Bidirectional impact between distributed RES and small island grids

Due to the ongoing integration of Renewable Energy Sources (RES) at all levels, the structures of Electric Power Networks (EPN´s) are transforming from vertical to horizontal. During this evolutional process the utility companies have to control, protect, maintain and manage properly their networks, with minimal financial, operational, efficiency, quality and availability impact. System Developers and Operators have to reconsider the applied principles, keeping in mind the potential of distributed RES in affecting the quality, safety, and reliability of the grid. The paper evaluates some effects on the grid voltage as a function of RES penetration. While a priori software simulations of the grid behavior already improve the design and development, real field data will verify it.