Planning the evolution of the European electricity transmission network is a complex task. Important issues have to be tackled and constitute a true challenge for today’s transmission system:

• integration of very large amounts of variable Renewable Energy Sources (RES), while keepingnetwork security and reliability at acceptable levels,

• balancing of renewable generation in Europe exceeding local needs, that requires to betransported elsewhere,

• aging of the present transmission grid,

• social and environmental constraints to get consensus for building new overhead lines,

• market liberalization, inducing further cross-border power exchanges that increase uncertaintiesand worsen congestion problems,

• increasing role of distributed generation and active demand: demand response programs at peakconsumption could help to relieve stress on European electricity system in the future.

Aim of REALISEGRID (REseArch, methodoLogIes and technologieS for the effective development of pan-European key GRID infrastructures to support the achievement of a reliable, competitive and sustainable electricity supply, web-site: http://realisegrid.rse-web.it) is to provide the scientific framework for a revision of the current transmission planning criteria in order to allow to design flexible, coordinated and secure transmission networks based on modern architectural schemes and including innovative technological solutions.