IEC 62751-2:20 14+A1:2019给出了计算基于“模块化多电平变流器”的HVDC系统阀门中功率损耗的详细方法，其中变流器中的每个阀门由多个串联连接的独立双端可控电压源组成。它既适用于每个模块单元在每个开关位置仅使用单个关断半导体器件的情况，也适用于每个开关位置由串联的多个关断半导体器件组成的情况(拓扑也称为“级联两电平转换器”)。给出了两级“半桥”配置的主要公式，但也给出了如何将结果扩展到某些其他类型的MMC构建块配置的指导。该合并版本由第一版（2014年）及其修正案1（2019年）组成。因此，除了本出版物之外，没有必要下令进行修订。

IEC 62751-2:2014+A1:2019 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. This consolidated version consists of the first edition (2014) and its amendment 1 (2019). Therefore, no need to order amendments in addition to this publication.