• 제목/요약/키워드: Low-voltage Distribution System

검색결과 201건 처리시간 0.029초

Quantitative Evaluation of the Impact of Low-Voltage Loads due to Repetitive Voltage Sags

  • Yun Sang-Yun;Kim Jae-Chul;Moon Jong-Fil;Kang Bong-Seok
    • KIEE International Transactions on Power Engineering
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    • 제5A권3호
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    • pp.293-299
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    • 2005
  • Automatic reclosing is a typical protection method in power distribution systems for the clearing of temporary faults. However, it has a fatal weakness in regards to voltage sags because it produces repetitive voltage sags. In this paper, we explored the repetitive impact of voltage sag due to the automatic reclosing of power distribution systems. The actual tests of low voltage loads were carried out for obtaining the susceptibility of voltage sags. The final results of the tests yielded power acceptability curves of voltage sag, and the curves transformed the 3-dimensional CBEMA (Computer Business Equipment Manufacturer Association) format. For the quantitative evaluation of the impact of repetitive voltage sags, an assessment formulation using the voltage sag contour was proposed. The proposed formulation was tested by using the voltage sag contour data of IEEE standard and the results of the test. Through the case studies, we verified that the proposed method can be effectively used to evaluate the actual impact of repetitive voltage sags.

PMSG 풍력발전시스템에서 전원 저전압 발생시 비틀림 진동 동특성 시뮬레이션 (Simulation of Dynamic Torsional Vibration during Grid Low Voltage in a PMSG Wind Power Generation System)

  • 권순형;송승호;최주엽;정승기;최익
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2011년도 전력전자학술대회
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    • pp.242-244
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    • 2011
  • A wind generator system model includes wind model, rotor dynamics, synchronous generator, power converter, distribution line and infinite bus. This paper investigates the low-Voltage Ride-Through capability of PMSG wind turbine in a variable speed. The drive train of a wind turbine on 2-mass modeling can observe the shaft torsional vibration when the low-voltage occur. To reduce the torsional vibration when the low-voltage occur, this paper designs suppression control algorithm of the torsional vibration and implements simulation. A Matlab/Simulink is used to investigate the response during the transient state.

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휴리스틱 탐색전략을 이용한 배전계통 계획의 급전선 최적 경로 선정 (Optimal Feeder Routing for Distribution System Planning Using a Heuristic Strategy)

  • 최남진;김병섭;신중린
    • 대한전기학회논문지:전력기술부문A
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    • 제49권11호
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    • pp.566-574
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    • 2000
  • This paper propose a heuristic algorithm based on the Branch-Exchange (BE) method to solve Optimal feeder Routing(OFR) problem for the distribution system planning. The cost function of the OFR problem is consisted of the investment cost representing the feeder installation and the system operation cost representing the system power loss. We propose a properly designed heuristic strategy, which can handle the horizon-year expansion planning problem of power distribution network. We also used the loop selection method which can define the maximum loss reduction in the network to reduce calculation time, and proposed a new index of power loss which is designed to estimate the power loss reduction in the BE. The proposed index, can be considered with both sides, the low voltage side and voltage side branch connected with tie one. The performances of the proposed algorithms and loss index were shown with 32, 69 example bus system.

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자율운전에 의한 계통연계형 도서의 저압 무순단 마이크로그리드 구축 (Development of Low-voltage Seamless Transfer Microgrid on Grid-connected Type Islands by Autonomous Operation)

  • 김정헌;권정민;윤상윤
    • 전기학회논문지P
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    • 제66권4호
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    • pp.169-176
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    • 2017
  • This paper presents research on low-voltage microgrids to maintain a continuous power supply to critical loads on grid-connected islands in Korea. The low-voltage microgrids of this paper focused on that changes public office buildings into uninterrupted microgrids by autonomous operation. For this, a microgrid controller (MGC) and a power conditioning system (PCS) that allow a seamless transfer between grid-connected and grid-isolated operation are proposed. The proposed PCS operates with a silicon controlled rectifier (SCR) switch and employs a simple structure. It supplies power continuously without operators through a coordinated operation between MGC and PCS. In addition, proposed MG has a schedule operation for minimizing electricity charges and provides ancillary services that enable the utilization of resources according to the operation purpose of utility distribution networks. To demonstrate the uninterrupted low-voltage microgrid proposed in this study, a microgrid was implemented and tested in a public office building in Anjwa Island, Jeollanam-do in Korea. A seamless, autonomous operation history, despite system disturbances, was obtained through a long-term demonstration of operation. The results showed that the proposed microgrid technology can be used to achieve energy resilience in grid-connected island areas.

전압변동과 부하량을 고려한 저압배전계통의 분산전원 설치용량 분석 (The Study on Permissible Capacity of Distributed Generation Considering Voltage Variation and Load Capacity at the LV Distribution Power System)

  • 문원식;조성민;신희상;이희태;한운기;추동욱;김재철
    • 전기학회논문지P
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    • 제59권1호
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    • pp.100-105
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    • 2010
  • This paper describes a capacity of distributed generation which will be interconnected at low voltage distribution systems. In order to set the capacity of distributed generation, a voltage variation of distribution system is considered. Besides, the capacity of distributed generation is classified according to a capacity of pole transformer and loads. The system constructions in this paper are analyzed by using PSCAD/EMTDC. In the immediate future, it is expected to increase the installation of New and renewable energy systems which are generally interconnected to distribution power systems in the form of distributed generations like photovoltaic system, wind power and fuel cell. So the study of this kind would be needed to limit the capacity of distributed generation.

상전압 및 선간전압에 대한 불평형율 (Voltage Unbalance Factor for Phase and Line Voltage)

  • 김종겸;박영진;이동주;이종한;이은웅
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2005년도 춘계학술대회논문집
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    • pp.74-77
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    • 2005
  • Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, voltage unbalance is generated at the user's 3-phase 4-wire distribution systems with single & three phase. Voltage unbalance is mainly affected by load system rather than power system. Unbalanced voltage will draws a highly unbalanced current and results in the temperature rise and the low output characteristics at the machine. It is necessary to analyse correct voltage unbalance factor for reduction of side effects in the industrial sites. Voltage unbalance is usually defined by the maximum percent deviation of voltages from their average value, by the method of symmetrical components or by the expression in a more user-friendly form which requires only the three line voltage readings. If the neutral point is moved at the 3-phase 4-wire system by the unbalanced load, by the conventional analytical method, line and phase voltage unbalance leads to different results due to zero-sequence component. This paper presents a new analytical method for phase and line voltage unbalance factor in 4-wire systems. Two methods indicate exact results.

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배전계통에서 UPFC를 이용한 순시전압상승 보상 (Voltage Swell Compensation using an UPFC in Distribution System)

  • 장원혁;이상봉;이명희;김철환
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 제39회 하계학술대회
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    • pp.488-489
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    • 2008
  • Based on the fact that renewable energies such as photovoltaic, wind power, etc. are increasingly used in distribution systems recently which affects overvoltage, this paper implements an unified power flow controller(UPFC) to compensate voltage swell. The implemented scheme employs an ac chopper and a low-pass filter along with a series transformer. The ac chopper converts the amplitude of the voltage down to the nominal value. The low pass filter makes the rough waveform of the output voltage of the ac chopper due to switching smoothly by eliminating harmonics. To verify the effectiveness of the implemented UPFC, the results by Electro-Magnetic Transients Program(EMTP) are presented for various overvoltage cases.

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신 에너지전원설비의 배전계통 연계에 의한 단락용량 검토 (Impacts on short-circuit capacity by interconnection of new energy source generation into the distribution system)

  • 김응상;김슬기
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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    • pp.476-479
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    • 2001
  • Interconnection of new energy sources, such as photovoltaic generation, wind power generation, etc., into the electric power distribution system may result in the increasing short-circuit capacity when a short circuit fault occurs. The short-circuit capacity becomes over the interrupting ratings of circuit breakers, and then they fails to operate in the proper way they prevent fault currents from flowing into the distribution facilities and thus causing them serious damages. This study deals with impacts on the respective short-circuit capacity of both low voltage and extra high voltage distribution systems at which new energy sources are installed. In order to obtain more accurate and all-case values very close to reality in the complicated distribution system, computer simulation tools should be required. In this paper, however, its focus is placed on examining the varying trend of short-circuit capacity, which may happen owing to new energy source interconnection, as a previewing step for exhaustive simulation studies.

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저압직류 배전계통의 구성 형태를 고려한 공급신뢰도 분석에 관한 연구 (A Study on the Reliability Analysis in LVDC Distribution System Considering Layout)

  • 김충모;노철호;한준;오윤식;김현수;백인호;김철환
    • 조명전기설비학회논문지
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    • 제29권2호
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    • pp.75-81
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    • 2015
  • At the end of the 19th century, Edison's DC power system and Tesla's AC power system was debated in power market. Finally, AC system became the primary system of the power market because both step-up and step-down of voltage by using transformer and long-distance power transmission are easily possible. However, nowadays the power market takes some action for introducing DC system. Both domestic and foreign researchers are conducting the study on the DC system as well. Some researchers have conducted the studies on power quality and economic evaluation of the DC distribution system but DC distribution system is still controversial in terms of the effectiveness and reliability. In this paper, we calculate the reliability indices of the Low Voltage Direct Current(LVDC) distribution system considering arrangement of power electronics, layout of the distribution system, and distance between load points.

A novel approach for optimal DG allocation in distribution network for minimizing voltage sag

  • Hashemian, Pejman;Nematollahi, Amin Foroughi;Vahidi, Behrooz
    • Advances in Energy Research
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    • 제6권1호
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    • pp.55-73
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    • 2019
  • The cost incurred by voltage sag effect in power networks has always been of important concern for discussions. Due to the environmental constraints, fossil fuel shortage crisis and low efficiency of conventional power plants, decentralized generation and renewable based DG have become trends in recent decades; because DGs can reduce the voltage sag effect in distribution networks noticeably; therefore, optimum allocation of DGs in order to maximize their effectiveness is highly important in order to maximize their effectiveness. In this paper, a new method is proposed for calculating the cost incurred by voltage sag effect in power networks. Thus, a new objective function is provided that comprehends technical standards as minimization of the cost incurred by voltage sag effect, active power losses and economic criterion as the installation and maintenance costs of DGs. Considering operational constraints of the system, the optimum allocation of DGs is a constrained optimization problem in which Lightning Attachment procedure optimization (LAPO) is used to resolve it and is the optimum number, size and location of DGs are determined in IEEE 33 bus test system and IEEE 34 bus test system. The results show that optimum allocation of DGs not only reduces the cost incurred by voltage sag effect, but also improves the other characteristics of the system.