• 전기학회논문지
• /
• 제58권2호
• /
• pp.342-348
• /
• 2009

This paper introduces a novel denoising algorithm for the partial-discharge(PD) signals from power apparatuses. The developed algorithm includes three kinds of specific denoising sub-algorithms. The first sub-algorithm uses the fuzzy logic which classifies the noise types in the magnitude versus phase PD pattern. This sub-algorithm is especially effective in the rejection of the noise with high and constant magnitude. The second one is the method simply removing the pulses in the phase sections below the threshold count in the count versus phase pattern. This method is effective in removing the occasional high level noise pulses. The last denoising sub-algorithm uses the grouping characteristics of PD pulses in the 3D plot of the magnitude versus phase versus cycle. This special technique can remove the periodical noise pulses with varying magnitudes, which are very difficult to be removed by other denoising methods. Each of the sub-algorithm has different characteristic and shows different quality of the noise rejection. On that account, a parameter which numerically expresses the noise possessing degree of signal, is defined and evaluated. Using the parameter and above three sub-algorithms, an adaptive complex noise rejection algorithm for the on-line PD diagnosis system is developed. Proposed algorithm shows good performances in the various real PD signals measured from the power apparatuses in the Korean plants.

• 제어로봇시스템학회논문지
• /
• 제6권11호
• /
• pp.968-973
• /
• 2000

Fault diagnosis plays an important role in the performance and safe operation of many modern engineering plants. This paper investigates the problem of fault detection using neural networks in dynamic systems. A general framework for constructing a nonlinear fault detection scheme for nonlinear dynamic systems containing modeling uncertaintly is proposed. The main idea behind the proposed approach is to monitor the physical system with an off -line learning neural network and then to approximate the upper and lower thresholds of acceleration of the nominal system with the model-based threshold(ThMB) method, The performance of the proposed fault detection scheme is investigated through simulations of a pendulum with uncertainty.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제51권5호
• /
• pp.204-212
• /
• 2002

In order to improve the reliability of high voltage rotating machines, it is necessary to understand the breakdown mechanism of stator windings. Especially partial discharge(PD) inception and growth are important in stator winding insulation. Recently, many research on the diagnosis of stator winding insulation for large rotating machines have been developed since the 1970s. Capacitive couplers have been the most widely used sensor for on-line partial discharge detection in rotating machines. This paper deals with the electrical on-line monitor characteristics of ceramic coupler(CC) which has been developed to continuously measure the PD activity in operating high voltage motor stator windings on site. We investigated the electrical characteristics(PD quantity, breakdown voltage and frequency response) to develop CC. This paper presents frequency characteristics and laboratory test result to compare conventional 80([F] epoxy-mica coupler(EMC) and 105[pF] CC for PD measurement with 6.6㎸ model stator windings.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.860-863
• /
• 1997

FCM(Fuzzy Cognitive Map) is a fuzzy signed directed graph for representing causal reasoning which has fuzziness between causal concepts. Authors have already proposed FCM-based fault diagnostic scheme. However, the previously proposed scheme has the problem of lower diagnostic resolution. In order to improve the diagnostic resolution, a new diagnostic scheme based on extended FCM which incorporates the concept of fuzzy number into FCM is developed in this paper. Furthermore, an enhanced TAM(Temporal Associative Memory) recall procedure and pattern matching scheme are also proposed.

• 전기전자학회논문지
• /
• 제27권4호
• /
• pp.601-609
• /
• 2023

본 논문에서는 DC 계통의 지락고장시 고속 고장진단을 위해 FPGA를 이용한 인공지능기반 고장진단 방법을 제안한다. 인공지능 알고리즘을 고장진단에 적용시 많은 연산량과 대용량의 실시간 데이터 처리가 요구된다. 또한 DC 계통에서의 고장 및 사고는 고장 전류의 빠른 상승률로 인하여 DC 차단기가 고속 차단능력이 필요하다. 인공지능기반 고속 고장진단이 가능한 FPGA를 사용하여 DC 차단기가 더 빠르게 동작함으로써, DC 차단기의 차단용량을 줄일 수 있다. 따라서 본 논문에서는 Matlab Simulink를 이용하여 DC계통의 고장 모의를 통해 고장데이터를 수집하여 지능형 고속 진단 알고리즘 구현하였으며, FPGA에 지능형 고속고장 진단 알고리즘을 적용 및 성능검증을 하였다.

• 한국생산제조학회지
• /
• 제22권3호
• /
• pp.343-348
• /
• 2013

In line with the advances in factory automation, various pieces of equipment are now operated in batch processes controlled by computers. However, many kinds of faults can occur in complicated and large systems, which can result in low productivity and economic loss. The reliability and safety of systems have been studied because of the difficulty of determining the severity and location of faults. Therefore, it is necessary to detect and diagnose such faults in order to guarantee the reliability and safety of the equipment. In this paper, a diagnosis method for the ball bearings of a hydraulic pump is applied using a vibration signal for the maintenance of injection molding equipment. The bearings' defects are selected as a main failure mode through a failure mode and effect analysis (FMEA). Usually, there are nonlinear and impulse components of vibration in a ball bearing with faults. For the effective fault diagnosis of a ball bearing, nonlinear diagnostic methods and time-frequency analysis are applied, in addition to the methods currently used, such as power spectrum, time series analysis, and statistical methods. As a result of this study, a failure diagnosis system is provided that is useful even for non-experts. This is a condition-based method that makes it possible to resolve problems in a timely and economical way, in contrast to the prior method, which required regular but wasteful maintenance based on the experience of expensive external experts.

• 대한의용생체공학회:의공학회지
• /
• 제12권2호
• /
• pp.113-120
• /
• 1991

This paper describes the implementation of a 3 channel ECG monitoring system. This system consists of an IBM-PC and simple accessory only. A PDTS (parallel data transmission system ) was designed to do monitor the data being operated with no effect and no exchange of software and hardware on the main transmission system in LOCAL mode. And it receives patient's ECG data from EPTS ( ECG processing and transmission system) of distant region. It provides on-line ECG waveform display, waveform storage, recall and editing the waveform. We have implemented the monitoring system by tw methods, and with system, we could directly monitor the EPTS and also receive the data from the remote ㅁe잉ion. This system was tested by experiments and examined its practical use.

• 대한전기학회논문지:전력기술부문A
• /
• 제52권5호
• /
• pp.271-278
• /
• 2003

Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability, this paper discusses a methodology to identify crucial transmission lines for stability Prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a Procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system and the KEPCO systems in the year of 2003 and it shows capabilities of the proposed method

• 설비공학논문집
• /
• 제21권11호
• /
• pp.591-598
• /
• 2009

The service quality with the various building equipments tends to depend on the individual superintendent's capability and efforts generally and this often lead to poor maintenances and managements of them. N-BMS(Networked Building Management System), proposed in this study, is a new type of building management method, which links principal equipments within many buildings into a communication network and carries out several significant missions such as fault detection, deterioration diagnosis and control the equipments and so on, as well as monitoring which is the main and unique purpose of the conventional BMS. How to construct the N-BMS was considered to keep performance of equipments high and thus to save energy and resource. LCC(Life Cycle Cost) based analysis was also performed in order to verify the effects of some maintenance and management works for the building HVAC systems.

• 조명전기설비학회논문지
• /
• 제12권4호
• /
• pp.114-121
• /
• 1998

본 논문에서는 건축물의 전기 수용설비에 대한 유지관리방법의 온라인화를 구현하기 위한 시스템을 제안하였다. 제안왼 시스템은 유지관리 방법에 대한 경험자 규칙을 활용한 데이터베이스를 구축하여 운전자가 응답파 대답을 통하여 유지관리에 업무가 수행되도록 하였다. 운전자는 본 시스템을 통하여 수용 설비의 정밀한 감시, 이상 상태의 조기발견, 올바른 조작 수행, 신속한 조치가 가능하며, 특히 비 전문가라도 설비의 유지관리업무가 가능하도록 개발되었다.