Designing HVDC grids for optimal reliability and availability performance

Since its modern re-incarnation, dating from the 1960’s onwards, High Voltage Direct Current (HVDC) schemes have principally been used as two-terminal schemes to connect remote energy sources to load centres or as interconnectors between asynchronous transmission networks. Although multi-terminal schemes, with three (or four) stations were built, the limitations of the prevailing Line Commutated Converter (LCC) technology meant that such schemes were the exception rather than the rule. With the advent of Voltage Source Converter (VSC) technology since the turn of the millennium, the application of multi-terminal schemes has become a more practical possibility and already there are schemes with up to five terminals in operation.

The functionality provided by VSC technology has opened up…