• Title/Summary/Keyword: distribution System

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A Reliability Analysis in LVDC Distribution System Considering Power Quality (전력품질을 고려한 LVDC 배전계통의 신뢰도 분석)

  • Noh, Chul-Ho;Kim, Chung-Mo;Kim, Doo-Ung;Gwon, Gi-Hyeon;Oh, Yun-Sik;Han, Jun;Kim, Chul-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.4
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    • pp.54-61
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    • 2015
  • Recently, DC-based power system is being paid attention as the solution for energy efficiency. As the example, HVDC (High Voltage DC) transmission system is utilized in the real power system. On the other hand, researches on LVDC (Low Voltage DC) distribution system, which are including digital loads, are not enough. In this paper, reliability in LVDC distribution system is analyzed according to the specific characteristics such as the arrangement of DC/DC converters and the number of poles. Furthermore, power quality is also taken account of since LVDC distribution system includes multiple sensitive loads and electric power converters. In order to achieve this, LVDC distribution systems are modeled using ElectroMagnetic Transient Program (EMTP) and both the minimal cut-set method and Customer Interruption Cost (CIC) are used in the reliability analysis.

A Study on the Prioritization of Sectional Switchgear Replacement for Intelligent Distribution Automation in Distribution System (배전지능화 시스템을 위한 배전계통 구분개폐기 교체 우선순위 결정에 관한 연구)

  • Sung, In-Je;Chai, Hui-Seok;Moon, Jong-Fil;Seo, In-Yong;Kim, Jae-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.9
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    • pp.51-58
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    • 2015
  • Intelligent distribution automation system includes operating a switchgear of distribution system remotely when switchgear are not available to operate quickly. This system makes it possible to reduce the interrupt time. It also aims to improve the reliability of customers. Currently, Intelligent distribution automation improves the reliability by replacing manual switchgear, which is installed as sectional switchgear. However the prioritization of the replacement for the switchgear is required for its intellectualization. Many studies have been conducted related with prioritization of switchgear replacement. But it is difficult to interpret and apply to the power distribution system. That is because most of the studies just considers customer numbers for prioritizing the replacement. In this paper presents an algorithm to determine the intelligent swichgear replacement priority considering customer number, load quantity and interruption cost. Further, this algorithm is verified by using system reliability index.

A Design of Multi-tier Structure Digital Content Distribution System based on Public Key (공개 키 기반의 계층 구조를 갖는 디지털콘텐트 분배 시스템의 설계)

  • Ko, Il-Seok;Na, Yun-Ji;Cho, Dong-Wook
    • The KIPS Transactions:PartA
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    • v.11A no.2
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    • pp.175-180
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    • 2004
  • Generally, as for the multimedia high quality contents, an illegality facsimile is possible without a damage of a quality. Also a distribution of contents duplicated illegality in an Internet is giving a great economic loss to digital contents provider. Therefore, a study for security and efficient distribution of digital contents is required. The most important issues in a design of digital contents distribution system are a user convenience, an execution speed and a security. In this study, we designed digital contents distribution system that used a web caching technology and an encryption/decryption technique on hierarchical structure. The proposed system was the digital contents distribution system that improved a security and execution speed, a convenience of a user. Also it verified performance superiority of a proposed system by an examination.

A New Distribution System Power Flow Method Using Symmetrical Components (대칭성분을 이용한 3상 배전계통 조류계산 기법)

  • Choe, Jeong-Hwan;Jeong, Seong-Il;Park, Je-Yeong;Kim, Gwang-Ho;Kim, Jae-Eon;Park, Jong-Geun
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.1
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    • pp.15-22
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    • 2002
  • This paper proposes a new power flow method for distribution system analysis by modifying the conventional back/forward sweep method using symmetrical components. Since the proposed method backward and forward sweeps with the variables expressed by symmetrical components, this method reduces computation time for matrix calculations; therefore, it is able to reduce the computational burden for real-time distribution network analysis. The proposed method was also developed to effectively analyze the unbalanced distribution system installing AVR(Auto Voltage Regulator), shunt capacitors. The proposed algorithm was compared with the conventional Back/forward Sweep method by applying both methods to three phase unbalanced distribution system of IEEE 123-bus model, and the test results showed that the proposed method would outperformed the conventional method in real-time distribution system analysis.

Development of an Algorithm for Detecting High Impedance Fault in Low Voltage DC Distribution System using Accumulated Energy of Fault Current (고장전류의 누적 에너지를 이용한 저압직류 배전계통의 고저항 지락고장 검출 알고리즘 개발)

  • Oh, Yun-Sik;Noh, Chul-Ho;Kim, Doo-Ung;Gwon, Gi-Hyeon;Han, Joon;Kim, Chul-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.5
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    • pp.71-79
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    • 2015
  • Recently, new Low Voltage DC (LVDC) power distribution systems have been constantly researched as uses of DC in end-user equipment are increased. As in conventional AC distribution system, High Impedance Fault (HIF) which may cause a failure of protective relay can occur in LVDC distribution system as well. It, however, is hard to be detected since change in magnitude of current due to the fault is too small to detect the fault by the protective relay using overcurrent element. In order to solve the problem, this paper presents an algorithm for detecting HIF using accumulated energy in LVDC distribution system. Wavelet Singular Value Decomposition (WSVD) is used to extract abnormal high frequency components from fault current and accumulated energy of high frequency components is considered as the element to detect the fault. LVDC distribution system including AC/DC and DC/DC converter is modeled to verify the proposed algorithm using ElectroMagnetic Transient Program (EMTP) software. Simulation results considering various conditions show that the proposed algorithm can be utilized to effectively detect HIF.

A Restoration Automation Algorithm on a Fault in Substation of SCADA-coordinated Distribution Automation System (SCADA가 통합된 배전자동화 시스템의 변전소 사고 시 복구 자동화 알고리즘)

  • Hong, Jun-Ho;Lim, Il-Hyung;Lee, Seung-Jae;Kim, Tae-Wan;Choi, Myeon-Song;Ha, Bok-Nam;Lee, Sung-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.11
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    • pp.2107-2114
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    • 2009
  • It is impossible to take the instant action in the distribution system When fault occures in a substation because operation of the substation and the distribution system are separated. However the power system automation has been studying about unity operation and co-operation between SCADA and DAS(Distribution Automation System). In this paper proposes a new algorithm of efficiency restoration using a outage load switching to a healthy MTR a fault occurrence at a MTR in united system between DAS and SCADA. In addtion, proposed algorithm includes a outage restoration method which keeps MTR optimal capacity with reorganization of distribution network in case it can not restore outage state loads caused by shortage of healthy MTR remain capacity. In case that proposed sequence still can not complete restoration, this paper suggests a efficiency outage restoration with objective function included priority in outage loads. In the case studies, the proposed algorithm have been verified in 2 MTR and 3 MTR substation

Design of a Cooperative Voltage Control System Between EMS (VMS) and DMS

  • Shin, Jeonghoon;Lee, Jaegul;Nam, Suchul;Song, Jiyoung;Oh, Seungchan
    • KEPCO Journal on Electric Power and Energy
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    • v.6 no.3
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    • pp.279-284
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    • 2020
  • This paper presents the conceptual design of a cooperative control with Energy Management System (EMS) and Distribution Management System (DMS). This control enables insufficient reactive power reserve in a power transmission system to be supplemented by surplus reactive power in a power distribution system on the basis of the amount of the needed reactive power reserve calculated by the EMS. This can be achieved, because increased numbers of microgrids with distributed energy resources will be installed in the distribution system. Furthermore, the DMS with smart control strategy by using surplus reactive power in the distribution system of the area has been gradually installed in the system as well. Therefore, a kind of hierarchical voltage control and cooperative control scheme could be considered for the effective use of energy resources. A quantitative index to evaluate the current reactive power reserve of the transmission system is also required. In the paper, the algorithm for the whole cooperative control system, including Area-Q Indicator (AQI) as the index for the current reactive power reserve of a voltage control area, is devised and presented. Finally, the performance of the proposed system is proven by several simulation studies.

Analysis on Bus Voltage Sag in Power Distribution System with SFCL according to Interconnected Locations of Small DG (초전도 한류기 적용시 소형 분산전원시스템의 연계 위치에 따른 배전계통의 전압강하 분석)

  • Moon, Jong-Fil;Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.62 no.4
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    • pp.210-215
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    • 2013
  • This paper analyze the bus voltage sags in the power distribution system with a small scale cogeneration system when the superconducting fault current limiter was introduced. Among the solutions to decrease the short-circuit current considering the locations of the small scale cogeneration system, the superconducting fault current limiter (SFCL) has been announced as one of the promising methods to reduce the fault current because the installation of the small scale cogeneration system which increases the short-circuit current. According to the application locations of the small scale cogeneration system in a power distribution system, it has caused the variations of voltage sag and duration which depends on the change of the short-circuit current, which can make the operation of the protective device deviate from its original set value when the fault occurs. To investigate the voltage sag when a SFCL was applied into a power distribution system where the small scale cogeneration system was introduced into various locations, the SFCL, small scale cogeneration system, and power system are modeled using PSCAD/EMTDC. In this paper, the effects on voltage sags are assessed when the SFCL is installed in power distribution system with various locations of the small scale cogeneration system.

Bus-voltage Sag Suppressing and Fault Current Limiting Characteristics of the SFCL Due to its Application Location in a Power Distribution System

  • Kim, Jin-Seok;Lim, Sung-Hun;Kim, Jae-Chul
    • Journal of Electrical Engineering and Technology
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    • v.8 no.6
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    • pp.1305-1309
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    • 2013
  • The application of the superconducting fault current limiter (SFCL) in a power distribution system is expected to contribute the voltage-sag suppression of the bus line as well as the fault-current reduction of the fault line. However, the application effects of the SFCL on the voltage sag of the bus line including the fault current are dependent on its application location in a power distribution system. In this paper, we investigated the fault current limiting and the voltage sag suppressing characteristics of the SFCL due to its application location such as the outgoing point of the feeder, the bus line, the neutral line and the 2nd side of the main transformer in a power distribution system, and analyzed the trace variations of the bus-voltage and fault-feeder current. The simulated power distribution system, which was composed of the universal power source, two transformers with the parallel connection and the impedance load banks connected with the 2nd side of the transformer through the power transmission lines, was constructed and the short-circuit tests for the constructed system were carried out. Through the analysis on the short-circuit tests for the simulated power distribution system with the SFCLs applied into its representative locations, the effects from the SFCL's application on the power distribution system were discussed from the viewpoints of both the suppression of the bus-voltage sag and the reduction of the fault current.

A Comparative Study on the Electric Power Efficiency of IDCs with AC and DC Distribution Systems (교류배전시스템과 직류배전시스템이 적용된 IDC 전력효율 비교연구)

  • Son, Sung-Yong;Mok, Hyung-Soo;Park, Kyung-Seok;Hong, Jun-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.8
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    • pp.38-44
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    • 2008
  • Internet Data Centers (IDCs), which are resulted by the rapid progress of Information Technology industry, consist of high-density digital loads with internet server systems. Introduction of DC distribution system may simplify the conventional electric power conversion system, and may result in the improvement of electric power efficiency. However, this conjecture has never been tested under Korean IDC environment. In this study, electric power efficiency of DC distribution system from KT Namsuwon IDC is contrasted with that of conventional AC distribution system from KT Bundang IDC. DC 48[V] based distribution system showed 13.2[%] higher efficiency than the conventional AC based distribution system. The further analysis with the assumption of DC 380[V] suggests efficiency improvement over 25[%] can be achieved.