• Title/Summary/Keyword: Grid fault

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Analysis of Transient Characteristics of a SFCL Applied Into Third-winding Transformer in a Single Line-to-ground Fault (1선 지락 사고 시 3 권선 변압기에 적용된 초전도 한류기의 동작 특성 분석)

  • Choi, Hye-Won;Choi, Hyo-Sang;Jung, Byung-Ik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.7
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    • pp.1033-1037
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    • 2013
  • Coercion transformer is commonly used in the electrical grid which in three phase of distribution system. The accident of the electrical grid is divided into a single, a double, a third line-to-ground faults and a double, a third line-to-line faults. A single line-to-ground fault accounts for nearly 75[%] among them. In this research, when a Superconducting Fault Current Limiters (SFCL) was applied to the three phase power system, operation in a single line-to-ground fault and limiting characteristics of fault current according to turns ratio of third winding were analyzed. When a single line-to-ground fault happened, secondary winding's circuit was open. Then third winding's circuit with a SFCL was closed. So fault current was limited by diverted circuit. At this time, we could find out that size of the limited fault current could be changed according to third winding rate. We confirmed that limiting operation of the fault current was carried out within one-period. These results will be utilized in adjusting the size of the SFCL.

Islanding detection algorithm for a micro-grid based on the active and reactive power in the time domain (시간영역에서의 유효/무효전력을 이용한 마이크로그리드의 단독운전의 판단 알고리즘)

  • Lee, Young-Gui;Lee, Hye-Won;Kim, Yeon-Hee;Zheng, Tai-Ying;Kang, Yong-Cheol
    • Proceedings of the KIEE Conference
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    • 2011.07a
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    • pp.145-146
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    • 2011
  • A micro-grid (MG) is usually interconnected to the main grid through the dedicated line. Immediately after the removal of the grid supply, the MG should be disconnected and remain disconnected until the main grid is re-energized. It should detect islanding condition as soon as it happens to adjust the setting of the protection relays in the MG. This paper proposes an islanding detection algorithm for the MG based on the active and reactive power delivered to the dedicated line in the time domain. The performance of the proposed algorithm is verified under islanding conditions and fault conditions using the PSCAD/EMTDC simulator. The results indicate that the proposed algorithm can discriminate the islanding conditions from the various fault conditions.

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Evaluation on Effect of Wind Power Generation System According to Transformer Winding Connection at Matlab&Simulink (MATLAB&SIMULINK에서 변압기 결선에 따른 풍력발전 시스템의 영향 평가)

  • An, Hae-Joon;Ro, Kyoung-Soo
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.772-773
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    • 2007
  • This study suggests a modeling of grid-connected wind power generation system that has induction generator, and aims to perform simulations for outputs by the variation of actual wind speed and for fault current of wind generation system by the transformer winding connection. This study is implemented by matlab&simulink. The simulation shall be performed by assuming single line to ground fault generated in the system. Generator power, rotor speed, terminal voltage, system voltage, and fault current shall be observed following the performance of simulation. The fault current change will be dealt through the simulation results for fault current of wind generation system following the grid-connected transformer winding connection and the simulation result by the transformer neutral ground method.

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Voltage Source Equipment for the Grid Fault Testing and Analysis of Total Harmonic Distortion According to PWM Methods

  • Gwon, Jin-Su;Kim, Chun-Sung;Kang, Dae-Wook;Park, Jung-Woo;Kim, Sungshin
    • Journal of Power Electronics
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    • v.14 no.6
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    • pp.1081-1092
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    • 2014
  • Renewable energy is being spotlighted as the electric power generating source for the next generation. Due to an increase in renewable energy systems in the grid system, their impact on the grid has become non-negligible. Thus, many countries in the world, including Europe, present their own grid codes for grid power conversion devices. In order to experiment with these grid codes, grid fault test equipment is required. This paper proposes both equipment and a control method, which are constructed with a 7-level cascaded H-bridge converter, that are capable of generating various grid faults. In addition, the Pulse Width Modulation (PWM) method for multilevel converters is compared and analyzed. The proposed structure, the control method, and the PWM method are verified through simulation and experimental results.

Simulation for Voltage Variations of a Grid-connected Wind Turbine Generation System by Simulink (Simulink에서 계통연계 풍력발전시스템의 전압변동 시뮬레이션)

  • Ahn Duck-Keun;Ro Kyoung-Soo
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.53 no.11
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    • pp.589-595
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    • 2004
  • This paper presents a modeling and simulation of a grid-connected wind turbine generation system with respect to wind variations, starting of large induction motor and three-phase fault in the system, and investigates voltage variations of the system for disturbances. It describes the modeling of the wind turbine system including the drive train model, induction generator model, and grid-interface model on MATLAB/Simulink. The simulation results show the variation of the generator torque, the generator rotor speed, the pitch angle, terminal voltage, system voltage, fault current, and real/reactive power output, etc. Case studies demonstrate that the pitch angle control is carried out to achieve maximum power extraction for wind speed variations, starting of a large induction motor causes a voltage sag due to a large starting current, and a fault on the system influences on the output of the wind turbine generator.

Investigation of the Feasibility of a Bus-bar coupled SFCL in the 154 kV KEPCO Grid (154 kV 초전도 한류기 모선연계 적용 연구)

  • 윤용범;현옥배;황시돌;김혜림
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2003.10a
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    • pp.291-293
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    • 2003
  • Applicability and economical feasibility of a Superconducting Fault Current Limiter (SFCL) have been investigated using the PSS/E simulation for a bus bar coupling at the real 154 ㎸ KEPCO power grid near Seoul. For the investigated substation, the maximum fault current exceeds the interruption rating of 4 circuit breakers (CB) out of 9 installed in the substation. The simulation showed that a SFCL installed in the bus tie position effectively limits the fault currents to save 4 CBs, which are to be replaced by ones of gloater interruption rating, otherwise. We suggest that the optimum resistance of the SFCL be 10 Ohm for the given grid.

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Nomadic Jini LUS Using Grid Service (Grid 서비스를 이용한 Jini 룩업서비스의 이동성)

  • Jung Seung-Hwan;Lee Tae-Dong;Jeong Hye-Sun;Yoo Seung-Hun;Choi Ki-young;Jeong Chang-Sung
    • Proceedings of the Korean Information Science Society Conference
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    • 2005.07a
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    • pp.40-42
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    • 2005
  • Jini는 네트워크를 통해 사람이나, 기기, 프로그램이 특정 자원을 찾거나 사용하고자 할 때, 관리자의 개입 없이 유연하게 동작하게 하는 분산 미들웨어의 하나이다. 기존의 Jini 서비스는 Lookup Service 데몬(Httpd, Reggie. Rmid)이 실행되어 Discovery, Join, Lookup, Service Invocation의 과정을 통해 이루어지는데, 데몬 fault 발생 시 어떠한 해결점이 없다는 것이 문제점이다. 이에 본 논문에서는 Jini 서비스 데몬 손실로 인한 Jini 서비스의 Fault 문제를 해결하기 위해 Grid환경 하에서 그리드 서비스를 사용하여 Jini 서비스에 Fault Tolerance를 제공하는 시스템의 구조와 방법을 제시한다.

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Simulation for balanced fault of a grid-connected wind generation system (계통연계 풍력발전 시스템의 평형고장에 대한 시뮬레이션)

  • Ahn, Duck-Keun;Ro, Kyoung-Soo
    • Proceedings of the KIEE Conference
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    • 2004.11b
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    • pp.17-20
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    • 2004
  • This paper presents a modeling and simulation of a grid-connected wind turbine generation system with respect to wind variations and three-phase fault in the system. It describes the modeling of the wind turbine system including the drive train model, induction generator model, and grid-interface model on MATLAB/Simulink. Case studies demonstrate that the pitch angle control is carried out to achieve maximum power extraction for wind speed variations and the duration of a fault on the system influences on the output of the wind turbine generator.

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Specifications of 22.9kV HTS cables and FCLs considering protection systems in Korean power distribution system (국내계통 보호시스템을 고려한 22.9kV 초전도케이블/한류기 설계사양 제안)

  • Lee, Seung-Ryul;Park, Jong-Young;Yoon, Jae-Young;Lee, Byong-Jun;Yang, Byeong-Mo
    • Progress in Superconductivity and Cryogenics
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    • v.11 no.3
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    • pp.50-54
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    • 2009
  • In Korea, 22.9kV 50MVA HTS (High Temperature Superconducting) cables and 630A/3kA hybrid SFCLs (Superconducting Fault Current Limiters) have been or are being developed by LS Cable, LS Industrial System, and Korea Electric Power Research Institute. They will be installed at Icheon 154kV Substation for real-power-distribution-system operation in 2010. This paper proposes specification of current limiting resistor/reactor for the SFCL and fault current condition of the HTS cable for applying the superconducting devices to Korean power distribution system, from the viewpoint of power system protection.

Use of Stored Energy in Rotor Inertia for LVRT of PMSG Wind turbine based on Sliding Mode Control (영구자석 동기발전기 시스템을 위한 회전자 관성에너지를 이용한 Sliding Mode제어 기반 LVRT 제어)

  • Jeong, Daeheon;Gui, Yonghao;Kim, Chunghun;Chung, Chung Choo
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.1058-1059
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    • 2015
  • This paper describes a low-voltage ride-through method for the permanent magnet synchronous generator (PMSG) wind turbine system at a grid fault. The generator side converter regulates the DC link voltage instead of the grid side converter by storing the surplus active power in the rotor inertia during grid fault by the sliding mode controller. The grid side converter controls the grid active power keeping a maximum power point tracking. Simulation results for small scale PMSG wind turbine verify the efficiency of the control method.

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