中文摘要：

海上风电场功率送出需求使得新型直流输电技术成为研究热点之一。我国海上风电多分布在风电资源较为丰富的深海区域,海上风电场和陆上受端站分布较为分散,为实现大规模远距离多区域海上风电功率的有效传输,提出多电压等级直流电网传输方法。文中设计并重点研究一个三电压等级五端直流电网的拓扑结构,并对所研究的3种运行工况,即海上风电功率波动,陆上电网功率需求波动及陆上换流站退出运行,提出相应的直流电网运行控制策略。通过PSCAD/EMTDC仿真软件建立该直流电网的仿真模型,并对所研究的运行工况进行仿真分析。仿真结果证明所提出的控制策略是有效的,该直流电网电压及功率可灵活控制,直流电网运行稳定可靠。该研究也为未来直流电网的互联提出了一种可行的解决方案。

英文摘要：

HVDC transmission technology has been regarded as one of the main solutions for grid integration of large remote offshore wind farms. As the locations of offshore wind farms are uniform depended on wind recourse locations and sea water depth, it is desirable and practical to develop a grid technology that can integrate and transmit large remote offshore wind power from various locations to various load centers. This paper proposed a DC grid technology with multi-voltage level for grid integration of large remote offshore wind farms. Particularly a five terminals DC grid with three voltage levels was presented and studied. DC grids with various voltage levels were interconnected by DC/DC converters. With the proposed technology and control strategies under the given operation conditions, the DC grid with multi-voltage level could be operated stably and reliably. The voltage and power dispatch of the DC gird could be controlled effectively as expected. Simulation results carried out by PSCAD/EMTDC software tool have proved that the proposed technology and operation control strategies were corrective and effective. It also provided the possibility to implement the interconnection between DC grids in the future.