EU transition in power sector: How RES affects the design and operations of transmission power systems

In the past, much of Europe's electricity grid network has been designed in consideration of the locations of conventional generation plants. However, a large share of today's renewables production – notably variable wind and solar – does not correspond to this grid architecture. Interconnectors, in addition to internal infrastructure, are key to creating new electricity corridors to connect areas of surplus to areas of scarcity. In this context, in 2014 the European Council, in recognizing that a fundamental role of transmission infrastructure is to enable the integration of areas of high renewable energy potential with main consumption areas, endorsed the proposal by the European Commission to extend the current 10% electricity interconnection target to 15%. In this way, more available interconnection capacity would enable the grid to accommodate such increasing levels of variable renewable generation in a secure and cost-effective way. The previously described changes in interconnected system operating conditions, resulting in potential occurrences of unforeseen serious disturbances – most notably the well-known system split observed in the continental synchronous area on 04 November 2006 – have led to create the first Regional Security Coordination Initiatives (RSCIs now RSCs) and establishment of Coreso and TSC back in 2008. These entities have allowed TSOs to further coordinate not only system operations but also network planning, system adequacy analysis, market setups, etc. However, given the challenges faced by the electricity industry in Europe, one may wonder whether the pace of developments in regulation and market design, system operations and system planning can keep up with the pace of change in the electricity system. In response to this concern, the present paper focuses on a central question: how the electricity system that is today primarily organized in a centralized, top-down manner will be reshuffled in the future? The structure of the paper is as follow. The authors begin by describing the changes that are occurring in the power system and market sector, together with their drivers and underpinning regulation. Then the paper presents the challenges in the Eu-wide planning process, starting from TYNDP and PCI and then proceeding also to technical aspects of cost-benefit analysis and interconnection targets