• Title/Summary/Keyword: EMTP/MODELS

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A Study on the Out-of-Step Detection Algorithm using Voltage Frequency Variation (전압의 주파수 변화를 이용한 동기탈조 검출 알고리즘에 관한 연구)

  • So, K.H.;Heo, J.Y.;Kim, C.H.
    • Proceedings of the KIEE Conference
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    • 2003.07a
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    • pp.335-337
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    • 2003
  • The protection against transient instability and consequent out-of-step condition is a major concern for the utility. The unstable system may cause serious damage to system elements such as generators and transmission lines. Therefore, out-of-step detection is essential to operate a system safely. This paper presents the Out-of-Step detection algorithm using voltage frequency variation. The digital filters based on Discrete Fourier Transforms (DFT) to calculate the frequency of a sinusoid voltage are used, and the generator angle is estimated using the variation of the calculated voltage frequency. The proposed out-of-step algorithm is based on the assessment of a transient stability using equal area criterion. The proposed out-of-step algorithm is verified and tested by using EMTP MODELS.

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Comparative Study on Transient Stability Improving Capability of Series and Shunt Compensation (비용함수에 의한 직병렬보상장치의 과도안정도 향상 특성 비교)

  • Choi, Kyu-Hyoung;Jeoug, Chang-Yang;Oh, Tae-Kyoo
    • Proceedings of the KIEE Conference
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    • 1996.07b
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    • pp.655-657
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    • 1996
  • The objective of this paper is to compare the series and shunt approaches of controlled reactive power compensation to improve power system transient stabilities. Including main circuit considerations of series and shunt compensators, application aspects are thought to have major impacts on efficiency and economy of the installation of the compensators. The concept is studied by means of EMTP simulations on one machine-Infinite Bus Test System which consists of a 612MVA steam turbin generator and transformer and double circuit 345KV transmission line. Idealized dynamic models of Thyristor Controlled Series Compensation and Shunt Compensation are used for the comparative study of the series and shunt compensation approach to damp power system oscillations.

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A Study on the Out-of-Step Detection Algorithm using Time Variation of Complex Power-Part I : The Variation of Complex Power trajectory in Complex plane (복소전력의 변화율을 이용한 동기탈조 검출 알고리즘에 관한 연구-Part I: 복소평면에서의 탁소전력의 궤적변화)

  • Kwon, O.S.;Kim, C.H.;Park, N.O.;Chai, Y.M.
    • Proceedings of the KIEE Conference
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    • 2005.07a
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    • pp.310-312
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    • 2005
  • An out-of-step condition results from the loss of the synchronism of the generators. A disturbance in a power system causes the generator angle to oscillate. When there is a severe disturbance such as a heavy current fault loss of major generation or loss of a large block of load the oscillation can be severe and even increase largely and finally the out-of-step condition may occur During the power swing and out-of-step conditions, the a apparent impedance at a relay location changes, and the power flow also changes as the angle difference is varied. This paper presents a method to analyze the trajectory of complex power during a power swing and out-of-step condition. The trajectory of the complex power is analyzed when a power swings and a fault occurs. Moreover, the complex power is analyzed when the ratios between the voltages at both sides and the line impedances are changed. These methods are verified through simulation using the ATP/EMTP MODELS.

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A Novel Algorithm for Fault Classification in Transmission Lines Using a Combined Adaptive Network and Fuzzy Inference System

  • Yeo, Sang-Min;Kim, Chun-Hwan
    • KIEE International Transactions on Power Engineering
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    • v.3A no.4
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    • pp.191-197
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    • 2003
  • Accurate detection and classification of faults on transmission lines is vitally important. In this respect, many different types of faults occur, such as inter alia low impedance faults (LIF) and high impedance faults (HIF). The latter in particular pose difficulties for the commonly employed conventional overcurrent and distance relays, and if undetected, can cause damage to expensive equipment, threaten life and cause fire hazards. Although HIFs are far less common than LIFs, it is imperative that any protection device should be able to satisfactorily deal with both HIFs and LIFs. Because of the randomness and asymmetric characteristics of HIFs, their modeling is difficult and numerous papers relating to various HIF models have been published. In this paper, the model of HIFs in transmission lines is accomplished using the characteristics of a ZnO arrester, which is then implemented within the overall transmission system model based on the electromagnetic transients program (EMTP). This paper proposes an algorithm for fault detection and classification for both LIFs and HIFs using Adaptive Network-based Fuzzy Inference System (ANFIS). The inputs into ANFIS are current signals only based on Root-Mean-Square (RMS) values of 3-phase currents and zero sequence current. The performance of the proposed algorithm is tested on a typical 154 kV Korean transmission line system under various fault conditions. Test results demonstrate that the ANFIS can detect and classify faults including LIFs and HIFs accurately within half a cycle.

A Study on the Out-of-Step Detection Algorithm using Time Variation of Complex Power-Part II : Out-of-Step Detection Algorithm using a trajectory of Complex power (복소전력의 변화율을 이용한 동기탈조 검출 알고리즘에 관한 연구-Part II: 복소전력의 궤적 변화를 이용한 동기탈조 검출 알고리즘)

  • Kwon, O.S.;Kim, C.H.;Park, N.O.;Chai, Y.M.
    • Proceedings of the KIEE Conference
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    • 2005.07a
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    • pp.313-315
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    • 2005
  • In a power system, an out-of-step condition causes a variety of risk such as serious damage to system elements, tripping of loads and generators, mal-operation of relays, etc. Therefore, it is very important to detect the out-of-step condition and take a proper measure. Several out-of-step detection methods have been employed in relays until now Mo,;t common method used for an out-of-step detection is based on the transition time through the blocking impedance area in R-X diagram. Also, the R-R dot out-of- step relay, the out-of-step prediction method and the adaptive out-of-step relay using the equal area criterion (EAC) and Global Positioning Satellite (GPS) technology have been developed. This paper presents the out-of-step detection algorithm using the time variation of the complex power. The complex power is calculated and the mechanical power of the generator is estimated by using the electrical power, and then the out-of-step detection algorithm, which is based on the complex Power and the estimated mechanical power, is presented. This algorithm, may detect the instant when the generator angle passes the Unstable Equilibrium Point (UEP). The proposed out-of-step algorithm is verified and tested by using Alternative Transient Program/Electromagnetic Transient Program (ATP/EMTP) MODELS.

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