I. Introduction
The competitive price of photovoltaic (PV) systems and the environmental impact of fossil fuels are only some of the main drivers for the massive penetration of PVs (more than 227 GW installed capacity by 2015). A significant portion of the solar energy is produced by rooftop PV systems installed in residential units, which transform the electricity consumers into “prosumers” [1] (consumers who can produce and consume energy to/from the grid respectively at the same time). The PV produced power is fed into the grid through a grid side converter (GSC), which is usually a three-phase inverter [2] for PVs higher than 4 kW rated power. On the other hand, residential or commercial three-phase consumers/prosumers are mainly based on several single-phase loads and as a result, they should be considered by their nature, as unbalanced loads. This unbalanced loading imposes several problems on the operation of the Distribution Network (DN) [3]: the power quality of the grid is decreased with asymmetric voltage and current conditions, the power losses of the DN are increased along with the grid loading (e.g., of distribution transformers, lines, and cables), the operation of machines is negatively affected with possible overheating and torque vibrations, etc. This paper proposes a flexible power control scheme for the GSC of PVs (Fig. 1), which tries to symmetrize the prosumer loads in order to overcome these issues, ensure a high quality DN operation, and enable a smooth and seamless interaction between the grid and the prosumer.