Mission profile based evaluation of capacitor reliability in two stage grid feeding photovoltaic inverter

A two-stage, single phase grid-connected photo-voltaic (PV) inverter requires Aluminum Electrolytic Capacitors (AECs) at PV terminal and dc-link of the inverter. These capacitors are subjected to different stress due to change in operating conditions. This results in degradation in their performance, leading to failure. This paper analyzes and identifies the degradation of both of these AECs based on physics of failure approach when subjected to mission profile data. Solar radiation and temperature at IIT-Kanpur (26.4499°N, 80.3319°E) for 1 month are used to generate mission profile. The suggested algorithm predicts the operational life of both the AECs. It is found that the AEC used at dc-link of the inverter faces higher stress, thereby leading to early failure as compared to AEC used at PV terminal in the two stage, single phase inverter.