• Title/Summary/Keyword: EMTP (electro-magnetic transients program)

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An Analysis on Fault Response Characteristics in Low Voltage DC Distribution System (저압직류 배전계통의 고장응답 특성 분석)

  • Noh, Chul-Ho;Gwon, Gi-Hyeon;Song, Jong-Il;Han, Joon;Oh, Yun-Sik;Kim, Chul-Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.6
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    • pp.911-917
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    • 2016
  • DC-based power system is paid attention as interests in energy efficiency and power quality are increased. However, standardization and researches for commercializing Low Voltage DC(LVDC) distribution system are still insufficient. Protection system, which is closely related with reliability, power quality, safety, and life expectancy of components in power system, is also included. This paper therefore analyzes fault response characteristics in LVDC distribution system as a preliminary study on protection schemes. A stepwise analysis on fault current from both AC/DC converter and DC/DC converter is performed and related expressions are derived. And then, modeling and simulation with various conditions are conducted by using ElectroMagnetic Transients Program (EMTP) to verify analysis results. Based on research results in the paper, direction for development of protection schemes for LVDC distribution system is suggested.

Analysis on Voltage Sag in Low Voltage DC Distribution System according to the Number of Poles (극 수에 따른 저압직류 배전계통의 순시전압강하 분석)

  • Noh, Chul-Ho;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.11
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    • pp.66-73
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    • 2015
  • AC-based power systems, having the advantages that voltage transformation and long distance transmission are easy, have been constructed since the last 19th century. However, DC-based power system is paid attention these days because of the development of power electronic devices as well as the increase of digital loads and distributed generation. For instance, the transmission systems using High Voltage DC (HVDC) are commercially operated in the world and the researches on distribution system using Low Voltage DC (LVDC) are gradually increased. This paper analyzes voltage sag, resulted from faults, in LVDC distribution system according to the number of poles. Modeling and simulation with various conditions are conducted by using ElectroMagnetic Transients Program (EMTP). Moreover, some countermeasures to reduce voltage sag in LVDC distribution system are suggested briefly.

A Study on Protective Coordination Setting of Positive Offset Mho Loss of Field Relay (Positive Offset Mho 계자 상실 계전기 보호 협조 정정에 관한 연구)

  • Kim, Kwnag-Hyun;Park, Ji-Kyung;Kim, Jun-Hyeok;Kim, Doo-Ung;Kang, Sung-Bum;Kim, Chul-Hwan;Lyu, Young-Sik;Yang, Jeong-Jae;Ko, Yun-Tae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.8
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    • pp.1326-1333
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    • 2016
  • It is important to clear the fault and prevent resulting in damage to power system. Although the frequency of generator internal fault is relatively low, it can lead to incalculable damage to power system as well as generator. Especially, loss of field on generator can cause the generator to lose synchronism for a short time if it is not removed promptly. Therefore, it is needed to conduct research on loss of field relay for detecting or clearing the loss of field. However, the setting of the relay may vary in generator operator or engineer, and the relay is not coordinated well with other elements associated with loss of field. In this paper, we address specifically the coordination of positive offset mho loss of field relay which is one of the protection schemes for loss of field. Computer simulations are performed by using ElectroMagnetic Transients Program-Restructured Version (EMTP-RV) based on actual data.