• Title, Summary, Keyword: DC Distribution

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Integrated Operation of Power Conversion Module for DC Distribution System (직류 배전 시스템을 위한 전력 변환 모듈의 통합 운전)

  • Lee, Hee-Jun;Shin, Soo-Choel;Hong, Suk-Jin;Won, Chung-Yuen
    • The Transactions of the Korean Institute of Power Electronics
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    • v.19 no.3
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    • pp.240-248
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    • 2014
  • It is DC power that Output of renewable energy being recently developed and researched. Also, demand of DC power will expect to proliferate due to increase of digital load. Thus, DC distribution system providing high quality of power and reliability has emerged as a new distribution system. If the conventional distribution systems are substituted by proposed DC distribution system, the output of renewable energy can be connected with distribution systems under minimum power conversion. Therefore, in the event of connection with DC load, it can construct an efficient distribution system. In this paper, the integrated parallel operation of power conversion module for DC distribution system is proposed. Also, this paper proposed modularization of power conversion devices for DC distribution system and power control for parallel operation of large capacity system. DC distribution system consists of three power conversion modules such as AC/DC power conversion module 2 set, ESS module 1 set. DC distribution system controls suitable operation depending on the status of the DC power distribution system and load. Integrated operation of these systems is verified by simulation and experiment results.

Lightning Surge Analysis on Underground System in DC Combined Distribution System (DC 혼합배전시스템에서 지중계통의 뇌과전압 해석)

  • An, Chun-Yong;Lee, Jong-Beom
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.6
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    • pp.737-743
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    • 2013
  • This paper describes the overvoltage through lightning surge analysis on underground system in DC combined distribution systems. It is considered that operating micro grid including distributed generation with smart grid can make possibility of composing new distribution system different from existing one. However, there are many papers about low voltage DC distribution in grids or buildings but not many about replacement or distributing 22.9kV AC distribution system to DC system. Among many research need for DC system development, overvoltage is studied in this paper. Overvoltage is simulated on DC cable when lightning strikes to overhead grounding wire which is installed at the nearest location from power cable section. Analysis as well as modeling is performed in EMTP/ATPDraw. It is evaluated that analysis results can be used to design of DC underground distribution power cable system.

The Application Method of DC Distribution in Microgrid (마이크로그리드의 직류 배전 적용 방안)

  • Lee, Soon-myung;Kim, Jeong-Uk
    • Journal of Energy Engineering
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    • v.25 no.1
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    • pp.92-99
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    • 2016
  • In this paper, After the Paris climate conference (COP21) in December 2015, 195 countries adopted the first-ever universal, legally binding global climate deal. As sustained increase of renewable energy and digital load, to implemented and operated Microgrid system's power distribution by DC power distribution. This reduce the loss of power conversion step occurring based on the AC power distribution system and eliminate the loss caused by the reactive power in power distribution system. For this reason, DC Microgrid will be extended to support evidence of National energy policies, Microgrid project status, DC distribution status, and to suggest process of DC power distribution in Microgrid construction project.

A Study on Bipolar DC-DC Converter for Low Voltage Direct Current Distribution (저압 직류 배전용 양극성 DC-DC 컨버터에 관한 연구)

  • Lee, Jung-Yong;Kim, Ho-Sung;Cho, Jin-Tae;Kim, Ju-Yong;Cho, Younghoon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.24 no.4
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    • pp.229-236
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    • 2019
  • This study proposes a DC-DC converter topology of solid-state transformer for low-voltage DC distribution. The proposed topology consists of a voltage balancer and bipolar DC-DC converter. The voltage and current equations are obtained on the basis of switching states to design the controller. The open-loop gain of the controller is achieved using the derived voltage and current equations. The controller gain is selected through the frequency analysis of the loop gain. The inductance and capacitance are calculated considering the voltage and current ripples. The prototype is fabricated in accordance with the designed system parameters. The proposed topology and designed controller are verified through simulation and experiment.

Lightning Overvoltage Analysis According to Interval of Arrester and Overhead Grounding Wire in DC Distribution System (직류배전시스템에서 피뢰기 및 가공지선 접지간격 변경에 따른 뇌과전압 해석)

  • An, Chun-Yong;Lee, Jong-Beom;Kim, Yong-Kap
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.4
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    • pp.474-481
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    • 2013
  • It is anticipated that AC distribution system can be replaced by DC distribution system in the near future because of the operation of various distributed source or microgrid system. However DC distribution system replacing 22.9kV AC distribution line is not sufficiently studied still. This paper describes lightning overvoltage analysis among many research fields should be studied to realize DC overhead distribution systems. DC distribution system is modeled using EMTP and overvoltage is analyzed according to interval of arrestor location, earth interval of overhead grounding wire and grounding resistance. It is evaluated that analysis results can be effectively used to design of future DC distribution system.

Power Flow Study of Low-Voltage DC Micro-Grid and Control of Energy Storage System in the Grid

  • Kim, Dong-Eok
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.549-558
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    • 2017
  • DC distribution has several differences compared to AC distribution. DC distribution has a higher efficiency than AC distribution when distributing electricity at the same voltage level. Accordingly, power can be transferred further with low-voltage DC. In addition, power flow in a DC grid system is produced by only a voltage difference in magnitude. Owing to these differences, operation of a DC grid system significantly differs from that of an AC system. In this paper, the power flow problem in a bipolar-type DC grid with unbalanced load conditions is organized and solved. Control strategy of energy storage system on a slow time scale with power references obtained by solving an optimization problem regarding the DC grid is then proposed. The proposed strategy is verified with computer simulations.

Modeling of Bi-directional DC/DC Converter for Connecting DC Distribution System using EMTP (EMTP를 이용한 직류배전계통 연계용 양방향 DC/DC 컨버터 모델링)

  • Han, Joon;Kim, Doo-Ung;Oh, Yun-Sik;Gwon, Gi-Hyeon;Noh, Chul-Ho;Jung, Tack-Hyun;Kim, Chul-Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.5
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    • pp.615-621
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    • 2014
  • With development of electrical power system, the DC distribution system has been considered as a promising technology to be used in the future smart distribution system. Among the various components comprising the DC distribution system, the bi-directional DC/DC converter is one of the most important equipment to interconnect between main power system and various renewable resources such as photovoltaic power generation, wind power generation, and electrical vehicles. In this paper, a bi-directional DC/DC converter based on three-phases interleaved method which is effective to reduce ripple of input current and output voltage is modeled using ElectroMagnetic Transient Program(EMTP), and the verification of modeled bi-directional DC/DC converter is conducted.

A Research on the Fault Current of DC distribution system considering Converter Characteristics (DC배전 시스템에서 컨버터 특성에 따른 수용가측 고장 영향 분석)

  • Yoon, Tae-Young;Byeon, Gil-Sung;Lee, Han-Sang;Jang, Gil-Soo;Chae, Woo-Kyu;Kim, Ju-Yong
    • Proceedings of the KIEE Conference
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    • pp.366-367
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    • 2011
  • The DC distribution system iis a new promising topologies in a field of future smart distribution system. This system has high efficiency and reliability. So it is expected that there would be an increase in the installation of DC distribution systems. In this paper, the parameter of the DC/DC converter impact on customer's the power quailty in the DC distribution system when the fault occurred. For the analysis, DC network to be modeled using PSCAD/EMTDC. The fault is occurred at phase A in secondary side of MTR which is AC system. Then compared voltage and power at the customer side by varying the capacity of capcitor in the DC/DC converter.

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Complementary Power Control of the Bipolar-type Low Voltage DC Distribution System

  • Byeon, Gilsung;Hwang, Chul-Sang;Jeon, Jin-Hong;Kim, Seul-Ki;Kim, Jong-Yul;Kim, Kisuk;Ko, Bokyung;Kim, Eung-Sang
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.786-794
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    • 2015
  • In this paper, a new power control strategy for the bipolar-type low voltage direct current (LVDC) distribution system is being proposed. The dc distribution system is considered as an innovative system according to the increase of dc loads and dc output type distribution energy resources (DERs) such as photovoltaic (PV) systems and energy storage systems (ESS). Since the dc distribution system has many advantages such as feasible connection of DERs, reduction of conversion losses between dc output sources and loads, no reactive power issues, it is very suitable solution for new type buildings and residences interfaced with DERs and ESSs. In the bipolar-type, if it has each grid-interfaced converter, both sides (upper, lower-side) can be operated individually or collectively. A complementary power control strategy using two ESSs in both sides for effective and reliable operation is proposed in this paper. Detailed power control methods of the host controller and local controllers are described. To verify the performances of the proposed control strategy, simulation analysis using PSCAD/EMTDC is being performed where the results show that the proposed strategy provides efficient operations and can be applied to the bipolar-type dc distribution system.

A Study on Power Flow Calculation Algorithm for DC System Analysis (직류시스템 해석을 위한 조류계산 알고리즘에 관한 연구)

  • Han, Jung-Hoon;Kim, Hong-Joo;Cho, Jin-Tae;Cho, Yoon-Sung
    • 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.