A collaborative framework for stability-aware expansion planning of offshore AC/DC microgrids with electrified maritime transport

Energy-sharing initiatives among offshore microgrids (OMGs) and electric vessel (EV) fleets are anticipated to pave the way toward a highly cost-effective and stable offshore power-transport system. To this end, this study proposes a collaborative framework for stability-aware expansion planning of alternating current/direct current (AC/DC) OMGs and the electrification of maritime passenger transport (MPT). The OMG planning is structured as a three-stage optimization model that enhances economic efficiency and stability by co-optimizing AC/DC retrofit investments, normal operation strategies, and transient responses under N-1 contingency conditions. The MPT electrification model coordinates EV deployment and the retirement of fossil-fueled vessels to determine the optimal composition of hybrid fleets, which provide energy-sharing and flexibility services for OMGs while meeting MPT demands. The two sub-models are further synthesized into a collaborative planning model for OMGs and hybrid vessel fleets through coordinated constraints. By embedding the proposed planning model into the Shapley value approach, a decentralized collaborative framework based on a multi-loop iterative procedure is developed. This framework ensures privacy protection and decision-making independence while capturing the coalition behaviors of all entities. Numerical studies verify the effectiveness of the proposed approach.