In an European perspective, the focus of Smart Grids initiatives (SET Plan - Strategic Energy Technology Plan) is strictly linked with the main commitment to achieve the goals of the Climate and Energy Package 20-20-20, at the light of the three main pillars of the European energy policy: competitiveness, sustainability and security of supply. Smart grid technologies will enable load levelling of the electrical grid, allowing a power company to run cleaner power sources - such as hydroelectric, wind, or solar - while reducing the need to use carbon-emitting gas, coal, or oil plants to meet peak demand. In this framework the proposed paper refers about the technical economical feasibility study and the preliminary design of a demonstrator of a distribution electrical system for the transition towards active networks. The study has been carried out by University of Palermo and ENEA (Italy), on a portion of real MV/LV distribution system of the research center ENEA of Casaccia (Rome, Italy).