• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.202-205
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• 2006

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.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.4
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• pp.169-174
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• 2001

A novel simulation scheme of transient phenomenon for the photovoltaic (PV) generation system under the real weather conditions has been proposed in this paper. A grid connected PV array is simulated using PSCAD/EMTDC. The transient changes of the output current of PV array under the real weather conditions is described and the output current of DC/AC converter flowing through the utility power network is also analyzed with the PWM switching width. Moreover, the MPPT control of PV generation system is combined to the system during the simulation for the comparison purposes of the control schemes. The outcome of the simulation demonstrates the effectiveness of the proposed simulation scheme. The result shows that the cost effective verifying for the efficiency or availability and stability of PV generation systems and the comparison research of various control schemes like MPPT under the same real whether conditions are eventually possible.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1211-1212
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• 2007

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.

• Journal of Power Electronics
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• v.9 no.2
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• pp.320-333
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• 2009

A Photovoltaic (PV) system's power output varies with the change of climate. Frequency deviations, tie line voltage swings are caused by the varying PV power when large PV power from several PV systems is fed in the utility. In this paper, to overcome these problems, a simple coordinated control method for smoothing the variations of combined PV power from multiple PV systems is proposed. Here, output power command is formed in two steps: central and local. Fuzzy control is used to produce the central smoothing output power command considering insolation, variance of insolation and absolute average of frequency deviation. In local step, a simple coordination is kept between the central power command and the local power commands by producing a common tuning factor. Power converters are used to achieve the same output power as local command power employing PI control law for each of the PV generation systems. The proposed method is compared with the method where conventional Maximum Power Point Tracking (MPPT) control is used for each of the PV systems. Simulation results show that the proposed method is effective for smoothing the output power variations and feasible to reduce the frequency deviations of the power utility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1537-1546
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• 2011

The photovoltaic(PV) generation system have recently become widely used to solve the environmental problems and running out of fossil fuels. However, the study on maintenance is inadequate for PV system. This paper proposes the novel diagnosis method of output power decline to maintain the normal output performance of PV array. The diagnosis method used the proportional relation of irradiation-output current(S-I) of PV array at maximum power point(MPP). And, first order polynomial using the relation is proposed to easily apply PV system. To estimate the relation in case of separation of PV array producer and diagnosis system producer. Kalman Filter algorithm is also proposed at 30.2kW grid-connected PV system. Then, the performance of diagnosis method is evaluated using the hardware tests as well as the simulation.

• Current Photovoltaic Research
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• v.2 no.4
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• pp.189-194
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• 2014

In this paper, We have simulated the output variation of the PV arrays installation with position & angle change. The existing 3 solar array system are $43^{\circ}$ southeast and each of the mounting angle is $17^{\circ}$. The PV output power is 240 kW. The composite studied systems in this paper arrays altered 2 PV array among 3 PV array system- the output 144kW. We simulated this system using Solar Pro ver.4.1. The simulation conditions are southwest $43^{\circ}/array$, mount angle $27^{\circ}/array$. Because the southeast have shadow effect-higher mountain The purpose of southwest $43^{\circ}$ is reduce the shadow effect. The simulation results of the suggestion design algorithm compared to 1,590 kWh/year output is increased with the southeast.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.38-42
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• 2017

PV system output is determined according to the weather conditions, the azimuth and tilt angle. Weather conditions are changing every moment and it seems to vary according to the daily, monthly, and annual basis. The azimuth and tilt angle is decided along the site conditions for the PV system installation. This paper analyzed the PV system output through the changing the weather conditions, the azimuth, and tilt angle. We compared the TMY data and analysis of the two major weather institutes which are KMA and METEONORM. PV system output trend were analyzed by changing the azimuth and tilt angle. We used simulation tool, which is named PVsyst for the entire PV system analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.407-412
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• 2012

This study investigated the process of thermal-induced growth of micro-crack developed at the crystalline solar cell using EL image, determined the output characteristic according to the pattern of micro-crack, analyzed the I-V characteristic according to the pattern of crack growth, and predicted the output value using simulation. The purpose of this study was, therefore, to investigate the process of thermal-induced growth of micro-crack developed at the early stage of PV module completion using EL image, to analyze the resulting decrement of output and predict the output value using simulation. It was observed that the crack grew increasingly by the thermal condition, and accordingly the lowering of output was accelerated. The output values of crack patterns with various direction were predicted using simulation, resulting in close I-V curve with only around 4% of error rate. It is considered that it is possible to predict the electric characteristic of solar cell module using only pattern of micro-crack occurred at solar cell based on our results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.25-31
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• 2007

In this paper, a novel MPPT(Maximum Power Point Tracking) algorithm for power of PV(Photovoltaic) systems is presented using a boost converter for a connected single phase inverter. On the basic principle of power generation for the PV(photovoltaic) module, the model of a PV system is presented. On the basis of this model, simulation of this PV system and algorithms for maximum power point tracking are described by utilizing a boost converter to adjust the output voltage of the PV module. Based on output power of a boost converter, single phase inverter uses predicted current control to control four IGBT#s switch in full bridge. Furthermore, a low cost control system for solar energy conversion using the DSP is developed, based on the boost converter to adjust the output voltage of the PV module. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation. Finally, experimental results confirm the superior performance of the proposed method.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.255-261
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• 2012

Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. And also, the switch device is not ideal, both each switching element of the voltage drop difference and on & off time delay difference generate DC offset. Thus, to compensate for deadtime and the switch voltage drop, feedback control by output current DC offset should be provided to compensate additional distortion of the output current. The validity of the proposed method is confirmed through PSIM simulation.