• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1222-1223
• /
• 2007

This paper suggests a 6-pulse-shift converter with PWM current-source inverter based on buck-boost configuration to improve the efficiency and to reduce the switching frequency of inverter for photovoltaic generation system, the device can be operated as interface system between solar module system and power system grid without energy storage cell. the circuit has six current-source buck-boost converter which operate chopper part has one full bridge inverter which make a decision the polarity of AC output. Therefore, the proposed PWM power inverter has advantages such as the reduction of witching loss and realization of unity power factor operation. the theoretical backgrounds are discussed and the input-output characteristics for the implemented prototype inverter using TMS320F2812 are verified experimentally in this paper.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.10
• /
• pp.1949-1954
• /
• 2016

Smart grid technology can be called grid techniques to improve the efficiency of the electric power by exchanging bidirectional information of electric power with real-time between electric power suppliers and consumers. Recently, the solar power generation system is being applied actively. However the solar power system has several problems leading to reduce overall electricity generation, because the difficult of the diagnosis and the solar power system failure such as PV(PhotoVoltaics) and inverter. In order to build an efficient smart grid, a stable electric power energy requirements capture and management and early fault detection is essentially required in solar power generation system. In this paper, it is designed to monitor the operating status of the solar power monitoring system from a remote location through a RS-485 or TCP/IP communication module to monitoring the output of solar power energy and abnormal phenomenon, to developing the measurement module and to transfer measured data.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.4_1
• /
• pp.559-567
• /
• 2020

As the renewable energy market grows, grid-connected inverters have been improving and expanding in several fields in recent years because energy conversion devices are the main components of solar systems. In this paper, a high-precision new grid-connected three-phase inverter system is proposed. The proposed system consists of a main inverter, a sub inverter and a transformer. The main inverter operates at a low switching frequency and high power and transmits power to the grid. A sub-inverter connected in series with the transmission line through a matching transformer operates at lower power than the main inverter to provide input values to the transformer. The transformer acts as a power supply according to the voltage compensation value. This study is based on the principle of operation of the UPFC(Unified Power Flow Controller) structure used to regulate power flow in AC transmission lines. The grid-connected inverter system proposed in this paper is implemented with high precision and high resolution. The proposed system was verified through its ability to enhance and ensure the safety of the proposed system through simulation and experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.12
• /
• pp.38-44
• /
• 2014

The photovoltaic power system is performing power generation by being installed in outdoors. Therefore it has the characteristics affected by environmental factors. In particular, if the solar power generation facility connected to the grid, the power can be generated continuously in a state of being secured operating voltage of the inverter and solar irradiation. In that case, if an abnormal situation such as flooding or heavy rains has occur, the possibility of electric shock or damage of facilities due to current leakage or a floating matters is present. In this paper, we performed electrical safety assessment about the connection part, junction box and cable of the solar module when the solar power system was flooded. we also assessed whether or not the leakage current is occurred in case of the cable was damaged. As a result, in case of the leakage current is large, we can be known that it is the risk of electric shock as well as cause of inverter damage.

• Journal of the Korean Solar Energy Society
• /
• v.33 no.5
• /
• pp.34-40
• /
• 2013

Islanding phenomenon of photovoltaic system is undesirable because it leads to a safety hazard to utility service personnel and may cause damage to power generation and power supply facilities as a result of unsynchronized re-closure. Anti-islanding protection is an important technical requirement for grid-connected PV system. Until now, various anti-islanding methods for detecting and preventing islanding of photovoltaic and other distributed generations have been proposed. Most of them are focusing on the anti-islanding performance of single PV system according to the related international and domestic standard test procedures. There are few studies on the islanding phenomenon for multiple photovoltaic operation in parallel. This paper presents performance analysis of anti-islanding function for grid-connected PV inverter systems when several PV inverters are connected in parallel.

• Proceedings of the KIEE Conference
• /
• 1995.07a
• /
• pp.443-445
• /
• 1995

Since the residential load is an AC load, while the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell and must provide the sinusoidal wave current and voltage with unity power factor in the case of driving to Interact with utility line. It is always necessary for the output of solar cell to operate in the vicinity of maximum power point, since it is greatly fluctuated by insolation. This paper treats that we will constitute a single phase PWM voltage source inverter and trace the modulation index which always maximize the output of solar cell in propotion to insolation variation and prove it by simulation that we can provide current wave, which is nearly sinusoidal wave with unity power factor, for load and utility line.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.47 no.4
• /
• pp.102-108
• /
• 2010

The photovoltaic system changes solar energy into DC by solar cell and this DC is inverted into AC which is used in general houses by inverter. Recently, the use of power of the photovoltaic system is increased. Therefore, the study of 3 phase solar system to transmit large power is very important. This paper proposes a method that finds simply faults and diagnoses the switch open faults of 3-phase pulse width modulation (PWM) inverter of grid-connected photovoltaic system. The proposed method in $\alpha\beta$ plane uses the patterns of trajectory image as the characteristic parameters and differenciates a normal state and open states of switches. Then, the result is made into tree. The tree is composed of 21 fault patterns and the parameters to classify faults are a shape, a trajectory area, a distributed angle, and a typical vector angle. The result shows that the proposed method diagnosed fault diagnoses, classified correctly them, and made a pattern tree by fault patterns.

• Journal of Power Electronics
• /
• v.5 no.3
• /
• pp.224-232
• /
• 2005

A new three phase three-level Pulse Width Modulation (PWM) Switched Voltage Source (SVS) inverter with zero neutral point potential is proposed. It consists of three single-phase inverter modules. Each module is composed of a switched voltage source and inverter switches. The major advantage is that the peak value of the phase output voltage is twice as high as that of a conventional neutral-point-clamped (NPC) PWM inverter. Thus, the proposed inverter is suitable for applications with low voltage sources such as batteries, fuel cells, or solar cells. Furthermore, three-level waveforms of the proposed inverter can be achieved without the switch voltage imbalance problem. Since the average neutral point potential of the proposed inverter is zero, a common ground between the input stage and the output stage is possible. Therefore, it can be applied to a transformer-less Power Conditioning System (PCS). The proposed inverter is verified by a PSpice simulation and experimental results based on a laboratory prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.1
• /
• pp.36-44
• /
• 2014

The conventional central photo voltaic inverters have several problems. First, shadow problem in each solar panel, and high DC voltage problem from each panel because of concentration to one central inverter. Therefore, module integrated inverter is proposed to solve these problems. The inverter should be small and cost effective. The cost and size in the inverter depend on the inductor. So the switching frequency should be increased to reduce the inductor and total size, but there is a problem in efficiency because of the losses in turn-on and turn-off. In the paper, the critical conduction mode(CRM) switching method is adopted to reduce the switching loss and interleaving method is proposed to increase the efficiency in Flyback converter. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype system rated at 200W.

• Solar Energy
• /
• v.19 no.4
• /
• pp.63-69
• /
• 1999

The conventional grid connected PV(Photovoltaic) system has a unstable output pattern due to its dependence on the weather condition, although solar-cell array averagely has a regular output characteristics to have a peak output nearly at noon. Therefore assuming the high density grid connection in the future, this unstable output pattern can be one of the main reasons to generate power disturbance such as voltage variation, frequency variation and harmonic voltage generation in low voltage distribution line. However general grid connected solar-cell system do not have functions to cope with these disturbances. Therefore this study proposed a advanced type grid connected PV system with functions to suppress output power fluctuation due to solar-cell array output variation and showed the levelling effect of fluctuation due to instantaneous array output variation.