Frequency dynamics of the Northern European AC/DC power system: a look-ahead study.

A large share of renewable energy sources integrated into the national grids and an increased interconnection capacity with asynchronous networks, are the main contributors in reducing the kinetic energy storage in the Nordic Power System. Challenges arise to operate system after a loss of generation and to minimize the offshore systems interaction with onshore grids. To assess the associated challenges, a novel dynamic model was developed under the phasor approximation to represent the future Northern European Power System, including High Voltage Direct Current (HVDC) links and future offshore energy islands in the North Sea. First, the future frequency response is provided for two large disturbances to highlight the benefit of the developed model and point out potential future frequency issues. Consequently, further actions are investigated to better utilize the existing frequency containment reserves or to partially replace them using emergency droop-based power control of HVDC links. Lastly, the offshore grid interaction and frequency support to the Nordic network is investigated, and the dynamic response is compared for zero- and low-inertia designs of the offshore energy islands. The simulations were performed using industrial software, and the associated material is made publicly available.