• 조명전기설비학회논문지
• /
• 제23권12호
• /
• pp.90-95
• /
• 2009

배전계통에서 전력수요의 증가와 분산전원의 증가로 대용량 변압기의 적용이 불가피하게 되었다. 하지만, 대용량 변압기로 교체할 경우 배전계통에 고장발생시 고장전류의 크기가 증가되어 기존에 설치된 차단기 및 보호기기의 차단용량 초과로 인해 교체에 따른 경제적 비용 상승이 우려된다. 따라서, 대용량 변압기의 교체시 고장전류 증가 문제를 해결하기 위한 방안 중 하나로 초전도한류기를 설치하는 방안을 검토하고 있다. 하지만, 초전도한류기는 도입위치에 따라 ��치 발생 시 초전도한류기의 저항 크기가 다르게 되며, 이로 인해 고장전류 제한효과가 다르게 되며 기존의 보호 장치들의 동작에 영향을 주게 된다. 본 논문에서는 모의 배전계통에 초전도한류기를 적용하였을 경우 도입위치에 따라 전류제한효과를 포함하여, 모선 전압강하, 고장제거에 따른 초전도한류기의 회복특성을 실험을 통해 비교 분석하였다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제6권4호
• /
• pp.32-36
• /
• 2004

AC loss is one of the important parameters in HTS (High Temperature Superconducting) AC devices. Among the HTS AC power devices, the transformer is an essential part in electrical power system. But, AC loss is one of the most serious problems of the HTS transformer, especially with pancake windings, because high alternating magnetic field is applied perpendicularly to the surface of BSCCO wire in HTS windings of that, comparing with the other HTS AC power devices. For the reason above the calculation of AC loss generated in the HTS windings should be carried out in advance when designing the HTS transformer. In the paper we performed study for optimization of winding design to minimize the magnetization loss of HTS winding such as the spaces between pancake windings and operating temperature of HTS wire. The calculation of the AC loss was accomplished by 2-demensional Finite Element Method.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제50권2호
• /
• pp.65-72
• /
• 2001

This paper presents the design and test results of a 10kVA single phase HTS transformer which is operating at 77K. Double pancake windings with BSCCO -2223 HTS tape and GFRP cryostat with room temperature bore are used in the transformer. Four double pan cake windings were used in pancake windings are connected in parallel to conduct the secondary current of 45.4A. the rated voltages of each winding are 440/220V. Numerical calculation using Finite Element Method was used to evaluated the performance of each arrangement. Considering the magnetizing reactance, leakage reactance, electrical insulation and the circulating current in low voltage winding which had two windings in parallel, HLLH arrangement was finally chosen. Estimation of the AC loss, magnetizing loss and self field loss, in the design stage, where effects of perpendicular field and parallel field are considered. Room temperature bore type cryostat has been constructed and its heat loss was measured.

• 한국초전도ㆍ저온공학회논문지
• /
• 제8권1호
• /
• pp.45-48
• /
• 2006

In the response to the demand for electrical energy , much effort was given to develop and commercialize high temperature superconducting (HTS) power equipments has been made around the world. Especially, HTS transformer is one of the most promising devices . but the cryogenic insulation technology should be established during development Hence many types of dielectric tests should be carried out to understand the dielectric phenomena at cryogenic temperature and to gather various dielectric data. Among the many types dielectric tests . the characteristic of barrier effect were conducted using simulated electrode after analysing the insulating configuration of HTS transformer main winding. The influence of a barrier on the dielectric strength was measured according to the position of the harriet the number of the barrier and thickness or the barrier. It was shown that the effectiveness . namely the ratio of the breakdown voltage in presence of barrier to the voltage without barrier, is highest when the barrier is placed at the needle electrode side. On the contrary, in the case of having the barrier between the electrodes, the harrier was placed between the electrodes the characteristic was even improved slightly.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.639-642
• /
• 2005

HTS Transformer developing is developing a power distribution and transmission class HTS transformer that is one of the 21st century superconducting frontier projects. Therefore, we prepared the model, that is Z continuous winding from Kapton insulated Cu tape for a small simulated the HTS transformer. For the development of electrical insulation design of a HTS transformer with Z continuous winding, we have been discussed insulation composition and investigated breakdown characteristics such as breakdown of liquid $N_2(LN_2)$, polymer and surface flashover on FRP and breakdown-surface combination in $LN_2$. Also we have been designed and manufactured a bobbin that has spiral slot for the Z continuous winding. The Z continuous winding mini-model from Kapton film insulated Cu tape for simulated 22.9kV class HTS transformer has been constructed using 0.1 % breakdown strength obtained by Weibull distribution. The widing model was measured their insulation characteristics such as ac (50kV, 1min) and impulse (154kV, $1.2\times50{\mu}s$ full wave, 3 times) withstand test and its excellent performance was confirmed.

• 조명전기설비학회논문지
• /
• 제21권8호
• /
• pp.107-112
• /
• 2007

자속구속형 초전도 한류기는 1차 권선과 초전도 소자가 직렬로 연결된 2차 권선을 갖는 변압기로 구성되어 있다. 이 초전도 한류기는 결선방향에 따라 감.가극 결선으로 나누어진다. 1차 권선과 2차 권선의 인덕턴스 비에 따라 자속구속형 초전도 한류기는 사고전류의 제한특성을 제어할 수 있다. 본 논문에서는 인가전압에 따른 자속구속형 초전도 한류기의 전압 전류 특성을 분석하였다. 감 가극 결선된 자속구속형 초전도 한류기의 인가전압을 증가시켰을 때, 초기에 제한되는 전류 및 초전도 소자의 ??치 시간은 증가하였다. 초전도 소자의 회복시간은 인가전압이 증가함에 따라 증가하였다. 그러므로 자속구속형 초전도 한류기의 회복특성은 초전도 소자의 소비전력이 증가하기 때문에 초전도 소자에서 소비되는 에너지에 크게 의존한다는 것을 확인할 수 있었다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제3권1호
• /
• pp.16-21
• /
• 2001

Bubble behavior is studied with an electrode system which consists of coaxial spiral coil-to-cylindrical electrode with an insulation barrier and spacers and is immersed in liquid nitrogen for simulation of insulation environments in high temperature superconducting(HTS) coils The results show that the bubble behavior Is affected severely by electric field: (1) under low applied voltage bubbles rise by buoyancy, but at higher applied voltage they are trapped in a lower electric field region below the coil electrode, and (2) the trapped bubble flows along the downside of coil electrode if no obstruction is in a groove between coil turns. but it splashes out of the groove after its growing if the obstruction such as spacer-exists.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2002년도 학술대회 논문집
• /
• pp.185-188
• /
• 2002

In the design of superconducting power equipments such as transformer, cable and fault current limit, knowledge of the dielectric behavior of both liquid and gaseous at very low temperatures is very importance. Especially, Electrical properties of liquid nitrogen($LN_{2}$) and gaseous nitrogen($GN_{2}$) have become of great interest again since the discovery of high temperature superconductors. However, many sources of $LN_{2}$and $GN_{2}$ problems in the test of pancake coil model arising form the deficiency of insulation data. Therefore, this paper describes the results of an experimental study on the ac breakdown voltage($V_{B}$) properties of $LN_2$ and Air under the electrode of simulated HTS pancake coil. The ac breakdown voltage of $GN_{2}$ have been measured by pancake coil-pancake coil gaps over the temperature range of 293 K to 77 K.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 추계학술대회 논문집
• /
• pp.213-213
• /
• 2009

In this paper, we investigated the current limiting characteristics due to the application location of the superconducting fault current limiter (SFCL) such as the feeder, the bus, the secondary side of transformer in a power distribution system. In addition, the quench and the recovery characteristics of the SFCL installed in each location of the power distribution system were compared each other. Through the analysis, in case that the SFCL was applied into the feeder line, its current limiting and voltage-drop compensating characteristics were confirmed to be the more effective. On the other hand, the power burden of the SFCL was increased higher compared to the SFCL'S other application location.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
• /
• pp.33-35
• /
• 1999

This paper describes the test results of the single phase 3kVA high temperature superconducting power trans-former. The tapes are made with Bi-2223 and have silver alloy as the matrix. Four double pancake windings are used in total. Among them two double pancake windings are connected in series for high voltage winding and two double pancake windings are connected in parallel for low voltage winding. The rated voltages of each winding are 220/110 V. Fundamental characteristics are obtained through short circuit and no load tests. The over load capability and characteristics are investigated.