• Journal of Power Electronics
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• 제19권6호
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• pp.1566-1574
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• 2019

Maximum power point tracking (MPPT) under the partial shading condition is a challenging research topic for photovoltaic systems. Shaded photo-voltaic module result in complex peak patterns on the power versus voltage curve which can misguide classical MPPT algorithms. Thus, various kinds of global MPPT algorithms have been studied. These have typically consisted of partial shading detection, global peak search and MPPT. The conventional partial shading detection algorithm aims to detect all of the occurrences of partial shading. This results in excessive execution of global peak searches and discontinuous operation of the MPPT. This in turn, reduces the achievable power for the PV module. Based on a theoretical investigation of power verse voltage curve patterns under various partial shading conditions, it is realized that not all the occurrences of partial shadings require a global peak search. Thus, an intelligent partial shading detection algorithm that provides exact identification of global peak search necessity is essential for the efficient utilization of solar energy resources. This paper presents a new partial shading determinant algorithm utilizing adaptive threshold levels. Conventional methods tend to be too sensitive to sharp shading patterns but insensitive to smooth patterns. However, the proposed algorithm always shows superb performance, regardless of the partial shading patterns.

• Journal of Power Electronics
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• 제19권5호
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• pp.1259-1269
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• 2019

PV system performance is dependent on different irradiations and temperature values in addition to the capability of the employed PV inverter / maximum power point tracker (MPPT) circuit or algorithm. Therefore, it would be appropriate to use a PV simulator capable of producing identical repeatable conditions regardless of the weather to evaluate the performance of inverter / MPPT circuits and algorithms. In accordance with this purpose, a photovoltaic (PV) array simulator is presented in this paper. The simulator is designed to generate current-voltage (I-V) and power-voltage (P-V) curves of a PV panel. Series connected cascaded modules constitute the basic part of the simulator. This feature also allows for the modeling of PV arrays since the number of modules can be increased and high voltage values can be reached with the simulator. In addition, the curves obtained at the simulator output become similar to the actual curves of sample PV panels with an increase in the number of modules. In order to show the validity of the proposed simulator, it was simulated for various situations such as panels under full irradiance and partial shading conditions. After completing simulations, experiments were realized to support the simulation study. Both simulation and experimental results show that the proposed simulator will be very useful for researchers to carry out PV studies under laboratory conditions.

• 반도체디스플레이기술학회지
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• 제17권2호
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• pp.76-80
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• 2018

In recent years, with the development of automobile technology, smart system technology that assists safe driving has been developed. A camera is installed on the front and rear of the vehicle as well as on the left and right sides to detect and warn of collision risks and hazards. Beyond the technology of simple black-box recording via cameras, we are developing intelligent systems that combine various computer vision technologies. However, most related studies have been developed to optimize performance in laboratory-like environments that do not take environmental factors such as weather into account. In this paper, we propose a method to detect object by restoring visibility in image with degraded image due to weather factors such as fog. First, the image quality degradation such as fog is detected in a single image, and the image quality is improved by restoring using an intermediate value filter. Then, we used an adaptive feature extraction method that removes unnecessary elements such as noise from the improved image and uses it to recognize objects with only the necessary features. In the proposed method, it is shown that more feature points are extracted than the feature points of the region of interest in the improved image.

• Advances in Energy Research
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• 제7권1호
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• pp.67-84
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• 2020

Given the recent surge of interest towards utilization of renewable distributed energy resources (DER), in particular in remote areas, this paper aims at designing an optimal hybrid system in order to supply loads of a village located in Esfarayen, North Khorasan, Iran. This paper illustrates the optimal design procedure of a standalone hybrid system which consists of Wind Turbine Generator (WTG), Photo Voltaic (PV), Diesel-generator, and Battery denoting as the Energy Storage System (ESS). The WTGs and PVs are considered as the main producers since the site's ambient conditions are suitable for such producers. Moreover, batteries are employed to smooth out the variable outputs of these renewable resources. To this end, whenever the available power generation is higher than the demanded amount, the excess energy will be stored in ESS to be injected into the system in the time of insufficient power generation. Since the standalone system is assumed to have no connection to the upstream network, it must be able to supply the loads without any load curtailment. In this regard, a Diesel-Generator can also be integrated to achieve zero loss of load. The optimal hybrid system design problem is a discrete optimization problem that is solved, here, by means of a recently-introduced meta-heuristic optimization algorithm known as Lightning Attachment Procedure Optimization (LAPO). The results are compared to those of some other methods and discussed in detail. The results also show that the total cost of the designed stand-alone system in 25 years is around 92M€ which is much less than the grid-connected system with the total cost of 205M€. In summary, the obtained simulation results demonstrate the effectiveness of the utilized optimization algorithm in finding the best results, and the designed hybrid system in serving the remote loads.

• 한국산학기술학회논문지
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• 제21권7호
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• pp.212-217
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• 2020

태양광 발전 시스템은 태양광 패널을 통해 발전된 전력을 계통연계를 통해 전송하는 종합 시스템이다. 발전량을 증대시키는 기술로써 태양광 입사각을 변화시켜 발전량을 증대시키는 추적식 태양광 발전장치 기술이 있다. 본 논문은 입사각을 변화시켜 발전량을 증대시키는 단축 추적식 태양광 발전장치의 구조물과 제어에 관한 연구이다. 핵심 내용은 태양광 구조물이 남북축을 중심으로 동서 방향으로 축회전하도록 구성한 단축 제어장치 및 기술이다. 일출로부터 일몰까지 동서방향으로 태양을 추종하는 태양광 구조물은 구조적 안정성과 태양광 추종 제어 성능 확보가 필요하다. 단축 추적 발전장치는 최대 25% 이상의 발전량 증대를 기대할 수 있다.

• 한국정보통신학회논문지
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• 제19권10호
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• pp.2450-2456
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• 2015

본 논문에서는 분산형 태양광 발전 시스템에 적용 가능한 실시간 원격 모니터링 시스템을 소개한다. 제안된 시스템은 상태정보 수집 장치인 PVC(PhotoVoltaic Client), 모바일 애플리케이션인 UTC(User Terminal Client), 시스템 운영프로그램인 OTC(Operating Terminal Client), 그리고 통신서버와 데이터를 저장하는 서버로 구성되어 있으며, 상태정보 수집 장치는 인버터와 시리얼통신을 통하여 운영정보를 수집하고, 수집된 정보는 서버에 전송되어 데이터 서버에 저장된다. 저장된 정보는 모바일 애플리케이션을 통하여 모니터링 되고, 수집장치 및 사용자 등의 정보는 운영프로그램을 통하여 관리된다. 또한, 제안된 시스템은 사용자에게 실시간으로 발전량 및 고장진단에 관한 정보를 제공함으로써, 고장인지 향상 및 유지보수비용 감소의 가능성을 제시해 주었다.

• 전기학회논문지
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• 제66권12호
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• pp.1905-1912
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• 2017

In recent years, Ulaanbaatar, a capital of Mongolia has witnessed major problem that air quality reaches hazardous level during the winter season. Coal combustion for heating of every house in "Ger" district is main reason. One way to reduce the air pollution is mass usage of electric heater. However, there are several difficulties such as overload and degradation of transformers and other equipment used in distribution and transmission systems as well as power shortage occurrence in evening peak period due to residential consumption. This study aims to contribute for solving the air pollution and power shortage problem in Mongolia. One possible solution could be distributed generation (DG) with photovoltaic (PV) penetration. In this study, PV with energy storage (ES) hybrid system to reduce peak load is analyzed. We proposed the suitable structure of PV-ES hybrid for Mongolian household, and suggested several operation scenarios. Optimal operation algorithm is carried out based on a comparison aspect from economical, grid impact and PV penetration possibility. The economic analyse shows annual income of 520USD, and has a payback period of 8 years for selected scenario. The proposed PV-ES system structure is verified by experimentation set on the building rooftop in city center. The suggested scenario is planned to apply for system in further research.

• 전기학회논문지
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• 제65권2호
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• pp.239-246
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• 2016

In recent years, the power demand has been increasing steadily and the occurrence of maximum power demand has been moving from the summer season to the winter season in Korea. And since the control of electric power supply and demand is more important under those situations, a micro-grid system began to emerge as a keyword for the sTable operation of electric power system. A micro-gird power system is composed of various kinds of distributed generators(DG) such as small diesel generator, wind turbine, photo-voltaic generator and energy storage system(ESS). This paper introduces a method to determine the optimal capacities of the distributed generators which are installed in a stand-alone type of microgrid power system based on the fundamental proportion of diesel generator. At first, the fundamental proportion of diesel generator will be determined by changing from 0 to 50 percent. And then we will optimize the capacities of renewable energy resources and ESS according to load patterns. Lastly, after recalculating the capacity of ESS with consideration for SOC constraints, the optimal capacities of distributed generators will be decided.

• 전기학회논문지
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• 제65권8호
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• pp.1340-1346
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• 2016

Utilization of Distributed Generations (DGs) using Renewable Energy Sources (RESs) has been constantly increasing as they provide a lot of environmental, economic merits. In spite of these merits, some problems with respect to voltage profile, protection and its coordination system due to reverse power flow could happen. In order to analyze and solve the problems, accurate modeling of DG systems should be preceded as a fundamental research task. In this paper, we present a PhotoVoltaic (PV) generation system which consists of practical PV cells with series and parallel resistor and an inverter for interconnection with a main distribution system. The inverter is based on controllable current source which is capable of controlling power factors, active and reactive powers within a certain limit related to amount of PV generation. To verify performance of the model, a distribution system based on actual data is modeled by using ElectroMagnetic Transient Program (EMTP) software. Computer simulations according to various conditions are also performed and it is shown from simulation results that the model presented is very effective to study DG-related researches.

• 전력전자학회논문지
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• 제7권2호
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• pp.171-177
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• 2002

계통연계형 태양광 발전시스템은 계절별 전력수요의 변동이 많은 경우에 첨두전력 삭감의 한 방안으로 고려된다. 본 시스템의 발전효율을 증가시킬 수 있는 방법으로는 근본적으로 태양전지 자체의 변환효율을 증가시키는 방법과 제어관점에서 일사량과 태양전지 표면온도에 따라 시시각각 변하는 태양전지의 최대출력 점에 시스템의 동작점을 추종하게 하는 최대 전력점추적 (Maximum Power point Tracking, 이하 MPPT) 기법을 들 수 있고 발전 효율을 높이기 위하여 자주 사용되어 왔다. 초기 투자비용을 줄이기 위해 후에 등장한 직류초퍼를 사용하지 않고 MPPT 기능을 구현하는 태양광 발전시스템의 경우에 MPPT 알고리즘은 기존의 방법들을 사용하였고 직류초퍼를 사용하지 않은 태양광발전시스템에 적합한 MPPT 알고리즘의 연구는 없었다. 따라서 직류초퍼를 사용하지 않은 태양광 발전시스템에 적합한 MPPT 알고리즘의 연구가 요구되며 본 논문에서는 초퍼 없는 계통연계형 태양광발전 시스템을 대상으로 기존 MPPT 알고리즘의 문제점을 밝히고 이를 해결할 수 있는 새로운 MPPT 알고리즘을 연구하였다.