Opportunities and Challenges Towards a Further Deployment of Facts and HVDC Technologies in the European Transmission System Context

Abstract Towards the integration of an increasing penetration of Renewable Energy Sources (RES) generation, the transition pattern in Europe requires careful planning and extensive investments in the electricity system. The needed RES integration especially concerns the electricity grids, as well as the enabling technologies and measures, which can ensure a clean, secure, flexible, and efficient energy supply. In particular, in the context of the integration of large-scale RES generation, the development of adequate HVAC (High Voltage Alternating Current) and HVDC (High Voltage Direct Current) transmission infrastructures and innovative technologies plays an increasingly pivotal role. The technological progress in power electronics over the latest twenty years has contributed to make HVDC more widespread also in terms of new applications. This has also impacted on the development of FACTS (Flexible Alternating Current Transmission System) devices that have recently seen a constant increase in penetration and deployment in the European power system. Both HVDC and FACTS technologies, with their flexibility increase capability, can play a crucial role towards the facilitation of RES integration. Within the European background and considering Italian experiences, the present paper first provides an updated overview of key features and benefits of different FACTS and HVDC technologies. These elements may support the European transmission network planners in their decision-making. Particular attention is devoted to the still open and crucial challenges that regard the further penetration of HVDC and FACTS technologies in the European and Italian system context.