Reliability and Lifetime Analysis Considering IGBT Thermal Resistance Performance Degradation based on Hydropower Mission Profile of MMC

Compared with traditional voltage sourced converter (VSC), modular multilevel converter (MMC) has obvious advantages and is more widely used in high-voltage direct current (HVDC) fields. Its reliability related research has been widely concerned by researchers. There are some researches on the degradation of physical characteristics in the device level failure rate, but most of the existing researches on the system level reliability analysis come from the failure manual. This paper presents a system level MMC reliability analysis method based on MMC operating power angle and insulated gate bipolar transistor (IGBT) lifetime degradation. According to the current and loss of IGBT in MMC, the annual mission profile is analyzed by rainflow counting algorithm in junction temperature calculation, and the influence of IGBT life degradation and thermal resistance rise on the reliability of system level MMC is analyzed under different power directions.