Loss analysis of two kinds of flexible HVDC converters

The two-level voltage source converter (2Level-VSC) with IGBTs directly in series and the modular multi-level converter (MMC) are two kinds of the most mainstream converters used in flexible HVDC, the external features of both of the converters are similar, however, their characteristics of losses are different and that affects their economy and applicable workplace. Based on the device parameters provided by the manufacturer, a general loss calculation model is proposed which is applicable to estimate the losses of both of the converters. Through analyzing the working status of devices of the two kinds of converters, loss calculation procedures of the two are analyzed detailedly. Finally, loss characteristics of 2Level-VSC and MMC are analyzed quantitatively through examples, the results show that the loss characteristics of the two kinds of converters are different, and the efficiency of MMC is higher than 2Level-VSC with IGBTs directly in series under different conditions.