Power systems have evolved at an incredible rate in recent years. To achieve goals of decarbonization and renewable generation targets and to face the new challenges like cyber-attacks and catastrophic weather events (High Impact Low Frequency events – HILF events) that reduce system strength and make the system no longer resilient, TSOs are implementing ambitious plans. HVAC and HVDC interconnections could be two areas of investment in support to overcoming those challenges and enhancing system resiliency.
Increased interconnectivity through cross border exchanges and expansion of electricity markets will intuitively strengthen individual regions of the grid with shared base generation supply and the creation of corridors for bulk power transport as well as reserves sharing. Conversely, such interconnections also expose new risk indeed HILF incidents originating in a single area could quickly cascade to neighboring regions. For instance, some extreme circumstances, such as a winter cold spell, a summer heat wave or a cyber-attack may affect entire regions at the same time (especially in a synchronous area), in a way that would otherwise be limited to the individual region. So, it is necessary to adopt appropriate procedures, schemes and devices together with infrastructural interventions.
This survey aims to identify the role of HVAC and HVDC interconnections for improving power system resiliency. The survey is divided in two parts:
• The first part investigates interconnections in general, focuses on type, number, capacity of existing interconnections, its development trends, the benefits, the technical and administrative barriers in expanding or strengthening the existing grid through added transmission lines and the role in to increase the system resiliency.
• The second part focuses on HVDC links, technology implemented, the most challenging aspects of the HVDC, the plans for new HVDC links, the objectives for HVDC links and the ancillary services provided to the power systems.