Medium Voltage Grid Connected MMC Operation with Reduced Sensors and Open Circuit Fault Diagnosis Feature

Recent research has focused on minimizing the number of sensors to reduce hardware complexity in Modular Multilevel Converter (MMC). While normal MMC operation with fewer sensors has shown reasonable performance, diagnosing switch or diode fault remains a challenge. Limited studies have addressed fault diagnosis in MMCs with reduced sensor operation, but these often suffer from either complex fault diagnosis methods or dependency on additional measurements. This work introduces a novel approach for diagnosing both switch and diode open circuit faults by leveraging existing measurements such as arm voltages, observed arm currents, and switching status, thereby eliminating the need for additional sensors. The proposed fault diagnosis method also avoids the use of a computationally intensive software approach. The simulation and experimental outcomes of a grid connected MMC validate the effectiveness of the proposed approach in diagnosing switch and diode open circuit fault.