IEC TS 63471:2023 provides a recommended DC voltage series for HVDC grids with a DC voltage above 1,5 kV. It concerns the selection of a nominal DC voltage of multi-terminal HVDC power transmission and distribution systems and meshed HVDC networks, grids, rather than a rated DC voltage or highest DC voltage.
There is no stringent requirement to consider this DC voltage series for the DC voltage selection for any stand-alone (not forming part of DC Grid) HVDC projects, e.g. a point-to-point HVDC power transmission and distribution system. However, in order to facilitate the later progression towards larger HVDC systems in the future the use of standardized DC voltages is very useful. At later stages, with multi-terminal systems and meshed HVDC grids, the use of harmonized voltages will indeed become essential in order to optimize both capital and operational costs. Also, for entirely new projects, system planning should include this outlook and can benefit from the use of the recommended DC voltage series.