Condition Monitoring for DC-link Capacitors and PV arrays based on the Start-up Process of the PV System

This paper proposes a method to enable condition monitoring of DC-link capacitors and PV arrays simultaneously based on the start-up process in the PV system. First, the start-up and DC-link capacitor pre-charge process of the PV system based on PV arrays is analyzed. Then, the capacitance is estimated based on the charging process, which does not require additional hardware and complex algorithms, and at the same time is not affected by operation conditions, e.g., capacitor temperature and load variations. Moreover, the capacitor charging profile also includes information of the output characteristics from PV arrays. Thus, a digital twin model of PV arrays is built to extract series resistance (R<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf>) as health indicators for evaluating the degradation of PV arrays. Proof-of-concept experiments have been carried out to verify the feasibility of the proposed method.