Review of grid code requirements for cost optimization of offshore energy hubs

In this paper, a review of grid code requirements (GCRs) applicable to wind power plants (WPPs) connected to energy islands, i.e., offshore energy hubs (OEHs), is presented. The main GCRs analysed are based on the impact they may have in the reduction of costs associated to the WPP based on a recommended optimization of the OEH. OEHs are currently developed and planned in the North and Baltic Seas, with an ambition to reach a capacity of over 300 GW by 2050. GCRs from European transmission system operators (TSOs), such as ENTSO-E, National Grid, ELIA and Energinet are reviewed and compared, giving particular attention to projects such as future OEHs, i.e., Princess Elisabeth by ELIA and Bornholm by Energinet and 50Hertz. The main GCRs analysed are, among others, voltage ranges, post-fault active power recovery and emergency power control. The relaxation of such requirements may bring positive cost optimization of the WPPs connected to the OEH. Furthermore, ancillary services such as grid-forming capability and inertia provision are reviewed, and recommendations towards additional revenue to the WPP operator are given. Overall, relaxation and/or shifting of GCRs may be possible and a good compromise for the TSOs, WPP operators and society.