A dynamic-simulation based workability and accessibility combined method for systematic analysis of floating wind operations

Abstract

This work aims at providing a new methodology to assess combined workability and accessibility (W&A) of a floating offshore wind turbine, that is, the capability to transfer technicians to perform maintenance work. The proposed approach accounts for site-specific met-ocean conditions and industry-typical W&A limits by virtue of significant wave height, peak wave period, and wave heading, in contrast to only considering wave height, as currently done to take operation and maintenance decisions. A multi-body model of the VolturnUS-S 15 MW floating platform with a Service Operation Vessel (SOV) is used to compute the accessibility based on time-domain simulations and motion-compensated gangway limits. An iterative algorithm is implemented to find the maximum accessible wave height for each period and wave heading. Then, based on the limiting accessibility, single-body hydro-aero-elastic simulations are used to compute the nacelle accelerations, in order to estimate workability. The accessibility is hereby found to be the most limiting factor, with significant changes depending on the peak wave period and wave heading.