Fault Ride-Through Response of VSC-HVDC Links Operating in Island Systems with Parallel AC Interconnectors

The main objective of this paper is to present a suitable dynamic model for a high-voltage dc link based on voltage source converters (VSC-HVDC), with fault ride-through (FRT) capability, suitable for dynamic studies dealing with island interconnection projects where external ac links are also present. The analysis provides insight to the expected response of dc and ac interconnectors operating in parallel, along with onsite conventional generation, under both balanced and unbalanced voltage dips. The presented model includes the necessary converter control features which provide immunity to voltage dips and regulation of output current. The study-case system selected in this work corresponds to the planning for the future interconnection of Crete island to the Greek mainland system with parallel ac and dc interconnectors. Time-domain simulations are performed in Matlab/Simulink, confirming the satisfactory response obtained by the developed model.