• Title/Summary/Keyword: Fault Mode

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On-board and Ground Autonomous Operation Methods of a Low Earth Orbit Satellite for the Safety Enhancement (저궤도 위성의 안전성 향상을 위한 위성체 및 지상의 자율 운영 방안)

  • Yang, Seung-Eun
    • Journal of Satellite, Information and Communications
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    • v.11 no.3
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    • pp.51-57
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    • 2016
  • Many kinds of telemetry should be monitored to check the state of spacecraft and it leads the time consumption. However, it is very important to define the status of satellite in short time because the contact number and time of low earth orbit satellite is limited. Also, on-board fault management should be prepared for non-contact operation because of the sever space environment. In this paper, on-board and ground autonomous operation method for the safety enhancement is described. Immediate fault detection and response is possible in ground by explicit anomaly detection through satellite event and error information. Also, satellite operation assistant system is proposed for ground autonomy that collect event sequence in accordance with related telemetry and recommend or execute an appropriate action for abnormal state. Critical parameter monitoring method with checking rate, mode and threshold is developed for on-board autonomous fault management. If the value exceeds the limit, pre-defined command sequence is executed.

Fault Detection Performance Analysis of GNSS Integrity RAIM (GNSS 무결성을 위한 RAIM 기법의 고장검출 성능 분석)

  • Kim, Ji Hye;Park, Kwan Dong;Kim, Du Sik
    • Journal of Korean Society for Geospatial Information Science
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    • v.20 no.3
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    • pp.49-56
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    • 2012
  • Performance analysis on RAIM, which is one of the techniques for monitoring integrity to ensure the reliability of GPS, was conducted in this study. RAIM is such a method which allows its user to monitor integrity in the stand-alone mode. Among the existing RAIM procedures, the representative methods including the RCM (Range Comparison Method), LSRM (Least Square Residual Method), Parity approach and WRAIM (Weighted RAIM) were evaluated, and their performance was analyzed. To validate the performance of the implemented algorithms, fault detection was tried on the clock malfunctioning event of PRN 23 occurred on January 1st, 2004. As a result, it was identified that the LSRM and the WRAIM detected all the faults happened in the event. In the case of RCM, all the states of fault were detected except for the error which occurred as a false alarm at one epoch. Furthermore, simulated biases were added for each satellite to analyze the sensitivity of each algorithm. Consequently, when biases of the 9-13 meters range were simulated for the RCM and LSRM algorithm, all the malfunctions were detected. For the WRAIM method, it could detect range biases greater than 15 meters.

Failure analysis of capacitor for sub-module in HVDC (HVDC 서브모듈용 커패시터의 고장 분석)

  • Kang, Feel-soon;Song, Sung-Geun
    • Journal of IKEEE
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    • v.22 no.4
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    • pp.941-947
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    • 2018
  • In general, capacitors have a large influence on the life of the system due to frequent charging and discharging. In this paper, we analyze the cause of the core failure of high voltage, high current HVDC sub-module film capacitor and analyze the precautions of the capacitor design and manufacturing process. First, the cause of the fault, the failure mode, and the effect are analyzed through the FMEA of the capacitor. To quantitatively evaluate the causes and effects of faults that have the greatest effect on the failure of a capacitor, a fault tree for the capacitor is presented and the failure rate is analyzed according to the design parameters and the driving conditions. It is verified that the main cause of capacitor failure is the capacitance change, and it is necessary to minimize the temperature rise, corona occurrence, electrode expansion, and insulation distance decrease during capacitor design and manufacturing process in order to reduce the failure rate of the capacitor.

Fault Detection on Voltage-source Inverter by Analytical Model (분석모델에 의한 전압헝 PWM 전동기 구동시스템에서의 고장검출)

  • Rim, Seong-Jeong
    • Proceedings of the KIEE Conference
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    • 2002.07b
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    • pp.1052-1054
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    • 2002
  • This paper presents an analytical model-based approach to detect and isolate faults in a voltage-source inverter. These faults do not affect the existing system protections. A diagnosis system which uses only the input variables of the drive is presented. It is based on the analysis of the current-vector trajectory in faulty mode. The proposed method has been verified in simulation results.

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Fault detection on voltage source inverter by knowledge-based model (지식기반 모델에 의한 전압형 인버터에서의 고장검출)

  • Rim, Seong-Jeong
    • Proceedings of the KIEE Conference
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    • 2001.07b
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    • pp.996-998
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    • 2001
  • This paper presents an approach based on knowledge models to detect and isolate faults in a voltage source inverter. These faults do not affect the existing system protections. A diagnosis system which uses only the input variables of the drive is presented. It is based on the analysis of the current-vector trajectory and of the instantaneous frequency in faulty mode. These two methods have been verified in simulation results.

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Design and Reliability Analysis of Concurrent System by Petri Nets: A Case on Lift System (패트리네트를 이용한 병행 시스템의 설계 및 신뢰성 분석 : 승강기 시스템을 중심으로)

  • 김기범;이강수
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.30B no.2
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    • pp.1-7
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    • 1993
  • In this paper, we show that Petri nets can be applied to design and reliability analysis of concurrent, parallel and embedded mode system such as a lift system that is familiar to our daily life. Modeling the behavioral characteristics of the lift system we extend the standard Petri nets by nadditionally constant timed transition, fault transition, stochastic imed ttransition and conditional transition concepts. Likewise, we present esults of rdesign and analysis of the system. This method can be applied to esign and danalysis of any other concurrent systems.

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Fault detections in ring structures using vibration modes (진동모드를 이용한 링 구조물의 결함 탐지)

  • Kim, Seock-Hyun;Jang, Ho-Sik
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1925-1932
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    • 2000
  • Damage detection methods using vibration modes are investigated on ring structures and. modal behavior of the slightly asymmetric rings is examined. Mode shapes changes, MSER(modal strain energy ratio) and MCR(modal curvature ratio) are applied to identify the locations of faults or damages. Parameters are calculated and compared by finite element analysis on rings with designed local damages. Damages are modeled as reduced stiffness in the analysis. The results show MSER and MCR can be proper factors to detect local damages in ring structures.

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Improved PWM for reducing torque ripple in PMSM with B4 inverter (인버터 폴트 (B4) 환경 하에 토크리플 절감을 위한 개선된 변조방식)

  • Park Jin-Sik;Jung Sin-Myung;Youn Myung-Joong
    • Proceedings of the KIPE Conference
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    • 2006.06a
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    • pp.292-294
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    • 2006
  • This paper presents a study on the use of improved space-vector modulation of VSI employing only four switches, four body diodes. Different switching sequence strategy for vector control for inverter fault mode are described. The influence of different switching patterns at same modulation index and improved PWM method is proposed. The proposed PWM is compared with conventional PWM. Simulation and experimental results are presented.

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A Case Study for Safety Analysis (안전성 분석에 대한 사례 연구)

  • Chang, Kwang-Chi;Lee, Key-Seo
    • Journal of the Korean Society for Railway
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    • v.7 no.3
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    • pp.251-258
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    • 2004
  • A systematic methodology to determine safety requirements for railway signalling system and safety requirement allocation into system are presented. THR concept is used for as an interface between Risk Analysis to be performed by railway operator and System Design Analysis by the supplier. This approach is based on Signalling Safety Standard EN50129 by CENELEC.

Fault Analysis of AC Electric Railway System Mode by EMTDC (EMTDC에 의한 교류 전철급전시스템 사고 해석)

  • 이한민;오광해;장길수;권세혁
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.9
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    • pp.521-527
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    • 2003
  • This study presents the AC railway system modeled by EMTDC in detail. The ,model made by EMTDC have a lot of advantages. It could be available for the system change, simulated repeatedly and also applied regarding very complicated systems. EMTDC simulations to verify this model are compared with the hand calculations. It is confirmed that the model made by EMTDC is correctly designed.