IEC/TR 60919-1:2020 provides general guidance on the steady-state performance requirements of HVDC systems. It concerns the steady-state performance of two-terminal HVDC systems utilizing 12-pulse converter units comprised of three-phase bridge (double- way) connections, but it does not cover multi-terminal HVDC transmission systems. Both terminals are assumed to use thyristor valves as the main semiconductor valves and to have power flow capability in both directions. Diode valves are not considered in this report. This edition includes the following significant technical changes with respect to the previous edition:
a) the changes have been made to the description of multi 12-pulse groups per pole, especially for a large scale ultra high-voltage direct current (UHVDC) converter arrangement;
b) the different arrangements of d.c. smoothing reactors have been included;
c) the figures depicting two 12-pulse groups per pole arrangement have been added.