• Journal of Power Electronics
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• v.17 no.3
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• pp.766-776
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• 2017

In modern power systems, high penetration of distributed generators (DGs) results in high stress on system stability. Apart from the intermittent nature of DGs, most DGs do not contribute inertia or damping to systems. As a result, a new control method named virtual synchronous machine (VSM) was proposed, which brought new characteristics to inverters such as synchronous machines (SMs). In addition, different active power droop controls for VSMs are being proposed in literatures. However, they are quite different in terms of their dynamic characteristics despite of the similar control laws. In this paper, mathematical models of a VSM adopting different active power droop controls are built and analyzed. The dynamic performance of the VSM output active power and virtual rotor angular frequency are presented for different models. The influences of the damping factor and droop coefficient on the VSM dynamic behaviors are also investigated in detail. Finally, the theoretical analysis is verified by simulations and experimental results.

• Current Photovoltaic Research
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• v.9 no.2
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• pp.31-35
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• 2021

Shingled module shows high ratio active area per total area due to more efficient packing without inactive space between cells. The module is fabricated by connecting the pre-cut cells into the string using electrically conductive adhesives (ECA). ECAs are used for electric and structural connections to fabricate the shingled modules. In this work, we investigated a correlation between ECA peel strength and the efficiency of pre-cut 5 cells module which are fabricated according to ECA interconnection conditions. The curing conditions are varied to determine whether ECA interconnection properties can affect module properties. As a result of the peel test, the highest peel strength was 1.27 N/mm in the condition of 170℃, the lowest peel strength was 0.89 N/mm in the condition of 130℃. The efficiency was almost constant regardless of the curing conditions at an average of 20%. However, the standard deviation of the fill factor increased as the adhesive strength decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.4
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• pp.262-270
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• 2015

In this paper existing buildings, not a new buildings and house for living people not just a displaying and a viewing, created by the imagine effect or virtual simulation was applied various Active and Passive elements. After constructing zero-energy houses, through default case happened during operation period it is described problems and solutions about field part, work classification, installation by Location part, and Installation equipment part. Since then, to take advantage of this thesis, it's the purpose of this paper using as the baseline data for building a zero-energy house in another similar case.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1111-1126
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• 2018

In modern power systems, distributed generators (DGs) result in high stress on system frequency stability. Apart from the intermittent nature of DGs, most DGs do not contribute inertia or damping to systems. As a result, a new control method referred to as a virtual synchronous machine (VSM) has been proposed, which brought new characteristics to inverters such as synchronous machines (SM). DGs employing an energy storage system (ESS) provide inertia and damping through VSM control. Meanwhile, energy storage presents some physical constraints in the VSM implementation level. In this paper, a VSM mathematical model is built and analyzed. The dynamic responses of the output active power are presented when a step change in the frequency occurs. The influences of the inertia constant, damping factor and operating point on the ESS volume margins are investigated. In addition, physical constraints are proposed based on these analyses. The proposed physical constraints are simulated using PSCAD/EMTDC software and tested through RTDS experiment. Both simulation and RTDS test results verify the analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.11
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• pp.42-50
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• 2014

In the thesis, the case of zero energy house construction applied with various Active factors and Passive factors which is the real residence as a standard not a normal experimental residence was evaluated, analyzed, and organized. The thesis can be the base data to construct another similar case of zero energy house.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.253-256
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• 2006

This paper shows operating characteristics of DFIG(Double Fed Induction Generator) for wind turbine. The back to back PWM voltage-fed inverter connected between the rotor and grid network operated sub and super-synchronous operating mode, and the vector-controlled DFIG enables the decoupling between active and reactive power as well as between torque and power factor. This paper is validated by simulations and experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.425-427
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• 2008

Active area of dye-sensitized solar cell (DSSC) has an effect on the efficiency of DSSC. As the active area increases, the efficiency goes down in a general way. This is caused by the increase of internal resistance in DSSC. The internal resistances are related to various resistant elements. The charge transfer processes at Pt counter electrode and the sheet resistance of TCO are two of these resistant elements. In this study, we try to divide the active area into several small sections in a large sized cell to reduce these two internal resistant elements. As a result, we find out that the fill factor is increased and then the conversion efficiency is improved as the number of dividing active area into several small sections is increased.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.514-517
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• 2008

Water gas shift(WGS) is an important step in fuel process for fuel cells, and improperness of commercial WGS catalysts for use in fuel cell systems has prompted numerous researches on noble metal catalysts. A selected noble metal catalyst for water gas shift reaction(WGS) was prepared with various metal loadings. The prepared catalysts were tested under two feeding conditions. At moderate residence time, carbon monoxide conversion was much higher on the noble metal catalysts as compared to commercial high-temperature shift catalyst. Effects of metal loading were examined by activity tests at short residence time. Higher metal loading effected higher reaction rate. The kinetic data was fitted to simple reaction equations and effectiveness factor was estimated. The results suggest the necessity of a structural design for the highly active noble metal catalysts.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.520-523
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• 2005

국내에서 대체에너지 공급 비율을 보면 청정에너지로 분류할 수 있는 태양열에너지, 태양 광 에너지, 풍력에너지를 모두 합하여 대체에너지의 $10\%$이하이며, 대체에너지 비율의 $90\%$ 이상을 폐기물로부터 얻은 에너지가 차지하고 있는 실정이다. 신재생에너지원에는 여러 종류가 있지만 해양에너지원에 대해 대상을 설정하고 이에 대한 부존량을 살펴보면 진도 주변의 해역에서 조류발전 부존량이 약 362만 kW가 되며, 시화호와 새만금 등지에서의 조력발전 부존량이 650만 kW, 동해안 후포 연안을 비롯한 파력발전 부존량이 20만kW가 되는 것으로 알려져 있다. 이에 따라 해양에너지를 실용화하기 위한 연구가 국내외에서 연구되고 있다. 본 논문은 권선형유도발전기를 갖는 조류발전 시스템을 대상으로 연구한 결과로 권선형유도발전기를 제어하기 위한 전력변환장치 개발과 관련한 내용이다. 신재생에너지원이 발전 단가 측면에서 경제성을 갖기 위해서 발전기 용량은 5MW 급까지 대용량화되어 있는 단계이지만 국내에서는 아직 MW급 이상이 되는 권선형 유도발전기와 권선형 유도발전기를 제어하는 전력변환장치에 대한 연구 실적이 없는 상황이다 이에 본 논문에서는 1MW급의 권선형유도발전기에 대한 개발 사례를 소개하면서 유효전력제어, 역률제어, 계통연계방법, 그리고 운전 속도에 따라 변동되는 회전자측에서의 피상전력 특성 등을 제시하고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.305-308
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• 2007

The field of dye-sensitized solar cell (DSC) is being researched actively at present. Because DSC has several advantages to pass the limits of Si solar cells such as a low manufacturing expense, a simple manufacturing process and its transparency. A lot of researches are underway about materials and processes in the field of dye-sensitized solar cell but its structure has been fixed up as the sandwich structure that both edges are used as positive and negative terminals. But the structure as of present is a factor of decreasing efficiency because the more electrons are recombined the further distance from terminal, considering about the characteristic of dye-sensitized solar cell that electrons generated inside cell are moved by diffusion. In this study, we made experiment on expanding the terminal to shorten internal moving distance of electron and compared the results according to the variation of active area to find out the effect of this trial. As a result, we achieved about 15.5% improvement of maximum power and 0.5% improvement of efficiency from terminal-expanded dye-sensitized solar cell of $2cm^{2}$ active area and concluded that the increasing rate of efficiency is raised as the active area becomes wider.