Compensation of voltage unbalances in LV networks due to single-phase generators

This paper approaches the problem of voltage unbalances due to single-phase Distributed Generation (DG), like small-scale photovoltaic power plants. In LV distribution lines, the random installation of energy sources on one of the three phases can significantly unbalance line currents, especially when the load demand is low; in weak networks, this can appreciably unbalance also line voltages. The possible use of static compensation devices derived from FACTS, such as Shunt Active Power Filters and Unified Power Quality Conditioners, is described and discussed. A Matlab-Simulink model operating in the sequence domain is proposed, implemented and applied to a real case study. Economical considerations about the cost-effectiveness of the proposed solutions are finally reported.