Diode Open-Circuit Fault Research on the Parallel-Connected 36-Pulse Rectifier With Dual Passive Harmonic Reduction Method

To clarify the influence of using different harmonic reduction circuits (HRCs) on open-circuit fault characteristics, and the relationship between steady-state and fault-state power quality of the multi-pulse rectifiers (MPRs), this article focuses on the diode open-circuit fault research of the parallel-connected 36-pulse rectifier with dc-side dual passive HRC. Based on the normal operation modes of the MPR, the fault characteristics under diode open-circuit fault in the main circuit and the HRC are discussed in detail. Besides, the power quality comparisons between the MPRs with single or dual passive HRC are presented under fault conditions. From the simulation and experiment verification results, the load voltage can exactly reflect the location of the fault diode, and fault diode located in the dc-side HRC causes less damage on the power quality of the MPR. In general, compared with single passive HRC, dual passive HRC can reduce the impact of diode open-circuit fault on ac-side power quality. Adding dual passive HRC is a reliable method to improve the power quality of MPRs.