http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
A Study on SFCL with IGBT Based DC Cir cuit Breaker in Electric Power Grid
배선호,김홍래,박정욱,이수형 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.5
Recently, DC systems are considered as efficient electric power systems for renewable energy based clean power generators. This discloses several critical issues that are required to be considered before the installation of the DC systems. First of all, voltage/current switching stress, which is aggravated by large fault current, might damage DC circuit breakers. This problem can be simply solved by applying a superconducting fault current limiter (SFCL) as proposed in this study. It allows a simple use of insulated-gate bipolar transistors (IGBTs) as a DC circuit breaker. To evaluate the proposed resistive type SFCL application to the DC circuit breaker, a DC distribution system is composed of the practical line impedances from the real distribution system in Do-gok area, Korea. Also, to reflect the distributed generation (DG) effects, several DC-to-DC converters are applied. The locations and sizes of the DGs are optimally selected according to the results of previous studies on DG optimization. The performance of the resistive type SFCL applied DC circuit breaker is verified by a time-domain simulation based case study using the power systems computer aided design/ electromagnetic transients including DC (PSCAD/ EMTDCÒ).
Optimal SOC Reference Based Active Cell Balancing on a Common Energy Bus of Battery
배선호,박정욱,이수형 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1
This paper presents a study on the state-of-charge (SOC) reference based active cell balancing in real-time. The optimal references of SOC are determined by using the proposed active cell balancing system with the bidirectional DC/DC converters via the dual active bridge (DAB) type. Then, the energies between cells can be balanced by the power flow control of DAB based bidirectional DC/DC converters. That is, it provides the effective management of battery by transferring energy from the strong cell to the weak one until the cell voltages are equalized to the same level and therefore improving the additional charging capacity of battery. In particular, the cell aging of battery and power loss caused from energy transfer are considered. The performances of proposed active cell balancing system are evaluated by an electromagnetic transient program (EMTP) simulation. Then, the experimental prototype is implemented in hardware to verify the usefulness of proposed system.
Application of Superconducting Flywheel Energy Storage System to Inertia-Free Stand-Alone Microgrid
배선호,최동희,박정욱,이수형 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.4
1Recently, electric power systems have been operating with tight margins and have reached their operational limits. Many researchers consider a microgrid as one of the best solutions to relieve that problem. The microgrid is generally powered by renewable energies that are connected through power converters. In contrast to the rotational machines in the conventional power plants, the converters do not have physical rotors, and therefore they do not have rotational inertia. Consequently, a stand-alone microgrid has no inertia when it is powered by the only converter-based-generators (CBGs). As a result, the relationship between power and frequency is not valid, and the grid frequency cannot represent the power balance between the generator and load. In this paper, a superconducting flywheel energy storage system (SFESS) is applied to an inertia-free stand-alone (IFSA) microgrid. The SFESS accelerates or decelerates its rotational speed by storing or releasing power, respectively, based on its rotational inertia. Then, power in the IFSA microgrid can be balanced by measuring the rotor speed in the SFESS. This method does not have an error accumulation problem, which must be considered for the state of charge (SOC) estimation in the battery energy storage system (BESS). The performance of the proposed method is verified by an electromagnetic transient (EMT) simulation.
배선호(Bai, Sun-Ho),김철(Kim, Chul) 대한생리학회 1975 대한생리학회지 Vol.9 No.1
뇌 해마가 전기충격에 의한 내력(tolerance)에 미치는 영향을 구명하기 위하여, 두정 후두 경계 부위의 대뇌피질을 양측성으로 둥글게 떼어내고, 이를 거쳐 해마를 평균 97%가량 떼어버린 흰쥐(해마군) 14마리와 해마를 덮는 대뇌피질 부분만을 떼어버린 흰쥐(대뇌피질 대조군) 17마리 및 두개골을 노출하는데 그치고 뇌에 손상을 주지 않은 흰쥐(정상 대조군) 17마리를 사용하여 다음과 같은 실험을 실시하였다. 24시간 동안 먹이 없이 물만으로 지나게 한 다음 구금판에 세 무리를 구금하고 24시간 동안 매회 1.5초 동안씩 계속되는 4mA의 교류전류에 의한 충격을 1분 간격으로 반복하여 폐사하는 동물의 수효를 세어 다음과 같은 결과를 얻었다. 1. 전기충격을 가하는 동안 폐사한 동물의 수효에서 해마군의 값은 두 대조군의 값에 비하여 유의하게 적었으나, 두 대조군 사이에는 이렇다 할 차가 없었다. 2. 전기충격으로 인하여 폐사한 예에서 전기충격의 시작부터 폐사할 때까지의 시간은 해마군의 값이 두 대조군의 값에 비하여 연장된 경향을 보여 주었다. 이상의 결과로 미루어 뇌 해마는 전기충격에 대한 내력(耐力)에 억제적 영향을 끼친다고 추리된다. A study was designed to clarify the influence of the hippocampus upon tolerance by electric shock. Forty-eight male rats were used, of which 14 rats had their hippocampal tissue on both sides removed through an opening in the parieto-occipital cortex (hippocampal group), 17 rats received damage to the parieto-occipital cortex only (cortical control group), and 17 rats served as normal control animals. After 24 hours fasting with water ad libitum, each animal was restrained on a plate with added electric shock (4 mA A.C., 1.5 sec in a duration, and once per minute in average) to the tail for the last 24 hours without food and water. The mortality in each animal group and the mean survival time of the dead animal during the repitition of electric shock were calculated. Results obtained were as follows: 1. The mortality was lower significantly in the hippocampal group than in the two control groups. 2. The mean survival time of the dead animal was longer insignificantly in the hippocampal group than in the two control groups. The inference from the above results is that the hippocampus exerts a inhibitory influence upon tolerance by electric shock.