Replacing the modular multilevel converter(MMC) with a diode rectifier unit(DRU) for the HVDC transmission of far-offshore wind power can significantly reduce the size and construction cost of offshore platforms while improving operational reliability. However

the unidirectional and uncontrolled characteristics of the DRU pose major challenges to wind turbine synchronization

frequency stability

and black-start capability

thereby constituting key bottlenecks to its engineering applications. Existing studies have primarily focused on specific technical solutions

whereas investigations into the fundamental operating principles of such systems remain relatively limited. To address this gap

this paper analyzes the operating principles of offshore wind farms connected through diode rectifier-based transmission systems from the perspectives of DRU commutation characteristics and wind turbine output characteristics. On this basis

existing topologies and their corresponding control methods are reviewed and classified

and the characteristics and applicable scenarios of different schemes are further discussed. Finally

the remaining challenges and future research directions for diode rectifier-based offshore wind power transmission are outlined.