A Review of Modular Multilevel Converters and Its Applications

Modular multilevel converters (MMC) have gained a notable attention of researchers from all over the world. There must be hundreds of individual modules connected in series for high-voltage applications. Depending on the sort of sub-module chosen for an application, an MMC can have anywhere from one-tomany switches built into it. In most cases, 2 or 3 years of trouble-free operation of the converter is necessary for MMC-based applications. Any of several types of electrical failure, including open circuit, short circuit, DC-bus short circuit, and single line to ground, can affect an MMC. If the MMC fails to function properly, the voltage in the system could drop. In light of this, it is essential to create a robust fault-tolerant strategy. Every fault-tolerant plan consists of three distinct phases: pre-fault preparation, fault isolation and localization, and post-fault restoration and control. The primary emphasis of this work is on the post-fault control procedures necessary to quickly and reliably restore voltage levels to those that existed before the fault.