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Extensive studies have been conducted in regards to estimating the useful life of power electronic converters in order to prevent failure related downtime. The state-of-the-art of converter reliability is based on the physics-of-failure approach, which involves some concerns such as the uncertainty introduced by extrapolating the accelerated test results to other usage conditions, which results in failure probability distributions inhibiting a variance of several years. In order to overcome this issue, the state-of-the-art is currently seeing an increase in research output, which are in favour of basing the reliability studies on physics-of-degradation based methods. The existing methods are restricted to only consider a single component and due to the impracticability of monitoring each single component, there is an essential need for methods, which can monitor the health state of the entire converter. This paper proposes a method which uses the converter operating efficiency to monitor parameter shifts of multiple components, which can be used to gain precision when stating the converter lifetime. A supervised classifier is used to detect the end-of-life while simultaneously coping with the fundamental issue of the loading influencing the efficiency. The method proves to have high accuracy even when measuring inaccuracies are taken into account.

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The reliability of power converters has been extensively examined in terms of component- and converter level. However, in case of multiple generation units, the evaluation of the performance of power systems requires system-level modeling. This paper aims to merge the prior art of reliability modeling of power converters with the adequacy evaluation of power systems through an extensive design and evaluation analysis of a microgrid based case study. The methodology proposed in the paper integrates the device-level analysis into the domain of the conventional power system reliability analysis while outlining the steps needed to deal with non-exponential distributed failures of power electronic-based generation units. A replacement policy of the power electronic-based units is adopted by means of evaluating the system risk of not supplying system loads, and, finally, an approach on how to ensure a desired replacement frequency is outlined.