Control functions for a radially operated three-terminal VSC-HVDC system: The SA.CO.I. HVDC case

The EU FP7 BEST PATHS research project is investigating in one of its Demos the possible refurbishment of the three-terminal HVDC link “SA.CO.I.2” (300 MW) between Sardinia, Corsica and the continental grid. The present paper proposes a dedicated control solution, based on the “voltage margin method”, for the future SA.CO.I.3 assuming the adoption of Voltage Source Converters “VSC” with a bipolar configuration and a 600 MW transmission capacity. The three-terminal VSC-HVDC SA.CO.I.3 has been modelled together with a “horizon year 2030” representation of the interconnected AC systems in the DigSILENT PowerFactory® software. The simulation of electromechanical transients in Sardinia demonstrated that the proposed control solution is able to exploit the VSC technical potentialities with advantage, in particular, for the insular Sardinian/Corsican frequency stability.