Reactive power reserves gap evaluation in clean energy production scenarios: the Sardegna study case

The transition towards high integration of Converter-Based Renewable Energy Sources (CB-RES) and the reduction of Synchronous Generators (SGs) in HV Transmission grids triggers the need to also re-evaluate the voltage security. The significant reduction of the reactive power capacity naturally available from SGs raises the question of whether the limited capability of the new CB-RES will be sufficient to cover the voltage security needs of future grids. This paper proposes a novel methodology to assess the reactive power needs of an electric grid by identifying the gaps in terms of quantity and location and how to cover it. The methodology is based on the traditional Optimal Reactive Power Flow (ORPF) adapted to include N-1 security constraints of large grids, and it was applied to the 2030 Sardegna grid (part of the HV Italian Transmission grid) considering various predicted operational scenarios. The results show the ability of the predicted future CB-RES to cover the system’s reactive power gaps if the future grid code requirements for CB-RES reactive power capability are deployed.