Toward smart grid: active management of MV network

Integrating Dispersed Generation (DG) in the grid is the most important challenge of the near future for power systems in most EU countries, and is the only way of exploiting Renewable Energy Sources (RES) for electric production, in the perspective of "20-20-20" targets. A high degree of DG penetration as well as RES placement and capacity have considerable impact on operation, control, protection and reliability of the existing power systems and involve a complete redeployment of both active and reactive power flow along distribution network. Several potential problems have been reported in literature (voltage control, rapid voltage changes, thermal limits of branches, short circuit currents, protection tripping etc). The huge DG penetration into the power system, particularly into medium and low voltage distribution networks, require an afterthought about the management modalities of such networks, which need to turn from "passive" into "active". Focusing on Italian system, it can be assumed that the Italian HV network has a very advanced structure and does not require substantial changes in order to face the DG increase. On the contrary, if distribution network is operated radially, the energy flows mainly from the primary substation to the lower voltage levels. Such architecture, which was chosen when DG was very rare, can entail several problems today. Smart grids represent a new framework for improved management of electric generation, transmission, and distribution with attention to interoperability, security, and resilience problems. It is recognized that Information and Communication Technology (ICT) is the only approach able to solve new problems arising from energy networks (enabling technology). Only an intelligent use of ICT will overcome the current limitations and make possible a larger DG penetration without hindering system security. The paper describes the innovations introduced by an ongoing project, founded by the Italian regulator authority (Autorità per l'energia elettrica e il gas, AEEG) and led by "Enel Distribuzione", that represent a first step towards the Smart Grids. The project introduces a new advanced management of RES in order to avoid the problems coming from reverse power flowing and maintain the necessary level of security, availability and quality of service (QoS).