Wear-out analysis of a grid-forming two-phase three-wire converter under unbalanced load

The grid-forming converter that supplies voltage magnitude and frequency is a key element for isolated remote communities, and then wear-out analysis is an essential figure of merit. Therefore, this paper proposes the two-phase three-wire (2Φ3W) grid forming converter applied in a case study of isolated riverside communities in the Brazilian Amazon region. The proposed xyn-converter displaces the voltage line angle in 180aaaaaaaaaaaaaaaaaaaaaa, differing from αβn-converter and abn-converter that displace voltage line angle in 90° and 120° respectively. First, the authors have also proposed a semiconductor current stress evaluation for 2Φ3W converters comparing the RMS current. Then, the lifetime evaluation of the three evaluated grid-forming converters is conducted. The results show that the converter operating in the xynconverter presents the highest reliability among the three converters. Finally, the thermal stress analysis is validated by means of a 2Φ3W converter prototype with an open semiconductor module. For the evaluated converters, the xyn-converter has the least thermal stress for balanced and unbalanced load conditions and therefore the longest lifespan. The experimental validation shows that the average temperature of the xynconverter is 19.4% and 23.3% lower than both the abn-converter and the αβn-converter under balanced load conditions.