• Title/Summary/Keyword: Power system faults

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Fault Simulation and Analysis of Generator (발전기의 사고 시뮬레이션과 분석)

  • Park, Chul-Won;Oh, Yong-Taek
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.62 no.3
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    • pp.151-158
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    • 2013
  • Large generator of power plant is very important. In order to protect large generator from faults, digital protective relay or IED is required. However, all protective relays for generators of the domestic power plant are operated by foreign products. And now, for technological independence from foreign and improvement of import substitution effect, IEDs using domestic technology are being developed. To evaluate performance of developing next-generation power devices, the study of the dynamic characteristics of the power plant, generator system modeling, fault simulation and analysis, should be considered. Specially, To obtain IEEE Standards COMTRADE format for relay operation test, generator system modeling and fault simulation using PSCAD/EMTDC tools must be preceded. Until now, a complete modeling of generator internal windings and fault simulation techniques dose not exist. In this paper, for evaluation performance of relay elements of developing IED, the generator system modeling and various faults simulation using PSCAD/EMTDC tools were performed. And then, the various transient phenomena through obtained relaying signal of developed modeling were analyzed.

A Case Study on Application of Fault Tolerant Control System to Boiler Controller in Power Plant (발전소 보일러 제어기에 대한 내고장성 제어 시스템의 적용에 관한 연구)

  • ;;;Zeung Nam Bien
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.1
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    • pp.10-19
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    • 1990
  • A fault tolerant control system, in which a digital back-up controller system is added on the existing analog control system, is developed for enhancing reliability of boiler control system in power plant. The digital back-up controller system(DBCS) has a multi-processor structure with capabilities of fault diagnosis, back-up control, self test, and graphic monitoring. Specifically, switching mechanism composed of expandable modules is designed so that back-up controller takes over any faulty control loops and the number of back-up control loops is determined as that of simultaneous faults. A process simulator that simulates the boiler analog control system is developed for safety test and performance evaluation prior to real plant application. DBCS is installed at the Ulsan thermal power plant, and fault tolerant control performance is assured under the faults that some controller modules are pulled out.

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A Study on Efficient Calculation of Effective Reactive Power Reserves Using Sensitivity Analysis

  • Bae, Moonsung;Lee, Byongjun
    • Journal of Electrical Engineering and Technology
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    • v.12 no.5
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    • pp.1689-1696
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    • 2017
  • In recent academic and industrial circles of the Republic of Korea, the securement of available reactive power reserve against the line faults is at issue. Thus, simulations have been performed for the securing of effective reactive power reserve (effective Q) to prepare for the line faults and improve reactive power monitoring and control methods. That is, a research has been conducted for the fast-decoupled Newton-Raphson method. In this study, a method that distinguishes source and sink regions to carry out faster provision of information in the event of line fault has been proposed. This method can perform quantification with the formula that calculates voltage variations in the line flow. The line flow and voltage changes can be easily induced by the power flow calculation performed every second in the operation system. It is expected that the proposed method will be able to contribute to securement of power system stability by securing efficient reactive power. Also, the proposed method will be able to contribute to prepare against contingencies effectively. It is not easy to prepare quickly for the situation where voltage drops rapidly due to the exhaustion of reactive power source by observing voltage information only. This paper's simulation was performed on the large scale Korean power system in steady state.

A Fault Diagnosis and Control Integrated System for an SP-100 Space Reactor (SP-100 우주선 원자로를 위한 고장진단 및 제어 통합 시스템)

  • Na, Man-Gyun;Yang, Heon-Young;Lim, Dong-Hyuk;Lee, Yoon-Joon
    • Proceedings of the KIEE Conference
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    • 2007.10a
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    • pp.231-232
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    • 2007
  • In this paper, a fault diagnosis and control integrated system (FDCIS) was developed to control the thermoelectric (TE) power in the SP-100 space reactor. The objectives of the proposed model predictive control were to minimize both the difference between the predicted TE power and the desired power, and the variation of control drum angle that adjusts the control reactivity. Also, the objectives were subject to maximum and minimum control drum angle and maximum drum angle variation speed. A genetic algorithm was used to optimize the model predictive controller. The model predictive controller was integrated with a fault detection and diagnostics algorithm so that the controller can work properly even under input and output measurement faults. With the presence of faults, the control law was reconfigured using online estimates of the measurements. Simulation results of the proposed controller showed that the TE generator power level controlled by the proposed controller could track the target power level effectively even under measurement faults, satisfying all control constraints.

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Task Scheduling to Minimize the Effect of Coincident Faults in a Duplex Controller Computer (고성능 컴퓨터의 고신뢰도 보장을 위한 이중(Duplex) 시스템의 작업 시퀀싱/스케쥴링 기법 연구)

  • Im, Han-Seung;Kim, Hak-Bae
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.11
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    • pp.3124-3130
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    • 1999
  • A duplex system enhances reliability by tolerating faults through spatial redundancy. Faults can be detected by duplicating identical tasks in pairs of modules. However, this kind of systems cannot even detect the fault if it occurs coincidently due to either malfunctions of common component such as power supply and clock or due to such environmental disruption as EMI. In the paper, we propose a method to reduce those effects of coincident faults in the duplex controller computer. Specifically, a duplex system tolerates coincident faults by using a sophistication sequencing of scheduling technique with certain timing redundancy. In particular when all tasks should be completed in the sense of real-time, the suggested scheduling method works properly to minimize the probability of faulty tasks due to coincident fault without missing the timing constraints.

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A Syudy on the Detection of High Impedance Faults using Wavelet Transforms and Neural Network (웨이브렛 변환과 신경망 학습을 이용한 고저항 지락사고 검출에 관한 연구)

  • 홍대승;배영철;전상영;임화영
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2000.10a
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    • pp.459-462
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    • 2000
  • The analysis of distribution line faults is essential to the proper protection of power system. A high impedance fault(HIF) dose not make enough current to cause conventional protective device operating. so it is well hon that undesirable operating conditions and certain types of faults on electric distribution feeders cannot be detected by using conventional protection system. In this paper, we prove that the nature of the high impedance faults is indeed a deterministic chaos, not a random motion Algorithms for estimating Lyapunov spectrum and the largest Lyapunov exponent are applied to various fault currents detections in order to evaluate the orbital instability peculiar to deterministic chaos dynamically, and fractal dimensions of fault currents which represent geometrical self-similarity are calculated. Wavelet transform analysis is applied the time-scale information to fault signal. Time-scale representation of high impedance faults can detect easily and localize correctly the fault waveform.

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A Study on the Classification of High Impedance Faults using Clarke Transformation and Plane Trajectory Method (Clarke법과 위상면궤적을 이용한 고저항 지락사고의 판별에 관한 연구)

  • Kim, C.H.;Shin, Y.C.;Ahn, S.P.
    • Proceedings of the KIEE Conference
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    • 2001.07a
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    • pp.243-245
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    • 2001
  • This paper presents a new classification method for high impedance faults in power systems. Results of phase plane trajectory with Clarke modal transformation using postfault current and voltage are utilized to classify types of arcing faults. The performance of the proposed method is tested on a typical 154 kV korean transmission system under various fault conditions using EMTP. As can be seen from results, phase plane trajectory of postfault current should be combined with that of o component from Clarke modal transformation to give reliability of clear fault classification. Thus the proposed method can classify arcing faults including LIFs and HIFs accurately in power systems.

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A Daubechies Wavelet Transform Based Criterion Logic Scheme for Discrimination Between Inter-Turn Faults and Magnetizing Inrush in Transformer (도비시 웨이브렛 변환을 이용한 변압기의 여자돌입과 내부 권선고장 판별논리 기법)

  • Kwon, Myong-Hyun;Park, Chul-Won;Shin, Myong-Chul
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.50 no.5
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    • pp.211-217
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    • 2001
  • This paper proposes a new fault detection criterion logic that extracts the features of magnetizing inrush and internal faults by making use of Daubechies Wavelet Transform which analyzes distinct features. To prove the effectiveness of proposed method, the paper constructs power system model including power transformer by using EMTP, and collects data through simulation using various fault inception angle and magnetizing inrush. The conclusions implemented by the C program and the Wavemenu of MATLAB Toolbos are more effective and simpler to distinguish inter-turn faults from magnetizing inrush states.

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Fuzzy Petri-net Approach to Fault Diagnosis in Power Systems Using the Time Sequence Information of Protection System

  • Roh, Myong-Gyun;Hong, Sang-Eun
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1727-1731
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    • 2003
  • In this paper we proposed backward fuzzy Petri-net to diagnoses faults in power systems by using the time sequence information of protection system. As the complexity of power systems increases, especially in the case of multiple faults or incorrect operation of protective devices, fault diagnosis requires new and systematic methods to the reasoning process, which improves both its accuracy and its efficiency. The fuzzy Petri-net models of protection system are composed of the operating process of protective devices and the fault diagnosis process. Fault diagnosis model, which makes use of the nature of fuzzy Petri-net, is developed to overcome the drawbacks of methods that depend on operator knowledge. The proposed method can reduce processing time and increase accuracy when compared with the traditional methods. And also this method covers online processing of real-time data from SCADA (Supervisory Control and Data Acquisition)

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A Study on the Fault Data Transmission through the Web using the XML Web Service and the Fault Type Determination of the Fault Data Received from the Web (XML Web Service를 이용한 고장 데이터의 웹 전송과 웹으로 수신된 고장 데이터의 고장 유형 판별에 관한 연구)

  • Kim In-Su;Hong Jung-Gi;Lee Hahk-Sung
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.1
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    • pp.18-23
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    • 2006
  • Recently as the power system has been becoming massive and complicated, most of the faults bring on severe proliferation effects. Because of the complexity of the power system it is not easy to analyze faults-the calculation of current flows under fault conditions. Therefore many researches have been performed in this area. As a result of those efforts, the protective equipments for a power system have been designed to operate properly and without damage when the highest possible fault current is flowing in the power system. Most of the fault data can be also acquired from intelligent protection equipments. The fault data saved in them don't always include the fault type information. n you don't have knowledge about the fault analysis, it becomes useless. So this paper presents 3 topics to increase a reusability of them as followings. First, describes a fault data using the XML(extensible Markup Language). It would be a well-formed and valid document complied with suggested XML DTD(Document Type Definition). In this paper I suggest a standard DTD to describe the power system fault. If the XML document describes any power system faults is validated against suggested DTD, it is possible to be used in any applications. Second, sends them through the web using the XML web service. Last, presents the rapid and accurate algorithm for a fault type determination of the fault data received from the web. In the ultimate the client to request the server to analyze a fault data is provided the correct information what kind of fault is occurred.