Within the framework of modernisation of the European electricity grid, multi-terminal HVDC offshore grids, evacuating several gigawatts of wind from the North and Baltic Sea, shall be integrated into power transmission systems and interconnect Europe’s synchronous zones. Nevertheless, future DC grids lead to novel challenges for transmission grid operators, grid planners and manufacturers. Especially, the experience regarding the operation of these systems as well as their interaction with the AC transmission system and the offshore wind power plants is limited.

Hence, the objective of Work Package 16 of the PROMOTioN project is to increase the confidence in the feasibility of MTDC operation. For this, the operation and control of a meshed HVDC system will be demonstrated using Power Hardware in the Loop (PHiL) and Controller Hardware in the Loop (CHiL) systems embedded in real-time simulators (RTS). Moreover, the technology readiness level of state-of-the-art HVDC controls for meshed networks shall be raised.

Within the first deliverable of WP16, test cases and scenarios are defined and specified. The test cases will be conducted in a DC network demonstrator embedded in a real-time simulation of wind farms and AC grids. The controllability and interoperability, fault handling and AC grid support by meshed offshore DC grids is evaluated by means of the defined test cases. Additionally, a wind turbine converter from leading manufacturers and the demonstrator’s multilevel converters will be analysed regarding their resonance behaviour. Afterwards, the origin of harmonic oscillations between converters, windfarms and the AC grid will be investigated. To ensure the link between the technical work packages as well as the standardisation efforts and deployment plan of PROMOTioN, the defined test cases were elaborated in close contact with the consortium.