NSON II: Next Steps in Economical Connection and International Integration of Offshore Wind Energy in the North Seas

The last two decades have been witness of a transformation on how electrical energy is supplied. This paper presents an overview of the North Seas Offshore Network II project investigating the required advancements to enable an effective deployment of further 30 GW of offshore wind to be installed in the German North Sea exclusive economic zone according to current grid development plans by 2035. Besides voltage source converter-based high-voltage direct current- (HVDC-) systems and alternative technologies such as line-commutated converters and diode-rectifier units, the parallel connection and operation of existing and new offshore wind farms (OWF) seem to be an effective way to optimize investments and increase operational flexibility. The offshore generation, connection and transmission capacities enable the possibility of creating an interconnected HVDC-grid. HVDC-grid structures introduce new opportunities for electricity trade but raise questions on the stability of the interconnected AC-grid. Realizing HVDC-interconnected European grids requires thorough planning of short- and medium-term tasks to keep long-term goals technically feasible while at the same time minimizing todays' and future investments. New and efficient options for OWF connection as well as control structures for point-t-point and parallel HVDC-connection systems have to be developed. In order to efficiently realize medium to long-term grid structures, methods and procedures for their optimized planning and operation and efficient methods to reduce and solve resulting large (non)linear optimization problems are to be realized. These fields of research are seen as next steps on the path to an economic connection and international integration of offshore wind energy in the German exclusive economic zone.