• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1777-1788
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• 2017

This paper presents the design and dynamic analysis of a stand-alone microgrid with high penetration of renewable energy. The optimal sizing of various components in the microgrid is obtained considering two objectives: minimization of levelized cost of energy (LCOE) and maximization of renewable energy penetration. Integrating high renewable energy in stand-alone microgrid requires special considerations to assure stable dynamic performance, we therefore develop voltage and frequency control method by coordinating Battery Energy Storage System (BESS) and diesel generators. This approach was applied to the design and development of Gasa Island microgrid in South Korea. The microgrid consists of photovoltaic panels, wind turbines, lithium-ion batteries and diesel generators. The dynamic performance of the microgrid during different load and weather variations is verified by simulation studies. Results from the real microgrid were then presented and discussed. Our approach to the design and control of microgrid will offer some lessons in future microgrid design.

• 조명전기설비학회논문지
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• 제23권10호
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• pp.52-58
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• 2009

본 논문에서는 마이크로그리드(Micro grid, MG)의 설계에서 필요로 되는 에너지저장장치(Energy storage system, ESS)의 최소설비용량을 산정할 수 있는 확률론적 방법론을 제시하였다. ESS기술은 아직까지 경제성 측면에서 매우 높은 설비비용이 필요로 되기 때문에 적정 설비규모를 산정하는 것과 MG의 안정적인 운영을 위해서 최소 설비용량에 대한 가이드라인의 제시가 필요로 된다. 본 논문에서 제시한 방법론은 Non-dispatchable 발전원 출력의 간헐성과 모든 발전기의 고장정지확률을 고려하여 MG가 자체적인 에너지 Self balancing을 유지할 수 있는 ESS의 최소설비용량을 산정할 수 있는 것을 특징으로 한다.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.11-18
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• 2012

Diesel fuel is expensive because transportation to remote areas adds extra cost, and it causes air pollution by engine exhaust. Providing a feasible economical and environmental solution to diesel generators is important. A hybrid system of renewable plants and diesel generators can benefit islands or other isolated communities and increase fuel savings. Renewable energy is, however, a natural source that produces a fluctuating power output. In this paper, hybrid power system of the marado lighthouse is proposed to supply stable power in the stand-alone hybrid power system. The proposed hybrid power system consists of the diesel generator, wind turbine, photovoltaic, fuel cell, and battery bank. To decrease the carbon emissions and find the optimization, the cost analysis of hybrid system is simulated using HOMER program and the optimized hybrid power system is designed.

• 한국전자통신학회논문지
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• 제13권4호
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• pp.837-844
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• 2018

신재생에너지의 발전량 변동에 따라 기존 발전기의 발전량을 증가시키거나 감소시켜야 하는데, 발전량 증 감발에 빠르게 반응을 하는 발전기들은 상대적으로 발전비용이 크므로 태양광발전의 예측 정확도에 따라서 기동발전계획의 비용 효율성이 영향을 받게 된다. 이에 본 논문에서는 태양광 발전량 예측의 불확실성을 최소화하기 위하여 빅데이터 분석 및 처리를 적용한 태양광발전설비 원격관제 시스템을 제안하였다.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.737-743
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• 2013

The small-scaled onsite generators such as photovoltaic power, wind power, biomass and fuel cell belong to decarbonization techniques. In general, these generators tend to be connected to utility systems, and they are called distributed generations (DGs) compared with conventional centralized power plants. However, DGs may impact on stabilization of utility systems, which gets utility into trouble. In order to reduce utility's burdens (e.g., investment for facilities reinforcement) and accelerate DG introduction, the advanced operation algorithms under the existing utility systems are urgently needed. This paper presents the advanced voltage regulation method in power systems since the sending voltage of voltage regulators has been played a decisive role restricting maximum installable DG capacity (MaxC_DG). For the proposed voltage regulation method, the difference from existing voltage regulation method is explained and the detailed concept is introduced in this paper. MaxC_DG estimation through case studies based on Korean model network verifies the superiority of the proposed method.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.114-123
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• 2018

Recently, as one of the countermeasures to reduce carbon dioxide($CO_2$) for global warming problems, operation methods in micro-grid systems replacing diesel generator with renewable energy sources including wind power(WP) and photovoltaic(PV) system have been studied and presented in energetic manners. However, it is reported that some operation problems in micro-grid systems without diesel generator for carbon-free island are being occurred when large scaled WP systems are at start-up. To overcome these problems, this paper proposes an operation strategy in micro-grid systems by adapting control devices such as CVCF(constant voltage constant frequency) ESS(energy storage system) for constant frequency and voltage regulation, load control ESS for balancing demand and supply and SVC(static-var compensator) for reactive power compensation. From the simulation results based on the various operation scenarios, it is confirmed that the proposed operation strategy in micro-grid systems without diesel generators is a useful tool to perform a stable operation in micro-grid systems without diesel generator and also make a contribution to reduce carbon dioxide in micro-grid systems.

• 전기학회논문지
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• 제67권4호
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• pp.498-504
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• 2018

The conventional photovoltaic(PV) systems are designed the installation angle for maximizing power output by considering a geographical characteristics, weather and climate conditions such as the solar radiation and atmosphere temperature. However, the PV generators must be designed to deal with the extreme situations like typhoons, earthquakes because PV systems are exposed to the ambient conditions and external shock due to condition of PV location. Especially, the wind has relatively higher influence on the design of PV systems, in this paper we proposed the method of determining the optimal nominal dimension of the facilities, which can withstand the maximum wind pressure. By using the proposed method, we determined the optimal installation angle for the aspect stability of PV facilities and amount of power output. Moreover, we analyzed the monthly amount of power for each installation angle of PV systems, and proposed the changing strategy of installation angle by determining the optimal angle to produce maximum power for each period.

• Journal of Power Electronics
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• 제6권3호
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• pp.226-234
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• 2006

Photovoltaic (PV) generators have nonlinear V-I characteristics and maximum power points which vary with illumination level and temperature. Using a maximum power point tracker (MPPT) with an intermediate converter can increase the system efficiency by matching the PV systems to the load. This paper presents a maximum power point tracker based on fuzzy logic and a control scheme for a single-phase inverter connected to the utility grid. The fuzzy logic controller (FLC) provides an adaptive nature for system performance. Also the FLC provides excellent features such as fast response, good performance and the ability to change the fuzzy parameters to improve the control system. A single-phase AC-DC inverter is used to connect the PV system to the grid utility and local loads. While a control scheme is implemented to inject the PV output power to the utility grid at unity power factor and reduced harmonic level. The simulation results have shown the effectiveness of the proposed scheme.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.461-470
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• 2014

This paper presents a probabilistic power flow (PPF) analysis method for distribution network incorporating the randomness and correlation of photovoltaic (PV) generation. Based on the multivariate kernel density estimation theory, the probabilistic model of PV generation is proposed without any assumption of theoretical parametric distribution, which can accurately capture not only the randomness but also the correlation of PV resources at adjacent locations. The PPF method is developed by combining the proposed PV model and Monte Carlo technique to evaluate the influence of the randomness and correlation of PV generation on the performance of distribution networks. The historical power output data of three neighboring PV generators in Oregon, USA, and 34-bus/69-bus radial distribution networks are used to demonstrate the correctness, effectiveness, and application of the proposed PV model and PPF method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1739-1741
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• 2005

Many photovoltaic(PV) systems are being developed and installed. For a PV developer, simulations are required before the experimental testing. However, most simulation tools do not offer data libraries for PV systems, so that some Institutes who try to use such software will be in difficulty. In this paper, simulations of performance and stability have been carried out using the software PSPICE. In this paper, the modelling of solar cell arrays, photovoltaic modules, PV generators, batteries and drive systems is carried out based on mathematical equivalence circuits and available data, and the models are converted into a data library for PSPICE that is user friendly. System variations can be modeled by simple parameter variation. To verify the accuracy of the simulation library, various models were run and compared to known systems.