• Title/Summary/Keyword: two fault

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Fault diagnosis based on likelihood decomposition

  • Uosaki, Katsuji;Kagawa, Tetsuo
    • 제어로봇시스템학회:학술대회논문집
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    • 1992.10b
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    • pp.272-275
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    • 1992
  • A novel fault diagnosis method based on likelihood decomposition is proposed for linear stochastic systems described by autoregressive (AR) model. Assuming that at some time instant .tau. the fault of one of the following two types is occurs: innovation fault (actuator fault); and observation fault (sensor fault), the log-likelihood function is decomposed into two components based on the observations before and after .tau., respectively, Then, the type of the fault is determined by comparing the log-likelihoods corresponding two types of faults. Numerical examples demonstrate the usefulness of the proposed diagnosis method.

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Two-Faults Detection and Isolation Using Extended Parity Space Approach

  • Lee, Won-Hee;Kim, Kwang-Hoon;Park, Chan-Gook;Lee, Jang-Gyu
    • Journal of Electrical Engineering and Technology
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    • v.7 no.3
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    • pp.411-419
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    • 2012
  • This paper proposes a new FDI(Fault Detection and Isolation) method, which is called EPSA(Extended Parity Space Approach). This method is particularly suitable for fault detection and isolation of the system with one faulty sensor or two faulty sensors. In the system with two faulty sensors, the fault detection and isolation probability may be decreased when two faults are occurred between the sensors related to the large fault direction angle. Nonetheless, the previously suggested FDI methods to treat the two-faults problem do not consider the effect of the large fault direction angle. In order to solve this problem, this paper analyzes the effect of the large fault direction angle and proposes how to increase the fault detection and isolation probability. For the increase the detection probability, this paper additionally considers the fault type that is not detected because of the cancellation of the fault biases by the large fault direction angle. Also for the increase the isolation probability, this paper suggests the additional isolation procedure in case of two-faults. EPSA helps that the user can know the exact fault situation. The proposed FDI method is verified through Monte Carlo simulation.

An Adaptive Reclosing Scheme Based on the Classification of Fault Patterns in Power distribution System (사고 패턴 분류에 기초한 배전계통의 적응 재폐로방식)

  • Oh, Jung-Hwan;Kim, Jae-Chul;Yun, Sang-Yun
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.50 no.3
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    • pp.112-119
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    • 2001
  • This paper proposes an adaptive reclosing scheme which is based on the classification of fault patterns. In case that the first reclosing is unsuccessful in distribution system employing with two-shot reclosing scheme, the proposed method can determine whether the second reclosing will be attempted of not. If the first reclosing is unsuccessful two fault currents can be measured before the second reclosing is attempted, where these two fault currents are utilized for an adaptive reclosing scheme. Total harmonic distortion and RMS are used for extracting the characteristics of two fault currents. And the pattern of two fault currents is respectively classified using a mountain clustering method a minimum-distance classifier. Mountain clustering method searches the cluster centers using the acquired past data. And minimum-distance classifier is used for classifying the measured two currents into one of the searched centers respectively. If two currents have the different pattern it is interpreted as temporary fault. But in case of the same pattern, the occurred fault is interpreted as permanent. The proposed method was tested for the fault data which had been measured in KEPCO's distribution system, and the test results can demonstrate the effectiveness of the adaptive reclosing scheme.

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Fault Detection and Isolation of Parallel Operation of Two Converters Using Zero Current Transformer Method (영상변류기 동작 방식을 이용한 2개의 컨버터 병렬 운전시 고장 탐지 및 분리)

  • 손승찬;성세진
    • The Transactions of the Korean Institute of Power Electronics
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    • v.5 no.4
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    • pp.409-416
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    • 2000
  • In case of operating two converters in parallel with ZCT operation method using one current sensor for fault tolerance by system characteristics, identifying fault detection and isolation is difficult of which converter is fault since the ZCT output is a difference of two converters' supply current when a converter has fault. This thesis suggest a fault detection and isolation method of converter in case of operating two converters in parallel for fault tolerant system and verified this suggested method through an experiment.

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Application of the fault detection filter to detect the dynamic faults of a two-motor driven electric vehicle system (Detection Filter를 적용한 two-motor구동방식 전기자동차의 고장감지에 관한 연구)

  • 김병기;장태규;박정우
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.341-344
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    • 1997
  • This paper presents a dynamics failure detection algorithm developed for the two-motor-driven electric vehicle system. The algorithm is based on the application of the fault detection filter. The fault detection includes the identification of sudden pressure drops of the two rear tires in driving axis and dynamics faults of the two inverter-motor-paired actuators An E.V. dynamics simulator is developed, which includes the modeling of the E.V. dynamics as well as the driving dynamics. The simulator, which allows the generation of various fault situations, is utilized in the verification of the developed fault detection algorithm. The results of the simulations are also presented.

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Study on Current Limiting Characteristics of a Flux-locktype SFCL using Series Connected Two Coils with Twice Triggering Operation

  • Han, Tae-Hee;Ko, Seok-Cheol;Lee, Byongjun;Lim, Sung-Hun
    • Journal of Electrical Engineering and Technology
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    • v.9 no.3
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    • pp.777-781
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    • 2014
  • The current limiting characteristics of the flux-lock type superconducting fault current limiter (SFCL) using series connected two coils with twice triggering operation, which consists of series connected two coils and two superconducting (SC) modules with the inserting resistance, was analyzed. The feature of the suggested SFCL is that it can limit the fault current by triggering either one SC module or two SC modules comprising the SFCL depending on the amplitude of the fault current. To verify the current limiting operation of the suggested SFCL, the short-circuits in the fault location with the different fault currents were tested and its useful operations were described through the analysis on the tested results.

Analysis on Power Burden of HTSC Module due to Fault Current's Amplitude of a Flux-Lock Type SFCL with Two Triggering Currents (두 트리거 전류를 갖는 자속구속형 초전도한류기의 고장전류 크기에 따른 초전도 모듈의 전력부담 분석)

  • Han, Tae-Hee;Lim, Sung-Hun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.29 no.7
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    • pp.424-428
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    • 2016
  • In this paper, the power burden of High-TC superconducting (HTSC) module comprising the flux-lock type superconducting fault current limiter (SFCL) with two triggering currents during the fault period was analyzed. The short-circuit tests for the simulated power system with the SFCL in the different fault positions, which were expected to affect the amplitude of the fault current, were carried out. Through the comparative analysis on the power burden of the HTSC modules, the proposed flux-lock type SFCL was confirmed to be effective to divide into two power burdens according to the amplitude of the fault currents.

Fault Detection And Isolation Of Two DC-DC Converters Parallel Operation By ZCT Method (ZCT방식을 이용한 두 개의 컨버터 병렬 운전 시고장 검출 및 분리)

  • 박상은
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.172-176
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    • 2000
  • The paper presents the fault detection and isolation of two DC-DC converters parallel operation by ZCT method. Two experimental prototype converters were designed and implemented for evaluation of fault tolerant system. The experimental results show that fault detection and isolation circuit works very well.

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A Fault Detection and Diagnosis in a PWR Steam Generator (PWM 증기발생기의 고장검출 및 진단에 관한 연구)

  • Park, Seung-Yub
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.40 no.1
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    • pp.120-127
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    • 1991
  • The purpose of this study is to develop a fault detection and diagnosis scheme that can monitor process fault and instrument fault of a steam generator. The suggested scheme consists of a Kalman filter and two bias estimators. Method of detecting process and instrument fault in a steam generator uses the mean test on the residual sequence of Kalman filter, designed for the unfailed system, to make a fault decision. Once a fault is detected, two bias estimators are driven to estimate the fault and to discriminate process fault and instrument fault. In case of process fault, the fault diagnosis of outlet temperature, feed-water heater and main steam control value is considered. In instrument fault, the fault diagnosis of steam genrator's three instruments is considered. Computer simulation tests show that on-line prompt fault detection and diagnosis can be performed very successfully.

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Fault Analysis, Using Two-Port Network (4 단자망을 이용한 고장해석)

  • Kim, Jo-Yong;Baek, Young-Sik
    • Proceedings of the KIEE Conference
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    • 1993.07a
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    • pp.124-127
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    • 1993
  • This paper presents the new algorithm for fault analysis and the fault analysis package for executing this algorithm. This algorithm obtains requisite term for fault analysis by the two-port network technique. Therefore, the fault calculation time is minimized because ${Y_{BUS}}^{-1}$ calculation time is removed. And, the graphic user environment for fault analysis is implemented in mouse-oriented user interface with window and pull-down menu. Therefore, this package can be a useful tool for fault analysis.

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