Design, operation and availability analysis of a multi-terminal HVDC grid - A case study of a possible Offshore Grid in the Norwegian Sea

Multi-terminal HVDC subsea cable grids have the ability to integrate offshore wind power and petroleum installations with the main land, as well as transferring energy in parallel with the onshore AC grid. Such grids have presumably lower investment costs than radial cables to each installation. It is shown in this paper that the reliability is higher as well. The operation of a multi-terminal HVDC grid calls for new methods for control and fault clearing. A case study with two land terminals and three offshore terminals is presented in this paper. The work is a part of Statnett´s R&D project “Offshore Grid - design and operation.”