Lifetime evaluation method of PV inverter considering the influence of fundamental frequency and low frequency junction temperature

Abstract

As an important part of photovoltaic (PV) system, the reliability of PV inverter is the key to ensure the safe and reliable operation of PV power generation system. The existing lifetime evaluation methods of PV inverter are restricted by the extraction accuracy of junction temperature profile, and it is impossible to accurately evaluate the service lifetime of PV inverter. This paper, thus, divides the junction temperature profile according to the time scales, defines the concepts of fundamental frequency junction temperature and low frequency junction temperature. Then, this paper reveals the influence mechanism of fundamental frequency and low frequency junction temperature on PV inverter lifetime evaluation, and proposes a PV inverter lifetime evaluation method considering the influence of fundamental frequency and low frequency junction temperature. Finally, based on this method, the lifetime damage of PV inverter under different mission profiles and different sampling periods is studied, and the influence of fundamental frequency and low frequency junction temperature on lifetime evaluation is analyzed, which improves the accuracy of lifetime evaluation of PV inverter. It is helpful to guide the regular maintenance of PV inverter and reduce economic losses.

Keywords

• Mission profile
• PV inverter
• Fundamental frequency junction temperature
• Low frequency junction temperature
• Lifetime evaluation