A protection coordination scheme for active distribution networks

New problems concerning the distribution grid protection system arise from the large diffusion of installed distributed energy resources. In particular, unwanted trips, unwanted island operations and worsening of power quality are the main issues coming from the interactions among active networks and grid protections. A possible new protection scheme, which can be employed in active networks, is proposed and discussed in the paper. Logic selectivity is implemented introducing communications among grid and distributed generator systems protections. Digital simulations confirm the suitability of the proposed solution for a large set of grid faults.