A front-to-front (FTF) system consisting of multiple modular multilevel cascade converters for offshore wind farms

This paper presents a front-to-front (FTF) system based on modular multilevel cascade converters (MMCC). It is called an FTF system because the ac sides of the MMCCs are connected together making a front-to-front configuration via a medium-frequency transformer for voltage matching and galvanic isolation. The system configuration is applicable to dc power collections. Moreover, it is suitable as a power converter for multi-terminal dc power networks since it can handle dc faults inherently without using costly dc circuit breakers. Simulated results using a “PSCAD/EMTDC” software package verify the operating principles and control method of the FTF system.