Hybrid-mode offshore hydrogen-producing wind turbine: Grid-following and grid-forming operation under variable grid conditions

This paper proposes a hybrid-mode operation strategy for an offshore hydrogen-producing wind turbine (OHP-WT) capable of grid-following (GFL) and grid-forming (GFM) operation under both normal and low-voltage ride-through (LVRT) conditions. Unlike conventional centralized wind-to-hydrogen (W2H) schemes, the proposed turbine-level architecture integrates W2H converters directly into the DC link of a three-level neutral-point-clamped converter. A supervisory power-sharing and mode-switch layer is developed above established GFL and GFM controls to coordinate active and reactive power regulation, DC-link balancing, and hydrogen-load management according to grid conditions. The proposed strategy is validated through detailed PLECS simulations and real-time hardware-in-the-loop experiments using identical parameters. Results show that the GFL mode achieves accurate power dispatch and shallow-fault LVRT compliance, while the GFM mode maintains voltage and frequency stability under weak grid and severe-fault conditions. In all cases, maximum-power-point tracking (MPPT) is preserved, and hydrogen production continuously absorbs surplus power to stabilize the DC link. The findings demonstrate that the hybrid-mode OHP-WT enables transition between grid support and hydrogen production, effectively reducing wind-power curtailment and enhancing offshore grid resilience. • A hybrid-mode offshore hydrogen-producing wind turbine is proposed, capable of transition and MPPT operation between grid-following and grid-forming operation under normal and LVRT conditions. • A turbine-level wind-to-hydrogen topology is developed where electrolyzer DC/DC converters share the DC link of a three-level neutral-point-clamped back-to-back converter without extra hardware. • A supervisory power-sharing and mode-switch management layer is formulated to coordinate active and reactive power, DC-link balancing, and hydrogen-load management according to grid conditions. • Comprehensive PLECS simulations and real-time HIL experiments validate accurate power dispatch, LVRT compliance, and continuous hydrogen production under varying grid conditions.