Decentralized Control Strategy for AC-Stacked PV Inverter Architecture Under Grid Background Harmonics

Grid background harmonics cause harmonic distortion on the output current of grid-tied inverters, and they require the inverter to have harmonic mitigation control. The main object of this paper is to propose a decentralized control strategy for mitigation of the impact of distorted grid on ac-stacked photovoltaic inverter architecture. Two control schemes for this architecture are proposed and analyzed in this paper to mitigate the harmonic current caused by distorted grid voltage without any handshaking among the inverter members and supervisory control center. The proposed control method improves the reliability of the architecture by increasing the operating margin and it improves the power quality by reducing the harmonic content of the output current. The proposed methods are analyzed by frequency analysis and grid disturbance impedance analysis. The feasibility and effectiveness of the proposed control scheme has been demonstrated and verified through a control-hardware-in-the-loop experiment.