Suppressing the effects of grid unbalances in current controlled grid connected inverter using virtual inductor

To design the current controller for the grid-connected inverter (GCI), the grid is usually assumed as balance. Hence, the current controller performance gets worse when the grid is unbalanced. In this paper, a virtual inductor is proposed to suppress the effects of grid unbalances. Virtual inductor is an additional control algorithm that changes the system behavior as if there is a real inductor connected to the system. As it is virtual, we have no penalties in terms of size, efficiency, and cost. Moreover, the virtual inductor can be designed in such a way so that it gives response to selected signals only. The effectiveness of the proposed virtual inductor in suppressing the effects of grid unbalances is verified by simulated results.