• Journal of IKEEE
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• v.22 no.3
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• pp.738-741
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• 2018

As DC power and DC load increase, unnecessary conversion process occurs in existing system. Due to these problems, interest in DC distribution systems has increased recently. As the importance of DC distribution system becomes higher, it is necessary to analyze the DC current. In this paper, we briefly describe the control method of the converter and describe the DC power flow calculation method. finally, we compared the simulation results of MATLAB and ETAP.

• The KIPS Transactions:PartD
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• v.10D no.7
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• pp.1207-1212
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• 2003

As development of the e-commerce, the distributing network for a logistics currency is more complicated. A management of the distributing network (DN) is important factor in distribution planning. The DN can be expressed to distribution center (DC) and the interaction of DC. An internal factor of DC and an external factor to occur by an interaction of DC have many influences on the DN. Therefore, for an efficient DN management plan, analysis of the DN that considered DC and an interaction of DC is required. Until now a study on a viewpoint of supply chain management as resources assignment was performed, but the study on analysis of the distribution network was not performed. This paper propose the distribution network analysis technique that considered DC and an interaction of DC. A proposed technique consists of two steps largely. First of all a DN is expressed with the graph that included an interaction of DC and DC. It uses a reachibility tree, and the following, a DN expressed with a graph is analyzed. Also we presented an example model, and show an usefulness of proposal technique with the analysis of this model.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.6
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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.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.353-359
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• 2017

To take advantage of electric propulsion, several large vessel kinds, namely, cruise vessels, icebreakers, drill ships, and warships, have been generally designed with Integrated Power System (IPS). Although most of these vessels have adopted AC distribution IPS, DC distribution IPS ships have recently emerged as a new promising technology thanks to the availability of the products related to the DC distribution system, in which the system's major advantages over AC distribution are reduced weight and fuel consumption. This paper presents the comparison results of a 10-t class fishing boat for the AC distribution and DC distribution cases. By replacing AC distribution system with DC distribution, 31-41% reduction in the weight of the electrical equipment weight and 20-25% reduction in the fuel consumption are expected.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.4
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• pp.275-286
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• 2019

This paper presents real-time Direct Current (DC) network analysis applications for operation of DC distribution system or DC microgrid. These applications are installed on central Energy Management System (EMS) and provide solutions of DC network operation. To analysis DC distribution network, this paper proposes composition and sequence of applications. Algorithm of applications is presented in this paper. Demonstration tests are performed on DC distribution site in Gochang Power Testing Center of Korea Electric Power Corporation (KEPCO). To verify the performance, developed DC applications installed on EMS. Scenarios for demonstration test of voltage control are presented. Finally, measured data, application output data and simulation data (by PSCAD/EMTDC) are compared and analyze accuracy of applications.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.3
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• pp.209-213
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• 2015

With the increasing popularity of renewable generation systems and the advancement of power electronics, DC distribution systems have recently received considerable research attention. DC distribution has numerous advantages, including reliability, power quality, and efficiency. Owing to these advantages, DC distribution has been applied to data centers and power quality-sensitive electronic load conditions. Because grounding electrodes in DC are much more susceptible to corrosion than in AC, the IT system defined in IEC Standard 60364 may be a good candidate for an earthing method for DC distribution systems. In addition, IEC Standard 61557 specifies the requirements for insulation monitoring devices (IMD) for protection of the IT system, which continuously monitors the insulation resistances between the power lines and the earth. This paper discusses the development and evaluation of IMD to promote the reliability of distribution systems and increase safety of humans and facilities.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.21-26
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• 2012

In recent years, DC distribution systems are becoming hot issue due to the increase in digital loads and DC generation systems according to the expansion of renewable energy technologies. However, removing the fault current in DC grids is comparably difficult since the current in DC grids has no zero-crossing point like in AC grids. Thus, developing dedicated DC circuit breakers for DC grids is necessary to get safety for people and electrical facilities. This paper proposes magnet arc extinguishing method to develop a 300[$V_{DC}$]/10[A] DC circuit breaker. The performance of the proposed DC circuit breaker was verified by an experimental circuit breaker test system built in this research.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.486-487
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• 2011

In this paper, a configurable DC distributiong system is being proposed considering national power systems conditions and a comparative analysis of the transient response of the contingencies is performed with the conventional AC systems. DC systems are evaluated as a promising next-generation distribution system that provides reliable operation through high efficiency of energy use and converter control. This paper discusses about the required elements for the national DC distribution system and has analysed the fault characteristics of the AC and DC distribution systems using PSCAD/EMTDC. According to the simulation results, the DC system has improved response, due to the DC/DC converter's charging/discharging characteristics, in terms of voltage and power system characteristics when compared to AC systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.42-48
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• 2015

DC distribution system is difficult to compose the single-system because of the capacity restriction of power semiconductors. Therefore, DC Distribution system needs parallel operation of AC/DC converters for increase to system capacity. However, this system generates the circulating current. This paper is reducing the circulating current and safely sharing the load using the proposed DC current droop control method when each other 3-phase AC/DC converter connected. This system confirms through the simulation and experiment. Also, when each other converter of parallel operate. it is compared the response characteristics

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.812-819
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• 2014

The proposed technical work attempts to compare the two key technologies of power distribution, i.e. direct current (DC) and alternating current (AC) in a fiscal manner. The DC versus AC debate has been around since the earliest days of electric power. Here, at least four types of a low voltage DC (LVDC) distribution are examined as an alternative to the existing medium voltage AC (MVAC) distribution with an economic assessment technique for a project investment. Besides, the sensitivity analysis will be incorporated in the overall economic analysis model to cover uncertainties of the input data. A detailed feasibility study indicates that many of the common benefits claimed for an LVDC distribution will continue to grow more profoundly as it is foreseen to arise with the increased integration of renewable energy sources and the proliferation of energy storage associated with the enhanced utilization of uninterruptible power supply (UPS) systems.