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Cross-Correlation Based Open-Switch Fault Detection Method in Parallel Inverters System

Ahmed Shahin

This paper proposes a new detection method of the open-switch fault, this method is based on the crosscorrelation of the zero-sequence current in N-parallel inverters system. Under the open-switch fault conditions, the appearance of the circulating currents between the faulty and healthy inverters, is inevitable. The zero-sequence current is used to identify the faulty open-circuited switch by the crosscorrelation. The line current of the faulty phase, is so small or nearly zero, while the resulting zero-sequence current will be synchronized with a reference current which is corresponding to the faulty phase current. So there is a significant correlation of the faulty phase by its reference and the resulting zero-sequence current. While the waveform between the healthy phases and the resulting zero-sequence current show a significant irrelevance. By taking the advantage of this feature between the healthy, faulty and zero-sequence current, the detection method can correctly select out the faulty open-circuited switch. The effectiveness of the proposed open-switch fault detection algorithm is theoretically analyzed and validated by the simulations and the experiments.