• Title/Summary/Keyword: Over current relay(OCR)

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A Study on the Over Current Relay Misoperation in Power System with Distributed Generations (분산전원 연계 계통에서의 과전류계전기 오동작에 관한 연구)

  • Park, Jong-Il;Lee, Kyebyung;Park, Chang-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.12
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    • pp.1705-1710
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    • 2018
  • This paper deals with an analysis of the causes of over current relay(OCR) misoperation in power system with distributed generations(DG). In general, Y-D and Y-Y-D transformer connections are used for grid interconnection of DG. According to the interconnection guideline, the neutral point on Y side should be grounded. However, these transformer connections can lead to OCR misoperation as well as over current ground relay(OCGR) misoperation. Several researches have addressed the OCGR misoperation due to the interaction between transformer connections and zero-sequence voltage of distribution system. Recently, a misoperation of OCR at the point of DG interconnection to the utility system has been also reported. With increasing the interconnections of DG, such OCR as well as OCGR misoperations are expected to increase. In this paper, PSCAD/EMTDC modeling including DG interconnection transformer was performed and various case studies was carried out for identifying the cause of OCR misoperation.

Response characteristic of over current relay using optical sensor (광센서를 이용한 과전류 보호계전의 응답특성 연구)

  • 박병석;안성준;조홍근
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.1364-1366
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    • 1997
  • To operate electric power systems economically and stably, and to supply the electric power of good quality, it is necessary that the measured information (current, voltage, and so on) be detected and transmutted with high reliability and high effieincy. For the reason, the optical magnetic field sensor is possible to rapidly detect to over current and recover when electric power line have fault. In addition, the optical sensor have no electro magnetic distortion and no electric insulation. In this study, we designed OCR(Over Current Relay) using optical sensor. The designed OCR using optical sensor was measured characteristic and compared contentional OCR. This system have highest optical advantages and reliability.

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A Novel Digital Over Current Relay with Variable Time-Current Characteristics for Protective Coordination

  • Park, M. S.;P. S. Cho;Lee, S. J.;S. H. Hyun;Kim, K. H.
    • KIEE International Transactions on Power Engineering
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    • v.2A no.3
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    • pp.83-88
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    • 2002
  • An over current relay(OCR), one of the most frequently used protective devices, has time-current characteristics (TCC) to control its trip time according to the current level. It is because an appropriate operating time interval is necessary for coordination with other protective devices. A set of TCC curves of an OCR is, in general, given by the supplier from which a curve is selected by the operator. Therefore, in many cases, it is impossible to consider the operation condition of the given power system exactly. A novel concept of an OCR is suggested in this paper. The proposed OCR has an internal correction module so that it may produce the most adequate TCC curve according to the given protective information for coordination with other devices. With the generated TCC curve, a variety of operation and coordination conditions can be taken into consideration in an effective manner. The suggested OCR is applied to a simple test power system to show very promising results from a coordination point of view.

The Modeling of OverCurrent Relay using Dynamic Link Library (Dynamic Link Library 기법을 이용한 과전류 계전기 모델링)

  • Seong, No-Kyu;Seo, Hun-Chul;Yeo, Sang-Min;Kim, Chul-Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.6
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    • pp.1065-1070
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    • 2009
  • This paper presents the new technique of modeling using Dynamic Link Library(DLL) in ElectroMagnetic Transients Program - Restructured Version(EMTP-RV) in which we have simplified the procedures of OverCurrent Relay(OCR) modeling. The DLL function is designed to allow EMTP-RV users to develop advanced program model modules and interface them directly and intimately with the EMTP-RV engine. The modeled OCR is verified by simulating the various fault cases in the distribution system. Also, the performance for the modeling of OCR using DLL is compared with that of the method using the control components of EMTP-RV and using EMTP/MODELS. The results show the validity of modeled OCR and the effectiveness of the method using DLL function.

Implementation of Optoelectric Over Current Relay (광전자식 과전류 보호계전기의 구현에 관한 연구)

  • Park, Byung-Seok;Oh, Myun-Taek;Lee, Hwa-Joon;Cho, Hong-Keun
    • Proceedings of the KIEE Conference
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    • 1998.07e
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    • pp.1846-1849
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    • 1998
  • An optical magnetic filed sensor, YIG (Yittrium Iron Garnet), response rapidly, to the power-line currents to be measured. In response to Faraday effect, it shows wide-and-linear measurable range. This paper reports the development and implementation of an OOCR (Optoelectric OverCurrent Relay) using this sensor. This relay is free from environmental electro-magnetic noises and has excellent insulation characteristics inherently. By using this OOCR, we can reduce insulation cost of protective relaying systems and its maintenance cost, and can achieve high reliability of the system.

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Time Delay Limit of Over Current Relay for Maintaining Stability in Industrial Power Systems (산업용 전력계통의 안정도 유지를 위한 과전류계전기의 시간지연 한계)

  • Kim, Bong-Hee
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.190-192
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    • 2002
  • The industrial power distribution system is a radial system and therefore usually protected with time delayed over current relays (OCR's). Proper time dial settings are provided at the OCR's. Meanwhile, the systems, where synchronous generator, or synchronous motors, or large induction motors are operating, can not be protected with only OCR's with time grading. This paper presents a technical limit and a suitable range of time delay in applying OCR's to clearing faults in the industrial power systems for maintaining stability. Dynamic simulations are made to show them employing a real power systems of a large petro-chemical complex.

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A Study on communication method between OverCurrent Relay Agents using DNP 3.0 (DNP3.0을 이용한 과전류 계전기 에이전트의 통신 방안 연구)

  • Lee, H.W.;Jung, K.H.;Lim, S.I.;Hyun, S.H.;Choi, M.S.;Lee, S.J.
    • Proceedings of the KIEE Conference
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    • 2002.11b
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    • pp.265-267
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    • 2002
  • In this paper, the communication between Over-Current Relay agents is realized using DNP(Distributed Network Protocol), which is the standard communication protocol of distribution automation system in KEPKO. The key words in OCR agent communication are defined and represented by use of DNP application function code. And the DNP index for OCR agent is defined. The proposed communication scheme is tested by use of Communication Test Harness, a test tool for DNP protocol to show its soundness.

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An Autonomous Optimal Coordination Scheme in a Protection System of a Power Distribution Network by using a Multi-Agent Concept

  • Hyun, Seung-Ho;Min, Byung-Woon;Jung, Kwang-Ho;Lee, Seung-Jae;Park, Myeon-Song;Kang, Sang-Hee
    • KIEE International Transactions on Power Engineering
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    • v.2A no.3
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    • pp.89-94
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    • 2002
  • In this paper, a protection system using a Multi-Agent concept for power distribution networks is proposed. Every digital over current relay(OCR) is developed as an agent by adding its own intelligence, self-tuning and communication ability. The main advantage of the Multi-Agent concept is that a group of agents work together to achieve a global goal which is beyond the ability of each individual agent. In order to cope with frequent changes in the network operation condition and faults, an OCR agent, suggested in this paper, is able to detect a fault or a change in the network and find its optimal parameters for protection in an autonomous manner considering information of the whole network obtained by communication between other agents. Through this kind of coordination and information exchanges, not only a local but also a global protective scheme is completed. Simulations in a simple distribution network show the effectiveness of the suggested protection system.

Analysis of effects of OCR in operation mode during fault ocuurs in Distribution System (배전계통 내 고장발생시 운전모드가 과전류계전기에 미치는 영향 분석)

  • Kim, Yong-Hwan;Rhee, Sang-Bong;Kim, Chul-Hwan
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.563-564
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    • 2015
  • Recently, distributed generation using renewable energy resources have increased due to the limitation of conventional energy. To utilize these energy source effectively, a method of applying the energy storage system(ESS) in distribution system has been considered. In this paper, we simulated the one line-to-ground fault in power system with ESS. Based on these simulations, we analyzed the effect on Over Current Relay(OCR) operation. As a result, ESS operation modes result fault current fluctuation. Thus, OCR need to reset the pick up current. This paper analyze effect of ESS in distribution system according to OCR setting by using ElectroMagnetic Transient Program(EMTP).

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Analysis of an Active Superconducting Current Controller (ASCC) Considering the Transient Stability and OCR Operation in Transmission and Distribution Systems

  • Gusheh, Ahmad Ghafari;Soreshjani, Mohsen Hosseinzadeh;Rahat, Omid
    • Journal of Electrical Engineering and Technology
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    • v.11 no.3
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    • pp.543-550
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    • 2016
  • The Active Superconducting Current Controller (ASCC) is a new type of Superconducting Fault Current Limiters (SFCL) which can limit the fault current in different modes. It also has the particular abilities of compensating active and reactive powers for electrical networks. In this paper, it is confirmed that the performance of ASCC in different operating modes introduces a limiting impedance in series with the network which can even degrade the transient stability and the operation of the Over-Current Relays (OCR) employed in a power system. In addition, the model of a three-phase ASCC is simulated, and the effect of descriptive modes on the current limiting level is investigated. For the transient stability analysis, a single machine-infinite bus system is tested, and the effect of operation modes is studied based on an equal area criterion obtaining the critical time and the critical angle. Modifying the setting parameters of OCR such as time dial and pick-up current, the protective coordination is also studied in different operating modes.