• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2002년도 학술대회 논문집
• /
• pp.368-370
• /
• 2002

We present current limiting properties of 1.2kV/70A superconducting fault current limiter based on YBCO thin films. This is consisted of 6 wafers (3 parallel $\times$ 2 serial connection) with 4 inch-diameter YBCO thin film. The quench current Iq of the switching elements vary between 33.9 and 35.6 A. Within the difference of 0.5 A in the sum of quench current Iq in two stacks, the serial connection of the stacks showed the simultaneous quench behavior in applied power of 1.2 kV/70A.

• 한국초전도ㆍ저온공학회논문지
• /
• 제5권3호
• /
• pp.52-56
• /
• 2003

This paper describes the results of a basic study (on a model samples) for the development of 22.9 kV high temperature superconducting (HTS) cable. The authors have established that the factors that decide the performance of HTS cables are butt gaps in tape insulation and carbon particles from semiconductive layer. The insulation performance of HTS cables is determined by size and quality of these elements. In the model tests of HTS cables, the minimum PD inception stress of the tape insulation impregnated with liquid nitrogen was found and insulation thickness was calculated from this result.

• 전기학회논문지P
• /
• 제58권2호
• /
• pp.227-230
• /
• 2009

In this paper, we performed the optimum design of reactors for matrix-type superconducting-fault current limiters (SFCLs), using electromagnetic analysis tools. We decided a optimun position within a reactor for superconducting elements of current-limiting parts and trigger parts from the calculation of magnetic flux internsity for reactor structures. Also we decided effective distance length between two reactors through the analysis of the distribution of magnetic field, according to distance lengths between them. We designed and characterized matrix-type SFCLs, based on our optimum design of a reactor. We confirmed uniform distribution of a fault current, resulted from the improvement of simultaneous quench characteristics within our matrix-type SFCL.

• Journal of Electrical Engineering and Technology
• /
• 제2권3호
• /
• pp.289-293
• /
• 2007

The fault current limiting characteristics of the separated and the integrated three-phase flux-lock type superconducting fault current limiters (SFCLs) were analyzed. The three-phase flux-lock type SFCL consisted of three flux-lock reactors and three $high-T_c$ superconducting (HTSC) elements. In the integrated three-phase flux-lock type SFCL, three flux-lock reactors are connected on the same iron core. On the other hand, three flux-lock reactors of the separated three-phase flux-lock type SFCL are connected on three separated iron cores. The integrated three-phase flux-lock type SFCL showed the different fault current limiting characteristics from the separated three-phase flux-lock type SFCL that the fault phase could affect the sound phase, which resulted in quench of the HTSC element in the sound phase. Through the computer simulation applying numerical analysis for its three-phase equivalent circuit, the fault current limiting characteristics of the separated and the integrated three-phase flux-lock type SFCLs according to the ground fault types were compared.

• 전기학회논문지P
• /
• 제58권3호
• /
• pp.334-338
• /
• 2009

In this paper, We report the miniaturization of superconducting microwave power dividers based on lumped element equivalent circuits. To do this, we analyzed a conventional branch-type power divider by using an ABCD matrix under even and odd mode excitation. Then, we calculated each lumped element impedance throughout this analysis of a transmission line matrix. Also we simulated our equivalent circuits made of lumped elements by using a full wave analysis, em Sonnet. Our deign of microwave power divider based on simulated results was fabricated on high-$T_c$ superconducting thin films deposited on MgO substrate. Experimental results were reported in terms of bandwidth, center frequency, and phase difference between $S_{21}$ and $S_{31}$. We confirm that our design will be useful in the future microwave power systum.

• 대한기계학회논문집
• /
• 제17권10호
• /
• pp.2407-2417
• /
• 1993

Thermal deformations and stresses due to temperature changes are the serious problems in cryogenic structures such as the torque tube in a superconducting generator, In this paper, the equations of thermal expansion coefficients expressed only by material properties and winding angles are derived for the filament wound composite tubes. The experimental results of thermal contraction of CFRP tubes are compared with those from theoretical approach. Composite tubes with optimally regulated thermal expansion coefficient are designed on the basis of the study for the torque tube in the superconducting generator with temperature distributions varying from 300K to 4.2 K. The filament winding angle of composites resisting thermal stresses properly is sought by the finite element method using layered shell elements. The results show that the composite tubes designed for the requirements in cryogenic environments can effectively cope with the thermal stress problem.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1999년도 전력전자학술대회 논문집
• /
• pp.427-430
• /
• 1999

This paper presents a S-FES(Superconducting magnetic bearing Flywheel Energy Storage System) for the purpose of replacing battery used to store the energy. Especially, the design elements of FES, such as the bearing, wheel material, and power converter, etc., is described. The design and manufacturing techniques of the controllable power converter are proposed to generate the sinusoidal output current in the high speed operation and to get the constant DC voltage in the regeneration mode. The cylindrical permanent magnet synchronous motor with halbach array of Nd-Fe-B permanent magnet which is the high coercivity material is used as the driver of FES. The proposed S-FES system shows the stable rotation characteristics at high speed range about 10,000 rpm. To verify the validity of proposed system, the comparative study with the conventional ball bearing system is proceeded and it is well confirmed with the result of the lower friction loss of S-FES system.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2002년도 학술대회 논문집
• /
• pp.365-367
• /
• 2002

A serious problem in using YBCO films for fault current limiter is inhomogeneities caused by imperpect manufacturing. So simultaneous quenches are a difficult problem which elements for current limiting are connected in series for increasing voltage ratings. We investigated extended electric field - current characteristics for current limiting element of YBCO film when 0-130mT magnetic field is applied. And quench characteristics were investigated in over all element and between elements of YBCO films. From the experiments, it was shown that applied magnetic fields using solenoid coil induced uniform quench distribution for over all stripes and simultaneous quench in all elements for current limiting of YBCO film was realized.

• 한국초전도ㆍ저온공학회논문지
• /
• 제4권1호
• /
• pp.84-88
• /
• 2002

The resistive fault current limiter (SFCL) is a very attractive device for power networks. But it has a serious Problem in using YBCO films for fault current limiter is inhomogeneities caused by imperpect manufacturing. So simultaneous quenches are a difficult problem which elements for current limiting are connected in series for increasing voltage ratings. We investigated extended electric field-current characteristics for current limiting element of YBCO film when O-130mT magnetic field is applied. And quench characteristics were investigated in over all element and between elements of YBCO films. From the experiments, it was shown that applied magnetic fields using solenoid coil induced uniform quench distribution for over all stripes and simultaneous quench in all elements for current limiting of YBCO film was realized. We have achieved resistive fault current limiter of 1.2kV/20A rating using magnetic field.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
• /
• pp.77-79
• /
• 2003

The quench characteristics of flux-lock type high-Tc superconducting fault current limiters(SFCL) was investigated. $YBa_2Cu_3O_{7-x}$(YBCO) thin film was used as the current limiting elements of the flux-lock type SFCL. The quench characteristics of current limiting elements consisting of the flux-lock type SFCL was more improved than that of the resistive type SFCL.