• Journal of Power Electronics
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• v.9 no.6
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• pp.866-873
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• 2009

In general, the output voltage level of a PV array varies widely at various irradiances and temperatures. The MPP (Maximum Power Point) range of a medium- or high-power PV PCS is normally 450~830Vdc or 300~600Vdc. This means the PV PCS should operate in a wide range of modulation indexes. The PV PCS should satisfy the harmonic current requirement that the TDD (Total demand distortion) shall not exceed 5%. This paper proposes a new PWM control method for a medium- or high-power PV PCS which increases the efficiency of power conversion in all operation ranges with acceptable harmonic ripple currents. This paper compares and analyzes appropriate PWM schemes for the PV PCS in the view points of conversion efficiency and current harmonics.

• New & Renewable Energy
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• v.3 no.4
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• pp.69-76
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• 2007

In this paper, a PV multi-string PCS with a grid-connection is proposed. An improved MPPT algorithm for the PV multi-string PCS is suggested. Each PV string has its own MPP tracker and the proposed MPPT algorithm prevents LMPP tracking due to power ripple. In the PV PCS with single-phase inverter has a large current ripple at twice the grid frequency. The current ripple reduction algorithm without external component is suggested. Also, this paper proposes a simple control method to achieve sharing of the PV string voltage and current among the interleaved parallel boost converters. All algorithms and controllers are implemented on a single-chip microcontroller. Experimental results obtained on a 3kW prototype show high performance of the proposed PV multi-string PCS.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.255-258
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• 2007

In this paper, a PV multi-string PCS with a grid-connection is proposed. An improved MPPT algorithm for the PV multi-string PCS is suggested. Each PV string has its own MPP tracker and the proposed MPPT algorithm prevents LMPP tracking due to power ripple. In the PV PCS with single-phase inverter has a large current ripple at twice the grid frequency. The current ripple reduction algorithm without external component is suggested. Also, this paper proposes a simple control method to achieve sharing of the PV string voltage and current among the interleaved parallel boost converters. All algorithms and controllers are implemented on a single-chip microcontroller. Experimental results obtained on a 3kW prototype show high performance of the proposed PV multi-string PCS.

• Journal of Power Electronics
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• v.11 no.4
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• pp.561-567
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• 2011

This paper presents a high-efficiency power conditioning system (PCS) for grid-connected photovoltaic (PV) modules. The proposed PCS consists of a step-up DC-DC converter and a single-phase DC-AC inverter for the grid-connected PV modules. A soft-switching step-up DC-DC converter is proposed to generate a high DC-link voltage from the low PV module voltage with a high-efficiency. A DC-link voltage controller is presented for constant DC-link voltage regulation. A half-bridge inverter is used for the single-phase DC-AC inverter for grid connection. A grid current controller is suggested to supply PV electrical power to the power grid with a unity power factor. Experimental results are obtained from a 180 W grid-connected PV module system using the proposed PCS. The proposed PCS achieves a high power efficiency of 93.0 % with an unity power factor for a 60 Hz / 120 Vrms AC power grid.

• Journal of Power Electronics
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• v.9 no.2
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• pp.300-307
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• 2009

In this paper, design and control is proposed for a four input-series-output-series-connected ZVS full bridge converter for the photovoltaic power conditioning system (PCS). The novel topology for a photovoltaic (PV) DC/DC converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing PV module characteristics is proposed. The control scheme, including an input voltage controller is proposed to achieve equal sharing of the input voltage as well output voltages by a four series connected module. Design methods for ZVS power stage are also introduced. The total PV system is implemented for a 250-kW PV power conditioning system (PCS). This system has only three DC/DC converters with a 25-kW power rating and uses only one-third of the total PV PCS power. The 25-kW prototype PV DC/DC converter is introduced to verify experimentally the proposed topology. In addition, an experimental result shows that the proposed topology exhibits good performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1174-1180
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• 2018

In December 2017, the government announced plans to increase the current proportion of renewable energy from 7% to 20% by 2030 through a plan called the Renewable Energy 3020 Implementation Plan. Therefore, the demand for installation of photovoltaic(PV), wind turbine(WT) and battery energy storage system(BESS) is expected to increase. In particular, the system combined with energy storage system(ESS) is expected to take up a large portion since PV and WT can receive high renewable energy certificates(REC) weights when combined with ESS. In this study, we calculate the optimal capacity of the power conditioning system(PCS) and the BESS by comparing the economical efficiency and maximize the efficiency of the PV-BESS system in which the PV and the BESS are connected. By analyzing the system marginal price(SMP) and REC, it maximize profits through application of REC weight 5.0 and optimal charge-discharge scheduling according to the SMP changes.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2272-2283
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• 2016

This paper proposes a power conditioning system (PCS) for distributed photovoltaic (PV) applications using an asymmetric cascaded multilevel inverter with a single PV source. One of the main disadvantages of the cascaded multilevel inverters in PV systems is the requirement of multiple isolated DC sources. Using multiple PV strings leads to a compromise in either the voltage balance of individual H-bridge cells or the maximum power point tracking (MPPT) operation due to localized variations in atmospheric conditions. The proposed PCS uses a single PV source with a flyback DC-DC converter to facilitate a reduction of the required DC sources and to maintain the voltage balance during MPPT operation. The flyback converter is used to provide input for low-voltage H-bridge cells which processes only 20% of the total power. This helps to minimize the losses occurring in the proposed PCS. Furthermore, transient analyses and controller design for the proposed PCS in both the stand-alone mode and the grid-connection mode are presented. The feasibility of the proposed PCS and its control scheme have been tested using a 1kW hardware prototype and the obtained results are presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.479-484
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• 2018

This paper describes domestic technical standard of Photovoltaic(PV) PCS(Power Conditioning Systems)-Characteristics of the utility interface. This standard tests utility compatibility and personnel safety and equipment protection of PV inverter performance functions. Especially utility compatibility part includes test items of 1)voltage, current and frequency, 2)normal voltage operating range, 3)DC injection, 4)normal frequency operating range, 5)harmonics and 6)waveform distortion, 7)power factor of PV inverter. Therefore in this paper each test item of domestic technical standard is studied and analyzed and finally full tested by PV inverter performance function.

• Journal of Power Electronics
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• v.8 no.2
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• pp.163-170
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• 2008

A BIPV(Building Integrated PV) system is united by a constituent outer covering and can expect dual effects that reduce expenses for the establishment of a PV system. It is a profitable technology because it does not need a building as it is a stand alone PV system. In this paper, output characteristics analysis of PCS and web-based monitoring of 10kW BIPV, were stimulated and examined for validity. The BIPV system proposed in this paper was established in at BIC (Biotechnology Industrialization Center) of Dongshin University, which was composed with PCS and Web-monitoring system.

• Journal of Power Electronics
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• v.10 no.1
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• pp.9-13
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• 2010

This paper proposes an input-series-output-parallel connected ZVS full bridge converter with interleaved control for photovoltaic power conditioning systems (PV PCS). The input-series connection enables a fully modular power-system architecture, where low voltage and standard power modules can be connected in any combination at the input and/or at the output, to realize any given specifications. Further, the input-series connection enables the use of low-voltage MOSFETs that are optimized for a very low RDSON, thus, resulting in lower conduction losses. The system costs decrease due to the reduced current, and the volumes of the output filters due to the interleaving technique. A topology for a photovoltaic (PV) dc/dc converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing the PV module characteristics is proposed. The control scheme, consisting of an output voltage loop, a current loop and input voltage balancing loops, is proposed to achieve input voltage sharing and output current sharing. The total PV system is implemented for a 10-kW PV power conditioning system (PCS). This system has a dc/dc converter with a 3.6-kW power rating. It is only one-third of the total PV PCS power. A 3.6-kW prototype PV dc/dc converter is introduced to experimentally verify the proposed topology. In addition, experimental results show that the proposed topology exhibits good performance.