• 전력전자학회논문지
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• 제17권6호
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• pp.495-499
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• 2012

Recently, DC distribution systems become hot issues since DC type loads increase rapidly according to the expansion of IT equipment such as computers, servers, and digital devices; DC type loads will cover 50% for all electricity loads in 2020 which was mere 10% in 2000. DC distribution systems are also accelerated by the expansion of renewable power systems since they are easy to be interfaced with DC grids rather than AC grids. However, removing the fault current in DC grids is comparably difficult since the current in DC grids has non zero-crossing point like in AC grids. Thus, developing dedicated DC circuit breakers for DC grids is necessary to get safety for human and electrical facilities. Magnet arc extinguishing method is proper to small size DC circuit breakers. However, simple Magnet arc extinguishing method is not enough to break inductive fault currents. This paper proposed a novel DC circuit breaker against inductive fault current defined by IEEE C37.14-2004 Standard for Low-Voltage DC Power Circuit Breakers Used in Enclosures. The performance of the proposed DC circuit breaker was verified by an experimental circuit breaker test system built in this research.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.504-505
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• 2011

Decreasing actual greenhouse gas will be difficult if it is not solved addressed in architectural fields. Zero emission building or zero energy building, maximize the efficiency of energy, which means the building can operate by their own renewable energy facility without any other supplying. To be a zero emission building, a building needs realization of high efficiency low energy consumption, construction of building its own energy production facilities and lastly a power grid connection. According to increasing of DC load about TV, LED lighting, computer, IT in building for living and business, it is expected the save of energy when the system of AC power distribution change into the system of DC power distribution. Renewable energy exists a big different rate produced by outside environment. When electrical power overproduce, it can supply for system. Otherwise, if electrical power produce less, it can receive supply from system. Send and receive power can lead to zero to annual standard. This paper shows the simulation about efficient control of power conversion which is related to DC power distribution of architecture and DC output of renewable energy by using L-type converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.201-202
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• 2011

Existing AC distribution system lower the efficiency of the commercial power, and also generate the conversion loss of renewable energy. In this study, DC distribution system interconnected with PV system is produced, and it is studied about characteristics of the system through the experiments which are uesd load of 3[kW].

• 해양환경안전학회지
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• 제29권6호
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• pp.666-671
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• 2023

국제적인 선박 배출 가스에 대한 환경 규제가 점차 강화됨에 따라 전기추진 및 하이브리드 추진선박에 대한 관심이 증대되고 있으며, 이러한 선박에 적용하기 위한 다양한 솔루션이 개발 및 적용되고 있는데 특히 전력계통의 안정화, 시스템의 효율성을 높이기 위한 방안으로 직류배전시스템이 적용되고 있다. 또한, 선박용 직류배전시스템에 대한 안전 및 성능에 대한 검증 및 시험의 중요성이 요구되고 있다. 본 연구는 직류배전 테스트베드 구축 및 직류배전(가변속 발전)시스템에 대한 성능을 검증하고 연료소모량 분석한 결과로서 선박용 직류배전에 적용되고 있는 가변속 발전시스템을 적용하였으며, 발전기에서 출력되는 전력을 정류기를 통해 직류전력으로 변환하여 시스템에 연계하고 이러한 장치들을 감시 및 제어하기 위한 시스템을 개발하였다. 이러한 직류배전 시스템을 적용한 시험을 통해 최대 전압은 751.5V이고 최소전압은 731.4V가 계측되어 전압변동률은 2.7%로 3% 이내에서 안정적으로 전압이 공급되는 것을 확인하였고 부하변동에 따라 가변속 발전시스템을 적용하였을 경우 연료소모량이 기존 정속발전시스템과 비교하여 구간에 따라 최대 20%이상 연료절감이 되는 것을 시험을 통해 확인하였다.

• 전기학회논문지
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• 제62권7호
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• pp.943-949
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• 2013

Recently, an electric vehicle (EV) has been become a huge issue in the automotive industry. The EV has many electrical units: electric motors, batteries, converters, etc. The DC distribution power system (DPS) is essential for the EV. The DC DPS offers many advantages. However, multiple loads in the DC DPS may affect the severe instability on the DC bus voltage. Therefore, a voltage bus conditioner (VBC) may use the DC DPS. The VBC is used to mitigate the voltage transient on the bus. Thus, a suitable control technique should be selected for the VBC. In this research, Current controller with fixed switching frequency is designed and applied for the VBC. The DC DPS consist of both a resistor load and a boost converter load. The load variations cause the instability of the DC DPS. This instability is mitigated by the VBC. The simulation results by Matlab simulink and experimental results are presented for validating the proposed VBC and designed control technique.

• 전기학회논문지P
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• 제66권4호
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• pp.267-273
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• 2017

In recent years, there is an increasing demand for DC microgrid because the digital load due to DC increases and the efficiency of the distribution system increases due to loss of conversion losses and conversion stages due to reactive power compared to AC distribution. Currently, with the support of the KEPRI, the development of an electronic large-capacity circuit breaker for DC distribution protection, which has been underway since 2016, is proceeding. In this paper, as a part of this project, we modeled the DC microgrid connected with PV using PSCAD. The converter station, AC/DC converter control, PV and MPPT controller are designed. In order to evaluate the performance of the modeled DC microgrid, it is examined whether the voltage is adjusted according to the load variation.

• ETRI Journal
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• 제32권6호
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• pp.940-949
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• 2010

Rack-level DC power supply is the optimal technology for providing DC power to a volume server without any power infrastructure changes in an existing AC data center. In this paper, we propose a smartly controllable and monitorable DC rack power system. The proposed system improves power efficiency by changing the power distribution architecture of a conventional method in the rack. We developed an optimal power control method in multipower modules to provide high efficiency at low loads. In addition, the proposed system provides real-time web monitoring of the rack power and environment around a rack. In our experiments, the proposed system improved the power efficiency by over 10% compared to an AC power system providing N+1 redundant power and power monitoring.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.516-517
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• 2015

This paper proposes the feedforward compensation method of output voltage with 3phase AC/DC PWM converter on DC distribution system for improved response. AC/DC PWM converter on DC distribution is required power supply of high quality because of renewable energy sources and load links. In general, Feedforward compensation method of 3phase AC/DC PWM converter receives the sensor input to the output current, load power. Resulting, error of the sensing values and communication cause time delay. Therefore, Feedforward compensation method through only the output voltage is proposed in this paper. The feedforward compensation method through only the output voltage can be applied to the two-level AC/DC PWM converters, as well as multi-level converter or inverter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.400-402
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• 1994

The voltage drop in distribution path of battery-reserved DC power system can affect the total of battery, cable and electricity costs. To determine an optimum voltage drop in distribution path for minimizing the total cost, battery, cable and electricity costs are represented as a function of the voltage drop, respectively, and are summed up to the total cost. An optimum voltage drop is selected as the value giving the minimum total cost. In this paper, a design technique of optimum voltage drop in distribution path of DC power system is proposed to minimize the total of battery, cable and electricity costs. The design procedure is described and design curve for selecting optimum voltage drop is also presented as a function of distribution distance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1141-1142
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• 2011

An electrical vehicle (EV) is a huge issue in the automotive industry. The EV have many electrical units: electric motors, batteries, converters, ets. The DC power distribution system (PDS) is essential for the EV. The DC PDS offers many advantages. However, multiple loads in the DC PDS may affect the severe instability on the DC bus voltage. Therefore, a voltage bus conditioner (VBC) may use the DC PDS. The VBC is used to mitigate the voltage transient on the bus. In this paper, sliding mode controller (SMC) is designed for the VBC of DC PDS in the EV. The simulation results by PISM simulation package are presented for validating the proposed control technique.