Control Strategy for Three-Phase Grid-Connected PV Inverters Enabling Current Limitation Under Unbalanced Faults

Power quality and voltage control are among the most important aspects of the grid-connected power converter operation under faults. Nonsinusoidal current may be injected during unbalanced voltage sag, and active or/and reactive power may include double frequency content. This paper introduces a nov...

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Bibliographic Details
Published inIEEE transactions on industrial electronics (1982) Vol. 64; no. 11; pp. 8908 - 8918
Main Authors Afshari, Ehsan, Moradi, Gholam Reza, Rahimi, Ramin, Farhangi, Babak, Yongheng Yang, Blaabjerg, Frede, Farhangi, Shahrokh
Format Journal Article
LanguageEnglish
Published New York IEEE 01.11.2017
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects
Active power oscillations
current limitation
DC-DC power converters
dc-link voltage oscillations
Faults
Frequency control
Inverters
low-voltage ride-through (LVRT)
Maximum power tracking
Oscillators
Overcurrent
photovoltaic (PV) systems
Photovoltaic cells
Power converters
Power quality
Reactive power
Solar cells
Voltage control
Voltage converters (DC to DC)
Voltage sags
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Summary:Power quality and voltage control are among the most important aspects of the grid-connected power converter operation under faults. Nonsinusoidal current may be injected during unbalanced voltage sag, and active or/and reactive power may include double frequency content. This paper introduces a novel control strategy to mitigate the double grid frequency oscillations in the active power and dc-link voltage of the two-stage three-phase grid-connected photovoltaic (PV) inverters during unbalanced faults. With the proposed control method, PV inverter injects sinusoidal currents under unbalanced grid faults. In addition, an efficient and easy-to-implement current limitation method is introduced, which can effectively limit the injected currents to the rated value during faults. In this case, the fault-ride-through operation is ensured, and it will not trigger the overcurrent protection. A non-maximum power point tracking (non-MPPT) operation mode is proposed for the dc-dc converter. The mode is enabled under severe faults when the converter cannot handle the maximum PV power. Finally, experimental validation is provided by implementing a method in an experimental setup, including a 2 kW PV inverter.
ISSN:0278-0046
1557-9948
DOI:10.1109/TIE.2017.2733481