In order to solve the problem in safe allocation of frequency support power from voltage source converter-based multi-terminal high-voltage direct current（VSC-MTDC） connected offshore wind farms（OWFs） and secondary frequency drop problem

this paper proposes a coordinated frequency support and wind turbine preset restoration scheme.The control scheme contains the onshore VSC stations’ level and the offshore wind turbines’ level. For onshore VSC stations

power-voltage droop control is adopted

and the power margin index is used to modify the adaptive droop coefficient to ensure reasonable power allocation and avoid the over-load accidents. For offshore wind turbine level

firstly

each wind turbine provides the inertial and primary frequency support by releasing the kinetic energy on frequency support stage to improve the frequency nadir. Secondly

to alleviate the secondary frequency drop problem of the restoration stage

this paper proposes a preset curve method and investigates the relationship between the different accelerating curves and secondary frequency drop. Compared with existing control schemes

the proposed control scheme can improve frequency nadir and reduce secondary frequency drop based on the safe operation of VSC stations. The proposed control scheme has been tested on a 3-area 4-terminal VSC-MTDC based offshore wind farms. The simulation results can verify the effectiveness of the proposed control scheme.