• 전기학회논문지
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• 제57권3호
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• pp.398-402
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• 2008

Recently, the development of superconducting fault current limiters (SFCLs) has been required as power demands increase in the power system. A distribution-level prototype resistive SFCL using coated conductor (CC) has been developed by Hyundai Heavy Industries Co., Ltd. and Yonsei University for the first time in the world. The ratings of the SFCL are 13.2kV/630A at normal operating condition. A novel non-inductive winding method is used in fabricating coils so there is almost zero impedance during normal operation. The distribution SFCL is cooled by sub-cooled liquid nitrogen $(LN_2)$ of 65K and 3 bar to enhance cryo-dielectric performance, critical current density, and thermal conductivity. In order to make reliable operation of an SFCL in real power systems, we monitored and controled its operation conditions by using supervisory control and data acquisition (SCADA) method. Thus, a monitoring system for the SFCL employing information technology (IT) is proposed and developed to be on the lookout for the operation conditions such as inside temperature, inside pressure, $LN_2$ level, voltage and current. Since operation temperature should be kept constant, bang-bang control for temperature feedback with a heater attached to the cold head of cryo-cooler is applied to the system. Short-circuit tests with prospective fault current of 10kA and AC dielectric withstand voltage tests up to 143kV for 1 minute were successfully performed at Korea Electrotechnology Research Institute. This paper deals with the development of a distribution level SFCL and its monitoring system for reliable operation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.501-505
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• 2001

The parallel operation system of UPS is used to increase reliability of power source at critical load. But parallel UPS system has a few defects, impedance is different from each other and circulating current occurs between UPSs, due to line impedance and parameter variation, though controlled by the same synchronization signal. According to such characteristic of parallel UPS, balanced load-sharing control is the most important technique in parallel UPS operation. In this paper, a novel power deviation compensation algorithm is proposed. it is composed of voltage controller to compensate power deviation that be calculated by using active and reactive current deviation between inverters on synchronous d-q reference frame.

• 한국태양에너지학회 논문집
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• 제36권5호
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• pp.19-30
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• 2016

In this study, realize voltage regulation $220Vac{\pm}10%$ or less, frequency fluctuation $60Hz{\pm}1%$ or less over the independent operation and grid-connected operation technologies for power stabilization relates to the ESS designed and manufactured in conjunction with solar installations and solar to compensate the output reduction due to the polarization of the solar module through the polarization prevention technology for preventing the optical module efficiency is lowered, in conjunction with the BMS inverter efficiency was more than 92%, more than 90% of the charging efficiency to the target. This study was designed in conjunction with the ESS solar power plants, grid-connected operation and independent operation, Peak-Cut, it can stabilize the grid via the Peak-Shifting operation

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3259-3263
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• 2007

This paper describes the proceedings of creating countermeasures after analysis and maintenance be able to conduct operation safely in a power plant. in order to operate the power plant in a stable and reliable way, the best condition of the govemor system can be maintained through the response characteristic analysis of the control device for the pitch blade control hydraulic actuator. The fan pitch blade control hydraulic actuator of a 500MW large-scale boiler is frequently operated under normal operation conditions. Common problems or malfunctions of the pitch blade control hydraulic actuators leads to the decline of boiler thermal efficiency and unexpected power plant trip. The inlet and outlet gas can be controlled by using the fan pitch blade control hydraulic actuator in order to regulate the internal pressure of the furnace and control the frequency in the power plant facility which utilizes soft coals as a power source.

• 전력전자학회논문지
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• 제9권3호
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• pp.294-302
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• 2004

본 연구에서는 수직순환식 입체주차설비용 유도전동기를 제어할 수 있는 인버터장치를 개발하였다 차량의 주차 공간인 파렛트를 호출하는 경우 종래 시스템에 있어서의 승강장 정위치 제어 불능 문제와 이동속도가 잔존한 상태에서의 강제 제동에 따른 제동장치계통의 급속한 마모현상을 근본적으로 해결하도록 하였다. 또한 전원회생기능을 구비한 컨버터제어기를 적용함으로써 수전단 전원용량의 축소와 동작빈도수의 증가에 따른 소비전력의 절감 효과를 기하도록 하였다. 본 연구를 통해 수직순환식 기계식 주차설비의 구동제어에 있어서 부하에 따른 위치 및 속도제어를 효과적으로 구현함으로써 정숙한 운전 특성을 확보하였고 역률제어에 따른 에너지 절감 효과를 기하였다. 실험은 55㎾급 유도전동기를 대상으로 하여 그 결과를 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제3권2호
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• pp.143-151
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• 2008

This paper presents the operation of Fuel Cell Distributed Generation(FCDG) systems in distribution systems. Hence, modeling, controller design, and simulation study of a Solid Oxide Fuel Cell(SOFC) distributed generation(DG) system are investigated. The physical model of the fuel cell stack and dynamic models of power conditioning units are described. Then, suitable control architecture based on fuzzy logic and the neural network for the overall system is presented in order to activate power control and power quality improvement. A MATLAB/Simulink simulation model is developed for the SOFC DG system by combining the individual component models and the controllers designed for the power conditioning units. Simulation results are given to show the overall system performance including active power control and voltage regulation capability of the distribution system.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.594-597
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• 2003

본 연구에서는 DLC와 경제운용을 연계시킴에 있어 계통운전예비력 특성을 감안할 수 있도록 하였다. 우선, 새로이 제약조건을 정식화하여 계통운전예비력을 고려하였으며 3차원 동적계획법을 적용하여 이들을 연계토록 한 결과, DLC와 경제운용을 동시에 경제적으로 구할 수 있게 하였다. 제안한 방법을 시험계통에 적용하여 종래의 방법보다 우수함을 입증하였다.

• Journal of Power Electronics
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• 제10권4호
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• pp.405-411
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• 2010

This paper proposes a novel tracking algorithm considering radiation to improve the power of a photovoltaic (PV) tracking system. The sensor method used in a conventional PV plant is unable to track the sun's exact position when the intensity of solar radiation is low. It also has the problem of malfunctions in the tracking system due to rapid changes in the climate. The program method generates power loss due to unnecessary operation of the tracking system because it is not adapted to various weather conditions. This tracking system does not increase the power above that of a power of tracking system fixed at a specific position due to these problems. To reduce the power loss, this paper proposes a novel control algorithm for a tracking system and proves the validity of the proposed control algorithm through a comparison with the conventional PV tracking method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.206-208
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• 2009

In this paper, a systematical controller design method for a twostage grid-connected photovoltaic power conditioning system is proposed. For a pre-stage boost converter to achieve the stable operation in the entire region of solar array, the digital resistive current mode controller is used. This algorithm is very simple to implement with a digital controller and there is no power stage parameter dependency in the controller design. For a post-stage single-phase full-bridge inverter, a PI controller with a feedforward compensation for the inner current control is employed. Furthermore, in case that the operating point of the solar array under varying environmental conditions is higher than the required voltage for the inverter current control, the bypass mode for the boost converter is possible for the more efficient operation. The proposed control scheme is validated through the experiment of the prototype two-stage power conditioning system hardware with a 200W solar array.

• Journal of Power Electronics
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• 제10권1호
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• pp.97-105
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• 2010

This paper presents the modeling, control and simulation of an interconnection system (ICS) of cascaded distributed generation (DG) modules for both grid-tied and stand-alone operations. The overall configuration of the interconnection system is given. The interconnection system consists of a cascaded DC/DC boost converters and a DC/AC inverter. Detailed modeling of the interconnection system incorporating a cascaded architecture has not been considered in previous research. In this paper, suitable control systems for the cascaded architecture of power electronic converters in an interconnection system have been studied and modeled in detail. A novel control system for DC/DC boost converters is presented based on a droop voltage controller. Also, a novel control strategy for DC/AC inverters based on the average large signal model to control the aggregated DG modules under both grid-tied and stand-alone modes is demonstrated. Simulation results indicate the effectiveness of the proposed control systems.