A Power Balancing Strategy in a PV-Based Modular Multilevel Converter During Mismatched Power Generation

In this article, we focus on the power balancing strategy in a modular multilevel converter (MMC) for a large-scale photovoltaic (PV) system. Large-scale PV-based MMC suffers from leg-leg and arm-arm power mismatch issues, leading to unbalanced power injection into ac grid. To inject balanced power...

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Bibliographic Details
Published in:IEEE transactions on industrial electronics (1982) 2024-07, Vol.71 (7), p.1-9
Main Authors: Nayak, Subhasis, Das, Anandarup
Format: Article
Language:English
Subjects:
Circulating current
Electric power generation
Gold
horizontal power mismatch
independent arm power control
Legged locomotion
Load balancing
modular multilevel converter (MMC)
Multilevel converters
Overcurrent
photovoltaic (PV)
Photovoltaic cells
power balancing
Power control
Power generation
Reactive power
Resonant frequencies
two-fundamental-frequency zero-sequence voltage (FFZSV)
vertical power mismatch
Voltage control
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Summary:In this article, we focus on the power balancing strategy in a modular multilevel converter (MMC) for a large-scale photovoltaic (PV) system. Large-scale PV-based MMC suffers from leg-leg and arm-arm power mismatch issues, leading to unbalanced power injection into ac grid. To inject balanced power into the ac grid, this article proposes a novel control technique, which minimizes the circulating current in the converter. A novel two fundamental frequency zero-sequence voltages injection technique is proposed for a leg-leg (horizontal) power mismatch by which the dc circulating current from the MMC legs can be minimized significantly. Simultaneously, an independent arm power control technique is proposed for an arm-arm (vertical) power mismatch, thereby minimizing the ac circulating current. With the proposed control strategies, overcurrent and subsequent losses in the converter due to circulating current can be reduced. Both horizontal and vertical power mismatch problems are theoretically analyzed and solved through the proposed technique to make the MMC more promising for large-scale PV applications where mismatched power generation is common. The theoretical analysis is verified through MATLAB/Simulink-based model and a 3-kW scaled-down experimental prototype.
ISSN:0278-0046
1557-9948
DOI:10.1109/TIE.2023.3303654