Coordinated control of active devices in an overlay grid to facilitate the integration of renewable energy sources in Europe

The establishment of a pan-European overlay grid is often seen as promising option to efficiently transmit electricity from centralized renewable energy sources (RES) to Europe´s load centers. One important question concerns the operation of such an overlay grid under consideration of the underlying transmission system. This paper studies the effects of the inclusion and coordinated control of active devices as a measure to increase the overall network benefit with respect to the integration of RES. A method is presented which integrates the different degrees of freedom of flexible AC transmission systems (FACTS), high voltage DC converters (HVDC) and other active power flow-controlling devices into power flow studies. The method is applied to a model of the existing European transmission system including a case study of an overlay grid structure. The impact of technological choices (AC or DC) and the level of controllability on generation costs and CO₂ emissions are investigated.