A Novel Control Strategy of Suppressing DC Current Injection to the Grid for Single-Phase PV Inverter

Photovoltaic (PV) inverters without the isolation transformer become more attractive due to higher efficiency and lower weight. However, it may have dc offset current problem and is critical to the power system. In this paper, a novel control strategy of suppressing dc current injection to the grid for PV inverters is investigated. It is based on the idea of accurately sensing the dc offset voltage of PV inverter output. Since dc component of the inverter output can be eliminated, dc injection to the grid can be effectively suppressed. Finally, the control scheme is verified by the experiment.