The Way Forward Towards the Italian “Hypergrid” Infrastructure Projects

As High Voltage Direct Current (HVDC) technology evolves to meet the growing demand for large-scale renewable integration and cross-border energy exchange, there is an increasing shift from traditional point-to-point (P2P) systems toward multi-terminal HVDC (MTDC) networks. This transition, beneficial for grid flexibility and resilience, introduces significant innovation in system design, control & protection design, HVDC equipment. Similar trends are visible in Italy, where the power system is facing rising congestion between Southern areas (rich in renewable energy generation) and northern regions (where demand is concentrated and keeps rising). In reaction, Terna aims to significantly increase the transmission capacity between market zones through a DC layer called Hypergid, enabled by several HVDC links. For the execution of such innovative transmission infrastructure projects, cooperation and early-engagement between Transmission System Operators (TSOs) and HVDC vendors is key to address and early-mitigate potential risks in project planning and delivery. Clear examples of partnership and innovation in the MTDC field with forward-looking procurement frameworks are already announced in the EU landscape. In fact, many Point-to-point projects are nowadays being specified with “multi-terminal readiness” requirements to assure smooth future expandability. The focus of this paper is on the 2 Hypergrid projects which are in MTDC configuration in the latest revision of Terna's Grid Development Plan: Milano-Montalto-Sardinia (MiMoSa project) and the Ionian-Tyrrhenian corridor. It is examined how varying degrees of “multi-terminal readiness” affect the technical scope and the execution strategy of HVDC/MTDC projects. Common understanding of modes of operations, DC grid control, energization sequences, and DC switching strategies into the early phases of system studies and technical specifications is key for the success of such infrastructure projects.