中文摘要：

随着传统高压直流输电容量的不断增大，受端系统电压支撑能力限制特高压直流应用的问题变得越来越突出。在分析特高压单端馈入存在的局限性的基础上，提出多端单层馈入和多端分层馈入2种方式。根据节点阻抗矩阵推导出不同馈入方式下的受端系统短路比，并进行对比分析。以向上和德宝直流工程为算例，比较不同馈入方式下的受端系统短路比及功率传输特性曲线，验证多端馈入的优势。从直流联网、系统扩建等方面给出了各种馈入方式的优缺点。最后对未来的特高压直流输电接入方式给出合理建议。

英文摘要：

With unceasing increase of traditional HVDC transmission capgcity, it became more and more obvious that the voltage supporting ability of receiving end power system restricts the application of HVDC power transmission. On the basis of analyzing the limitation existing in UHVDC transmission system with single infeed terminal, two infeed modes, i.e., the multi infeed terminals connected in UHVDC transmission system with single voltage grade and multi infeed terminals transmission system with different voltage grades, are proposed. According to the nodal impedance matrix, short-circuit ratios of the receiving end system under different infeed modes are derived and the contrastive analysis of them are performed. Taking ＋800kV UHVDC transmission project from XianNiaba to Shanghai and _＋500kV HVDC transmission project from Deyang to Baoji as examples, the short-circuit ratios of receiving end systems and power transfer characteristic curves under different infeed modes are compared to validate the superiority of multi infeed terminals. From the aspects of the interconnection, the control strategy, the extension and the construction cost of UHVDC transmission system, the advantages and disadvantages of various infeed modes are listed. Finally, several suggestions on infeed modes for UHVDC transmission system in future are given.