Deliverable 1.3: Synthesis of available studies on offshore meshed HVDC grids

This deliverable brings together existing studies of offshore meshed HVDC grids and synthesizing them in order to create a baseline.

This deliverable collates existing studies on offshore meshed HVDC grids and synthesizing them in order to create a baseline.

This is the next deliverable of Work Package 1 (WP 1) of the PROMOTioN project, and it aims to collate existing studies studying offshore meshed HVDC grids and synthesizing them in order to create a baseline for the justification of the PROMOTioN project with regard to current barriers and gaps. The deliverable therefore seeks to provide a state-of-the-art picture of offshore meshed HVDC grids and has, like all of the work related to WP 1, involved a large number of project partners and contributors.

This deliverable includes seven chapters in total, each looking at different components of HVDC meshed grids analysed in previous studies. Chapters 1-2 provide a general introduction to the studies and the topic, as well as system planning and grid topologies. Chapters 3-6 look into various technical aspects of complex offshore topologies, such as DC grid protection systems and HVDC circuit breaker performance. The final chapter then looks into the non-technical aspects of regulation and financing.

By analysing various existing studies, D 1.3 identifies some key trends. Firstly, it is unlikely that the final solution for a meshed HVDC offshore grid consists of a single large one; instead, the studies come to the conclusion that several grids, which are not connected together by DC branches, will form the entire grid. Furthermore, the included studies appear to suggest that complex offshore topologies (i.e. radial multi-terminal and meshed grids) appear to only be cost efficient when geographical spreading takes place and a network of high-capacity offshore wind turbines with multiple offshore hubs to collect wind energy is in place. Finally, the studies outline that the economic advantages of complex offshore topologies can only be demonstrated when the overall grid structure is optimized.

The report also outlines various technical challenges, ranging from steady-state control of the DC grid in order to maintain voltage levels across the grid in an acceptable range, to analysing new interactions between components from different manufacturers in the creation of meshed offshore grids in the coming decades. The problems relating to DC grid protection are also extensively examined.

Last but not least, the release of D 1.3 also sketches the current state of research in the financing and regulatory framework for the establishment of complex offshore topologies, mainly outlining the limited available literature in existing studies and the lack of unanimity when it comes to the alleviation of regulatory and financial barriers.