一种适用于远海风电直流汇集送出换流阀的拓扑及其技术经济性分析

高压直流送出技术是大规模、远距离海上风电开发的重要手段，送出换流阀是其核心装备。基于模块化多电平换流器(MMC)的交流汇集送出换流阀存在成本高、体积和重量大等问题，海上平台工程建设成本高，而基于直流变压器(DCT)的直流汇集送出换流阀有望解决这一问题。首先，通过分析直流汇集送出换流阀的技术特征和可行的拓扑结构，明确了采用容性能量转移型直流变压器(CET-DCT)构成直流汇集送出换流阀，具有成本低、体积和重量小、效率高等特点。然后，进一步将CET-DCT拓扑改进为适用于工程应用的双极拓扑，介绍了所提拓扑的基本工作原理，并搭建了仿真模型和实验平台，仿真结果和实验结果充分验证了拓扑的可行性。最后，与基于MMC的交流汇集送出换流阀拓扑综合对比表明，基于CET-DCT的直流汇集送出换流阀技术经济性更好。

A Feasible Topology of DC Collection Valve for Long-Distance Offshore Wind Farms and Cost-Effective Analysis

HVDC is a preferred technology for high-power and long-distance offshore wind farms, and the valve plays a pivotal role. Due to the high cost, large footprint and weight of valve, and high construction cost of offshore platform, an evolution is anticipated from traditional modular multilevel converter (MMC) based AC collection valve to the DC/DC transformer (DCT) based DC collection valve. Firstly, based on analyzing the technical characteristics and feasible topology of the DC collection valve, it is proposed to adopt the capacitive energy transmission (CET) principle based DCT, which presents low-cost, small footprint, light weight and low power loss. And then the topology of CET-DCT is improved into the bipolar topology for engineering applications, and the operation principle is also discussed. The effectiveness of the DC collection valve has been verified by simulation and experimental results, and the cost-effectiveness of the CET-DCT based DC valve is concluded by comparison with the MMC based AC collection valve.