[Objective] High voltage direct current system is a common scheme for far-offshore wind power and has already been implemented in practical engineering projects. But this scheme is still facing the problems of high cost of offshore converter station platforms and large losses in the collector system. To address this problem

this paper investigated the optimal frequency selection for the far-offshore wind power medium frequency gathering system. [Methods] Firstly

finite element modeling was used to accurately calculate the distribution parameters and current carrying capacity of submarine three-core cables at different frequencies. According to the calculation results

referred to the wiring scheme of similar scale offshore wind farms for the selection of submarine cables. Then

the power losses in the collector system and the losses in the offshore diode rectifier platform were calculated

and converted the losses to the price of electricity. Finally

the optimal operating frequency of the offshore wind power high voltage direct current transmission system was selected by integrating the economic analyses of submarine cables

collector losses and offshore converter platforms. [Results] The increase in operating frequency would increase the investment cost of the collector system and the loss of the converter platform

would reduce the investment cost of the converter platform

and the optimization of the submarine cable selection could prevent the excessive increase in the investment cost of the collector system. [Conclusion] In this paper

the economic analyses of submarine cables

collector losses and offshore converter platforms are synthesised to conclude that the optimal operating frequency of the offshore wind power high voltage direct current system is 180 Hz

which achieves a good balance between technical feasibility

cost-effectiveness and operational efficiency.