• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.363-367
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• 1996

The robustness issues in fault detection and isolation(FDI) have received considerable attenuation in recent years, due to the increasing demand for safe and reliable operation of uncertain and complex dynamic systems. The aim of this paper is to present the FDI method by using proportional integral(PI) observer and unknown input observer(UIO) under the faults of actuators and sensors. Due to this simple residual generator, the PI observer can easily detect the both faults of actuator and sensor. A simulation results show the effectiveness of this methods.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.56-66
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• 2016

Robustness is essential for model based FDI (Fault Detection and Isolation) and it is inevitable to have modeling errors and sensor signal noises during the process of FDI. This study suggests an improved method by applying NARX (Nonlinear Auto Regressive eXogenous) model and Kalman estimator in order to cope with problems caused by linear model errors and sensor signal noises in the process of fault diagnoses. Fault decision is made by the probability of the trend of gradually accumulated errors applying Fuzzy logic, which are robust to instantaneous sensor signal noises. Reliability of fault diagnosis is verified under various fault simulations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.6
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• pp.40-51
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• 2009

To analyze influences under open faults in switching devices of the PWM inverter and under the isolation between the inverter and motor terminal, a faulty model for the inverter-driven permanent magnet synchronous motor is presented. Even though the conventional dq motor model obtained through the transformation of phase voltage model is widely used to analyze and control AC motor, it can not be used under open faults in switching devices since the 3-phase balanced condition is no longer hold under the open fault and it is not easy to obtain motor input voltages in open phase from the pole voltage. To deal with this problem, a faulty model for an inverter-driven permanent magnet synchronous motor is derived by using the line voltage of motor according to switch open, which can be effectively used for performance evaluation of the diagnostic algorithm. The validity of the proposed faulty model is verified through comparative simulations and experiments using DSP TMS320F28335.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.722-723
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• 2011

국가차원의 신재생에너지 활성화 방안에 따라 지자체 등의 분산전원 시설계획이 점차 증가하고 있다. 이에 따라서 기존의 radial 구조가 아닌 closed loop을 운영하기 위해서는 보호협조에 대한 문제가 확실히 해결되지 않고서는 계통을 안정적으로 운영할 수 없다. 따라서 본 논문에서는 radial 계통 및 계통이 변경되거나 분산전원이 연계 시 closed loop 구조를 가지는 계통의 보호기기 및 자동화 개폐기들을 Agent화 시켜 통신을 이용한 보호 및 고장 구간 분리 알고리즘을 제안 하고자 한다.

• Tribology and Lubricants
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• v.3 no.1
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• pp.12-17
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• 1987

밀봉장치는 밀봉요소 또는 시일(seal)이라 불리우며, 서로 접촉한 부분 사이에서 유체의 누설방지 및 이물질의 침입방지에 이용되고 있다. 밀봉면에 거시적인 상대운동이 있는가 없는가에 따라 동적요소와 정적요소로 분리된다. 동적밀봉요소를 운동용 시일 또는 패킹(packing)이라하고 크게 접촉형과 비접촉형으로 분리된다. 정적밀봉요소를 정지용 또는 고정용 시일이라하며 가스켓(gasket)이라고도 한다. 오일 시일의 일반적인 사항에 대해 설명하였다. 사용기기의 고속, 고성능화에 다라 오일 시일의 사용조건이 점점 가혹하게 되고 있으므로 신뢰성과 안정성에 대한 요구도 증가하고 있다. 특히 트러블 원인은 살펴보면 취급법이나 축에 기인하는 초기 고장이 많으므로, 사용조건에 적당한 오일 시일을 선정하고 올바른 사용 방법을 지키므로서 초기 고장을 대폭 감소시킬 수 있다. 보다 전문적인 내용들은 관련 문헌을 참조바란다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.333-334
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• 2015

2015년 발,송,배전 설비 신설, 변경과 최대부하82,000MW에 대비하여 우리나라 전력계통의 운영방안을 검토하였다. 고장전류를 차단기 정격 내에 유지할 수 있도록 모선분리, 선로분리 등을 적용하였고, 특히 765kV 송전선로 고장시 계통안정을 위해 수도권의 부하를 차단하는 장치를 정지하는 방안을 마련하여 수도권 계통안정에 기여하였다. 인천지역에서 나타난 과전압 및 안정도 약화에 대해 적절한 발전및 송전제약 한계값을 적용하여 인천지역의 안정 운영에도 기여하였다.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.179-187
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• 2004

We consider some problems of the Modified SPRT(Sequential Probability Ratio Test) method for fault detection and isolation of inertial redundant sensor systems and propose an Advanced SPRT method which solves the problems of the Modified SPRT method. The problems of the Modified SPRT method to apply to inertial sensor system come from the effect of inertial sensor errors and the correlation of parity vector components. We use a two-stage Kalman filter to remove effects of the inertial sensor errors and propose the modified parity vector and the controlled parity vector which reduces the effect of correlation of parity vector components. The Advanced SPRT method is derived form the modified parity vector and the controlled party vector. Some simulation results are presented to show the usefulness of the Advanced SPRT method to redundant inertial sensor systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.835-844
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• 2021

In this paper, a power facility communication control device was designed to autonomously determine and separate the fault section through communication between power facilities in the smart grid distribution system. In the power facility communication control device, the control module was designed as a DSP to measure three-phase voltage and current, and the communication module was designed as an embedded-based Raspberry Pi to determine the fault section and realize the fault section separation through communication between power facilities. Communication between DSP and Raspberry Pi was designed by SPI communication, and communication between Raspberry Pi was designed based on Wi-Fi. Finally, a performance evaluation system based on three power facility communication control devices was built, and simulation verification was conducted for various fault events that may occur on the distribution line. As a result of the test evaluation, it was possible to confirm the effectiveness of the design methodology of the communication control device by showing the required response of the communication control device to all test cases.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.756-757
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• 2011

보호장치는 전력계통에 고장이 발생할 경우 신속 정확 하게 고장을 검출하여 고장부분을 계통으로부터 분리시킴으로써 각종 설비의 손상을 막고 정전구간을 최소화 하여 계통의 안정화를 향상시키는 장치이다. 현재 한전 및 발전사 뿐만아니라 수자원공사의 수도사업장에서도는 원격감시 제어를 통한 무인화와 함께 디지털보호계전기가 설치 운영되고 있다. 디지털 보호계전기는 기존의 기계식 보호계전기가 수행하는 보호기능보다 우수한 성능이 입증되었으며 최근 반도체 기술의 비약적 발전과 보호 알고리즘의 지속적인 개발로 보호계전기의 디지털화가 가속되고 있고 더욱 개선된 고성능, 다기능의 보호계전기 또는 IED가 산업현장에 적용되는 추세에 있다. 본 논문에서는 과전압 보호계전기와 부족전압 보호계전기의 기능 및 동작특성에 대하여 연구하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.138-145
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• 2000

This paper presents a robust fault diagnosis and fault tolerant control method for the control systems in closed-loop affected by unknown inputs or disturbances. The fault diagnostic scheme is based on the disturbance-decoupled state estimation using a 2-stage state observer for state, actuator bias and sensor bias. The estimated bias show the occurrence time, location and type of the faults directly. The estimated state is used for state feedback to achieve fault tolerant control against the faults. Simulation results show that the method has definite fault tolerant ability against actuator and sensor faults, moreover, the faults can be detected on-line, isolated and estimated simultaneously.