【目的】柔性直流送出系统是中远海风电的常见方案，已在实际工程中投入使用，但该方案目前仍面临海上换流站平台成本高、集电系统损耗大等问题。针对此问题，本文对中远海风电中频汇集系统的最优频率选择进行了研究。【方法】首先，利用有限元建模对不同频率下海底三芯电缆分布参数和载流量进行精确计算。根据计算结果，参考类似规模海上风电场的接线方案进行海缆选型。然后，通过对集电系统的功率损耗及海上二极管整流平台的损耗进行计算，并将其折算为电价。最后，综合海缆、集电损耗和海上换流平台等经济性分析，对海上风电柔性直流送出系统的最优运行频率进行了选择。【结果】运行频率提升会增大集电系统投资成本和换流平台的损耗，降低换流平台的投资成本，经过海缆选型优化可以防止集电系统投资成本过分增加。【结论】本文综合海缆、集电损耗和海上换流平台等经济性分析，得出海上风电柔性直流送出系统的最优运行频率为180 Hz，在技术可行性、成本效益和运行效率之间实现了良好的平衡。

[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.

江苏省研究生科研与实践创新计划项目(SJCX25_1270)