• 한국전자통신학회논문지
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• 제11권4호
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• pp.395-402
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• 2016

DC ${\mu}$-Grid 기반의 충/방전 시스템에서 배터리의 동작 변환 시, 망 전압의 fluctuation이 발생하게 되며, 과다한 fluctuation은 충/방전 시스템의 손상 및 고장을 일으킬 수 있다. 따라서 본 논문에서는 DC ${\mu}$-Grid 기반의 충/방전 시스템에서 fluctuation 완화용 커패시터의 적용 및 설계 포인트에 대하여 연구하였다. 컴퓨터 시뮬레이션 결과, 3개의 충전 배터리 set와 5개의 방전 배터리 set의 조건으로 운영되는 DC ${\mu}$-Grid 기반 충/방전 시스템에서 600V/35mF의 초기 값을 갖는 fluctuation 완화용 커패시터를 적용하였을 때 충/방전에 의한 fluctuation을 약 66.3% 감소시킬 수 있었으며, 추가적으로 초기 망 전압 안정화 시 발생하는 fluctuation 또한 약 73% 감소시킬 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2227-2236
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• 2017

In order to solve the neutral-point voltage fluctuation problem of three-phase three-level T-type inverters (TPTLTIs), the unbalance characteristics of capacitor voltages under different switching states and the mechanism of neutral-point voltage fluctuation are revealed. Based on the mathematical model of a TPTLTI, a feed-forward voltage balancing control strategy of DC-link capacitor voltages error is proposed. The strategy generates a DC bias voltage using a capacitor voltage loop with a proportional integral (PI) controller. The proposed strategy can suppress the neutral-point voltage fluctuation effectively and improve the quality of output currents. The correctness of the theoretical analysis is verified through simulations. An experimental prototype of a TPTLTI based on Digital Signal Processor (DSP) is built. The feasibility and effectiveness of the proposed strategy is verified through experiment. The results from simulations and experiment match very well.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.287-289
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• 2009

This paper deals with a parallel processing uninterruptible power supply (UPS) for sudden voltage fluctuation in computer applications to integrate power quality improvement, load voltage stabilization and UPS. To reduce the complexity, cost and number of power conversions, which results in higher efficiency, only one voltage-controlled voltage source inverter (VCVSI) is used. The system provides sinusoidal voltage at the fundamental value of 220V/60Hz for the load during abnormal utility power conditions or grid failure. Also, the system can be operated to mitigate the harmonic current and voltage demand from nonlinear loads and provide voltage stabilization for loads when sudden voltage fluctuation occur, such as sag and swell. System operation simulation demonstrates that the system protects against outages caused by abnormal utility power conditions and sudden voltage fluctuations and changes.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.456-459
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• 2009

we studied a data acquisition and control system of a wind turbine for measuring and controlling a voltage fluctuations of a wind turbine system. The wind turbine system is installed out control area. So, it is so important for supervising to wind turbine of a maintenance, wind speed, optical resources wind turbine output, wind speed, wind direction, over voltage of a generator. This system can be supplied a data of over voltage, under voltage, voltage fluctuations of a wind turbine for controlling an EMS : Energy Management System or a SCADA : Supervision Control and Data Acquisition at a constitute of a wind farm. The of voltage fluctuation system of a wind turbine is improving an electric power supply power quality of a distribution line and unspecified individuals of used wind turbine.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.107-111
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• 1996

In this paper, the voltage monitoring system is designed to monitor the outage and voltage fluctuation by using a dial-up telephone. The master station receives tire outage signal-such as interruption and voltage sag etc. - from the remote in on-line of real-time. The SCC(Serial Communication Controller) is adapted to monitor voltages multiple clients(about 256 clients) simultaneously. The voltage fluctuation in a normal range shall be transmitted to the master station, at early morning the clients use the telephone less frequently. The operating system shall be "window 95" and the database is programmed in Visual-basic for a easy analysis of voltage fluctuation.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.659-668
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• 2018

This paper proposes an optimization approach of a grid-connected photovoltaic and wind hybrid energy system including energy storage considering voltage fluctuation in the electricity grid. A techno-economic analysis is carried out in order to minimize the size of hybrid system by considering the benefit-cost. Lithium-ion battery type is used for both managing the electricity selling to the grid and reducing voltage fluctuation. A new technique is developed to limit the voltage perturbation caused by the solar irradiance and the wind speed through determining the state-of-charge of battery for every hour of a day. Improved particle swarm optimization (PSO) methods, referred to as FC-VACPSO which combines Fast Convergence Particle Swarm Optimization (FCPSO) method and Variable Acceleration Coefficient Based Particle Swarm Optimization (VACPSO) method are used to solve the optimization problem. A comparative study has been performed between standard PSO method and PSO based methods to extract the best size with the benefit cost. A sensitivity analysis has been studied for different kinds and costs of batteries, by considering variable and constant state-ofcharge of battery. The simulations, performed under Matlab environment, yield good results using the FC-VACPSO method regarding the convergence and the benefit cost of the hybrid system.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.481-482
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• 2022

본 논문은 MOSFET 트랜지스터로 구성된 monolithic 3D 인버터의 구조에서 하부 MOSFET 게이트 전압의 변화에 따라서 상부 MOSFET 트랜지스터의 random dopant fluctuation(RDF) 영향을 3차원 소자 시뮬레이션을 통하여 조사하였다. RDF 영향 조사를 위한 표본화는 kinetic monte carlo 방식을 통하여 진행하였으며, RDF 영향이 트랜지스터의 임계전압 변동에 영향을 주는 것을 확인하였고, 상부 트랜지스터와 하부 트랜지스터 사이에 전기적 커플링을 조사하였다.

• Journal of Power Electronics
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• 제17권4호
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• pp.942-952
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• 2017

Modular multilevel converters (MMCs) have been receiving extensive research interest in high/medium-voltage applications due to its modularity, scalability, reliability, high-voltage capability, and excellent harmonic performance. Submodule capacitors are usually rather bulky because they have to withstand fundamental frequency voltage fluctuations. To reduce the capacitance of these capacitors, this study proposes a modified MMC with an active power decoupling circuit within each submodule. The modified submodule contains an auxiliary half bridge, with its capacitor split in two. Also, the midpoints of the half bridge and the split capacitors are connected by an inductor. With this modified submodule, the fundamental frequency voltage fluctuation can be suppressed to a great extent. The second-order voltage fluctuation, which is the second most significant component in submodule voltage fluctuations, is removed by the proper control of the second-order circulating current. Consequently, the submodule capacitance is significantly reduced. The viability and effectiveness of the proposed new MMC are confirmed by the simulation and experimental results. The proposed MMC is best suited for medium-voltage applications where power density is given a high priority.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.535-538
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• 2005

We report the influence of the threshold voltage and mobility fluctuation in TFT on current mode digital circuit performance. We found that the threshold voltage showed more serious circuit malfunction. We studied new circuit configuration for improvement.

• 전기학회논문지
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• 제65권1호
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• pp.179-193
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• 2016

In power quality monitoring, voltage fluctuation is one of the power quality problems, which cause light flickers. To determine the flicker severity, the flicker meter concept was developed in an IEC 61000-4-15 standard. Generally, voltage fluctuations are described as an amplitude modulation(AM). The flicker meter of IEC 61000-4-15 as an international standard for flicker measurement recommends square demodulation method to detect flicker signals from voltage fluctuation signals. This paper suggests a new effective method using filter bank to detect and estimate flicker signals, which do not need square demodulation. For the accurate detection of flicker signals, the filter bank is designed with a full consideration of the spectrum characteristics of voltage fluctuation signals described as AM. The frequency and magnitude of the detected flicker signals are estimated using recursive method. Computer simulations were performed on synthesized signals to prove validity of the proposed method.