Proposals should demonstrate the reliability and resilience of the energy system through HVDC interconnections integrated in the AC grid while coping with faster dynamics, in particular by addressing at least two of the following topics:

• Proposals of optimal grid architecture concepts using HVDC (e.g. multi terminal, hub operation, etc.) and related demonstrated advantages, with a careful overview of planning aspects and deployment methodologies. Proposals should investigate and identify the technological (e.g. coordination between HVDC converters in close vicinity, modelling of HVDC submarine cables for transient phenomena, etc.), contractual and regulatory barriers for the deployment and present solutions to remove them.
• Real-time monitoring and assessment of the level of system stability and vulnerability against disturbances of future AC systems characterised by more HVDC and less conventional power generation.
• Reliability model for HVDC and its impact on the overall transmission system reliability with the HVDC link acting as ‘firewall‘ within the synchronous AC transmission system.
• Technical-economic benefits of the HVDC interconnection solution with the “firewall” functionality as well as in combination of other advantages contributing to the system security such as relieving heavily loaded AC corridors, etc.
• Simulation, real time demonstration of the avoidance or containment of cascading effects and resilience to cyberattacks or faults of the HVDC connection in the AC network.
• Simulation, real time demonstration of the co-ordinated use of HVDC-connected RES for containment of cascading faults and contribution to system restoration.
• Evaluation of the impact on system reliability of an increasing number of HVDC links incorporated in the transmission system through modelling and quantification of the dynamic “firewall” properties of the HVDC links incorporated in the transmission system. etc. (see page 159-160 of the work programme)