• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.42-47
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• 2011

Automatic generation control (AGC) is an important function for load frequency control, which is being implemented in Energy Management System (EMS). A key feature of AGC is to back up governors to enhance the performance of frequency control. The governor regulates system frequency in several to ten seconds, while the droop control concept results in steady-state control error. AGC is a supplementary tool for compensation of the steady-state error caused by the droop setting of the governors. As the AGC target is delivered to each generator as an open loop control target, the generator output is not guaranteed to follow the AGC target. In this paper, we introduce generating unit controller (GUC) control block, which has the purpose of enabling the generator output to track the AGC target while maintaining the governor performance. We also address the tuning methods of GUC for better performance of AGC in the Korea Energy Management System (K-EMS).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.601-604
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• 1996

It is well known that steam generator water level control at low power operation has many difficulties in a PWR (pressurized water reactor) nuclear power plant. The reverse process responses known as shrink and swell effects make it difficult to control the steam generator water level at low power. A new automatic control logic to remove the reverse process responses is proposed in this paper. It is implemented in PLC (programmable logic controller) and evaluated by using test equipment in Korea Atomic Energy Research Institute. The simulation test shows that the performance requirements is met at low power (below 15%). The water level control by new control logic is stabilized within 1% fluctuation from setpoint, while the water level by YGN 3 and 4 control logic is unstable with the periodic fluctuation of 25% magnitude at 5% power.

• 조명전기설비학회논문지
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• 제29권11호
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• pp.47-52
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• 2015

This paper derives the problems that occur when asynchronous transfer in case of phase, frequency, voltage between the emergency generator and the grid and proposed the countermeasure to solve this problem when the transfer switch replace ATS(Automatic Transfer Switch) with CTTS(Closed Transition Transfer Switch) for the non-interrupting switching. In order to simulate above cases, modelling was used the transient analysis program PSCAD/EMTDC. By using this, the customer installed emergency generator and the grid was implemented. We compared three cases of asynchronous transition based on the basic case and proposed improvement by controlling the governor of emergency generator.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1575-1585
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• 2017

This paper presents a synchronous generator with a distributed system of multiple parallel three-phase power cells. This generator can immediately output high DC. Each power cell comprises three-phase windings and a three-phase synchronous rectification bridge with a deadbeat control of load power feedforward, which can improve the characteristics of dynamic response and reflect the load variance in real time. Furthermore, each power cell works well independently and modularly using the method of automatic maximum current sharing. The simulation and experimental results for the distributed controller of multiple power cells demonstrate that the deadbeat control method can respond quickly and optimize the quality of the energy. Meanwhile, automatic maximum current sharing can realize the validity of current sharing among power cells.

• 한국음향학회지
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• 제23권3호
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• pp.248-252
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• 2004

실제 언어생활에 있어서 여러 다양한 경제적 문화적 사회적 환경에 따라 다른 어휘가 사용되고, 각각의 다양한 환경에서 새롭게 신조어가 추가되는 등 어휘의 양적인 변화가 일어난다. 이러한 역동적인 언어 현실을 자동 발음열 생성기에 반영하기 위하여, 본 논문은 추가된 텍스트로부터 예외발음사전을 구축하는 방법을 제안하고, 이러한 방법으로 구축된 예외발음사전을 이용한 자동 발음열 생성 시스템의 성능을 실험하였다. 본 시스템에 대하여 ETRI에서 출시된 음성인식용 텍스트 코퍼스 가운데 한 달 동안의 신문기사를 모은 53,750문장 (740,497 어절)을 이용하여 실험한 결과 100%의 성능을 얻었다.

• 대한전자공학회논문지SD
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• 제38권3호
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• pp.220-228
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• 2001

새로운 마이크로프로세서의 설계, 최적화, 그리고 완성 후 어플리케이션의 작성 단계에서 칩의 명령어 집합 시뮬레이션은 필수적인 요소이다. 그러나, 기존의 시뮬레이션 툴들은 저 수준의 하드웨어 기술언어와 게이트 레벨 이하의 시뮬레이션으로 인해 시뮬레이터 구성과 실행 시에 상당한 시간적 지연을 초래하고 있다. 본 논문에서는 이러한 문제들을 해소하고 칩 제작과정에서 발생하는 잦은 설계 변경에 유연성 있게 대응할 수 있는 레지스터 전송 수준의 명령어 집합 시뮬레이터 생성기를 제안하며 그 설계 및 구현에 관해 기술한다.

• 한국농공학회지
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• 제37권2호
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• pp.21-30
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• 1995

In order to save time and efforts in generating finite element meshes in irregular houndaries of domains, it is needed to develop an automatic mesh-generator which can hoth promote the accuracy of solutions and reduce the run-time in operating finite ele- ment models. In this study, the advancing front technique of triangular mesh generation and the transforming technique from triangular meshes to quadrilateral meshes were used to de- velop a computer program for the automatic triangular and quadrilateral meshes in the mixed shape. Furthermore, to enhance the quadrilateral mesh quality, the techniques of Laplancian smoothing and interior mesh modification were employed. The mesh genera- tor was applied to evaluate its applicability to irregular and complex geometries such as Nakdong river bay. In has hoen shown that the automatic mesh generator developed is capable of automatically generating meshes for irreguiar and complex geometries with high qualities of meshes and with the simple input data of arbitrarily specified nodal spacing in bound- aries.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2268-2275
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• 2018

This paper presents a high-efficiency low-power permanent magnet (PM) generator for the power supply of the generator exciter. In the conventional generator system, the power for the exciter is fed by the generator output power or an emergency battery for the starting. The proposed low-power PM generator can generate the proper power and voltage to excite the exciter field winding. According to the starting of the generator, the designed PM generator can supply the constant voltage to the Automatic Voltage Regulator (AVR), then it can be used to control of exciter field current for the generator. Because of the designed PM generator which is placed inside the conventional generator system, the emergency battery and Potential Transducer(PT) for AVR can be removed. Thus, the total efficiency can be improved. The proposed generator system is tested in the practical system. And the efficiency characteristic is analyzed.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.121-125
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• 2014

This paper presents a successful stand-alone pico-hydro generation system using a high-efficiency interior permanent-magnet (IPM) synchronous generator. A 1-kW 4-pole V-type IPM generator with low voltage regulation is used for laboratory test in stand-alone hydro energy conversion system. It has been found from experimental results that the constant output voltage is supplied stably by the proposed system under wide speed range.

• 전력전자학회논문지
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• 제14권1호
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• pp.38-45
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• 2009

일정 출력을 얻기 위해 동기발전기 계자 여자는 AVR에 의해 제어된다. 대부분의 선박용 동기발전기 AVR은 사이리스터 위상제어 방식을 사용한다. 하지만 이 방식은 제어 주기가 MOSFET이나 IGBT로 구성된 컨버터에 비해 느리므로 속응 제어를 구현하는데 어려움이 있다. 따라서 본 논문에서는 선박용 동기발전기에 MOSFET을 사용한 PMG형 디지털 AVR을 구현하였다. PMG형 디지털 AVR 회로 구성은 간단하고 단락 시 발전기 출력전압이 영으로 되어 AVR이 동작하지 못하므로 출력전류를 여자회로로 흐르도록 하는 CBC가 요구된다. 본 논문에서 연구된 여자 시스템은 실제 선박용 발전기를 대신하여 10[kVA]급 프로토타입의 실험을 통하여 시스템의 타당성을 검증하였다.