Harmonized Converter Station Design for Tyrrhenian Link and Adriatic Link and Outlook Towards Italian Hypergrid

In Italy, the electricity system is advancing, in accordance with the challenging objectives set in the National Integrated Energy and Climate Plan (“PNIEC”) and the targets in the EU's Green Deal, which aim to cut at least 55 % greenhouse gas emissions by 2030. In addition to facilitating development and integration of renewable sources, the construction of the HVDC lines Tyrrhenian Link East and West connecting Campania, Sicily and Sardinia regions and Adriatic Link connecting Marche and Abruzzo regions will resolve grid congestion, boosting transmission capacity between the various market areas and improving quality of service. The links are constructed using VSC half-bridge converters, high voltage DC cables and sea electrodes for the neutral return path. On the AC side the converter stations are connected to Italian 400 kV AC system. This paper outlines various aspects of the converter station design, control and protection system features, system planning, commissioning sequence and future network extensions in Italy. Main topic is the discussion of a harmonized design which is chosen for all six converter stations of the three HVDC links. The technical requirements are analysed with special focus on Italian stringent environmental conditions to elaborate benefits and boundaries of common choice of HVDC equipment. Furthermore, for converter station layouts concepts using fixed building blocks are discussed enabling the adjustment to site specific topographies. For Control and Protection C&P a country specific implementation of Human Machine Interface HMI is followed. Using identical C&P hardware for the three projects allows common development of software with flexibility towards different commissioning stages which are defined by the stagewise availability of HVDC cables. Based on common requirements of the AC networks to which HVDC schemes will be connected a joint approach to C&P studies is discussed. As part of the Italian national strategy for energy transition and decarbonization, Tyrrhenian Link and Adriatic Link together with the HyperGrid project, represent a fundamental step toward modernizing and strengthening the transmission network, enabling a more efficient integration of renewable energy sources while ensuring system stability and security.