电力电子变压器可靠性评估与故障预诊断

Reliability Evaluation and Fault Diagnosis and Prognosis of Power Electronic Traction Transformer

目前的电力电子变压器(PETT)故障预诊断大多关注因瞬时过冲造成的有明显特征的故障,但对长时间运行下因器件老化磨损造成的故障研究较少。因此,建立了长期任务剖面下多时间尺度的可靠性模型,并基于可靠性评估结果进行器件级与系统级的故障预诊断,不仅能识别最易出现故障的器件,还能给出故障发生的概率和时间,为PETT的冗余、容错控制和运维提供指导,实现可靠性与经济成本的综合优化。此外,通过对比不同时间尺度热载荷下的器件损伤大小,揭示了工频热载荷是导致交流变换器中功率器件故障最主要的因素。

Power electronic traction transformer(PETT) fault diagnosis methods mostly focus on faults with obvious characteristics caused by transient over-shoot,but there are few studies of faults caused by device aging and wear-out under long-term operation.Therefore,a multi-time scale reliability model is established under a long-term mission profile and device-level and system-level fault diagnosis and prognosis are conducted based on the reliability evaluation results.It can not only identify the most vulnerable devices,but also give the probability and time of failure,provide guidance for PETT redundancy,fault-tolerant control and maintenance and realize the comprehensive optimization of reliability and economic costs.In addition,the damage of power semiconductor devices is compared under different time scale thermal loads,and line frequency thermal load is found to be the main factor leading to the failure of power semiconductor devices in alternating current converters.