Zero-Sequence Current Based Diagnostic Method for Open-Switch Fault Detection in Parallel Inverters System

Abstract

In this paper, a practical online open-switch fault detection method is presented. The proposed open-switch fault detection method is used to detect the open-circuited fault switch in the parallel inverters system. This method can relieve the severe effects of the over-current stress, to avoid the secondary fault to the electrical components in the parallel inverters system. This method is based on the detection of the resulting zero-sequence current, under the fault conditions. The proposed algorithm is activated by detecting the zero-sequence current between the parallel units, under the open-switch fault conditions. The sign of the resulting zero-sequence current is related to the upper or the lower open-switch fault case. The faulty phase identification relies on the analysis and the investigation of only the current measurements information of the faulty inverter. This method can get rid of the effects of the load, to obtain a reliable identification. The effectiveness of the proposed open-switch fault detection algorithm is theoretically analyzed and validated by the simulations and the experiments.