• Title/Summary/Keyword: Internal fault

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A Faulty Synchronous Machine Model for Efficient Interface with Power System

  • Amangaldi Koochaki
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.812-819
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    • 2015
  • This paper presents a new approach for simulating the internal faults of synchronous machines using distributed computing and Large Change Sensitivity (LCS) analysis. LCS analysis caters for a parallel solution of 3-phase model of a faulted machine within the symmetrical component-based model of interconnected network. The proposed method considers dynamic behavior of the faulty machine and connected system and tries to accurately solve the synchronous machine’s internal fault conditions in the system. The proposed method is implemented in stand-alone FORTRAN-based phasor software and the results have been compared with available recordings from real networks and precisely simulated faults by use of the ATP/EMTP as a time domain software package. An encouraging correlation between the simulation results using proposed method, ATP simulation and measurements was observed and reported. The simplified approach also enables engineers to quickly investigate their particular cases with a reasonable precision.

Fault Pattern Analysis and Restoration Prediction Model Construction of Pole Transformer Using Data Mining Technique (데이터마이닝 기법을 이용한 주상변압기 고장유형 분석 및 복구 예측모델 구축에 관한 연구)

  • Hwang, Woo-Hyun;Kim, Ja-Hee;Jang, Wan-Sung;Hong, Jung-Sik;Han, Deuk-Su
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.9
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    • pp.1507-1515
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    • 2008
  • It is essential for electric power companies to have a quick restoration system of the faulted pole transformers which occupy most of transformers to supply stable electricity. However, it takes too much time to restore it when a transformer is out of order suddenly because we now count on operator in investigating causes of failure and making decision of recovery methods. This paper presents the concept of 'Fault pattern analysis and Restoration prediction model using Data mining techniques’, which is based on accumulated fault record of pole transformers in the past. For this, it also suggests external and internal causes of fault which influence the fault pattern of pole transformers. It is expected that we can reduce not only defects in manufacturing procedure by upgrading quality but also the time of predicting fault patterns and recovering when faults occur by using the result.

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.

The Evaluation of Signal Reliability for single Stuck-at-type Fault in Digital Circuit (디지털회로의 단일고착형 결함에 대한 신호적 신뢰도계정)

  • 김영일;오영환
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.12 no.2
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    • pp.139-147
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    • 1987
  • This paper presented a method evaluating the signal reliability for signal stuck-at-type in digital circuits. Here, the signal reliability is defined as the probability that circuit output is correct, even though the fault existed at the internal parts of digital circuit. In evaluating the signal reliability, this paper presented not only fault model and algorithm for signal stuck-at-type fault but also computer program for evaluating the signal reliability with respect to complex and large circuit.

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Physical Properties and Friction Characteristics of Fault Cores in South Korea (단층핵의 물리적 특성과 마찰 특성의 상관관계 분석)

  • Moon, Seong-Woo;Yun, Hyun-Seok;Seo, Yong-Seok
    • Economic and Environmental Geology
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    • v.53 no.1
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    • pp.71-85
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    • 2020
  • To understand behavior of fault cores in the field of geotechnical and geological engineering, we present an investigation of the physical properties (breccia and clay contents, unit weight, porosity, and water content) and friction characteristics (internal friction angle and cohesion) of fault cores, in granitic, sedimentary, and volcanic rocks in South Korea. The breccia contents in the fault cores are positively correlated with unit weight and negatively correlated with clay content, porosity, and water content. The inter-quartile ranges of internal friction angles and cohesion calculated from direct shear tests are 16.7-38.1° and 2.5-25.3 kPa, respectively. The influence of physical properties on the friction characteristics of the fault cores was analyzed and showed that in all three rock types the internal friction angles are positively correlated with breccia content and unit weight, and negatively correlated with clay content, porosity, and water content. In contrast, the cohesions of the fault cores are negatively correlated with breccia content and unit weight, and positively correlated with clay content, porosity, and water content.

Feature Extraction of Partial Discharge for Stator Winding of High Voltage Motor (고압전동기 고정자권선의 부분방전 특징추출)

  • Park, Jae-Jun
    • The Journal of Information Technology
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    • v.7 no.4
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    • pp.61-69
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    • 2004
  • On-line monitoring of fault discharge is an important approach for indicating the condition of electrical insulation of stator winding in high voltage motor. In this paper, several key aspects of on-line monitoring system are discussed, involving the characteristics of fault discharge of stator winding in high voltage motor, spectrum analysis of four simulation fault signals, feature extraction of internal fault discharge from apply voltage to breakdown. The study of the partial discharge activities allows to highlight the ageing stage in the winding fault under test. During the life of the winding insulation fault, the shape of PD signal change relating to the ageing stage. The ageing of stator winding insulation fault of high voltage motor is investigated based on the characteristics of partial discharge pulse distribution and statistical parameters, such as maximum, skewness and kurtosis using discrete wavelet trnasform coefficients.

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A numerical study on the feasibility evaluation of a hybrid type superconducting fault current limiter applying thyristors

  • Nam, Seokho;Lee, Woo Seung;Lee, Jiho;Hwang, Young Jin;Ko, Tae Kuk
    • Progress in Superconductivity and Cryogenics
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    • v.15 no.4
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    • pp.26-29
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    • 2013
  • Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

A Study on DC Offset Removal using Low-Pass Filter in AT Feeder System for Electric Railway (전기철도 AT급전계통에 Low-Pass Filter를 이용한 직류옵셋 제거에 관한 연구)

  • Lee, Hwan;Jung, No-Geon;Kim, Jae-Moon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.6
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    • pp.1108-1114
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    • 2016
  • The cause of failure in the AT feeding system is divided into grounding, short-circuit of feeding circuit and internal faults of the railway substation. Since the fault current is very high, real-time current is detected and the failure must be immediately removed. In this paper, a new DC offset elimination filter that can remove component to decrease in the form of exponential function using low-pass filter was proposed in order to extract the fundamental wave from distorted fault current. In order to confirm the performance of the proposed filter method, AT feeder system was modelled by simulation tool and simulations were performed under various conditions such as fault location, fault resistance and fault voltage phase angle in case of trolley-rail short-circuit fault. When applying the proposed DC-offset removal method, it can be seen that the phase delay and gain error did not appear.

A Study on the Constructions of Fire Events Probabilistic Safety Assessment Model for Nuclear Power Plants (원자력발전소의 화재사건 확률론적안전성평가 모델 구축에 관한 연구)

  • Kang, Dae Il;Kim, Kilyoo
    • Journal of the Korean Society of Safety
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    • v.31 no.5
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    • pp.187-194
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    • 2016
  • A single fire event within a fire area can cause multiple initiating events considered in internal events probabilistic safety assessment (PSA). For an example, a fire event in turbine building fire area can cause a loss of the main feed-water and loss of off-site power initiating events. This fire initiating event could result in special plant responses beyond the scope of the internal events PSA model. One approach to address a fire initiating event is to develop a specific fire event tree. However, the development of a specific fire event tree is difficult since the number of fire event trees may be several hundreds or more. Thus, internal fire events PSA model has been generally constructed by modifications of the pre-developed internal events PSA model. New accident sequence logics not covered in the internal events PSA model are separately developed to incorporate them into the fire PSA model. Recently, many fire PSA models have fire induced initiating event fault trees not shown in an internal event PSA model. Up to now, there has been no analytical comparative study on the constructions of fire events PSA model using internal events PSA model with and without fault trees of initiating events. In this study, the changing process of internal events PSA model to fire events PSA model is analytically presented and discussed.