A New DC-DC Converter Linking LCC-HVDC Transmission Networks

Transferring bulk power via high voltage direct current (HVDC) transmission is dominated by line commutated converters (LCC). This is due to the robustness and higher ratings of the thyristors as well as the higher converter efficiency. Nevertheless, most of these transmission networks are point to point. This is due to the challenges of allowing multi-terminal LCC based networks and power reversal. This paper introduces a new dc-dc converter topology that allows connecting two independent LCC networks. The proposed converter is based on insulated gate commutated thyristors (IGCTs). Utilizing IGCTs allow mimicking similar control and performance as in insulated gate bipolar transistor (IGBT) based voltage source dc-dc converters. However, IGCTs have more superior features over IGBTs such as higher efficiency, higher short circuit current and higher power ratings. Detailed analysis and simulations are provided to validate the proposed converter topology, which confirms its potential in connecting HVDC-LCC networks.