Introduction The mission of modern power systems is to supply electric energy satisfying the following con- flicting requirements: – High reliability and security of supply – Most economic solution – Best environmental protection The first requirement of reliability and security of supply has always been and still remains a key objective and has shaped the design and opera- tion of power systems from the very beginning of their formation. In the last few decades, the need for a more efficient operation of the system with the aim to reduce prices and increase the qual- ity of service has led to the unbundling of the power system and to the liberalization of the energy markets. It is fair to say that these actions are probably the last decade’s landmark of the electric electric power systems framework. In more recent years, the increasing concern about climate change and the effects energy production may have on greenhouse gas (GHG) emissions have led to the wide integration of Renewable Energy Sources (RES) and Dispersed Generation (DG) in the power system with obvious advantages for the environmental behaviour of the power systems. Aggressive targets for the increased share of renewable generation in the overall power supply have been set, e.g. the EU Commission target known as 20-20-20 for 2020. Similar targets are set in US, Canada, Japan, and most parts of the devel- oped and developing world. The efficient integra- tion of large shares of RES and DGs imposes the need to revisit the current ways of thinking in respect of the planning, management and control of the power systems both at transmission and dis- tribution level, with the introduction of higher intel- ligence to help further improve efficiency. These aims, which are primarily driven by the environ- mental concerns are the landmark of this decade and will certainly shape the Energy Supply Sys- tems of the Future. Acknowledgements. This brochure is based on the work produced by the CIGRE Advisory Group “Networks of the Future” composed by the 2008 Chairmen of SC B4 Marcio Szechtman, C1 Colin Ray and C6 Angelo Invernizzi (chair). The con- tributions of the 2010 SC Chairmen A1 Erli Ferreira Figueiredo, A2 Claude Rajotte, A3 Mark Andrew Waldron, B1 Pierre Argaut, B2 Konstantin Papail- iou, B3 Mr. Franz Besold, C2 Joachim Vanzetta, C5 Mr. Olav Fosso, D1 Josef Kindersberger, and D2 Otero Carlos Samitier are gratefully acknowledged. CIGRE is in a unique position to provide an independent and highly specialized vision of the Energy Supply Systems of the Future, since its membership includes a very large number of experts within the electric energy sector from all over the world, who are ideally positioned to express the views of industry and academia. The aim of this brochure is to CIGRE WG “Network of the Future” Electricity Supply Systems of the future On behalf of the Technical Committee Nikos Hatziargyriou, Convener (SC C6), Javier Amantegui (SC B5), Bjarne Andersen (SC B4), Michel Armstrong (ex-SC C2), Pierre Boss (ex-SC A2), Bernard Dalle (ex-SC B2), Georges De-Montravel (ex-SC D2), Antonio Negri (SC C3), Carlo Alberto Nucci (SC C4), Phil Southwell (SC C1) ELECTRA N° 256 - Juin 2011 42 Report 1105-014 Electra256.qxp:0507-012Mep221 23/05/11 16:04 Page 42