• Title/Summary/Keyword: fault and recovery

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Fault-tolerance Performance Evaluation of Fieldbus for NPCS Network of KNGR

  • Jung, Hyun-Gi;Seong, Poong-Hyun
    • Nuclear Engineering and Technology
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    • v.33 no.1
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    • pp.1-11
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    • 2001
  • In contrast with conventional fieldbus researches which are focused merely on real-time performance, this study aims to evaluate the real-time performance of the communication system including fault-tolerant mechanisms Maintaining performance in presence of recoverable faults is very important in case that the communication network is applied to a highly reliable system such as next generation Nuclear. Power. Plant (NPP). If the tie characteristics meet the requirements of the system, the faults will be recovered by fieldbus recovery mechanisms and the system will be safe. If the time characteristics can not meet the requirements, the faults in the fieldbus can propagate to the system failure. In this study, for the purpose of investigating the time characteristics of fieldbus, the recoverable faults are classified and then the formulas that represent delays including recovery mechanisms are developed. In order to validate the proposed approach, we have developed a simulation model that represents the Korea Next Generation Reactor (KNGR) NSSS Process Control System (NPCS). The results of the simulation show us the reasonable delay characteristics of the fault cases with recovery mechanisms. Using the simulation results and the system requirements, we also can calculate the failure propagation probability from fieldbus to outer system.

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Improvement of Current Limiting and Recovery Characteristics in Series Connection Type SFCL with Added Third Winding (3차권선이 추가된 직렬연결형 초전도한류기의 전류제한 및 회복 특성 향상)

  • Ko, Seok-Cheol;Han, Tae-Hee;Lim, Sung-Hun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.8
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    • pp.62-68
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    • 2014
  • The series connection type superconducting fault current limiter (SFCL) with added third winding, which was magnetically coupled in one iron core, was proposed. The proposed SFCL was expected to be more improved by just adding third winding into the conventional series connection type SFCL with two coils. To analyze the contribution of the third winding for the current limiting and the recovery characteristics of the SFCL, the short-circuit tests for the series connection type SFCL with the added third winding were performed together with the analysis on its electrical equivalent circuit. From the comparative analysis on the amplitude of the limited fault current and the power burden of the high-TC superconducting (HTSC) element comprising this SFCL, the improved current limiting and recovery characteristics of the series connection type SFCL using the third winding could be confirmed.

A Novel Reclosing Scheme in Distribution System using Carrier Signal (Carrier 신호를 이용한 배전계통의 새로운 재폐로 방식)

  • Ko, Yun-Tae;Seo, Hun-Chul;Rhee, Sang-Bong;Kim, Chul-Hwan;Kim, Jae-Chul;Hyun, Ok-Bae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.11
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    • pp.2115-2121
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    • 2009
  • This paper proposes the new reclosing scheme considering the recovery time of SFCL in distribution systems which is based on variable dead time control. The main idea is that it uses the carrier signal to distinguish whether the fault is instantaneous or permanent after tripping the line by recloser. The system and SFCL is modeled by using Electromagnetic Transient Program(EMTP) and the validity of the reclosing scheme presented in this paper is analyzed according to the fault resistance, the recovery time of SFCL and the fault clearing time.

Design of a Fault-tolerant Embedded Controllerfor Rail-way Signaling Systems

  • Cho, Yong-Gee;Lim, Jae-Sik
    • 제어로봇시스템학회:학술대회논문집
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    • 2002.10a
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    • pp.68.4-68
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    • 2002
  • $\textbullet$ This report presents an implementation a set of reusable software components which use of fault-tolerance embedded controller for railway signalling systems. These components can be used in real-time applications without application reprogramming. $\textbullet$ This library runs under VxWorks operating system and is oriented on real-time embedded systems. The library includes fault detection, fault containment, checkpointing and recovery components. $\textbullet$ The library enables to support high-speed response to fault occurrence in application software. Garbage collector together with VxWorks Watchdog provides both dead tasks detection and useless resources removing to avoid an overflow. Control flow...

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Performance of Position Based Fast Fault Recovery Protocol for Industrial Bridged Ring Networks (산업용 브리지 망을 위한 위치 기반의 신속한 망 장애 복구 절차의 성능분석)

  • Seo, Ju Sang;Yoon, Chong Ho;Park, Hong Soon;Kim, Jin Uk
    • KEPCO Journal on Electric Power and Energy
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    • v.6 no.3
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    • pp.259-269
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    • 2020
  • With the proposal-agreement procedure, RSTP can reduce the network recovery time to 400 ms or less in the case of 40 bridges. While the legacy RSTP reverts the previous agreement at the bridge with the alternate port role in the ring during the fault recovery, a new position based fast fault recovery procedure is proposed in this paper to guarantee a single proposal-agreement transaction which can provide more faster recovery. By knowing the relative position of the faulty link or bridge in hops, the bridge on the middle of the ring can complete the recovery procedure without revert. The performance of proposed procedure is numerically calculated and verified by simulation and the result shows that the recovery time can be reduced up to 100 ms, which is 1/4 times of the legacy RSTP.

Comparative Analysis on Current Limiting Characteristics of Hybrid Superconducting Fault Current Limiters (SFCLs) with First Half Cycle Limiting and Non-Limiting Operations

  • Kim, Jin-Seok;Lim, Sung-Hun;Kim, Jae-Chul
    • Journal of Electrical Engineering and Technology
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    • v.7 no.5
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    • pp.659-663
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    • 2012
  • The application of large power transformer into a power distribution system was inevitable due to the increase of power demand and distributed generation. However, the decrease of the power transformer's impedance caused the short-circuit current of the power distribution system to be increase thus, the higher short-circuit current exceeded the cut-off ratings of the protective devices such as circuit breaker. To solve these problems, several countermeasures have been proposed to protect the power system effectively from higher fault current and the superconducting fault current limiter (SFCL) has been expected to be the promising countermeasure. In spite of excellent current limiting performances of the SFCL, on the other hand, the efforts to apply the SFCL into power system has been delayed due to both the limited spaces for the SFCL's installation and its long recovery time after the fault removal. In order to solve these problems, a hybrid SFCL, which can perform either first half cycle limiting of first half cycle non-limiting operation, has been developed by corporation of LSIS (LS Industrial System) and KEPCO (Korea Electric Power Corporation). In this paper, we tried to requirements hybrid SFCL by PSCAD/EMTDC. Simulation results of our analysis of the hybrid SFCL is that its accompanied the characteristics both the limit the fault current and quick recovery caused by the less impact from superconductor.

Implementation of Under Voltage Load Shedding for Fault Induced Delayed Voltage Recovery Phenomenon Alleviation

  • Lee, Yun-Hwan;Park, Bo-Hyun;Oh, Seung-Chan;Lee, Byong-Jun;Shin, Jeong-Hoon;Kim, Tae-Kyun
    • Journal of Electrical Engineering and Technology
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    • v.9 no.2
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    • pp.406-414
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    • 2014
  • Significant penetration of induction motor loads into residential neighborhood and commercial regions of local transmission systems at least partially determine a vulnerability to a fault induced delayed voltage recovery (FIDVR) event. Highly concentrated induction motor loads with constant torque could stall in response to low voltages associated with system faults. FIDVR is caused by wide spread stalling of small HVAC units (residential air conditioner) during transmission level faults. An under voltage load shedding scheme (UVLS) can be an effective component in a strategy to manage FIDVR risk and limit the any potential disturbance. Under Voltage Load Shedding take advantage of the plan to recovery the voltage of the system by shedding the load ways to alleviation FIDVR.

Simplified Synthetic Testing Facility with Modified TRV Circuit

  • Chong, Jin-Kyo;Lee, Kyung Seob;Lee, Chang-Hoon;Kim, Gyu-Tak
    • Journal of Electrical Engineering and Technology
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    • v.13 no.2
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    • pp.881-885
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    • 2018
  • In order to develop a gas circuit breaker (GCB), the breaking performance of the short line fault (SLF) should be prioritized over that of the breaker terminal fault (BTF). In brief, it is necessary to evaluate the thermal characteristics of the insulating gas that is filled in a GCB. In the process of developing a GCB, many companies use the simplified synthetic testing facility (SSTF).In order to evaluate the SLF breaking performance of a GCB with a long minimum arcing time, a modifications to the conventional SSTF was proposed. In this study, we developed the SSTF with a modified transient recovery voltage circuit. The performance of the newly developed SSTF was verified by an $L_{90}$ breaking performance test on a rating combination of 170 kV, 50 kA, and 60 Hz.

Analysis on Current Limiting and Recovery Characteristics of a SFCL using Magnetic Coupling of Two Coils with Series Connection (직렬연결된 두 코일의 자기결합을 이용한 초전도 전류제한기의 전류제한 및 회복특성 분석)

  • Lim, Sung-Hun;Kim, Jin-Seok;Ahn, Jae-Min;Moon, Jong-Fil;Kim, Jae-Chul
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.10a
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    • pp.281-283
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    • 2008
  • The superconducting fault current limiter (SFCL) using magnetic coupling of two coils with series connection, which was suggested by us, has the merit to increase the operational current and the limiting impedance of the SFCL through the adjustment of the inductance ratio and the winding direction of two coils. In addition, the recovery characteristics of the SFCL is affected by the winding direction of two coils as well as two coils' inductance ratio. In this paper, the fault current limiting and recovery characteristics of a SFCL using magnetic coupling of two coils with series connection were analyzed. Through the analysis based on the experimental results, the recovery characteristics and the current limiting characteristics of the SFCL were confirmed to be improved more in case of the additive polarity winding.

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A Study on Digital Fault Locator for Transmission Line (송전선로용 디지털 고장점 표정장치에 관한 연구)

  • Lee, Kyung-Min;Park, Chul-Won
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.64 no.4
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    • pp.291-296
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    • 2015
  • Transmission line is exposed to a large area, and then faults are likely to occur than the other component of power system. When a fault occurs on a transmission line, fault locator helps fast recovery of power supply on power system. This paper deals with the design of a digital fault locator for improvement accuracy of the fault distance estimation and a fault occurrence position for transmission line. The algorithm of a fault locator uses a DC offset removal filter and DFT filter. The algorithm utilizes a fault data of GPS time synchronized. The computed fault information is transmitted to the other side substation through communication. The digital fault locator includes MPU module, ADPU module, SIU module, and a power module. The MMI firmware and software of the fault locator was implemented.