Coordinated frequency regulation scheme for renewable integrated green hydrogen hubs

Green hydrogen hubs will likely play a significant role in future energy systems, including electricity networks. They are designed with multiple sources with power electronic interfaces. Therefore, green hydrogen hubs can be used to provide ancillary services to power grids. This paper investigates the capability of a green hydrogen hub, comprising a full-converter wind farm, a fuel-cell and an electrolyser stack, to provide frequency support services to the power grid. A novel two-layer frequency support framework is designed for the hydrogen hub to obtain frequency support in a coordinated manner. The fidelity of the frequency support framework is validated by considering two grid connection configurations (e.g., AC and high voltage direct current (HVDC) transmission links). The frequency regulation performance is verified considering an AC-interconnector and a HVDC-link, and with four operating scenarios. According to the simulation studies, the hydrogen hub can effectively provide frequency support to the main grid under contingencies. In particular, the proposed strategy could improve the frequency nadir ∼ 21–30 mHz compared with the traditional droop control strategy with a ∼ 200 MW regulation reserve at the green-hydrogen hub. However, the hydrogen hub frequency could collapse under certain operating conditions. Therefore, additional precautionary measures (e.g., disabling dynamic droop and augmenting the frequency regulation reserve) or a fast-acting source at the hydrogen hub (e.g., a battery energy storage system) should be implemented to avoid such catastrophic conditions when obtaining frequency support services from green hydrogen hubs. • Detailed dynamic modelling of a green hydrogen hub for frequency support services. • A novel two-layer coordinated frequency controller for green-hydrogen hubs. • Frequency support performance analysis of AC and HVDC-connected green-hydrogen hubs. • Implementation of instability mitigation techniques when providing frequency support services.