All‐DC offshore wind farms: When are they more cost‐effective than AC designs?

Abstract

Abstract The use of MVDC collector systems has been proposed as a way to reduce the levelised cost of energy (LCOE) of offshore wind farms. This study provides a quantitative assessment of the conditions required for such all‐DC wind farms to be cost‐effective. A comprehensive LCOE analysis of two AC and two all‐DC wind farm designs is performed, with sensitivity studies on wind farm size, distance from shore, collector voltage, and component costs. The results show that for MVDC‐based wind farms to be more cost‐effective than equivalent HVDC wind farms, the DC/DC converter cost must be less than 90% of the cost of an equivalent MMC, with a cost reduction of 25% for the DC platform. Alternatively, if cost reductions of 30% can be achieved for the DC platform, then the DC/DC converter can be the same cost as an equivalent MMC. For all‐MVDC wind farms without HVDC conversion stage to have the lowest LCOE, the collector voltage must be increased, preferably to ±100 kV or above. The all‐MVDC configuration can also become cost‐effective if a reduction of more than 50% in the cable installation cost can be achieved, for example, through the simultaneous burial of multiple cables.