The impact of mission profile on system level reliability of cascaded H-bridge multilevel PV inverter

Abstract

Nonetheless, the photovoltaic (PV) system's reliability performance remains a major challenge. The factors that affect the reliability of a PV system include the location of the plant, its environmental conditions, and the type of equipment that it uses. Researchers noted that the performance of a PV inverter is dependent on the environment variations like mission profile. Hence to understand the impact of environmental conditions on the system's performance, mission profile analysis is required. The objective of this study is to perform reliability oriented lifetime assessment of a cascaded H-bridge multilevel inverter (CHMI) considering the mission profile to account for the factors that affect its performance. CHMI consists of a large number of switches and DC-link capacitors which increases the probability of failure. So, a lifetime assessment of CHMI is required. A test case of 3 kW 1-phase CHMI based PV system is considered and modelled in PLECS. To determine the effect of the installation site on the lifetime of the cascaded H-bridge multilevel PV inverter (MLPVI), real-time mission profiles for one-year recorded in South India and Denmark are considered. With this mission profile from installation locations, system-level reliability assessment of MLPVI is carried out based on the loss model and thermal model of the insulated gate bipolar transistors (IGBTs) and DC-link capacitors. The results reveal that environmental conditions have a considerable impact on the reliability performance of PV inverter.