Impact of Distributed Generation on Italian Distribution Network Protection

The presence of a significant DG capacity in distribution networks will result in some conflicts with the operation of the system, mainly because, unlike the meshed transmission system, the distribution system is usually designed as a “passive” radial system. In general, the impact of DG depends on its penetration level in distribution network as well as on DG technology (e.g. synchronous generators, asynchronous generators, static converter interfaced generation systems). In order to maintain correct distribution operating conditions and provide a high quality service to customers, various issues such as voltage control, power quality, short circuit currents, system protection have to be taken into consideration. In particular, the present paper deals with the analysis of protection issues arising in distribution networks in the presence of DG, and examines some practical cases with reference to Italian networks. Key-Words: Power Distribution, Distributed Generation, Distribution Protection, Power distribution control.