Reliability Evaluation for the DC-Link Capacitor Considering Mission Profiles in Wind Power Converter

DC-link capacitor are a weak component of wind power converters which are proven to have high fault rate in wind turbines. Therefore, correct reliability evaluation of dc-link capacitor is crucial for the reliability improvement and also for cost reduction of wind power technology. Unfortunately, the exiting reliability evaluation methods for power electronic converter are not yet suitable in the wind power application, because a majority of previous studies on the reliability of insulated-gate bipolar transistor (IGBT) modules, but, researching on the reliability of capacitor for dc-link applications is paid little attention relatively. On the basis of analyzing the reliability evaluation methods of devices based on physical failure mechanism of capacitor, this paper proposes the lifetime estimation method of dc-link capacitor considering mission profiles. A 1.2MW wind turbine of permanent magnetism synchronous generator (PMSG) is regarded as a case study, and this paper serve to translate real filed mission profiles (i.e. wind speed and ambient temperature) into current and thermal stresses to evaluate the reliability of dc-link capacitor. As a consequence, it offers new insights into the reliability-oriented design and analysis of dc-link capacitors in wind power converters.