Abstract: The modular multilevel converter（MMC）based high voltage direct current（HVDC）system（MMCHVDC）is an ideal solution for large-scale grid-connected and clustered offshore wind farms. But the interaction between the doubly fed induction generator（DFIG）and the MMC-HVDC system has a risk of subsynchronous oscillation（SSO）. To solve this problem，a method to suppress the subsynchronous oscillation caused by the interaction between the DFIG and the MMC-HVDC system was presented by using the cooperative damping controller of the hydrogen production system and the DFIG control system. Firstly，the models of offshore wind farm ，MMC-HVDC and hydrogen production system were established. On this basis，a coordinated damping control scheme based on hydrogen production system was proposed to improve the suppression ability of the system to the phenomenon of subsynchronous oscillation. Finally，the MMC-HVDC grid-connected model for offshore wind farm was built on the PSCAD/EMTDC simulation platform for electromagnetic transient simulation analysis. The results show that the proposed coordinated damping control method based on hydrogen production system can effectively suppress the subsynchronous oscillation caused by the system，which provides a new solution to the SSO problem of theMMC-HVDC grid-connected system for offshore wind farm.

      Key words: hydrogen production system；coordinated damping control；subsynchronous oscillation（SSO）；

suppression strategy；modular multilevel converter based high voltage direct curren（t MMC-HVDC）