Open-circuit fault detection and localization in Modular Multilevel Converter

Multilevel converters use increased number of semiconductors compared to the conventional two-level inverters, which increases the possibility of switch failures. This paper presents an open-circuit fault detection and localization method in Modular Multilevel Converters (MMCs). This method uses gate signals, measured values of capacitor voltages and phase voltage to calculate the expected current behavior. The measured current behavior is compared to the expected current behavior to detect the fault occurrence and its location due to gate signals and the sign of arm current. Simulation results in a three-phase MMC are carried out to confirm the validity of the proposed method.