中文摘要：

直流背靠背换流单元容量达到1000MW,换流单元直流系统的额定电压和额定电流选择存在多种组合的技术方案。以某背靠背直流异步联网工程为背景，根据目前设备制造能力，从技术和经济的角度对额定电压和额定电流的选择方案进行对比研究，提出优化的换流单元接线和换流单元布置方案。

英文摘要：

When the capacity of the convener unit gets to 1 000 MW, there are several selection programs on the rated currenl and rated votage of the converter DC system. A back-to-back DC asynchronously interconnected power grid is refered to. Depending on the current equipment manufacturing level,the comparison of DC converter systerm programs are studied in the light of technology and economy, and the optimized single line diagrams and general station layout are proposed.