Flexible Power Control of PV Grid-connected Quasi-Z Source Inverter under Unbalanced Faults

Zhao, Z; Elgendy, MA; Armstrong, M; Muhammad, M

doi:10.1049/icp.2023.2391

Flexible Power Control of PV Grid-connected Quasi-Z Source Inverter under Unbalanced Faults

Lookup NU author(s): Dr Zhengyu Zhao, Dr Mohammed Elgendy, Dr Matthew Armstrong, Dr Musbahu Muhammad ORCiD

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Abstract

© The Institution of Engineering & Technology 2023.Under unbalanced grid voltages, the currents injected into the grid become non-sinusoidal and unbalanced. The unbalanced grid current and voltage may lead to double-frequency oscillations in the active and reactive power. This paper proposes a flexible power control method for the quasi-Z source inverter in PV grid-connected systems under unbalanced conditions. The proposed control strategy can inject a sinusoidal current and mitigate the double-frequency oscillation of the active or reactive power delivered to the network. Furthermore, an easy-to-implement current limitation strategy is proposed to protect the power converter and deliver maximum power to the grid. A non-MPPT mode is triggered to handle the injected current under severe faults. Finally, simulation results are presented to validate the theoretical analysis and controller design.