• 드라이브 ㆍ 컨트롤
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• 제18권4호
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• pp.28-34
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• 2021

Among the currently available types of fuel, LNG emits a relatively small amount of nitrogen oxide and carbon dioxide when it burns in the engine. However, since LNG is a flammable material, leakage during bunkering can lead to accidents, such as fires. Therefore, it is necessary to install a remote operation emergency shut-down (ESD) valve to block the flow and leakage of LNG in an emergency situation that occurs during bunkering. The ESD valve uses a hydraulic driving device consisting of a hydraulic control valve and a hydraulic motor to control globe valve disc displacement, which regulates the flow path for LNG transfer. At this time, there are various nonlinearities in hydraulic driving devices; hence, it is necessary to design a controller with robust control performance against these uncertainties. In this study, modeling of the ESD valve was carried out, and a sliding mode controller to control the displacement of the globe valve disc was designed. As a result, it was confirmed that the designed control performance could be achieved by overcoming nonlinearity characteristics using the designed controller.

• International Journal of Computer Science & Network Security
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• 제22권3호
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• pp.355-363
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• 2022

This paper presents the modeling for islanded hybrid AC/DC microgrid and the verification of the proposed supervisory controller for energy management for this microgrid. The supervisory controller allows the microgrid system to operate in different power flows through the proposed control algorithm, it has several roles in the management of the energy flow between the different components of the microgrid for reliable operation. The proposed microgrid has both essential objectives such as the maximum use of renewable energies resources and the reduction of multiple conversion processes in an individual AC or DC microgrids. The microgrid system considered for this study has a solar photovoltaic (PV), a wind turbine (WT), a battery (BT), and a AC/DC loads. A small islanded hybrid AC/DC microgrid has been modeled and simulated using the MATLAB-Simulink. The simulation results show that the system can maintain stable operation under the proposed supervisory controller when the microgrid is switched from one operating mode of energy flow to another.

• 전력전자학회논문지
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• 제6권3호
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• pp.291-298
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• 2001

본 논문은 차세대 FACTS(flexible AC Transmission Systems)기술인 UPFC(Unified Power Flow Controller)의 시뮬레이션을 다룬다. UPFC의 해석과 모델을 통하여 전력조류제어를 시뮬레이션 한다. 전력시스템의 과도상태 및 제어에 대한 시간영역 시뮬레이션 프로그램인 EMTDC(Electro-Magnetic Transients in DC systems)를 사용하여 전력조류제어인 유효전력 및 무효전력제어를 수행하고 더불어 모선입력전압의 크기를 제어한다. 시뮬레이션 결과를 통하여 UPFC의 제어성능을 검증한다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.47-50
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• 2001

In order for effective operation of existing power systems, introduction of the so-called FACTS(Flexible AC Transmission System) such as SVC and UPFC etc, is unavoidable. The UPFC(Unified Power Flow Controller) is composed of STATCOM(Static Compensator) and SSSC(Static Synchronous Series Compensator), and is used to control the magnitude and phase angle of injected sources which are connected bothin series and in parallel with the transmission line to control the power flow and bus voltages. This paper presents a UPFC simulation on RTDS. The voltage and phase angle of a system have been analyzed by regulating the firing angle inside the UPFC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2475-2477
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• 1999

This paper describes a simulation model and scaled hardware model to analyze the dynamic performance of Unified Power Flow Controller, which adjust flexibly the active and reactive power flow through the ac transmission line. The design of control system was developed using vector control method. The results of simulation and scaled hardware test show that the developed control system works accurately. And both models are very effective to analyze the dynamic performance of the Unified Power Flow Controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.781-786
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• 1998

Since a gas turbine is still a significant contributor to peak time, it is very important to tune the gains of P. I. D to get a maximum power and stability within permissible limits. In the gas turbine, the main control loop must adjust the fuel flow to ensure the correct output power and frequency. but it is not easy, because the control loop is composed of many subsystems. In this paper we acquire a transfer function based on the operations data of Gun-san gas turbine and study to apply a loop compensation type 2-DOF PID controller tuning by neural-network to control loop of gas turbine to reduce phenomena caused by integral and derivative actions through simulation. We obtained satisfactory results to disturbances of subcontrol loop such as, fuel flow, air flow, turbine extraction temperature.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2000년도 추계학술대회 논문집
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• pp.174-179
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• 2000

Proposed in the paper is a V-FMS (Virtual Flexible Manufacturing System) model to be used as a prototyping tool for FMS design. The proposed V-FMS framework follows an object-oriented modeling (OOM) paradigm and is based on a set of user requirements for FMS prototyping. The V-FMS model consists of four types of object: virtual device, transfer handler, state manager and flow controller. A virtual device model, which corresponds to a static model in OOM, consists of two parts, shell and core, for reusability. A transfer handler corresponds to a functional model of OOM and it stores low level device commands required to perform job flow operations between giving and taking devices. The state manager and the flow controller constitute a dynamic model of OOM. The proposed V-FMS model has been implemented for a couple of linear type FMS-lines

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권9호
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• pp.422-430
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• 2005

This paper describes experimental analysis of UPFC, which is composed of cascaded H-bridge modules and single-phase multi-winding transformers for isolation. The operational characteristic was analyzed through experimental works with a scaled model, and simulation results with PSCAD/EMTDC. The UPFC proposed in this paper can be directly connected to the transmission line without series injection transformers. It has flexibility to expand the operation voltage by increasing the number of H-bridge modules. The analysis results can be utilized to design the actual WFC system applicable for the transmission system.

• 조명전기설비학회논문지
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• 제12권1호
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• pp.78-84
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• 1998

발전소나 화학플랜트의 급수 및 순환수 계통은 물론 건물의 공조설비 유체계통, 정수 또는 폐수설비에서의 원수유량 및 약품 주입제어 등과 같은 유체계통은 대부분 밸브와 동력 펌프를 이용해 유량 제어를 한다. 따라서 이들 유체계통의 제어방법 및 정밀도에 따라 그 시스템의 성능 및 에너지 절약에 많은 영향을 미치게 된다. 지금까지 이들 계통은 주로 PI제어기를 이용하였으나 이 제어 방법으로는 루프간의 간섭현상으로 정밀하게 유량부하를 제어 할수 없는 문제점이 있다. 본 논문에서는 유체계통 동력부하 설비를 다변수로 구성하여 2-자유 PID제어를 적용하고 신경망을 이용해 튜우닝함으로서 효과적으로 정밀하게 제어 할수 있는 방법을 제시하고 시뮬레이션을 통해 그 방법의 우수성을 입증하였다. 시뮬레이션 결과 설정치를 잘 추종하고 외란에 대해서는 강인성을 갖는 것으로 나타났다.

• 한국지능시스템학회논문지
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• 제14권5호
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• pp.648-654
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• 2004

반도체 제조 장비에서 가스의 질량 흐름 제어기(Mass Flow Controller: MFC)가 차지하는 비중은 매우 크다. 가스의 흐름 제어가 곧 반도체 소자의 품질 및 수율을 결정하는 중요한 요소이기 때문이다. 따라서 MFC의 고속, 고정밀 제어를 구현하기 위한 요구가 높아지고 있다. MFC의 제어 알고리즘에 관한 연구 선례는 찾아보기가 매우 힘들다. 그러나 일반적으로 PID 제어 알고리즘을 사용되는 것으로 알려지고 있다. MFC 제어의 어려움은 열에 의해 흐름을 감지하는 시스템일 경우 느린 응답 특성과 비선형성을 포함한다는 데 있다. 본 논문에서는 기존의 PID 알고리즘 보다 더 우수한 성능을 보이는 MFC 제어 알고리즘을 제시하고 실험을 통해 그 우수성을 보인다. 비선형성과 느린 응답 특성을 보상하기 위하여 퍼지제어 알고리즘을 적용하였으며 그 성능을 현재 상용화된 제품과 비교하였다. 본 논문에서 제안한 알고리즘은 PC와 PC에 장착된 데이터 획득 보드를 통하여 제어루프를 형성하였고, PC상에서 LabWindows/CVI 프로그램으로 제어알고리즘을 구현하였다. 또한, 느린 응답 특성이 존재하는 센서출력으로부터 실제의 흐름을 추정하는 하나의 방법도 제시하였다. 실험결과 본 논문에서 제안하는 알고리즘이 기존의 제품보다 더 빠르고, 더 정확한 제어성능을 보였다.