• 한국정보통신학회논문지
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• 제11권3호
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• pp.532-539
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• 2007

신재생 에너지 자원의 하나로 각광받고 있는 태양광발전시스템은 분산형 발전시스템으로서 설치 이후의 효율적인 시스템 관리와 운영이 중요한 문제로 대두되고 있다. 이러한 문제점을 해결할 수 있는 방법 중 하나는 원격 모니터링 및 제어 시스템을 적용하는 것이다. 본 논문에서는 태양광 발전 시스템의 효율적인 관리와 운용을 위한 LabVIEW 기반의 모니터링 및 제어시스템을 제안한다. 모니터링부와 태양광 인버터의 DSP(Digital Signal Processor) 제어기간의 인터페이스에 대하여 자세히 설명하고, 계통연계형 태양광발전시스템에 적용하여 제안된 시스템의 타당성을 검증한다.

• 전력전자학회논문지
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• 제9권6호
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• pp.568-576
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• 2004

본 논문은 신$.$재생에너지를 이용한 분산전원시스템을 위한 새로운 단독운전 방지기법을 제시한다. 유효전력과 무효전력 불균형의 개념에 근거해서 3가지 다른 단독운전 조건이 분석된다. 단독운전 전압이 유효전력의 함수이고 그 주파수는 유효전력과 무효전력의 함수임이 분석을 통해 보여준다. 이 분석결과를 이용해서 새로운 단독운전 방지기법이 개발되었다. 제안된 보호 알고리즘은 분산전원에 의해 공급되는 무효전력을 계속적으로 $\pm$5% 변화시키면서 동시에 계통전압과 주파수를 관측한다. 만일 단독운전에 의해 측정할 정도의 주파수 이탈이 발생하면 더 나아가 분산전원의 유효전력을 80%로 감소시킨다. 이 검출기법은 공진부하에서도 빠르게 동작됨을 보여준다. 가능한 단독 운전조건이 모의되고 분석 증명된다. 0.5 kW 연계형 연료전지 시스템의 실험결과가 제시된다.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.382-388
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• 2009

Recently, hydrogen energy has been anticipated to change the paradigm of conventional power systems because it can expand sustainable energy utilization and conceptually provide remarkable flexibility to power system operation. Since hydrogen energy can be converted to electric energy through fuel cells, fuel cells are expected to play an important role in the future hydrogen economy. In this paper, a Proton Exchange Membrane Fuel Cell (PEMFC) is modeled as an equivalent circuit and its steady-state characteristics investigated using the model. PEMFCs can be connected to power systems through power conditioning systems, which consist of power electronic circuits, and which are operated as distributed generators. This paper analyzes the effects of the characteristics of the PEMFC internal voltages and investigated the dynamic responses of the PEMFC under fault conditions. The results show that the fault current contribution of the PEMFC is different from those of conventional generators and is closely related to its operating point.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.320-327
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• 2002

In concert with the growing emphasis placed on distributed power generation there will be a need, in the first decade of the 21th century, for a compact thermal energy system capable of providing the total energy needs of individual homes. A natural gas fueled co-generation micro-turbine with ultra low emission will meet this need. Market opportunities for a distributed micro turbine co-generation system are projected to increase dramatically. In this paper, It was determined that with current state of art component performance levels, metrallic materials, thermal efficiency goal of $28\%$ at sea level standard day conditions are attainable. Higher overall thermal efficiency of $78\%$ is attainable with micro-turbine combined with exhaust fired boilers.

• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.9-16
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• 2012

The present study presents the Phasor Discrete Particle Swarm Optimization (PDPSO) algorithm, an effective optimization technique, the multi-dimensional vectors of which consist of magnitudes and phase angles. PDPSO is employed in the configuration of micro-grids. Micro-grids are concepts of distribution system that directly unifies customers and distributed generations (DGs). Micro-grids could supply electric power to customers and conduct power transaction via a power market by operating economic dispatch of diverse cost functions through several DGs. If a large number of micro-grids exist in one distribution system, the algorithm needs to adjust the configuration of numerous micro-grids in order to supply electric power with minimum generation cost for all customers under the distribution system.

• 신재생에너지
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• 제2권2호
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• pp.108-117
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• 2006

This paper focus on power development options for remote islands. Recently, in accordance with progress in distributed generation technologies including renewable energy sources, many options are possible as power development option for island. At first we estimate generation cost by generation technology then recommend and suggest some countermeasures and implementation for institutional improvement.

• Journal of Electrical Engineering and Technology
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• 제4권1호
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• pp.1-12
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• 2009

In recent years, integration of new distributed generation (DG) technology in distribution networks has become one of the major management concerns for professional engineers. This paper presents a dynamic methodology of optimal allocation and sizing of DG units for a given practical distribution network, so that the cost of active power can be minimized. The approach proposed is based on a combined Genetic/Fuzzy Rules. The genetic algorithm generates and optimizes combinations of distributed power generation for integration into the network in order to minimize power losses, and in second step simple fuzzy rules designs based upon practical expertise rules to control the reactive power of a multi dynamic shunt FACTS Compensator (SVC, STATCOM) in order to improve the system loadability. This proposed approach is implemented with the Matlab program and is applied to small case studies, IEEE 25-Bus and IEEE 30-Bus. The results obtained confirm the effectiveness in sizing and integration of an assigned number of DG units.

• 한국전기전자재료학회논문지
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• 제31권3호
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• pp.182-187
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• 2018

In this study, 20.8% of a p-type Si bifacial solar cell was used to develop a photovoltaic (PV) module to obtain the maximum power under a limited installation area. The transparent back sheet material was replaced during fabrication with a white one, which is opaque in commercial products. This is very beneficial for the generation of more electricity, owing to the additional power generation via absorption of light from the rear side. A new model is suggested herein to predict the power of the bifacial PV module by considering the backside reflections from the roof and/or environment. This model considers not only the frontside reflection, but also the nonuniformity of the backside light sources. Theoretical predictions were compared to experimental data to prove the validity of this model, the error range for which ranged from 0.32% to 8.49%. Especially, under $700W/m^2$, the error rate was as low as 2.25%. This work could provide theoretical and experimental bases for application to a distributed and microgrid network.

• 전력전자학회논문지
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• 제18권1호
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• pp.63-71
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• 2013

This paper describes the coordinated droop control method for stand-alone type DC micro-grid to improve reliability and utilization of distributed generations and energy storage. The stand-alone type DC micro-grid consists of several distributed generations such as a wind power generation, solar power and micro-turbine, and energy storage. The proposed method which is based on autonomous control method shows high reliability and stability through coordinated droop control of distributed generations and energy storage and also capability of battery management. The operation of stand-alone type DC micro-grid was analyzed using detail simulation model with PSCAD/EMTDC software. Based on simulation results, a hardware simulator was built and tested with commercially available components and performance of system was verified.

• KIEE International Transactions on Power Engineering
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• 제5A권1호
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• pp.9-15
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• 2005

In the operation of distribution systems, DGs (Distributed Generations) are installed as an alternative to extension and the establishment of substations, transmission and distribution lines according to the increasing power demand. In the operation planning of DGs, determining optimal capacity and allocation achieves economical profitability and improves the reliability of power distribution systems. This paper proposes a determining method for the optimal number, size and allocation of DGs in order to minimize the operation costs of distribution systems. Capacity and allocation of DGs for economical operation planning duration are determined to minimize total cost composed with power buying cost, operation cost of DGs, loss cost and outage cost using the GA (Genetic Algorithm).