The integration of renewable energy sources presents a promising pathway to sustainable hydrogen production by offshore wind power. Nevertheless, high costs of the grid connection for offshore wind turbines result in the need for alternative energy transportation options. Therefore, the option to produce hydrogen directly offshore with no gird connection is getting more interesting, which holds the challenge that all generated power must be consumed on-site, and no grid can supply balance of plant (BoP) components. For stable and efficient system operation, energy management is crucial. In this paper, we analyse supervisory control concepts for a multi-physics green hydrogen offshore wind turbine (GHOWT) by using co-simulation. We address the challenge of ensuring that all ancillary components are sufficiently powered by the wind turbine, thereby enhancing the feasibility of hydrogen production in isolated scenarios.

Our methodology employs multi-physics system simulation, incorporating key components such as the wind turbine, electrical systems, desalination processes, and a first principle-based electrolyzer stack model, which is generated from the information on the structure and materials for cell composition, considering thermal and fluid dynamics. In addition, an external degradation model is connected. The central research question focuses on identifying a beneficial rule-based multi-stack power allocation control concept for directly coupled GHOWTs. We compare three rule-based power allocation strategies: two conventional approaches, “Daisy Chain” and “Equal”, as well as an innovative rule-based concept, which considers degradation. Through this comparative analysis, we evaluate hydrogen production efficiency and the degradation progression of electrolysers under various supervisory control scenarios.

Our findings demonstrate that co-simulation is a useful method for analysing supervisory control concepts applicable to GHOWTs, with models from different physical domains and modelling platforms. We provide insights into BoP power consumption, especially in times when fresh water supply and stack heating are required. Also, operational limitations for island grid hydrogen production scenarios are analysed. In the final evaluation, we can recommend a preferred operational strategy for GHOWT operation that balances hydrogen production with the demands of fresh water supply from desalination. This work contributes to advancing the understanding of rule-based supervisory control in off-grid green hydrogen systems, contributing to enhanced energy transition.