• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.316-318
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• 1994

Photovoltaic is considered to be one of the most promising technologies which can greatly contribute to future energy supply because or a large, secure, essentially inexhaustible and broadly available resource -sunlight. This paper analyzes reduction of synthetic power peak value through weather data and quantity or generation. This explanation and estimations analyses grid connected power system.

• 한국태양에너지학회 논문집
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• 제26권1호
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• pp.91-98
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• 2006

Islanding phenomenon of utility-connected photovoltaic power conditioning systems(PV PCS) can cause a variety of problems and must be prevented. If the real and reactive power supplied by PV PCS are closely matched to those of load, islanding detection by passive methods becomes difficult. The active frequency drift(AFD) method, called the frequency bias method, enables islanding detection by forcing the frequency of the voltage in the islanding to drift up or down. In this paper, non-detection zone(NDZ) of AFD is analyzed for the islanding detection method of utility-connected PV PCS by the simulation software tool PSIM.

• 경영과학
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• 제33권1호
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• pp.35-47
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• 2016

Generation of electricity using wind power has received considerable attention worldwide in recent years mainly due to its minimal environmental impact. However, volatility of wind power production causes additional problems to provide reliable electricity to an electrical grid regarding power system operations, power system planning, and wind farm operations. Those problems require appropriate stochastic models for the electricity generation output of wind power. In this study, we review previous literatures for developing the stochastic model for the wind power generation, and propose a systematic procedure for developing a stochastic model. This procedure shows a way to build an ARIMA model of volatile wind power generation using historical data, and we suggest some important considerations. In addition, we apply this procedure into a case study for a wind farm in the Republic of Korea, Shinan wind farm, and shows that our proposed model is helpful for capturing the volatility of wind power generation.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2017년도 추계학술발표대회
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• pp.954-956
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• 2017

본 연구에서는 X-선 영상을 이용한 비산란 그리드의 검사 자동화 시스템에서, 결함후보 ROI에 대한 판단정확도를 향상시킬 수 있는 최적영상 획득을 위한 임계치결정 기법을 제안한다. 주파수 도메인에서 영상히스토그램을 분석 및 재구성한 후 최적임계치의 결정에 필요한 요소를 추출하며, 재구성 히스토그램으로부터 영상패턴을 판단하여 각 유형에 따른 최적 임계치를 결정한다. 50개의 영상에 적용한 실험 결과 제안된 방법은 4.8/5.0의 성능 (Inter-class correlation, ICC: 0.985, 95% CI, p-value<0.05)을 보였다.

• 전기의세계
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• 제58권8호
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• pp.51-60
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• 2009

지능형 전력망은 통신 기술을 통해 에너지 사용을 최적화 하고 안정성을 높이는 차세대 전력망으로서 그 내부에는 다양한 통신 환경과 특성이 존재한다. 지능형 전력망에서는 일반 수용가의 부하특성이나 전기 사용량 등 비실시간 정보뿐만 아니라 전력망의 안정적이고 지능적인 운영을 위한 다양한 감시제어 데이터와 같은 실시간 정보가 함께 전달된다. 이러한 정보들은 전달 과정에서 누출, 번조가 되지 않고 원하는 사용자에게 원히는 시간과 장소에 정상적으로 전달될 수 있도록 높은 수준의 정보 보안이 뒷받침 되어야 한다. 그러나 최근, 감시제어 정보 전달은 보통 인터넷과 같은 일반적인 통신보다 고품질을 요구하기 때문에, 통신 품질을 저하시킬 수 있는 보안 서비스를 지능형 전력망에 적용하기에는 제약이 따른다. 본 논문은 지능형 전력망의 주요 통신 환경별 요구사항을 살펴보고, 이러한 요구사항을 만족시키면서 높은 수준의 정보 보안을 제공하기 위해 어떠한 보안서비스가 제공되어야 하는지 알아본다.

• Journal of Power Electronics
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• 제9권4호
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• pp.575-581
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• 2009

In this paper two modes of operating a wound rotor induction machine as a generator at sub-and super-synchronous speeds in wind energy conversion systems are investigated. In the first mode, known as double fed induction generator (DFIG), the rotor circuit is fed from the ac mains via a controlled rectifier and a forced commutated inverter. Adjusting the applied rotor voltage magnitude and phase leads to machine operation as a generator at sub-synchronous speeds. In the second mode, the machine is operated in a slip recovery scheme where the slip energy is fed back to the ac mains via a rectifier and line commutated inverter. This mode is described as double output induction generator (DOIG) leading to increase the efficiency of the wind-to electrical energy conversion system. Simulated results of both modes are presented. Experimental verification of the simulated results are presented for the DOIG mode of operation, showing larger amount of power captured and better power factor when compared to conventional induction generators.

• 전력전자학회논문지
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• 제17권1호
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• pp.8-13
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• 2012

DSTATCOM is active filter that reduces nonlinear and unbalanced currents. Researches about DSTATCOM are mainly divided two parts, one is the reference value calculation of compensation current depending on the calculation of the load-side average active power and dc-link capacitor average voltage, the other part is actual current control depending on the reference value of compensation current. This paper proposes a calculation of dc-link capacitor average voltage ripple voltage extraction instead of conventional method using LPF. The utility of the proposed algorithm is verified through the theoretical analysis and the experiment under unbalance loads and non-linear load.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.481-482
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• 2013

This paper presents the method to determine the battery capacity for controlling the wind power with BESS for stabilizing the output of HanGeong wind farm in accordance with grid codes for distributed generators in Jeju Island. To find appropriate capacity of BESS, three kinds of simulations are carried out : There are focused on smoothing control, the frequency fluctuation and the renewable energy resources standards, respectively. As the simulation result, maximum C-rates of BESS for the wind farm are calculated as 2C, 5C and 2C that are for each method and battery capacities have 25%, 20% and 10% of total capacity of HanGeong wind farm. Finally, simulations for this paper are carried out by using PSCAD/EMTDC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.111-114
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• 1999

This paper deals with the rated output power using grid-connected Doubly-Fed Induction Generator(DFIG) in the supersynchronous speed regions. The rated output power is controlled by both magnitude and frequency of the voltage fed to the rotor. And this rotor voltage is controlled by control of inverter switching frequency and fire angle. A DFIG generating characteristic is analyzed by simulation of steady-state algebraic equation of equivalent circuit using numerical analysis. And it is compared with results of experiment. Consequently, This paper presented to control method for rated output power of DFIG in variable wind speed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2064-2067
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• 2000

In our country, most region is composed of mountains and people have recently been displeased with the construction of the substations in their vicinity so the substations newly built are mainly constructed with GIS system in the small area that has high soil resistivity near mountain. Therefore, nowadays the design of substation grounding system has been difficult, and the additional considerations are needed. UC substation was also difficult to design the grounding system because of so small substation area and high soil resistivity. This paper shows the examples of reducing the grounding system resistance reasonably by using several ways. Designing the ground grid electrode in the access road, deep electric earth probe, changing the substation soil with the law level resistivity soil. This report deals with the computer simulation of the grounding system resistance about the ways illustrated above.