用于海上风电并网的柔性直流系统接地方式研究

柔性直流输电技术凭借其为无源电网提供同步交流电源支撑的能力,正逐渐成为远距离海上风电并网的首选方案。主要针对柔性直流系统用于海上风电并网时的接地方式进行了深入的研究。首先对比分析了目前已有工程中的几种换流站接地方式,描述了几种接地方式的优缺点。然后介绍了柔性直流系统用于海上风电并网的拓扑结构和控制策略,选出了三种适用于该场景的换流站接地方式。最后针对国内某规划海上风电场,在电磁仿真软件PSCAD/EMTDC中搭建了±320 kV/1 100 MW柔性直流系统仿真模型。并基于该模型对柔性直流系统进行了故障扫描,研究对比了三种接地方式下系统的过电压特性,得出三种接地方式下的柔性直流系统均具有相似的过电压特性。该研究成果填补了相关研究领域的空白,可以为国内的海上风电并网工程提供参考依据。

Study on grounding methods of VSC-HVDC for off-shore wind farm integration

Based on its ability to provide synchronous AC power support for passive grids, Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) is gradually becoming the preferred solution for long-distance offshore wind farm integration. It focuses on the grounding method of VSC-HVDC used for offshore wind farm integration. Firstly, several grounding methods of converter stations in the existing engineering are compared and analyzed, and the advantages and disadvantages are described. Then the structure and control strategy of VSC-HVDC for offshore wind farm integration are introduced. And three grounding methods for converter stations suitable for this situation are proposed. Finally, for a domestic planned offshore wind farm, a simulation model of ±320 kV/1 100 MW MMC system is built in the electromagnetic transient simulation software PSCAD/EMTDC. The fault scanning of MMC system is carried out based on the simulation model and the overvoltage characteristics of the system under three grounding methods are compared and the results show that VSC-HVDC in the three grounding methods have similar overvoltage characteristics. The research results of this paper fill the gaps in related research fields and provide reference for domestic offshore wind farm integration projects in future. This work is supported by National High-tech R & D Program of China (863 Program) (No. 2012AA051704).