Switch Fault Diagnosis of Grid-Connected Inverter Using Symmetrical Components

The reliable operation of grid-connected inverters is crucial for maintaining stability and ensuring the resilience of modern power systems, particularly given the increasing reliance on renewable energy sources. This article proposes a robust fault diagnosis method based on symmetrical component analysis to address faults such as open-circuit faults (OCFs). By precisely decomposing three-phase signals into positive and negative components, our approach extracts fault features, including amplitudes and corresponding angles, essential for accurate OCF detection and open-phase fault localization. In addition, for single-switch fault localization, our method leverages the polarity of the highest normalized dc component of the currents. Most of our results were obtained using a converter model with a peak phase current of 20 A. Through extensive simulation and experimental data, we confirm that the approach reliably achieves fault detection times from 10 to 16 ms. These results emphasize the utility of symmetrical components analysis as a valuable tool for diagnosing OCF in grid-connected inverters.