Diode Open-Circuit Fault Diagnosis Based on Hausdorff Distance for Autotransformer Rectifier Unit

Autotransformer rectifier unit (ATRU) is one of the most important high power AC-DC electrical equipment. The electrical performance of ATRU is severely degraded under the condition of the diodes open-circuit, which causes the subsequent loads to work abnormally. This paper presents a diode open-circuit fault (OCF) diagnosis method based on the difference of DC output voltage between normal and fault conditions. Due to the absence of the specific output path for voltage phasor caused by the OCFs, the waveforms for DC output voltage will appear the sags, which are considered as features of OCFs and extracted by calculating the Hausdorff distance (HD) between the output voltage sampling and the template sequence. Then, fault diodes can be further located according to the difference of sags positions and the phase of the input voltage. The proposed method is simple and easy to implement since only the output voltage and single-phase input voltage need to be sampled. Simulation and experimental results confirm that the proposed method can detect and locate the diodes of OCF accurately. Moreover, the proposed method is beneficial to the isolation of the faulty ATRU and greatly shortens its repair time.