Tool for predesign and sizing of transmission systems for offshore wind power plants

Offshore wind farms are often located tens to hundreds of kilometers from their onshore grid connection point, so the choice and configuration of the export system strongly affect overall capital and operating expenditure. Although high voltage alternating current (HVAC) links still dominate, high voltage direct current (HVDC) technology becomes more cost-effective beyond roughly 120–160 km [1], depending on technical and economic inputs. Long HVAC cables also demand careful reactive-power control and tap-changer regulation to stay within grid-code voltage and current limits [4]. This paper presents an automated design tool that combines deterministic Alternating Current Optimal Power Flow (ACOPF) analysis with heuristic search to size conductors, select voltage levels, and place compensation devices for hybrid onshore–offshore transmission corridors. Multiple operating scenarios, defined by a combination of wind availability and grid voltage conditions sampled over provided measurements, are evaluated so that every candidate design is compliant under all scenarios, including those specifically defined in grid codes [6]. The framework outputs a Pareto front that trades Capital Expenditure (CAPEX) against expected revenue. A North Sea-style case study illustrates how the tool finds technically and economically attractive solutions, improving handpicked configurations and providing a grid model that can be solved to determine the optimal operating point.