Optimal Unbalance Mitigation for Three-Phase Distribution Networks Equipped with Single-Phase PV Systems

A large number of small scale single-phase Distributed Generation units (DGs) are widely used worldwide. Therefore, the impact of their high level penetration can increase distribution networks three-phase unbalance. To mitigate this effect, a new control topology is introduced to maintain the unbalance of the network's three phase currents within distribution codes' limits by switching the single-phase inverter output between the three phases according to the level of current flows in each network's phases. An adequate PQ controller with unbalance controller reference is implemented through detecting the highest error value to select the single-phase inverter's connection point. The synergy between the multilevel inverter topology and the proposed unbalance controller with adequate PQ controller, would be a major enhancement in PV single-phase systems, which in return facilitates smart grid technology applications.