Fault detection and location of IGBT short-circuit failure in modular multilevel converters

Abstract

A single fault detection and location for Modular Multilevel Converter (MMC) is of great significance, as numbers of sub-modules (SMs) in MMC are connected in series. In this paper, a novel fault detection and location method is proposed for MMC in terms of the Insulated Gate Bipolar Translator (IGBT) short-circuit failure in SM. The characteristics of IGBT short-circuit failures are analyzed, based on which a Differential Comparison Low-Voltage Detection Method (DCLVDM) is proposed to detect the short-circuit fault. Lastly, the faulty IGBT is located based on the capacitor voltage of the faulty SM by Continuous Wavelet Transform (CWT). Simulations have been done in the simulation software PSCAD/EMTDC and the results confirm the validity and reliability of the proposed method.