Implementation of high speed control network with fail-safe control and communication cable redundancy in modular multilevel converter

A simple and fast internal communication system (ring communication network) had been proposed to simplify the wiring system in complex multilevel converter, such as Modular Multilevel Converter (MMC). This paper will present a fail-safe control and communication system for a MMC. A fail-safe control is demanded to ensure MMC continue operating without interruption when a malfunction power switch is detected. On the other hand, if a section of the communication cable breaks, the data transfer will be interrupted. Hence, a communication cable redundancy protocol must be enhanced in a ring control interface to increase the reliability of the MMC.