IEC 62751-2:2014

FOREWORD
1 Scope
2 Normative references
3 Terms, definitions, symbols and abbreviated terms
4 General conditions
5 Conduction losses
6 DC voltage-dependent losses
7 Losses in d.c. capacitors of the valve
8 Switching losses
9 Other losses
10 Total valve losses per HVDC substation
Annex A (informative) - Description of power loss
        mechanisms in MMC valves
Bibliography

IEC 62751-2:2014 gives the detailed method to be adopted for calculating the power losses in the valves for an HVDC system based on the "modular multi-level converter", where each valve in the converter consists of a number of self-contained, two-terminal controllable voltage sources connected in series. It is applicable both for the cases where each modular cell uses only a single turn-off semiconductor device in each switch position, and the case where each switch position consists of a number of turn-off semiconductor devices in series (topology also referred to as "cascaded two-level converter"). The main formulae are given for the two-level "half-bridge" configuration but guidance is also given as to how to extend the results to certain other types of MMC building block configuration.