new systemic approach Angelo L’Abbate*; Gianluigi Migliavacca*; Gianluca Fulli **, Madeleine Gibescu*** Ana R Ciupuliga*** 10th IAEE European Conference Energy, Policies and Technologies for Sustainable Economies Vienna, 7-10 Settembre 2009 PRESENTAZIONE POWER POINT * ERSE SPA ** COMMISSIONE EUROPEA JRC *** TU DELFT In Europe, as well as in other continents/countries, electricity industry in the latest years has been changing from a regulated structure dominated by vertically integrated utilities to a deregulated one organised in competitive markets. The liberalisation process in Europe, with the formation of regional electricity markets, has led to the facilitation of cross-border power trade; consequently, inter-area power exchanges in electricity networks have significantly increased and further growth can be foreseen. This generally results in more recurrent, and more frequently changing, congestion events on transmission networks. Moreover, the penetration of Renewable Energy Sources for Electricity (RES-E), in particular onshore wind power plants, connected to the European grids, has been impressive in recent years; further grid connection of large-scale onshore and offshore wind power plants is expected, in order to meet Europe’s environmental and energy policy targets for 2020 and beyond. Then, the large amount of variable RES-E connected to the grids will have to be reliably integrated into the European power system. Additional factors regarding the security of electricity supply and environmental constraints may also impact on the development of the European power system [1]. These issues characterised by increasing uncertainties, mostly related to market decisions and growing variable RES-E deployment, pose new challenges on the European TSOs (Transmission System Operators), whose role has become more complex. In fact, in the past, before the electricity market liberalisation, in a centrally managed power system, the system operator generally controlled the generating units, the transmission and distribution networks and the demand. The goal of the planners was then to expand the transmission network in such a manner that both generation and transmission costs were minimised subject to meeting technical constraints to ensure a secure and economically efficient operation. Nowadays, in a competitive European system, the TSO, in charge of the only transmission system after the utilities’ unbundling, plans in general the expansion of its network minimising transmission costs and pursuing maximum social welfare, while meeting technical constraints to ensure a secure and economically efficient operation. In this frame, transmission expansion planning criteria crucially need to be revised and expanded in order to design flexible, coordinated and secure transmission networks based on modern architectural schemes and including innovative technological solutions. More robust methodologies for transmission planning must be pursued to address the above challenges faced by TSOs. The present work, carried out in the frame of REALISEGRID project [2], co-funded by the European Commission, aims to provide an updated picture of the current European transmission network planning challenges and practices and to put forward innovative planning methods and tools to monitor and steer the ongoing changes in the European power system. Particular attention is paid to the cost-benefit analysis on new grid investments, a fundamental stage of the planning process, towards a new systemic approach to transmission expansion planning.