• 전기학회논문지
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• 제64권1호
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• pp.182-187
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• 2015

In the three-phase power system, when any one-phase or two-phases is open-phase, the unbalanced current flows and the single-phase power supplies to three-phase loads. Specially, motor coil and transformer coil receive over-current. As a result, great damage as well as electrical fire can occur to the power system. In order to improve these problems, this paper proposes that an open-phase detection device is designed by a new algorithm using electric potential difference between the resultant voltage of neutral point and ground, and a control circuit topology of open-phase protector is composed of highly efficient semiconductor devices. It improves response speed and reliability. The control algorithm circuit also operates the cut-off of a conventional residual current protective device (RCD) which flows an enforced leakage current to ground wire at open-phase accident. Furthermore, time delay circuit is added to prevent the incapable operation of open-phase protector about instantaneous open-phase not open-phase fault. The time delay circuit improves more reliability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.737-739
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• 1996

Abnormal conditions and disturbances in distribution system cause an immediate influence to the customers. Conventional detection schemes for the distribution abnormalities have been applied in limited extents mainly because of their low reliability. In this paper, we developed a disturbance identification system which monitors the load level after a transient, checks the harmonic behavior of the load, and finally makes decision on the cause of the disturbance. This system identifies and discriminates overcurrent faults, arcing ground faults, recloser activities, and foreign object or tree contacts. In the implementation of the identification system, we applied fuzzy logic to better represent some variables whose Quantities are expressed only in non-numerical terms.

• 전기학회논문지
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• 제61권7호
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• pp.937-943
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• 2012

Most of faults occurred in transmission lines are single-phase to ground faults and transient faults. Single-phase auto reclosing is an appropriate scheme to maintain the system stability and restore the system effectively when those faults are occurred. In single-phase auto reclosing scheme, the secondary arc is generated after faulted phase is tripped to eliminate the fault and it is sustained by the capacitive and inductive coupling to the healthy phases. It is important to reclose the faulted phase after fully extinction of secondary arc because of the damage applied to system. Therefore, it is necessary to research on the detection of secondary arc extinction to ensure high success rate of reclosing. In this step, firstly, the accurate modelling of secondary arc should be performed. In this paper, the modelling of secondary arc is performed by using EMTP-RV and the simulation results show that the implemented model is correct and effective.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 추계학술대회
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• pp.9-11
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• 2018

This paper studies on the development of an electric fire prevention system with the detection and alarm in case of parallel arc fault occurrence in low voltage distribution lines. The proposed detector has the characteristics of high speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. The line voltage is always feedback, and when an arc or a spark occurs, these are detected by the microcomputer. In addition, we design and develop algorithms using high speed and high precision microcomputer. A new conceptual control technique is adopted that RCD cuts-off by forming a forced short circuit between the phase voltage and ground in the event of an electrical accident. Some experimental tests of the proposed system also confirm practicality and the validity of the analytical results.

• 한국안전학회지
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• 제12권3호
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• pp.166-172
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• 1997

배전선로에서 지락사고가 발생할 경우 신속한 검출은 감전사고 예방, 전기화재 방지 및 전력설비의 최적 운용에 있어서 중요하다. BEF(Back-fed Earth Fault)는 일종의 배전선로 지락사고로 부하측이 지락되는 경우이며 지락전류가 매우 작기 때문에 전류 검출에 의하여 배전 계통을 보호하기는 어려우나 배전 자동화 지역에서는 UVR(Under Voltage Relay)을 이용하여 보호한다. 그러나 배전 자동화가 되지 않은 지역에서는 UVR에 의해 보호가 불가능하므로 BEF의 특성을 해석하여 경제적으로 BEF를 방지하여야 한다. 본 논문에서는 RTDS, EMTP 시뮬레이션, ETSA의 실증 시험 데이터를 비교, 검토하여 기준 영상전류치를 설정하고, 이를 적용하여 측정된 영상 전류와 설정된 기준치를 비교하여 3상-단일 접지 배전 시스템의 정상 상태와 BEF의 구분이 가능한 BEF검출 알고리즘을 제안하였다. 다양한 조건에서 ETSA의 현장 시험에 적용하여 검토한 결과 3상-단일 접지 배전 시스템에서 제안된 BEF 검출 알고리즘의 타당성이 입증되었다. 따라서 본 알고리즘을 적용하여 배전선로를 운용하면 BEF에 의한 재해의 예방이 가능하리라 사료된다.

• Spatial Information Research
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• 제14권1호
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• pp.57-65
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• 2006

일반적으로 퇴적물 준설에 대한 조사는 GPS/Echo Sounder 및 Total Station/Echo Sounder를 조합한 음파탐사 방법을 이용하여 대상지의 수평위치 및 수심에 대한 관측을 실시하고 있으며, 하상의 단면계산, 저수량 및 준설계획량 등을 추정하게 된다. 이후 준설계획에 대한 계획고 및 준설토량에 대한 세부적인 계획을 수립하게 된다. 하지만 Echo Sounder를 사용하는 음파탐사 방법은 퇴적물에 대한 정확한 분포를 파악할 수 없는 단점이 있다. 본 연구는 저수지 하부의 퇴적물 및 이의 분포를 파악하여 저수지 준설계획을 수립하여 기존의 탐사방법에 대한 준설능력 향상에 중점을 두었다. 또한 기존의 음파탐사 방식과 다른 레이더탐사 장비를 이용한 GPS/GPR(Ground Penetration Radar)을 사용하여 저수지의 수평위치, 수심값을 결정하고 동시에 원지반에 분포하고 있는 퇴적물의 분포를 추정, 준설에 적용하고자 하였다. 우선 현장의 시료채취를 통한 수조모형실험을 실시하여 장비에 대한 정확도 검증을 거친 후 현장적용에 적용하여 그 가능성을 평가하였다.

• 제어로봇시스템학회논문지
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• 제11권7호
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• pp.633-643
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• 2005

An unmanned aerial vehicle (UAV) is an aircraft controlled by .emote commands from ground station and/o. pre-programmed onboard autopilot system. A navigation system in the UAV provides a navigation data for a flight control computer(FCC). The FCC requires accurate and reliable position, velocity and attitude information for guidance and control. This paper proposes an ADGPS/INS integrated navigation system for a UAV. The proposed navigation system comprises an attitude determination GPS (ADGPS) receive., a navigation computer unit, and a low-cost commercial MEMS inertial measurement unit(IMU). The navigation algorithm contains a fault detection and isolation (FDI) function fur integrity. In order to evaluate the performance of the proposed navigation system, two flight tests were preformed using a small aircraft. The first flight test was carried out to confirm fundamental operation of the proposed navigation system and to check the effectiveness of the FDI algorithm. In the second flight test, the navigation performance and the benefit of the GPS attitude information were checked in a high dynamic environment. The flight test results show that the proposed ADGPS/INS integrated navigation system gives a reliable performance even when anomalous GPS data is provided and better navigation performance than a conventional GPS/INS integration unit.

• 문화기술의 융합
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• 제6권4호
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• pp.783-788
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• 2020

낙뢰의 직격이나 유도에 의해 발생되는 서지, 전력계통의 차단기의 빈번한 개폐동작 등은 과도 과전압이 발생하며 이는 변압기, 차단기, 전력기기의 정상운전에 지장을 초래하게 된다. 본 연구는 이러한 현상을 예방하기 위해 전력기기 또는 선로에 피뢰기를 병렬로 설치하여 대책을 수립하는 방법에서 한층 더 나아가 원격으로 피뢰기의 상태를 점검하며 이벤트 발생 시 즉각적인 대책을 마련하여 부가적으로 발생하는 피해를 미연에 방지함에 그 연구의 목적이 있다.

• 한국전기전자재료학회논문지
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• 제31권4호
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• pp.255-260
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• 2018

In recent years, increasing electricity use has led to considerable interest in green energy. In order to effectively supply, cut off, and operate an electric power system, many electric power facilities such as gas insulation switch (GIS), cable, and large substation facilities with higher densities are being developed to meet demand. However, because of the increased use of aging electric power facilities, safety problems are emerging. Electromagnetic wave and leakage current detection are mainly used as sensing methods to detect live-line partial discharges. Although electromagnetic sensors are excellent at providing an initial diagnosis and very reliable, it is difficult to precisely determine the fault point, while leakage current sensors require a connection to the ground line and are very vulnerable to line noise. The partial discharge characteristic in particular is accompanied by statistical irregularity, and it has been reported that proper statistical processing of data is very important. Therefore, in this paper, we present the results of analyzing ${\Phi}-q-n$ cluster distributions of partial discharge characteristics by using K-means clustering to develop an expert partial discharge diagnosis system generated in a GIS facility.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권12호
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• pp.562-567
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• 2003

Lightning arresters are deteriorated by repetition of protective operation against overvoltages or impulse currents in environments of its use. If a deteriorated arrester is left in power lines, it can lead to an accident such as a line to ground fault even in a normal system. Therefore, it is necessary to eliminate the deteriorated arrester in advance by checking the soundness of arresters on a regular basis, and to ensure the reliability of power systems by preventing accidents. Various deterioration diagnostic techniques and devices are suggested, and most of which measure leakage current components as an indicator of arrester ageing. However, the techniques based on the magnitude of leakage current measure simply RMS or peak value of leakage current components and do not provide detailed information needed in the diagnosis. In this study, we found that the wave height distributions of the total leakage currents are remarkably changed or a new wave height are produced with the progress of arrester deterioration. To propose a new technique for the diagnosis, we designed a leakage current detection unit and an analysis program which can measure leakage current magnitudes and analyze wave height distributions. From the experimental results, we confirmed that the proposed technique by analyzing the wave height distribution can simply diagnose the mode of defects such as a partial damage and an existence of punctures in arresters as well as deterioration of arresters.