The report describes new network analyses carried out on the projected 2030 system in Sicily and investigations of various innovative transmission technologies. The activities reported—carried out in collaboration with the University of Padua—are geared toward the development of a methodological approach for applications and technical and economic evaluations relating to the conversion of a transmission power line from HVAC (High Voltage Alternating Current) to HVDC (High Voltage Direct Current).

The network analyses were carried out considering a 2030 electricity reference scenario for Italy, focusing in particular on the electricity system in Sicily. In this context, also taking into account the new situation of planned internal reinforcements of the Sicilian grid included in the 2030 model used, the transmission line selected as a candidate for potential conversion from HVAC to HVDC is the 220 kV Partanna-Partinico double circuit.

Starting from an appropriately identified 2030 operating point, the static analysis of the Sicilian network—by running power flows with nonlinear models implemented in the DIgSILENT tool (PowerFactory)—identified the effects of line conversion from HVAC to HVDC— using Line-Commutated Converter (LCC) and Voltage Source Converter (VSC) technologies—on the electrical quantities of the system, including voltage and reactive power.

The results of the network analysis confirmed that using VSC-HVDC technology allows better adaptation to the different conditions that may be required by the system management, insofar as its characteristic greater flexibility and control successfully limits the excursion of voltage levels at the nodes in the Sicilian network, carrying the necessary power.

The report also presents an examination of the innovative transmission technologies available today, considering their reliability, costs and environmental impacts, with the aim of first identifying the most important parameters for calculating the overall costs of each technology, with a view to comparing various alternatives. The analysis focused mainly on overhead HVAC and HVDC lines and cables, Gas Insulated Lines (GILs), Flexible Alternating Current Transmission System (FACTS) devices, and superconducting cable systems.
All the elements and investigations conducted during the activity are geared toward defining a more comprehensive methodology to support evaluations on the conversion of lines from HVAC to HVDC, which also takes into account additional economic and environmental factors.