic of a model coil fabricated with the same conductor of 500 m. The results show that the measured critical current and N-value of the conductor for parallel field are constant in external magnetic fields less than about 0.2 T. However, for oblique fields, its critical current and N -value abruptly decrease in all external magnetic fields. Moreover, the measured critical current of the model coil well agrees with the numerically calculated one based on the DC V - I characteristic measured for the short sample conductor. This suggest that losses and critical currents for an HTS-SMES magnet made up of a high temperature superconductor with anisotropic characteristic are predictable from the data of a short sample conductor.
류경우,마용호,Ryu, Kyung-Woo,Ma, Yong-Ho 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.4
AC loss of a superconducting conductor has a strong influence on the economic viability of a superconducting fault current limiter, which offers an attractive means to limit short circuit current in power systems. Therefore, the AC loss characteristics in several fault current limiting elements of a coil type have been investigated experimentally. The test result shows that AC losses measured in the fault current limiting elements depend on arrangement of a voltage lead. The AC loss of a bifilar coil is smallest among the fault current limiting elements of the coil type. The measured AC loss of the bifilar coil is much smaller than that calculated from Norris's elliptical model. However, the loss measured in a meander, which is frequently used in a resistive fault current limiter, agrees well to the theoretical one.
단층 초전도케이블 샘플에서 교류손실의 수치해석에 대한 연구
이주영,마용호,류경우,황시돌,Li, Zhu-Yong,Ma, Yong-Hu,Ryu, Kyung-Woo,Hwang, Si-Dole 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.7
AC loss is one of the important factors for commercialization of a high temperature superconducting (HTS) cable from an economic point of view. But AC loss characteristics of the HTS-cable are not elucidated completely because of its complex structure. As an earlier stage of analyzing the AC loss in the 22.9 kV/50 MVA, 100m HTS-cable system of Korea Electric Power Corporation (KEPCO) which is now in collaboration with us, a two-dimensional (2D) numerical model, which takes into account the nonlinear conductivity properties of a high temperature superconductor, has been developed. In order to examine our 2D model, we have prepared several single-layer cable samples whose AC losses are sufficiently reliable due to their simple structure. The AC losses of the samples were experimentally investigated and then compared with our 2D model. The results show that the numerically calculated AC losses are not in good agreement with the measured ones for the cylindrical cable and deca-cable samples with low critical current density. However, the numerically calculated and measured AC losses are relatively in good agreement for the deca-cable and hex-cable samples with high critical current density, although the difference between these two loss data in the deca-cable sample tends to increase in the low current region.