MMC子模块关键器件长时间尺度运行工况老化分析与可靠性评估

Long-time Scale Working Condition Based Aging Analysis and Reliability Evaluation of Key Devices in MMC Submodule

模块化多电平换流器(modular multilevel converter,MMC)可靠性研究,近年来在关键器件物理特性退化方面取得丰富成果。然而,相关研究成果没能在系统级可靠性评估中得到充分体现。为了将运行工况与器件老化以及可靠性相关联,提出了一种基于MMC任务剖面的器件老化可靠性评估方法。首先推导MMC关键器件功率损耗,结合任务剖面,在结温计算中采用雨流计数算法,根据线性疲劳累积损伤原理,得到在电热耦合工况下器件的损伤与寿命。针对器件老化问题,通过分析不同工况下的老化增量,得到相较于变应力工况,在恒高应力下更为明显的器件的老化现象。改进了基于指数分布的可靠性分析方法,为定期维护中模块器件更换方案提供了参考依据。

In the reliability study of modular multilevel converter(MMC),the research of key devices mainly focuses on the degradation of physical performance,but its results are not well used in the system level reliability evaluation.In order to correlate operating conditions with device aging and reliability,a reliability evaluation method of device aging based on MMC task profile is proposed.Firstly,the power loss of MMC key devices is deduced.Combined with the mission profile,the rainflow counting algorithm is used in the junction temperature calculation.According to the linear fatigue cumulative damage principle,the damage and lifetime of the devices under the electric heating coupling condition are obtained.According to the aging problem of the device,the aging phenomenon of the device is more obvious than that of the varying working stress under constant high stress by analyzing the aging increment under different working conditions.The reliability analysis method based on exponential distribution is improved,which provides a reference for the replacement of module components in regular maintenance.