High-Frequency-Link-Based Grid-Tied PV System With Small DC-Link Capacitor and Low-Frequency Ripple-Free Maximum Power Point Tracking

This paper proposes a grid-tied photovoltaic (PV) system consisting of modular current-fed dual-active-bridge (CF-DAB) dc-dc converter with cascaded multilevel inverter. The proposed converter allows a small dc-link capacitor in the three-phase wye-connected PV system; therefore, the system reliabil...

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Bibliographic Details
Published in:IEEE transactions on power electronics 2016-01, Vol.31 (1), p.328-339
Main Authors: Shi, Yuxiang, Li, Rui, Xue, Yaosuo, Li, Hui
Format: Article
Language:English
Subjects:
Algorithms
Capacitance
Capacitors
Control systems
Converters
Current-fed dual-active-bridge
DC-DC power converters
Electric potential
Frequencies
high-frequency-link
Inverters
low-frequency ripple
Maximum power
Maximum power point trackers
MPPT
Photovoltaic cells
Reliability
small dc-link capacitor
Solar cells
Tracking
Tracking control systems
Voltage control
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Summary:This paper proposes a grid-tied photovoltaic (PV) system consisting of modular current-fed dual-active-bridge (CF-DAB) dc-dc converter with cascaded multilevel inverter. The proposed converter allows a small dc-link capacitor in the three-phase wye-connected PV system; therefore, the system reliability can be improved by replacing electrolytic capacitors with film capacitors. The low-frequency ripple-free maximum power point tracking (MPPT) is also realized in the proposed converter. First of all, to minimize the influence resulting from reduced capacitance, a dc-link voltage synchronizing control is developed. Then, a detailed design of power mitigation control based on CF-DAB dynamic model is presented to prevent the large low-frequency voltage variation propagating from the dc-link to PV side. Finally, a novel variable step-size MPPT algorithm is proposed to ensure not only high MPPT efficiency, but also fast maximum power extraction under rapid irradiation change. A downscaled 5-kW PV converter module with a small dc-link capacitor was built in the laboratory with the proposed control and MPPT algorithm, and experimental results are given to validate the converter performance.
ISSN:0885-8993
1941-0107
DOI:10.1109/TPEL.2015.2411858