• 전력전자학회논문지
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• 제10권6호
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• pp.610-617
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• 2005

가변속 풍력발전 시스템의 시뮬레이션 모델을 PSCAD/EMTDC 기반으로 개발하였다. 개발된 시뮬레이션 모델은 바람 모델, 회전자 다이나믹스, 동기 발전기, 전력 변환기, 변압기, 배전 선로, 무한 모선 등으로 구성되어 있다. 특히 블레이드의 공기역학적 특성과 전력 변환기의 제어 전략도 포함되어 실질적인 풍력발전기의 동작 특성을 시뮬레이션 할 수 있다. 개발된 시뮬레이션 모델을 이용하여 입력 풍속의 변동, 발전기 주변 부하의 변동, 계통측 전원 전압의 불평형 등의 다양한 조건에서 풍력발전기의 과도 상태 거동 특성을 확인하였다. 본 연구 결과는 앞으로 가변속 풍력발전기와 전력계통의 연계 운전시 신뢰성을 높이고 전력 시스템을 보호하기 위한 기초자료로서 활용될 수 있을 것으로 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.9-11
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• 2008

A protection current transformer (CT) has been widely used for protection devices. When a fault occurs, a CT should provide the faithful reproduction of the primary fault current. However, a CT may saturates due to the magnitude of fault current, dc component primary time constant and the remanent flux of the iron core, and the secondary current of a CT is distorted. The distorted current can cause mal-operation or the operating time delay of a protection relay. This paper provides a modeling of CT saturation using EMTP-RV. The performance of the proposed CT saturation modeling was investigated under various fault conditions varying the fault distance, fault inception angle, and remanent flux of the iron core. The results indicate that the proposed EMTP-RV modeling can operate correctly, and the reasons for CT saturation are verified by EMTP-RV simulations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2035-2037
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• 1999

This paper describes an ASM(All Solid-state Modulator) pulsed power generator for non-thermal plasma applications. The proposed generator can produce 20kV, 500A, 100ns pulses at repetition rates up to 10kHz, and it is composed of 30 series connections of power circuit card assembly which contains paralleled MOSFETs, MOSFET drivers, energy storage capacitors and specially designed 1:1 pulse transformer. Higher pulse voltages and currents can easily be obtained by increasing the numbers of series and parallel connections of power circuit card and MOSFETs, respectively. Component layouts are optimized to minimize the leakage inductance and the voltage spikes across switching devices. Especially it put emphasis on the over-current protection (including short circuit) for the reliable operation in real situations. Experimental results show that the proposed pulser is very efficient in air pollution control application and could be useful for other applications such as synthesis of nanosize powders and non-thermal food processing.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2256-2261
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• 2015

In the power plant using high temperature fuel cells such as Molten Carbonate Fuel Cell(MCFC), and Solid Oxide Fuel Cell(SOFC), the generated electric power per area of power generation facilities is much higher than any other renewable energy sources. - High temperature fuel cell systems are capable of operating at MW rated power output. - It also has a feature that is short for length of the line for connecting the interior of the generation facilities. In normal condition, these points are advantages for voltage drops or power losses. However, in abnormal condition such as fault occurrence in electrical system, the fault currents are increased, because of the small impedance of the short length of power cable. Commonly, to minimize the thermal-mechanical stresses on the stack and increase the systems reliability, we divided the power plant configuration to several banks for parallel operation. However, when a fault occurs in the parallel operation system of power main transformer, the fault currents might exceed the interruption capacity of protective devices. In fact, although the internal voltage level of the fuel cell power plant is the voltage level of distribution systems, we should install the circuit breakers for transmission systems due to fault current. To resolve these problems, the SFCL has been studied as one of the noticeable devices. Therefore, we analyzed the effect of application of the SFCL on bus tie in a fuel cell power plants system using PSCAD/EMTDC.

• 조명전기설비학회논문지
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• 제30권2호
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• pp.43-48
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• 2016

Operational applications such as service restoration, voltage control and protection coordination are calculated based on the active and reactive power loading of the sections in the distribution networks. Loadings of the sections are estimated using the voltage and current measured from the automatic switches deployed along the primary feeders. But, due to the characteristics of the potential transformer attached to the switches, accuracy of the voltage magnitude is not acceptable to be used for section loading calculation. This paper proposes a new accurate section loading estimation method through voltage measurement error compensation by calculating voltage drop of the distribution line. In order to establish feasibility of the proposed method, various case studies based on Matlab simulation have been performed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.762-763
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• 2011

19세기말에 차동보호계전방식이 이미 적용되었고 시스템 보호에 가장 먼저 사용되는 방식 중에 하나였다. 이 방식은 고장전력설비의 기기를 보호하기위해 전류의 입출력값을 비교함으로 고장을 검출하는 방법을 사용한다. 결과적으로 비율차동보호방식은 완벽하게 고장구간을 검출할 수 있으므로 전력설비의 중요기기의 주보호로 적합한 시스템이라고 볼 수 있다. 본 논문 변압기의 내/외부사고유형에 따른 전자기계식과 디지털 보호계전기의 동작특성을 컴퓨터기반의 해석 S/W를 이용하여 모델링과 동작특성에 대한 분석을 통해 보호계전기 동작특성의 신뢰성검증과 전력계통을 시뮬레이션하기 위해 구성하였다. 특히, 비율차동특성 보호 알고리즘을 계전기별로 모듈화하기 위한 기본 구조설계에 초점을 맞추었고 외부사고에 대해 각 보호계전기 동작특성을 비교함으로써 보호계전기 응답특성에 검증하는 기초 데이터를 생성하는 과정도 기술하였다.

• 전기학회논문지
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• 제56권3호
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• pp.472-480
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• 2007

This paper analyzes overvoltage on testing line for various parameter effect examination. Model systems consist of overhead line and underground cable. The model considered actual characteristic data of distribution lines. and will be constructed at testing yard. The simulations were performed under various line configuration such as cable kinds, cable length, lightning wave, lightning wave time, transformer and branch circuits. The simulation models are established by EMTP/ATPDraw and Line Constants are calculated by ATP_LCC. When lightning surge strikes on conductor of overhead line, EMTP/ATPDraw calculates overvoltage in many cases. Simulation results will be compared with real testing results at testing yard. The compared results will be used to establish protection methods in actual underground distribution systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.293-295
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• 2008

초전도 한류기의 용량증대를 위해서는 초전도 소자의 직 병렬 연결이 필요하다. 저항형 초전도 한류기는 초전도 소자의 불균형 퀜치로 인해 초전도 소자의 전력분담이 불안정하다. 변압기형 초전도 한류기는 2차측 코일과 초전도 소자 2개를 중성선을 이용하여 직 병렬로 연결하였다. 중선선 연결을 통해 사고전류에 따른 초전도 소자의 퀜치 특성이 개선되었다. 초전도 소자의 동시 ��치는 전력 부담을 각 소자에 동일하게 부담시킴으로서 한 소자에 편중되는 것을 방지한다. 또한 전압분배도 동일하게 할 수 있게 된다. 결론적으로 변압기형 초전도 한류기의 용량증대를 위해서는 2차측 코일과 초전도 소자 사이에 중선선 연결을 함으로써 그 답을 얻을 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.710-713
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• 1992

An AVR for OLTC controls motor tap in transformer in order to supply constant power source. Recently for society which is higher informative and more automatic, in our research, the digital AVR for OLTC is developed that can perform more functions and higher functions ( mesurement, display, protection, control ) using microprocessor in a different control method than the conventional AVR. The experiment result is also present.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.444-446
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• 2005

This paper describes a current differential relaying algorithm for power transformers with an advanced compensation algorithm for the secondary current of CTs. The comparative study was conducted with and without the compensating algorithm. The algorithm can reduce the operating time of the relay in the case of an internal fault and improve security for external faults. The performance of the proposed algorithm was investigated when the C100 CT, a quarter of the rated CT(C400), is used.