Earticle

Solar panels installed on the ground receive wind load. A wind experiment was conducted to evaluate the wind force coefficient acting on a single solar panel and on solar panels arranged in an array. Surface roughness did not have a significant effect on the change in vertical force, which is the wind force coefficient acting on the vertical surface of the single solar panel. An examination of the change in wind direction angle showed that the largest vertical force coefficient was distributed in the 0° forward wind direction based on the front of the solar panel, the 345° reverse wind direction based on the rear side, and the 135° and 225° diagonal directions based on the rear panel. Furthermore, an examination of the change in wind force coefficient according to the change in solar panel inclination angle (β) showed that the drag coefficient was the highest at the 40° inclination angle of the panel (β), followed by the 30° and 20° inclination angles. However, the lift coefficient and vertical force coefficient were not significantly affected by the inclination angle of the panel. The wind force coefficient of the panels arranged in an array was influenced by the wind direction angle and the panel position. With the exclusion of the nearest row a at the wind direction angle of 0°, all the panels in the array showed lower coefficients than that of the single panel experiment. In the case of the panels placed inside, the wind speed was decreased by the surrounding panels, and as a result, the wind force coefficient was lower than that of the single panel experiment. This outcome is attributed to the small delamination at the end of the panels by the surrounding array of panels compared to that of the single panel experiment.

The renewable energy sources penetration has increased nowadays. Numerous techniques are developed for grid connected photovoltaic system for intensive penetration of photovoltaic (PV) production into the grid from various research papers. Several researches have been carried out in the field of PV design, but few work for grid connected multi-junction solar cell. Cascaded multilevel inverter provides many advantages over conventional inverters to improve the overall efficiency and reduce harmonics with the grid integration of renewable energy sources. The paper proposes a design of multi-junction photovoltaic solar cell with maximum power point tracking and a novel topology of cascaded multilevel inverters to improve power quality delivered to grid in terms of harmonics, by minimizing total harmonic distortion of microgrid (MJSC) interface. A model was developed and the system was tested for performance. The results found were encouraging as compared to the traditional methods. MATLAB/Simulink platform is used to model and simulate the entire system.

The output characteristics of photovoltaic array was related with the topology of array, shadow distribution and illumination level. The theoretical analysis and simulation modeling of output characteristics of photovoltaic array including series array, parallel array and series-parallel array were made under the non-uniform illumination environment based on the circuit analysis. The photovoltaic cell was modeled by use of the improved two-diode model. Non uniform illumination is expanded from two illumination levels of traditional to N illumination levels and from the single series array to any number series-parallel array. The different analysis methods were adopted in different arrays for mathematical modeling and simulation. The current analysis was used in series arrays and voltage analysis used in parallel arrays. Analysis of current in branches and voltage between branches was used in series-parallel array. Then the mathematical models were established and programmed in m-file by MATLAB. The simulation models had a high computational accuracy, and were suitable for any simulation output characteristics of PV in different light environment and array topology. They could provide a theoretical basis for constructing the topological structure on the same condition and studying MPPT of PV array under non-uniform illumination.

A new method of array configuration for solar tracking photovoltaic (PV) devices is proposed. By analyzing the affecting factors of shadows, a calculation model of PV cell panels’ shadow in the sunlight is structured. And the variation rule of shadows in a year is founded by simulation program. Then a spacing calculation method of the solar tracking device array is proposed. The experiment result shows that the proposed method can minimize the installation spacing of PV device by ensuring PV cell panels without shadow shading and save area effectively in PV power station construction.

태양광 PCS개발과정에서는 온도나 방사량 등을 변화시키며 태양전지 패널의 I-V곡선을 모사할 수 있는 태양광 시뮬레이션 모델이 필요하다. 이러한 용도로 볼 때 특히 다이오드 기반의 등가회로 모델은 물리적인 성질을 바탕으로 태양광 패널의 특성을 비교적 정확히 설명할 수 있으나 특유의 비선형성으로 인하여 복잡한 회로 모델 파라미터 추출 기법을 필요로 한다. 본 논문에서는데이터 시트값에 기반한 새로운 태양광 패널 회로 모델링 알고리즘을 제안한다. 제안한 방법의 성능을 검증하기 위해 단결정 태양광 패널의 실제 데이터를 기반으로 최대전력점 ${\pm}10%$부근의 전류오차 적분값을 기준으로 기존 방법과 정확도를 비교한 결과 20%의 정확도 개선을 얻었다.

In this paper, Maximum Power Point Tracking Method using Fuzzy controller is proposed to improve energy conversion efficiency. The solar cell has an optimum operating point to be able to get maximum power. To obtain maximum power from photovoltatic any, photovoltatic power system usually requires maximum power point tracking controller. The output characteristics of solar cell are nonlinear. To obtain maximum power from photsvoltatic array, the fuzzy controller only uses the output power. Therefore this control method is easy to implement to real system.

Since solar cells have non-linear voltage-current output characteristics, Photovoltaic systems require the Maximum Power Point Tracking(MPPT) function. For this reason, a large number of MPPT techniques have been studied. However, the conventional MPPT techniques may fail to track the maximum power point when partial shading occurs in the solar cell array due to its characteristics. Therefore, it is necessary to research the MPPT technique that can follow the maximum power point in the partial shadow condition. In this paper, the characteristics of solar cell arrays in partial shadowing are analyzed and the MPPT technique which can follow the maximum power point in partial shadow condition has been proposed. To validate the proposed MPPT method, simulation and experimentation results are provided.

This paper proposes the microprocessor-based step-up chopper system used for the battery charge from the photovoltaic arrays. The proposed scheme tracks the maximum power point by analyzing the voltage and power phasors which vary as the solar irradiation quantity. In this system, protection for the overcharge and overdischarge in also provided.

A great deal of study for loss reduction of photovoltaic system is conducted currently. It is hard to distinct the fault of photovoltaic system with the naked eye. For that reason, it is essential to repair and maintain the PV system by monitoring the system. The fault of individual modules can cause the huge loss of the entire system because of the mismatch. Therefore, the method of diagnosing the PV array is necessary by measuring the multi-channel arrays simultaneously. In this paper, it is presented the method of measuring I-V curve of multi-channel arrays simultaneously by using the charge and discharge characteristics of capacitor. Generated DC power at PV arrays is charged and discharged at the capacitors in a moment. By measuring the charged voltage and current, it is possible to diagnose of performance of PV arrays.

극초소형 위성으로 분류되는 큐브위성의 경우, 표준화된 위성의 크기로 인하여 위성의 전력생성을 목적으로 하는 태양전지판 장착을 위한 공간이 극히 제한적이며, 자세제어 적용 방식에 따라서는 태양전지판에 입사되는 태양광의 각도가 변화하고 이는 태양전지의 전력생성 양을 결정하는 주요 요인으로 작용한다. 본 논문에서는 극초소형 위성 적용을 목적으로 태양광과 태양전지판이 이루는 각도가 $0^{\circ}$인 조건에서도 태양전지판 외곽에 배치된 렌즈어레이를 통해 태양광을 효율적으로 조사하여 전력생성 효율 향상이 가능한 우주용 집광형 태양전력 시스템을 제안하였으며, 극초소형 위성으로의 적용 가능성 검토를 위해 상용 렌즈어레이를 적용한 기능시험을 통해 유효성을 입증하였다.

A pico-class satellite has limitation to generate power from the solar cells due to its limited accommodation area to install the solar cells. The variation of incidence angle between solar panels and sunlight induced by the revolution and rotation of the satellite is one of the key parameters to determine the power generation. In this study, we proposed a concentrating photovoltaic system for pico-class satellite applications to enhance power generation when the ${\beta}$ angle between the sunlight and the solar panel is zero by effectively concentrating solar energy on solar panels. The feasibility of the conceptual idea has been demonstrated by power measurement test using solar simulator and commercial multi-array lens system.

In the PV power system, output of the PV array must contain inherent ripples due to the single-phase inverter. So, the function of maximum power point tracking to increase the output efficiency of PV system is degraded. Therefore, to overcome this problem, this paper presents a control strategy for the reducing ripples of the PV array output in grid-connected photovoltaic power system. The proposed control system consists of two loops; the maximum power point tracking loop using the perturbation and observation method is used to calculate the reference solar array terminal voltage(Vref) for reducing ripples of the PV array output and the PI control loop is used to regulate the solar array output voltage according to the Vref. The performance of proposing control strategy is analyzed by means of the PSCAD/EMTDC simulation and experiment. As a result, we may obtain the high performance of the proposed control strategy.

In the PV power system, output of the PV array must contain inherent ripples due to the single-phase inverter. So the function of maximum power point tracking to increase the output efficiency of PV system is degraded. Therefore, to overcome this problem, this paper presents a control strategy for the reducing ripples of the PV array output in grid-connected photovoltaic power system. The proposed control system consists of two loops the maximum power point tracking loop using the perturbation and observation method is used to calculate the reference solar array terminal voltage(Vref) for reducing ripples of the PV array output and the PI control loop is used to regulate the solar array output voltage according to the Vref. The performance of proposing control strategy is analyzed by means of the PSCAD/EMTDC simulation. As a result, we may obtain the high performance of the proposed control strategy.