Effect of Network Protection Requirements on the Design of a Flexible AC/DC-link

This study explores how protection systems affect the design of a medium-voltage (MV) flexible AC/DC link (FDCL). To show this impact, two FDCL designs are analysed. The first designed before considering protection and the second created specifically to solve the protection issues realised in the first. One of the main aspects of the FDCL is to be placed into an existing network, reuse existing equipment, and not require any changes outside of the substations of installation. In this way, the converters must be sized in such a way to retain selectivity of the lower network as well as be able to secure a continuous supply of power through the link even in the case of a DC-side fault. How this is performed and the converter overrating requirements are determined for a 10 kV MV link.